Tesi: "Refractory materials"

1

Akpan, Edem T. Gogot︠s︡i I︠U︡ G. "Viscoelastic toughening of refractory ceramics /". Philadelphia, Pa. : Drexel University, 2004. http://dspace.library.drexel.edu/handle/1860/284.

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2

Pandhari, Abhijit. "Modeling of thermal stress cycling in refractory materials". Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/62359.

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In metallurgical reactors, the thermal stress field of refractories always changes with the heat transfer conditions at the hot-face. It is suggested that ‘thermally induced refractory cracking’ is often the primary cause of in-service refractory failure but quantitative support for this is lacking. The current work is focussed on studying this aspect by developing an experimentally validated thermomechanical model that considers refractory strength degradation under repeated thermal cycling. A thermo-mechanical model has been developed with ABAQUS to predict thermal stress and damage in a refractory specimen subjected to thermal cycling. An experiment based on the “contact-conduction method” that uses a hot/cold metal block to heat/cool a refractory specimen was carried out to validate the model. The experiments were run for up to 3-cycles starting from cold- and hot-refractory specimens. Thermocouples were used to gather temperature data from refractory and steel block. An inverse heat conduction model was developed to predict the heat flux applied to the refractory specimen by the steel block based on the temperature history from the steel block. Ultrasonic testing was carried out on the refractory specimens before and after the thermal cycling tests. The contact-conduction method was successful in creating significant thermal gradients in the refractory specimens. Thermocouples on refractory located at 1cm from the steel-refractory show temperature variation of about 500°C and 575°C for cold- and hot-refractory specimen, respectively after 3-cycles. The model was capable of predicting the temperature changes and damage in the refractory material after multiple cycles. Ultrasonic velocity tests show significant change in the sound velocities in the areas experiencing thermal cycling, indicating significant micro-cracking damage in those areas. It was seen that with multiple cycles the damage penetrated further into the specimen, however the magnitude of the damage does not increase significantly. Application to an example tundish operation indicated that the model was capable of analyzing an ideal preheating schedule and was capable of predicting the effect of idle time and multiple thermal cycles on the damage in refractories. However, to predict thermal spalling more precisely, an integrated model that considers the effect of thermal gradients, chemical reactions and mechanical loads is needed.
Applied Science, Faculty of
Materials Engineering, Department of
Graduate

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3

Davis, Robert Bruce. "Design and development of advanced castable refractory materials /". Full text open access at:, 2001. http://content.ohsu.edu/u?/etd,187.

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4

Angara, Raghavendra Phani Krishna. "Recovery of materials from recycling of spent furnace linings". Diss., Rolla, Mo. : Missouri University of Science and Technology, 2008. http://scholarsmine.mst.edu/thesis/pdf/Angara_Raghavendra_09007dcc80575b94.pdf.

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Thesis (M.S.)--Missouri University of Science and Technology, 2008.
Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed November 4, 2008) Includes bibliographical references (p. 69-71).

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5

Martin, Rachel (Rachel M. ). "Mechanical testing of rapid-prototyping refractory ceramic print media". Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/86278.

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Thesis: S.B., Massachusetts Institute of Technology, Department of Materials Science and Engineering, February 2013.
Page 30 blank. Cataloged from PDF version of thesis.
Includes bibliographical references.
Additively manufactured (3D-printed) refractory alumina-silica ceramics were mechanically tested to ascertain their ultimate tensile strengths and observed to determine their dimensional consistency over the printing and post-printing process. The equipment used to perform tensile testing was designed and built for use with custom-designed tensile test samples. Two ceramic powders, V18 (electronic-grade alumina, colloidal silica, and organic content) and 403C (200-mesh mullite, organic content, and magnesium oxide), were printed into test samples on ZCorporation ZPrinter® 310 and 510 machines, before being infiltrated with tetraethylorthosilicate (TEaS), and in some cases infiltrated again with a 40% by weight suspension of silica in water (Ludox). Ludox-infiltrated V18 proved to be the strongest medium, with a UTS of 4.539 ± 1.008 MPa; non-Ludox-infiltrated V18 had a UTS of 2.071 ± 0.443 MPA; Ludox-infiltrated 403C was weakest with a UTS of 1.378 ± 0.526 MPa. Within V18, greater silica content lead to greater tensile strength, but this did not hold true for 403C. 403C displayed volumetric shrinkage of about 1.5%, while V18's volumetric shrinkage ranged from 7% to 14%.
by Rachel Martin.
S.B.

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6

Bullard, Daniel Edward. "Processing of refractory oxides in a nonequilibrium plasma". Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/186440.

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This investigation focuses on the uses of non-equilibrium plasmas to enhance the chemical reactions used in metallurgical process chemistry. The main emphasis of this work was the reduction of TiO₂ and FeTiO₃ in a hydrogen plasma. The plasma was maintained in a single resonant cavity using microwave energy (2.45 GHz). The reaction was monitored for volatile species by a quadrupole mass spectrometer. The extent of reaction during hydrogen reduction experiments was performed using an external standard X-ray diffraction technique. The effect of process variables (absorbed power, chamber pressure, time of plasma solid contact, applied voltages) on the extent of the reactions and the sample temperature were investigated. An investigation into the chlorination of TiO₂ in a chlorine plasma was also performed, however, the numerous side reactions that developed during these experiments made analysis difficult. Attempts were made to identify the volatile species from the mass spectra obtained during the chlorination experiments. The reduction of fused silica as a result of contact with the plasma is also investigated. Thermodynamic calculations suggest that the reduction proceeds by the formation of silane in the plasma; metallic silicon is formed by the subsequent thermal decomposition of silane in a non-oxidizing environment. A mechanism for the formation of silane is proposed. Finally, one proposed use for this technology is presented: The production of oxygen in situ form the lunar soil. Experimental values and thermodynamic data are used to develop a plasma process flow diagram for the production of oxygen. The mining requirements, the hydrogen flow rates and the power demands for this system are compared to more conventional process under consideration for the production of lunar oxygen.

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7

Gentile, Maria. "Alkali attack of coal gasifier refractory lining". Thesis, Virginia Tech, 1987. http://hdl.handle.net/10919/45668.

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An experimental test system was designed to simulate the operating conditions found in nonslagging coal gasifiers. The reaction products that form when refractory linings in coal gasifiers are exposed to alkali impurities (sodium or potassium) were experimentally determined. Analysis of selected physical and chemical properties of the reaction products, which typically form between the alkali and the refractory will lead to a better understanding of the mechanisms behind refractory failures associated with alkali attack.

The reaction products sodium aluminate (Na₂O⋅Al₂O₃), N₂C₃A₅ (2Na₂O·3CaO·5A1₂O₃), nepheline (Na₂0â ¢Al₂0₃â ¢2SiO₂), potassium aluminate, (K₂Oâ ¢Al₂0₃), and kaliophilite (K₂Oâ ¢Al₂0₃â ¢2Si0₂) were synthesized and their solubility in water and coefficients of linear thermal expansion were: measured. Of the compounds tested, the formation of potassium aluminate would be the most detrimental to the gasifier lining. The linear thermal expansion of potassium aluminate was 2.05% from room temperature to 800°C, which was twice as large as the other compounds. Potassium aluminate also possessed the highest solubility in water which was 8.893/L at 90°C.

Master of Science

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8

Sobrosa, Fabiano Zanini. "Desenvolvimento de materiais cerâmicos refratários com adição da sílica residual proveniente da queima da casca de arroz". Universidade Federal do Pampa, 2014. http://dspace.unipampa.edu.br:8080/xmlui/handle/riu/767.

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Submitted by Cátia Araújo (catia.araujo@unipampa.edu.br) on 2017-01-25T12:34:29Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Desenvolvimento de materiais cerâmicos refratários com adição da sílica residual proveniente da queima da casca de arroz.pdf: 10705111 bytes, checksum: f3dc853aa0f1b672236697852c098384 (MD5)
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Made available in DSpace on 2017-01-25T12:37:45Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Desenvolvimento de materiais cerâmicos refratários com adição da sílica residual proveniente da queima da casca de arroz.pdf: 10705111 bytes, checksum: f3dc853aa0f1b672236697852c098384 (MD5) Previous issue date: 2014-03-20
Com a intenção de agregar valor à cinza da casca de arroz, subproduto da indústria orizícola, e colaborar para um desenvolvimento sustentável do país, esta pesquisa buscou desenvolver materiais cerâmicos refratários com a substituição parcial da argila pela sílica de casca de arroz (SCA) produzida a partir da geração de energia elétrica. Atualmente, na região da fronteira oeste do Estado do Rio Grande do Sul, existem várias usinas termoelétricas de biomassa para geração de energia elétrica através da queima da casca de arroz. Essa tecnologia vem ao encontro da necessidade de diversificação da matriz energética no país. A indústria orizícola produz no Brasil aproximadamente 12 milhões de toneladas por ano de arroz, e aproximadamente 2,5 milhões de toneladas por ano são convertidos em casca. Caso toda esta casca fosse queimada, gerar-se-iam aproximadamente 500 mil toneladas de cinza, a qual é rica em sílica. Portanto, viabilizar seu aproveitamento tende a reduzir o passivo ambiental, além dos benefícios econômicos. No presente trabalho foi analisado o efeito da substituição parcial da argila refratária por sílica da casca de arroz (SCA) nas propriedades mecânicas e termomecânicas dos materiais cerâmicos refratários produzidos, em percentuais de 5, 10 e 20%. Foram analisadas as propriedades mecânicas desses materiais através de ensaios de resistência à compressão, tração direta, flexão em três pontos e dureza superficial Vickers. Analisaram-se também a retração linear, absorção de água, porosidade aparente e resistência ao choque térmico. Conforme se aumentou a substituição parcial de argila refratária por SCA, foi obtido um melhor empacotamento da mistura granular e, consequentemente, ocorreu uma melhora nas propriedades mecânicas das amostras. Por outro lado, o material apresentou-se mais frágil, com menor resistência ao choque térmico. Não foi encontrada variação na retração linear após a queima, já a absorção de água e porosidade aparente diminuíram conforme se aumentou a substituição da argila pela SCA. A microestrutura do material foi analisada através de análise por microscopia eletrônica de varredura (MEV) e difração de raios-x, onde se identificaram as fases cristalinas na mineralogia do material resultante. Na análise da mineralogia do material observou-se um aumento de pico de cristobalita conforme se aumentou o teor de SCA na mistura, em função da cristalização da sílica livre. Um menor volume de porosidade foi encontrado conforme se aumentou o teor de substituição de argila pela SCA.
With the intention of adding value to rice husk ash, a byproduct of paddy industry, and contribute to sustainable development of the country, this research sought to develop refractory ceramic materials with refractory partial replacement of clay by silica from rice husk (SCA) produced from electricity generation. Currently on the western border of the State of Rio Grande do Sul, there are several biomass power plants for generating electricity by burning rice husk. This technology comes against the need for diversification of energy sources in the country. The paddy industry in Brazil produces approximately 12 million tons of rice per year, of which approximately 2.5 million tons per year are converted into shell. If all this bark was burned, it would generate approximately 500 tons of ash, which is rich in silica. Thus enabling its use tends to reduce the environmental liability beyond economic benefits. In the present work, the effect of partial replacement of silica refractory clay for rice husk (SCA) on the mechanical and thermomechanical properties of refractory ceramic materials was analyzed for percentages of 5, 10 and 20%. The mechanical properties of these materials were analyzed by testing compressive strength, direct-drive, three point bending and superficial hardness. We also analyzed the linear shrinkage, water absorption, apparent porosity and resistance to thermal shock. As increased the partial replacement of refractory clay for SCA in the mixture was obtained a better packing of the granular mixture and, consequently, better results in mechanical properties were found. On the other hand, the material appeared more brittle, with a lower thermal shock resistance. Was not found in the linear shrinkage after firing, the water absorption and apparent porosity decreased as the clay was increased by replacement SCA. The microstructure of the material was analyzed by scanning electron microscopy (MEV) and x-ray diffraction where the crystalline phases identified in the mineralogy of the resulting material. The analysis of the mineralogy of the material was observed an increase of cristobalite peak was increased as the content of SCA, depending on the crystallization of the free silica. A smaller volume of porosity is found according to the increased content of clay replacement SCA.

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9

Palin, Francis Terence. "Engineering data of refractory materials and their significance in real structures". Thesis, Staffordshire University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254393.

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10

Donald, Jeffrey Richard. "Surface interactions between non-ferrous metallurgical slags and various refractory materials". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ27913.pdf.

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11

Ye, Jianke. "Preparation and characterisation of novel carbon materials for refractory castable applications". Thesis, University of Sheffield, 2014. http://etheses.whiterose.ac.uk/5654/.

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To overcome the difficulty of incorporation of hydrophobic carbon materials into refractory castables, TiC and SiC coatings with much better water-wettability were prepared on carbon particles from metallic powders (Ti or Si) by using a novel low temperature molten salt synthesis technique. The preparation conditions were optimized by varying processing parameters including synthesis temperature, holding time, salt assembly and metal/carbon molar ratios. Homogeneous TiC coatings were prepared on carbon black (CB) particles by firing them with Ti powders in KCl or KCl-LiCl at 750-850 C for 4 hours. Alternatively, TiC coatings could be prepared at a lower cost by firing the mixture of TiO2 and Ti (in molar ratio of 1/3) with CB in KCl at 950 C for 4 hours. High quality SiC coatings were prepared on CB spheres after firing them with Si powders in a binary NaCl-NaF salt for 6 hours at as low as 1100 C. NaF was proven to be essential in the molten salt synthesis of SiC and its optimal amount was 2.5-5 wt% in the binary salt. In addition, graded SiC/SiO2 composite coatings were prepared by controlled oxidation of SiC-coated CB in air at 450 C for 90 minutes to further improve their water-wettability. Carbide-coated CB spheres were identified as having a core-shell structure by scanning/transmission electron microscopy (SEM/TEM) and the thicknesses of TiC and SiC shells (Ti/C or Si/C =1/8 in molar ratio) were estimated as ~10 nm and ~12 nm, respectively. Nevertheless, the coating thickness and corresponding particle density could be readily tailored by controlling the metal/carbon molar ratio in the initial batch mixture to meet practical requirements in real castable systems. The coated CB particles retained similar morphologies and sizes to as-received CB, indicating the formation of carbide coatings in molten salt at test temperatures was governed by a template growth mechanism: dissolution of Ti or Si in molten salt and subsequently fast delivery of dissolved Ti or Si species to the surface of carbon particles, forming carbide coatings on the template. The growth of carbide coatings was dependent on the inward diffusion of Ti or Si and outward diffusion of carbon through an initially formed carbide coating layer. The water-wettability, dispersion behaviour and flowability of CB after carbide coating were evaluated by sedimentation comparison, zeta potential measurement and rheology testing. Owning to the formation of hydrophilic Ti-OH and Si-OH groups on the surface of carbide-coated CB particles, they were able to be immediately wetted by water and well dispersed in aqueous solutions. Moreover, improved dispersivity and flowability of CB after carbide coating were verified by the increased zeta potential values (e.g. at pH=10, ~46.1 mV for TiC-coated CB, ~54.7 mV for SiC-coated CB and ~65.9 mV for SiC/SiO2-coated CB but only ~22.6 mV for uncoated CB) and lowered apparent viscosity (e.g. the apparent viscosity of suspensions containing 25 wt% coated CB was over one order of magnitude lower than that containing as-received CB) of coated CB containing suspensions. In addition, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) verified that the improvement in oxidation resistance of carbon after carbide coating was limited, however, the annealing treatment at 1200-1500 C could promote the growth of carbide nanocrystals and make the carbide coating denser, thus effectively improving carbon’s oxidation resistance. Both weight-loss curve (TGA) and exothermic peaks of carbon oxidation (DSC) were right shifted to higher temperatures. It was also found that annealing atmosphere and temperature were influential on the oxidation resistance of coated CB particles. To investigate the effect of carbide coating on water demand for preparation of carbon-containing castables, both uncoated and carbide-coated carbon particles (carbon black and graphite fakes) were incorporated into model low cement Al2O3-C castables. The water addition was found to decrease dramatically, from 8.5-9.7 wt% required for uncoated carbon containing castables to 6.5-7.0 wt% for carbide-coated carbon containing castables when both of them reached the similar flow values. The evident decrease in water addition led to a considerable drop in apparent porosity and increase in bulk density. As a result, castables containing carbide-coated carbon particles after coking at 1500 C showed over 6 times higher compression strength and 3-5 times higher bending strength than uncoated carbon containing castables. Furthermore, oxidation resistance of carbon-containing castables was improved as well. Uncoated CB containing castable was severely oxidised at 1000 oC for 3 hours and showed the decarbonized depth of 10.48 mm, whereas TiC-coated and SiC-coated CB containing castables showed respectively 6.82 mm and 6.35 mm decarbonized depths under the same oxidation conditions.

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12

Pallay, Krista Joy. "Surface Modifications to Mitigate Refractory Degradation in High-Temperature Black Liquor Gasifiers". Thesis, Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/10488.

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Ceria (CeO2), chromia (Cr2O3), yttria-stabilized zirconia (Y2O3-ZrO2), and sodium cerium oxide (Na2CeO3) were used as barrier coatings on Ufala, an alumina-based ceramic refractory, to determine if they were effective at increasing the life of the refractory in a high-temperature black liquor gasification environment. The ceria, chromia, and yttria-stabilized zirconia coatings were applied at atmospheric pressure using a coating applicator at the Institute of Paper Science and Technology at the Georgia Institute of Technology. The sodium cerium oxide coatings in addition to the three other coating types were applied under atmospheric pressure at C3 International Technologies in Alpharetta, GA. The coated refractory, as well as a set of uncoated refractory used for baseline analysis, were tested using molten synthetic smelt at 1000C for 36 hours. Uncoated refractory samples were also tested for 12, 72, 120, and 168 hours in order to make a kinetic reaction rate determination. The refractory were analyzed using gravimetric and dimensional analysis, X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy to determine the severity of the physical changes that occurred after exposure to molten smelt. The data gathered from these experiments were not able to conclude that barrier coatings are sufficient to impede corrosion of the Ufala refractory material in molten smelt.

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13

Mølnås, Håvard. "Compatibility Study of Carbon-Based Refractory Materials utilized in Silicomanganese Production Furnaces". Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for materialteknologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-16345.

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Tap hole refractories constitute critical parts of the refractory lining in submerged arc furnaces. For several hours every day, molten slag and metal flow through the tap hole calling for thorough selection of refractory materials able to withstand the intense thermal, corrosive and erosive conditions present in this area. Carbon-based refractories have shown excellent thermal properties and high strength, as well as low wettability towards process materials, and are therefore utilized in silicomanganese production furnaces both as side lining, in the hearth, and in the tap hole area. The aim of this investigation was to determine the compatibility of five refractory materials utilized in the tap hole area of an industrial silicomanganese furnace with two industrial silicomanganese slags: •Investigate the suitability of the selected refractory materials for confining the process materials during industrial production of silicomanganese alloys. •Identify critical refractory wear mechanisms upon slag-refractory interaction at industrial tapping temperatures.Compatibilities were investigated through 12 static crucible tests and two static plate tests in a vertical tube furnace redesigned during this investigation. Slag-refractory interaction was studied after two and four hours holding time at 1367°C ± 1.8°C, 1464°C ± 2.1°C and 1600°C - 0.6°C /+ 0.2°C. Holding temperatures were verified through the wire-bridge method at the melting points of gold and palladium. Visual inspection, as well as optical microscopy and SEM, were utilized to examine the samples after heat treatment.During compatibility experiments, dissolution of refractory matrix due to solubility of oxide refractory binder phases in silicomanganese slags was observed, as well as disintegration of refractory particles due to gas formation at slag-refractory interface, or expansion as a result of phase transformations in refractory material. Direct reduction of manganese oxide from slags and iron oxide present in refractories by carbon and silicon carbide was also observed. Establishment of partial slag-metal equilibriums between iron oxide and silicon metal originally present in slag was observed, as well as formation of silicon carbide at the slag-refractory interfaces. The latter may serve to protect the refractory from wear caused by slags.Based on observations of extensive interaction between silicomanganese slag sample I and ramming paste at 1600°C, the ramming paste investigated cannot be recommended for usage during tap block repair in an industrial silicomanganese furnace. Incipient electrode paste disintegration by slags and silicon carbide tap block – slag interaction were observed after compatibility tests at 1464°C, calling for further investigations of these refractory materials. Tap hole clay and carbon tap block showed minimal signs of interaction with process materials at 1464°C. Refractory porosity seemed to have a larger effect on refractory wear than refractory ash content. Contrary to industrial observations, silicomanganese slag sample I was more corrosive towards the ramming paste and electrode paste investigated than silicomanganese slag sample II.

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Brenneman, Chad. "Evaluating Worker Exposure to Hexavalent Chromium in Refractory Materials During Demolition Activities". University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1267736529.

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15

Corradetti, Stefano. "Study and development of high release refractory materials for the SPES project". Doctoral thesis, Università degli studi di Padova, 2013. http://hdl.handle.net/11577/3422608.

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Throughout the last century, theoretical and experimental research made by the international nuclear physicists community has led to important advancement in the knowledge of the mechanisms that govern the behavior and stability of the nuclei. The technological improvements necessary to support this research has often opened the way to new applications in other field of science and industry which directly reflects in our common life experience. Nowadays, Europe is becoming more and more a leader in both theoretical and experimental nuclear physics, as testified by the presence on its territory of several institutes and laboratories dedicated to this field of research, like CERN (Organisation Européenne pour la Recherche Nucléaire), the world’s largest particle physics laboratory. Italy, represented mainly by INFN (Istituto Nazionale di Fisica Nucleare), is one of the main members of this community. One of the most important projects supported by INFN is SPES (Selective Production of Exotic Species), which aim is to develop a facility for the production of radioactive ion beams (RIBs) in one of the four national laboratories of INFN, LNL (Laboratori Nazionali di Legnaro). The facility is designed to produce and deliver to users both proton-rich and neutron-rich nuclei (range of mass 80-160 amu) to be used for nuclear physics research, as well as other applications in different fields of science. The generation of the aforementioned isotopes will occur inside a properly designed target, which represents the core of the whole project. The choice of the proper material for the target, both in terms of composition and properties, is of vital importance in determining the quantity and type of the produced isotopes. In this work, the synthesis and characterization of different types of target materials are presented. The results of experimental tests performed on some of the produced materials, in configurations very similar to those intended for the final SPES facility are also reported. Chapter 1 gives a general overview of the SPES project and its context whereas chapter 2 introduces the main topics related to the on-line behavior of the SPES target, relative to both its layout and to the properties of the material constituting it. Chapter 3 is focused on uranium carbide, which will be used at SPES to produce neutron-rich isotopes; after a description of its main physicochemical properties, the results of two on-line tests performed on target prototypes made of this material is reported and discussed into detail. In chapter 4 the synthesis methods and release-related properties of two potential materials to be used as SPES targets for the production of proton-rich isotopes, boron and lanthanum carbides, are presented
Nel corso dell’ultimo secolo, la ricerca teorica e sperimentale condotta dalla comunità internazionale in fisica nucleare ha portato ad importanti passi avanti nella comprensione dei meccanismi che governano il comportamento dei nuclei e della loro stabilità. In molti casi, le innovazioni tecnologiche che si sono rese necessarie per supportare tali ricerche hanno aperto la strada verso nuove applicazioni scientifiche ed industriali con ripercussioni dirette nella vita di tutti i giorni. Attualmente, l’Europa è sempre più leader nel campo della fisica nucleare, teorica e sperimentale, come testimoniato dalla presenza nel suo territorio di svariati istituti e laboratori dedicati a questa specifica area di ricerca, come ad esempio il CERN (Organisation Européenne pour la Recherche Nucléaire), il più grande laboratorio al mondo per la fisica delle particelle. L’Italia, principalmente rappresentata dall’INFN (Istituto Nazionale di Fisica Nucleare), è uno dei principali membri di questa comunità. Uno dei progetti più importanti finanziato dall’INFN è SPES (Selective Production of Exotic Species), la cui finalità è la costruzione di una facility per la produzione di fasci di ioni radioattivi, in uno dei quattro laboratori nazionali dell’INFN, LNL (Laboratori Nazionali di Legnaro). La facility è progettata per produrre e fornire agli utenti isotopi proton-rich e neutron-rich (massa compresa fra 80 e 160 amu) utilizzabili per esperimenti di fisica nucleare, ma anche per altre applicazioni in diversi settori scientifici. La formazione di tali isotopi avverrà all’interno di uno specifico bersaglio (target), che rappresenta il cuore dell’intero progetto. La scelta dell’opportuno materiale per il target, sia in termini di composizione che di proprietà è di vitale importanza nel determinare la quantità e tipo di isotopi prodotti. In questo lavoro, vengono descritte nel dettaglio la sintesi e caratterizzazione di diversi tipi di materiali proposti come target, ed inoltre vengono riportati i risultati di test sperimentali condotti su alcuni di essi, ottenuti in modalità molto simili a quelle a cui saranno sottoposti nella facility SPES. Il capitolo 1 fornisce una presentazione generale del progetto SPES e del contesto scientifico ad esso legato, mentre nel capitolo 2 viene descritto nel dettaglio il comportamento operativo del target SPES, con particolare riferimento alla sua geometria e alle proprietà del materiale che lo costituirà. Nel capitolo 3 vengono presentate le proprietà del materiale scelto come bersaglio per produrre isotopi neutron-rich, ovvero il carburo di uranio; vengono inoltre presentati i risultati di un test sperimentale di produzione di isotopi da parte di un prototipo di target SPES costituito di tale materiale. Il capitolo 4 descrive la sintesi e caratterizzazione di carburi di boro e lantanio, con particolare riferimento alle proprietà riconducibili alla capacità di rilascio di isotopi; tali materiali rappresentano dei potenziali target SPES per la produzione di isotopi proton-rich

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16

Bheemineni, Veerabhadrarao. "Gaseous corrosion of magnesium oxide in hydrogen /". The Ohio State University, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487259125218742.

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17

Steenkamp, J. D. (Joalet Dalene). "Chemical wear of carbon-based refractory materials in a silicomanganese furnace tap-hole". Thesis, University of Pretoria, 2014. http://hdl.handle.net/2263/45951.

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The aim of the study presented here was to investigate the potential for chemical wear of carbon-based refractory materials in a silicomanganese furnace tap-hole. In the study, three research questions were addressed: 1. Is chemical reaction between refractory and slag or refractory and metal a potential wear mechanism? 2. Is the choice in carbon-based refractory material important from a tap-hole refractory life perspective? 3. What are the implications for the life of the tap-hole in a SiMn furnace? To study the potential for chemical wear, thermodynamic calculations were conducted to determine the potential for the formation of SiC and SiMn at 1600°C through reduction of SiO2 and MnO and dissolution of C (and subsequent reaction with Si) in metal. The thermodynamic calculations were based on published [1] metal and slag composition and carbon. Cup test experiments based on synthetic slag and graphite proved SiC formation conclusively, but not SiMn formation. To study the effect of the choice in carbon-based refractory material, two types of refractory materials – carbon block and ramming paste – available commercially and industrial slag were sourced, prepared and characterised. Wettability studies proved the formation of SiC at 1588°C with slag being wetting towards refractory in an argon atmosphere and non-wetting in a CO-atmosphere. Under wetting conditions, the wetting angle of slag on carbon block was slightly higher (50°) at holding temperature compared to that of ramming paste (30°). Under non-wetting conditions the angles were 160° and 150° respectively. Cup test experiments based on industrial slag and carbon-based refractory material proved both SiC and SiMn formation at 1600°C conclusively and confirmed the wetting behaviour of slag towards refractory at larger scale. To study the implications for the life of the tap-hole in a SiMn furnace, the tap-hole of a 48 MVA SiMn furnace was excavated and profiled. The wear predicted by thermodynamic modelling was supported by mass flow calculations. It was concluded that chemical reaction between carbon-based refractory materials and slag and metal is one of the mechanisms responsible for wear in the tap-hole of a silicomanganese furnace.
Thesis (PhD)--University of Pretoria, 2014.
tm2015
Materials Science and Metallurgical Engineering
PhD
Unrestricted

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18

Jansson, Sune. "A study on molten steel/slag/refractory reactions during ladle steel refining". Licentiate thesis, Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-312.

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19

Kuhr, Samuel J. "CHARACTERIZATION AND DEFORMATION BEHAVIOR OF MICROSTRUCTURAL GRADIENTS IN THE LOW SOLVUS HIGH REFRACTORY (LSHR) NICKEL BASE SUPERALLOY". The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1462629676.

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20

Kuntamalla, Praveen Kumar. "Finite element simulation of creep behavior in enhanced refractory material for glass furnace". Morgantown, W. Va. : [West Virginia University Libraries], 2004. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=3629.

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Thesis (M.S.)--West Virginia University, 2004.
Title from document title page. Document formatted into pages; contains xiv, 78 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 64-66).

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21

Gunter, Mickey E. "Refractometry by total reflection". Diss., Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/77798.

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Refractometry is a means to measure the refractive indices of liquids, gases, and dielectric solids, either isotropic or anisotropic, by observation of light refraction or reflection with a microscope, refractometer or other more specialized equipment. For anisotropic solids, refractometry by total reflection (RTR) is by far the simplest, most rapid, and precise method to determine the refractive indices, provided a polished surface of sufficient size exists. Its precision exceeds that for routine oil immersion techniques but compares less favorably to that for minimum deviation methods. However, minimum deviation requires large crystals and, moreover, specifically oriented prisms, one for each principal refractive index to be measured and, for triclinic crystals, one for each wavelength of measurement. The phenomenon of polarized light reflection from randomly oriented anisotropic materials has been modeled because, only after a complete understanding of these phenomena could the R TR method be automated. The mathematics and physics required for this stem from theories and equations presented in the literature of ellipsometry, polarized light, and physical optics. These were then modified, rewritten, and unified to suit the requirements of R TR. RTR, first used by Wollaston ( l 802a, l 802b ), was later perfected for the measurement of the refractive indices and orientation of biaxial minerals in thin section (Viola l 899a, l 899b, 1902; Comu 1901, 1902). RTR with the Abbe-Pulfrich refractometer yielded refractive indices to a precision of ±0.0002, or better. Later, Smith (1905a, 1905b) introduced a simpler refractometer, now known as the jeweler's refractometer, which had a precision of ±0.001 to ±0.002. This refractometer is still in use by gemologists. During this century familiarity with the early work has declined; thus several recent papers display a lack of knowledge of aspects of R TR which were already documented in the early 1900s. A new automated refractometer, designed by Bloss, has precision of ±0.0002 and will be able to measure the refractive indices and orientation of a biaxial mineral in a petrographic thin section. Even for triclinic crystals, a single polished surface arbitrarily oriented will suffice for measurement of all three principal refractive indices, whatever the wavelength supplied. The design and testing of this refractometer has taken approximately three years. Two prototypes have been built and tested. Results from the second prototype are presented.
Ph. D.

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22

Nowrozi, Mojtaba Faiz. "A systematic study of LPCVD refractory metal/silicide interconnect materials for very large scale integrated circuits". Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184396.

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Abstract (sommario):

Recently, refractory materials have been proposed as a strong alternative to poly-silicon and aluminum alloys as metallization systems for Very Large Scale Integrated (VLSI) circuits because of their improved performance at smaller Integrated Circuit (IC) feature size and higher interconnect current densities. However, processing and reliability problems associated with the use of refractory materials have limited their widespread acceptance. The hot-wall low pressure chemical vapor deposition (LPCVD) of Molybdenum and Tungsten from their respective hexacarbonyl sources has been studied as a potential remedy to such problems, in addition to providing the potential for higher throughput and better step coverage. Using deposition chemistries based on carbonyl sources, Mo and W deposits have been characterized with respect to their electrical, mechanical, structural, and chemical properties as well as their compatibility with conventional IC processing. Excellent film step coverage and uniformity were obtained by low temperature (300-350 C) deposition at pressures of 400-600 mTorr. As-deposited films were observed to be amorphous, with a resistivity of 250 and 350 microohm-cm for Mo and W respectively. On annealing at high temperatures in a reducing or inert atmosphere, the films crystallize with attendant reduction in resistivity to 9.3 and 12 microohm-cm for Mo and W, respectively. The average grain size also increases as a function of time and temperature to a maximum of 2500-3000 A. The metals and their silicides that are deposited, using silane as silicon source, are integratable to form desired metal-silicide gate contact structures. Thus, use of the low resistivity of the elemental metal coupled with the oxidation resistance of its silicide manifests the quality and economy of the process. MOS capacitors with Mo and W as the gate material have been fabricated on n-type (100) silicon. A work function of 4.7 +/- 0.1 eV was measured by means of MOS capacitance-voltage techniques. The experimental results further indicate that the characteristics of W-gate MOS devices related to the charges in SiO₂ are comparable to those of poly-silicon; while, the resistivity is about two orders of magnitude lower than poly-silicon. It is therefore concluded that hot-wall low pressure chemical vapor deposition of Mo and W from their respective carbonyl sources is a viable technique for the deposition of reliable, high performance refractory metal/silicide contact and interconnect structures on very large scale integrated circuits.

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23

Aramide, FO, KK Alaneme, PA Olubambi e JO Borode. "In-Situ Synthesis of Mullite Fibers Reinforced Zircon-Zirconia Refractory Ceramic Composite from Clay Based Materials". International Journal of Materials and Chemistry, 2015. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1001844.

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Abstract Understanding the phase transformations/developments that result due to varying the production parameter of engineering materials is vital to development of new materials. The effects of yttria and niobium oxide on the phase changes and mechanical properties of mullite fiber reinforced zircon-zirconia ceramic composites produced by in-situ sintering of raw materials was investigated. Varied amounts of powder zirconia, yttria and niobium oxide were mixed in a turbula mixer with a fixed composition of clay (70% volume) of known mineralogical composition and mechanically milled in a planetary ball mill. The blended powders/clay were compacted into standard sample dimensions, and finally fired at 1400°C and held at varied time of one, two and three hours. The fired samples were characterized using ultra-high resolution field emission scanning electron microscope (UHR-FEGSEM) equipped with energy dispersive spectroscopy (EDX), and X-ray diffractometry (XRD). Various mechanical properties of the sintered samples were also investigated. It was observed that the investigated mechanical properties (with the exception of shrinkages) improved with the amount of raw zirconia initially used in the samples. It was also observed that addition of niobium oxide favours the formation polymignite phase, while the presence of both yttria and niobium oxide in the raw materials resulted in the formation of fergusonite phase in the samples. Both additives favour the phase transformation of zirconia from monoclinic to tetragonal and cubic phases even at temperature as low as 1400°C. It was concluded that the improved mechanical properties of the samples was due to strengthening by both mullite fibers reinforcement and phase transformation strengthening.

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24

Aleknevičius, Marius. "The influence of oil cracking catalyst waste on the properties of refractory castables". Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2011. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2010~D_20110120_134405-85598.

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Fluidized bed catalytic cracking catalyst waste is a zeolite material. Its unique properties are underused in cementitious materials production technology. Various additives, modifiers used in refractory castables are very expensive, so the use of catalyst waste as a modifying additive of castable properties has not only an ecological (waste recycling) but also an economical basis. Medium cement refractory castable was developed using 70 % and 40 % of aluminium oxide containing aluminate cement and catalyst waste additive, respectively 2,5 % and 5,0 %. The work also reveals an efficient effect of catalyst waste on alumina cement hydration, structure formation during cement solidification and after treatment at high temperature.
Naftos krekinge naudotas katalizatorius yra ceolitinė medžiaga, kurios unikalios savybės mažai išnaudojamos cementinių medžiagų gamybos technologijoje. Ugniai atspariuose betonuose naudojami įvairūs priedai-modifikatoriai yra labai brangūs, todėl naudoto katalizatoriaus panaudojimas, kaip modifikuojančio betono savybes priedo, turi ne tik ekologinį (atliekų utilizavimas) bet ir ekonominį pagrindą. Vykdant šį darbą sukurti vidutinio cemento kiekio ugniai atsparūs šamotbetoniai su 70 % ir 40 % aliuminio oksido turinčiais aliuminatiniais cementais ir naudoto katalizatoriaus priedu atitinkamai 2,5 % ir 5,0 %. Darbe taip pat atskleistas efektyvus katalizatoriaus poveikis aliuminatinio cemento hidratacijai, cemento akmens struktūros susidarymui kietėjimo metu ir jos pokyčiams veikiant aukštoms temperatūroms.

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25

Cockcroft, Steven Lee. "Thermal stress analysis of fused-cast Monofrax-S refractories". Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/30991.

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Mathematical models of heat flow and elastic stress generation based on the finite-element method have been developed and utilized to analyze the Epic-3 Monofrax-S casting process (Monofrax-S is primarily composed of 47-57% A1₂O₃, 34-41% ZrO₂ and 10-15% SiO₂). The results of the mathematical analysis, in conjunction with information obtained from a comprehensive industrial study, has led to the development of mechanisms for the formation of the various crack types found in this casting process. Thermal stresses have been predicted to be generated early in the solidification process in association with rapid cooling of the refractory surface as it contacts the initially cool mould and again later in the solidification process in conjunction with the tetragonal-to-monoclinic phase transformation which occurs in the zirconia component of Monofrax-S. The mathematical analysis has also helped to identify indirectly a potential mechanism for the generation of mechanical stresses. Based on an understanding of the generation of tensile stresses, recommendations have been made for modifications to the moulding and casting procedures in order to reduce the propensity for the formation of cracks. The modifications have included changes to the mould construction and geometry to reduce the generation of mechanical stresses and changes to the moulding materials to impact on the flow of heat at key times during solidification and cooling. With the recommendations in place, the casting process has been re-examined with the mathematical models to verify the impact of the modifications. The predictions show that the modifications have acted to reduce tensile stresses associated with the formation of Type-A and -B cracks. Preliminary industrial trials with the modified mould have yielded blocks free of these defects.
Applied Science, Faculty of
Materials Engineering, Department of
Graduate

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26

Sandin, Pierre. "Characterization of a refractory cement and sensor development for temperature measurements in molten steel". Thesis, Uppsala universitet, Mikrosystemteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-353490.

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In steel manufacturing, temperature control is a critical parameter,as it is extremely important for the steel quality. In general,disposable sensors are regularly immersed in the melt for temperaturemeasurements. There are commercially available sensors for continuoustemperature measurements. In this study, a refractory cement is used for encapsulation andcarrier of a resistive temperature detector, for continuoustemperature measurements in molten steel. This cement is normallyused for manufacturing of steel melt crucibles. The work in thisstudy is mostly experimental and consist of characterization of thecement and development of the sensor. The characterization includesthe mechanical properties, the thermal shock resistance, the steelmelt resistance and obtainable surface roughness, for differentpowder fractions, water-to-cement ratio, firings and mixing method.Process developments were also done for the manufacturing of thesensor element and its carrier system. The end goal for continuous temperature measurement in molten steelfor more than 60 minutes was not reached. However, functional sensorswere developed where temperatures up to 1000 °C were measured duringcalibrations, and the cement was well characterized. This work has been carried out within the Strategic innovationprogram "Smartare Elektroniksystem", a joint investment of Vinnova,Formas and Energimyndigheten.

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27

Morel, Bayram Murat. "Investigation Of The Effects Of Temperature On Physical And Mechanical Properties Of Monolithic Refractory Made With Pozzolanic Materials". Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/2/12606700/index.pdf.

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In recent years, scientific studies are carried out to find new refractory material. Having good mechanical properties under very high temperatures, refractories are widely used in industries like iron, steel, glass, cement and pottery. Researches are focused on monolithic refractory making because of their superior properties comparing to conventional firebrick refractories. Providing a mono-block body, having no joints makes the monolithic refractories more durable at elevated temperatures. Easier production and installation are two main points that people are choosing monolithic refractories, thus an economy is made. In this study, for monolithic refractory production, high alumina cement was used as binding material. It is known that the increase in alumina (Al2O3) content increases the high temperature resistance, so that crushed firebrick, having 85% Al2O3 was used as aggregate. Pozzolanic materials, which are silica fume, fly ash, ground granulated firebrick and ground granulated blast furnace slag, were added to improve physical and mechanical properties of mortar. With the addition of steel fibres, change in compressive strength and flexural strength was observed.Superplasticizer was used to understand its behaviour under high temperatures. Portland cement containing mortars were also prepared to make comparison with high alumina cement containing specimens. Specimens were prepared in 5x5x5 cm and 4x4x16 cm prisms. They were cured for one day at curing room, then heated to 105°
C and then heated to 1100°
C. Weight, size and ultrasound velocity change, compressive strength and flexural strength tests were done to determine physical and mechanical properties of the monolithic refractories, before and after heating. Heated and non-heated specimens were pulverized for microstructural investigation with X-Ray diffraction (XRD) method. Using high alumina cement with 50 &ndash
60 % granulated blast furnace slag or granulated firebrick, by the weight of cement, and crushed firebrick as aggregate, a satisfactory monolithic refractory material was made. It was observed that, mechanical properties were decreased at the Portland cement used mortars after several times of heating and cooling cycles. Also, it was determined that the microstructure of the high alumina cement containing mortars did not deteriorate much at 1100°
C, as long as there was no change observed from the results.

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28

Jahn, Constantin [Verfasser], Christos G. [Akademischer Betreuer] Aneziris, Christos G. [Gutachter] Aneziris e Helge [Gutachter] Jansen. "Calcium zirconate materials for refractory applications / Constantin Jahn ; Gutachter: Christos G. Aneziris, Helge Jansen ; Betreuer: Christos G. Aneziris". Freiberg : Technische Universität Bergakademie Freiberg, 2020. http://d-nb.info/1221140981/34.

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29

Jagtap, Pranav. "A Pre-Assessment related to Refractory Waste Management in Sweden : Pre-study of the performance of MgO-C bricks made from recycled MgO-C refractory materials for use in steel production". Thesis, KTH, Materialvetenskap, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-298064.

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Abstract (sommario):

Steel industries consume refractory materials on a large scale. High temperature resistant refractory materials are essential for linings of the steelmaking vessels, to protect them from corrosive environments, high temperatures, molten steels and slags during transportation and steelmaking operations. Furthermore, with the increasing demand in steel production the usage of refractory materials has substantially increased, resulting in an increasing demand for refractory raw materials. However, with the hike in prices and abundancy for raw materials there is a need for recycling and reusing of spent refractory materials, which are otherwise sent to landfill. Nowadays the environmental as well as economic aspect regarding the recycling of spent refractories are of interest for the steel industries for achieving a solution towards zero waste. Several projects have been launched to investigate and generate new ideas with different ways to recycle refractory materials, but there is much more research and planning that needs to be done in order to find a large scale solution towards achieving zero waste. One of the simplest solutions to avoid landfilling of spent refractory is to introduce and manage a good sorting of the breakout scrap refractory, which can later be recycled or reused depending on their condition. The thesis work was carried out in collaboration of KTH – The Royal Institute of Technology/ Stockholm/ Sweden and Jernkontoret – The Swedish Steelmaking Association / Stockholm / Sweden. The work includes a collection of information regarding the current refractory waste management situation within some of the Swedish steel producers as Ovako AB, Uddeholm AB and SSAB. The information were collected on the basis of their refractory usage and practises. The thesis as well provides some suggestions for recycling and reusing of spent refractory waste materials collected from literature. Additionally some experimental work was carried out on whether an MgO-C refractory brick made of recycled materials can perform similarly against slag as a brick made from virgin materials. Experimental corrosion trials with one industrial slag composition were carried out using a hot-finger test apparatus for bricks with different amounts of recycling content in comparison to a brick made of virgin materials. After experiments, the samples were analysed using a Light Optical Microscope (LOM). A similar performance of all bricks against the slag composition was observed. Additional laboratory tests with different slag compositions, holding times and stirring rates are required to reach more profound conclusions. Industrial trials are essential with bricks containing recycled raw materials to reach a final performance status.
Stålindustrin konsumerar eldfasta material i stor skala. Högtemperatur resistenta eldfasta material är nödvändiga för att fodra skänkugnen, för att skydda den från frätande miljöer, höga temperaturer av smält stål och slagg, samt transport och blandning av smält stål under ståltillverkning. Vidare har användningen av eldfasta material ökat avsevärt med den ökande efterfrågan inom stålproduktion, vilket har resulterat i en ökande efterfrågan på eldfasta råvaror. Men i och med prishöjningen och avhållsamheten för råvaror behövs en idé om återvinning och återanvändning av eldfasta material som annars skickas till deponi. Numera är den miljömässiga och ekonomiska aspekten av återvinning av förbrukade eldfasta ämnen av intresse för stålindustrin för att kunna nå en lösning mot zero waste. Flera projekt har påbörjats för att undersöka och generera nya idéer med olika sätt att återvinna eldfasta material, men det finns mycket mer forskning och planering som behöver göras för att hitta en storskalig lösning mot netto noll avfall. En av de enklaste lösningarna för att undvika deponering av använt eldfast material är att införa och hantera en bra sortering av använt eldfast avfall, som senare kan återvinnas eller återanvändas beroende på dess tillstånd. Avhandlingsarbetet utfördes i samarbete med KTH – Kungliga tekniska högskolan / Stockholm / Sverige och Jernkontoret – Svenska stålföreningen / Stockholm / Sverige. Informationen samlades in angående användning och praxis av eldfasta material. Avhandlingen innehåller också några förslag för återvinning och återanvändning av använt eldfast avfall som samlats in från litteraturen. Dessutom utfördes experiment för huruvida en eldfast infodring av återvunnen MgO-C kan motstå reaktioner mot slagg som en infodring tillverkad av ny utvunna råvaror. Experimentella korrosionsförsök med en industriell slaggkomposition utfördes av en ugn designad för hot finger test för eldfasta material gjorda av olika mängd återvunnet material samt inget återvunnet material alls. Efter experimenten analyserades proverna med ett ljusoptiskt mikroskop (LOM). En liknande prestanda för alla tegelstenar mot slaggkompositionen observerades. Ytterligare laboratorietester med olika slaggkompositioner, hålltider och omrörningshastigheter krävs för att nå en djupare slutsats. Industriella försök är väsentliga med eldfast tegel som innehåller återvunna råvaror för att kunna nå en slutlig prestandastatus.

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30

Jensen, Jacob K. "Characterization of a High Strength, Refractory High Entropy Alloy, AlMo_0.5NbTa_0.5TiZr". The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492175560975813.

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31

Simon, Hellgren. "Secondary Steel Metallurgy Slag Design and MgO-C Refractory Implications : Theoretical and Practical Considerations". Thesis, Luleå tekniska universitet, Industriell miljö- och processteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-76339.

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Abstract (sommario):

MgO-C based refractory materials, often used in secondary steel making, are exposed to variouswear mechanisms in its application. The wear could be divided into oxidative, chemical andabrasive categories, all behaving differently and all being influenced by different factors. Dueto the importance of minimizing material loss and to the environmental challenges to run asustainable industry, it is of interest to gain more knowledge of the behavior of the refractorymaterial in use. The present thesis work specifically investigated slag designed of the CaOSiO2-Al2O3-MgO (CSAM) system as well as the chemical and oxidative wear mechanisms ofthree different MgO-C based refractory materials from Höganäs AB, Halmstadverken, whichcontained 5, 10 and 12 wt% carbon (labeled T05, T10 and T12). Different CSAM slags weredesigned to meet certain process criteria such as MgO and CaO saturations and wereinvestigated through thermodynamic calculations using the FactSage software and throughlaboratory scaled slag smelting experiments. The oxidation effect on the refractory material wasalso studied through pre-heating simulations in chamber furnaces, similar to the pre-heating ofa re-built ladle furnace.The thermodynamic calculations made in FactSage 7.0, using the FactPS and FToxid databases, resulted in a few different slag designs with different properties. A few different slagsfulfilled the CaO and MgO saturation limits proposed by Höganäs AB and could be consideredto test experimentally for further evaluation. The simulations also showed trends on how theliquid viscosity behaved with different slag compositions and how the solids content changedwith temperature.The oxidation experiments were performed on the different MgO-C refractory types, where thebricks with 10% carbon also contained Al2O3 antioxidants. The experiments showed that themass loss during the pre-heating is greater for refractory with higher carbon content, withexception to T10, where the mass losses were measured to 3.76 – 4.01%, 1.06 – 1.28% and6.28 – 6.33% for T05, T10 and T12 respectively. Further, the oxidation depth of each materialwas measured to 9-10 mm, 2-3 mm and 2-5 mm for the T05, T10 and T12. The experimentsalso showed that T12 refractory in particular was very susceptible to abrasive wear after beingoxidized.The slag smelting experiments were carried out through two different methods, by melting slagin MgO-C crucibles and by melting pressed slag briquettes on top of refractory bricks. Theformer tests mainly showed that the methodology was not suitable for this type of refractorymaterial due to the crucibles cracking during the experiments. The latter experiments showedsome general behaviour of the different components in the slag, where Ca, Al and Fe stayednear the surface, and Si and Mg penetrated deeper. The spinel formation at the refractory surfacewas then concluded to be the reason for Al not penetrating deeper. Further it was concludedthat no significant difference in refractory dissolution was seen between slags with- and withoutMgO, other than possibly a small increase in refractory dissolution for the latter.

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32

Svantesson, Jonas. "Development Towards Sustainable Ironmaking : The IronArc Process". Licentiate thesis, KTH, Processer, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-286031.

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Abstract (sommario):

The IronArc process is a novel process for a more sustainable production of liquid pig iron using electricity for heating and hydrocarbons for reduction. This thesis aims to facilitate its use by investigating possible refractory solutions and the gas blowing in the process which is done by a plasma generator. The process involves a slag with a high FeO content of 90 wt % and gangue content of approximately 5 wt % SiO2 and 5 wt % CaO. The interaction between such a slag and refractories of MgO, Al2O3, Cr2O3, SiC, ASZ,and C was investigated by high temperature experiments at 1700 K and by thermodynamic calculations in Thermo-calc and FactSage. In the high temperature experiments it was found that all of the studied refractory materials experienced signicant wear after 3 h, but the MgO-Al2O3 spinel refractories were the least affected. The thermodynamic calculations show fair agreement to the experiments, with the exception for the Cr2O3-spinel refractory which performed much worse than predicted by thermodynamic equilibrium calculations. It was concluded that the thermodynamic equilibrium calculations in Thermo-calc and Factsage can be used as an indicator for the stability of a refractory material, but with varying accuracy depending on the quality of the data in the database used. Since industrial refractory materials are not viable as refractory for the IronArc process a freeze-lining approach was evaluated by using CFD in ANSYS Fluent. The flow of a slag was simulated through two different designs of slag runner to investigate how well a freeze-lining protects the walls in a region with rapid flow and the cooling required to form and maintain said freeze-lining. It was found that the enthalpy porosity model in ANSYS Fluent in combination with the RSM turbulence model accurately predicts the thickness of a freeze lining when validated against experiments in the CaCl2-H2O system. For optimal protection of the refractory walls the reactor and runner should be designed to minimize the movement close to the walls as high near-wall turbulence will reduce the thickness and stability of the freeze-lining, leading to greater cooling requirements to maintain afreeze-lining. The IronArc process uses a plasma generator to supply heat to the reactor using electricity. By blowing gas and hydrocarbons through an electric arc, superheated gas is formed which when injected into the reactor provides both stirring and heating for the process. To study the behavior of the injected gas a simulation model was developed in OpenFOAM. The model for simulating gas blowing was tested in both incompressible and compressible simulations in the air-water system which were veried against an experimental study in the air-water system and found good agreement. The simulations of the plasma generator blowing were done in the compressible model to account for the high temperature and pressure present in the IronArc process. It was found that the stability of the gas blowing is dependent on the Froude number where low values cause an unstable and pulsating plume and higher values produce a more stable jet. It was also found that the empirical equation for penetration length is only valid for gas blowing with suciently high Froude numbers to produce a jetting behavior. It was found that the transition from pulsating to steady jetting in the IronArc system occurred around Froude numbers of 300 and higher values further increased the stability of the jet. For gas blowing below the transition region, the penetration length of the unstable and pulsating jet will be severely underpredicted by the empirical equation. This behavior must be considered when designing the gas blowing system for the IronArc process as the gas penetration length will signicantly influence the stirring in the reactor. Additionally, a pulsating and unstable jet produces large bubbles which risk coming in contact with the refractory walls which in previous studies has been shown to be very detrimental to the refractory lifetime. A decrease of the inlet diameter for the gas blowing increases the Froude number and the stability of the jet. By implementing the proposed refractory protection by freeze-lining and the small changes to the plasma generator inlet diameter the IronArc process can be developed into a promising industrial process capable of producing liquid pig iron in a more sustainable way.
Sammanfattning IronArc processen är en nytänkande metod för att producera flytande råjärn på ett mer hållbart sätt genom att använda elektricitet för uppvärmning och kolväten för reduktion. Denna avhandling ämnar att utvärdera möjliga metoder för att skydda infordingen i processen och undersöka gasblåsningen i processesen som görs med en plasma generator. Ett av huvudstegen av IronArc processen är tillverkningen av en slagg med upp till 90 vikts % järnoxid samt 5 vikts % kiseldioxid och 5 vikts % kalciumoxid från gångarten. Interaktionen mellan en sådan slagg och olika infodringar baserade på MgO, Al2O3, Cr2O3, SiC, ASZ, och C undersöktes i högtemperaturexperiment vid 1700 K samt med termodynamiska beräknar i Thermo-calc och FactSage. Experimenten visade att alla de undersökta infodringsmaterialen bröts ned under de 3 timmar de var i kontakt med slaggen, men de två MgO-Al2O3 spinel baserade infodringarna visade högst motståndskraft mot slitaget. De termodynamiska beräkningarna överrensstämde bra med de experimentella resultaten för alla infodringsmaterial förutom den kromoxid baserade infodringen som bröts ned fullständigt trots att de termodynamiska beräkningarna påvisade viss stabilitet. Slutsatsen är att inget av de studerade infodringsmaterialen är bra anpassat för IronArc processen men att metoden som användes för de termodynamiska beräkningarna i Thermo-calc och FactSage kan användas för att ge en indikation om stabiliteten för olika infodringsmaterial i kontakt med slagg. Dock så kommer resultaten av de termodynamiska beräkningarna vara beroende av kvalitén av databasen som används för beräkningen. Eftersom infodringsmaterialen inte kunde motstå slitaget från slaggen undersöktes en dynamisk infodring för slaggrännan i IronArc processen. Detta gjordes genom att simulera flödet och stelningen av slagg i flödesberäkningar i ANSYS Fluent i två olika typer av slaggrännor. Studien visade att enthalpy-porosity modellen för stelning samt RSM modellen för turbulens kunde förutspå stelningsförloppet i slaggrännan samt beskriva hur väl den dynamiska infodringen skyddar väggen och vilken kyleffekt som krävs för att bibehålla den. Denna modell validerades mot experimentella studier i CaCl2-H2O systemet med god överrensstämmelse. För optimalt skydd av väggarna i IronArc processen borde reaktorn och slaggrännan utformas så att flödet nära väggarna minimeras då ett turbulent flöde nära väggen är negativt för stabiliteten och tjockleken hos den dynamiska infodringen. IronArc proceesen använder sig av en plasmagenerator för att förse processen med värme via elektricitet. Genom att blåsa gas och kolväten genom en ljusbåge värms gasblandningen och trycks in i reaktorn vilket ger både värme och omrörning till processen. För att undersöka hur den varma gasen beter sig i reaktorn utvecklades en simuleringsmodell i OpenFOAM. Modellen utformades som både inkompressibel och kompressibel för blåsning av luft i vatten och jämfördes med experiment där gas blåstes i vatten. De båda modellerna överrensstämde bra med de experimentella resultaten och kunde därför användas för att studera gasflödet i IronArc processen. För simuleringen av IronArc processen valdes den kompressibla versionen av simuleringen då den tar hänsyn till de höga temperaturer och tryck som uppstår i reaktorn. Simuleringarna visade att den inblåsta gasen kan ge en stabil gas-jet om Froude-talet för inblåset är tillräckligt högt. Om Froude-talet för gasblåsningen är för lågt så kommer gasen pulsera på ett instablit sätt och skapa stora bubblor som kommer i kontakt med infodringsmaterialet, vilket tidigare har påvisats orsaka ökat slitage på infodringsmaterialet. För IronArc processen krävdes ett Froude tal på ca 300 eller högre för att skapa en stabil jet av gas, där högre värden vidare ökar gas-jettens stabilitet. Studien visade också att den empiriska ekvationen som används för att beräkna penetrationslängden vid gasblåsning endast är korrekt om gasen är en stabil jet. Om ekvationen används för att beräkna penetrationslängden för gasblåsning med mindre än det krävda Froude talet kommer penetrationslängden kraftigt underskattas vilket kan medföra att fel beslut tas när en process utformas. Genom att minska diametern på dysan som används för gasblåsningen ökas Froude-talet och därmed stabiliteten av gasjetten, vilket gör den mer förutsägbar och bättre för processen. För att vidare utveckla IronArc processen så bör den undersökta dynamiska infodringen samt de föreslagna modifieringarna till gasblåsningen användas. Då kan en lovande industriell process utformas som har möjlighet att producera flytande råjärn på ett mer hållbart sätt. Keywords: IronArc, infodringsslitage, plasmagenerator, dynamisk infodring

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33

Angelici, Avincola Valentina [Verfasser], e H. J. [Akademischer Betreuer] Seifert. "Experimental and numerical investigation of silicon carbide and refractory materials under extreme conditions / Valentina Angelici Avincola. Betreuer: H. J. Seifert". Karlsruhe : KIT-Bibliothek, 2016. http://d-nb.info/1100529446/34.

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34

Rockett, Chris H. "Flexural Testing of Molybdenum-Silicon-Boron Alloys Reacted from Molybdenum, Silicon Nitride, and Boron Nitride". Thesis, Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/16293.

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Abstract (sommario):

MoSiB alloys show promise as the next-generation turbine blade material due to their high-temperature strength and oxidation resistance afforded by a protective borosilicate surface layer. Powder processing and reactive synthesis of these alloys has proven to be a viable method and offers several advantages over conventional melt processing routes. Microstructures obtained have well-dispersed intermetallics in a continuous matrix of molybdenum solid-solution (Mo-ss). However, bend testing of pure Mo and Mo-ss samples has shown that, while the powder processing route can produce ductile Mo metal, the hardening effect of Si and B in solid-solution renders the matrix brittle. Testing at elevated temperatures (200°C) was performed in order to determine the ductile-to-brittle transition temperature of the metal as an indication of ductility. Methods of ductilizing the Mo-ss matrix such as annealing and alloying additions have been investigated.

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35

Kubů, Marek. "Návrh zefektivnění technologie obrábění komínové vložky". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-241905.

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Diploma thesis contains introduction of a company P-D Refractories CZ a. s., where the manufacture of ceramic chimney liners is. Followed by a description and analysis of the product in the entire production cycle, material and product spectrum. Based on the results of current production is created proposal to streamline the machining technology with a view to increase productivity and reduce defective products, which means determine the material of a tool and the method of machining. The work is finished by technical-economic assessment, where the summary and recommendation of the proposed solution are.

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36

Супрун, О. В. "Перспективи використання матеріалів на основі MAX-фаз". Thesis, Сумський державний університет, 2016. http://essuir.sumdu.edu.ua/handle/123456789/47982.

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В останні кілька років зростає інтерес учених до матеріалів на основі безкисневої кераміки – тернарних сполук, або так званих МАХ-фаз. Матеріали на основі шаруватих МАХ фаз або наноламінатна кераміка – новий вид легкооброблюваної конструкційної кераміки, яка потенційно може використовуватися в багатьох галузях техніки, і особливо перспективна при роботі в екстремальних умовах. Вважається, що дана кераміка може знайти широке застосування для виготовлення деталей складної форми, що зазнають термічних, хімічних і механічних впливів [1].

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37

Jogdand, Surbhi Shivaji. "Some Study related to Refractory Waste Management in Sweden : A move towards a greener and sustainable Swedish steel industry". Thesis, KTH, Materialvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-286836.

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Decades ago, 1 ton of steel required 80 kg of refractory material. While the scenario has completely changed over the years. Today, 1 ton of steel needs approximately 11 kg of refractory material depending on the steelworks. Refractories are accustomed to high-temperature processes, for example, producing steel, glass, etc. The amount of spent refractories has also increased with the increase in demand for its production. For the manufacturing of refractories, there is a tremendous use of virgin raw materials but with the increase in price and reducing raw material sources, it will be difficult to continue in that way in the future. While, the environmental concerns in steel industries are increasing on a rapid scale such as global environmental pollution, natural resource conservation, and the most important increase in cost for landfilling. Therefore, achieving zero waste and proper usage of material from spent refractories is necessary for economic and environmental reasons in future. This project work focuses on collecting information regarding the refractory waste management for aid towards more sustainable Swedish steel industries. The project is carried out in collaboration with KTH Royal Institute of Technology and the Swedish steel producers association Jernkontoret. This work focuses on a survey of well-known Swedish steel companies Sandvik Materials Technology (SMT) AB and Höganäs AB. The scientific work concentrates on the investigation of MgO-C bricks mixed waste, collected from Mireco AB, up to a grain size of 20 mm. Three samples of varying compositions and different grain sizes were collected from the recycling site and processed for carbon reduction. On several trails, the maximum carbon elimination was achieved at a temperature higher than 800°C with holding time longer than 5h. The fines underwent mechanical pressing of 40 MPa to form pellets of 16 mm and 32 mm in diameter. The main traced elements of MgO, SiO2, CaO, Al2O3 and Fe2O3 can be utilized for applications in the agricultural industry. MgO is present in the maximum quantity (70-80%). By possible extraction of MgO from the fines can be employed in the crucible industry, construction industry and steel industry for slag formation. The MgO in the form of supplements for magnesium deficient soils or calcium magnesium oxide for neutralizing the pH of the soil by balancing the acidity can be employed. The compatibility of the fines can be helpful to resolve transportation issues and benefit convenient addition to processes. Overall, this work brings to the fore a high potential for using such waste refractory materials forapplications besides landfilling with an emphasis on agriculture.
För decennier sedan krävde 1 ton stål 80 kg eldfast material. Medan scenariot har förändrats helt genom åren. Idag behöver 1 ton stål cirka 11 kg eldfast material beroende på stålverk. Eldfasta produkter är vana vid högtemperaturprocesser, till exempel produktion av stål, glas etc. Mängden förbrukade eldfasta produkter har också ökat med ökad efterfrågan på dess produktion. För tillverkning av eldfasta produkter finns det en enorm användning av jungfruliga råvaror men med prisökningen och minskade råvarukällor blir det svårt att fortsätta på det sättet i framtiden. Medan miljöproblemen inom stålindustrin ökar i snabb skala, såsom global miljöförorening, bevarande av naturresurser och den viktigaste ökningen av kostnaderna för deponering. Därför är det nödvändigt att i framtiden uppnå noll slöseri och korrekt användning av material från förbrukade eldfasta anläggningar av ekonomiska och miljömässiga skäl. Detta projektarbete fokuserar på att samla in information om eldfast avfallshantering för stöd till mer hållbar svensk stålindustri. Projektet genomförs i samarbete med KTH Royal Institute of Technology och den svenska stålproducentföreningen Jernkontoret. Detta arbete fokuserar på en undersökning av välkända svenska stålföretag Sandvik Materials Technology (SMT) AB och Höganäs AB. Det vetenskapliga arbetet koncentrerar sig på undersökningen av blandat avfall av MgO-C-tegel, samlat från Mireco AB, upp till en kornstorlek på 20 mm. Tre prover med olika kompositioner och olika kornstorlekar samlades från återvinningsstället och bearbetades för kolreduktion. På flera stigar uppnåddes den maximala kolelimineringen vid en temperatur högre än 800 ° C med en hålltid längre än 5 timmar. Böterna genomgick mekanisk pressning av 40 MPa för att bilda pellets med 16 mm och 32 mm i diameter. De viktigaste spårade elementen i MgO, SiO2, CaO, Al2O3 och Fe2O3 kan användas för applikationer inom jordbruksindustrin. MgO finns i den maximala kvantiteten (70-80%). Genom möjlig utvinning av MgO från böterna kan användas i degelindustrin, byggindustrin och stålindustrin för slaggbildning. MgO i form av tillskott för magnesiumbristjord eller kalciummagnesiumoxid för neutralisering av jordens pH genom balansering av surheten kan användas. Böternas kompatibilitet kan vara till hjälp för att lösa transportproblem och gynna praktiska tillägg till processer. Sammantaget ger detta arbete en hög potential för att använda sådana eldfasta avfallsmaterial för applikationer förutomdeponering med tonvikt på jordbruk

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38

Aleknevičius, Marius. "Naftos krekinge naudoto katalizatoriaus poveikis ugniai atsparių betonų savybėms". Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2011. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2010~D_20110120_134413-03760.

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Abstract (sommario):

Naftos krekinge naudotas katalizatorius yra ceolitinė medžiaga, kurios unikalios savybės mažai išnaudojamos cementinių medžiagų gamybos technologijoje. Ugniai atspariuose betonuose naudojami įvairūs priedai-modifikatoriai yra labai brangūs, todėl naudoto katalizatoriaus panaudojimas, kaip modifikuojančio betono savybes priedo, turi ne tik ekologinį (atliekų utilizavimas) bet ir ekonominį pagrindą. Vykdant šį darbą sukurti vidutinio cemento kiekio ugniai atsparūs šamotbetoniai su 70 % ir 40 % aliuminio oksido turinčiais aliuminatiniais cementais ir naudoto katalizatoriaus priedu atitinkamai 2,5 % ir 5,0 %. Darbe taip pat atskleistas efektyvus katalizatoriaus poveikis aliuminatinio cemento hidratacijai, cemento akmens struktūros susidarymui kietėjimo metu ir jos pokyčiams veikiant aukštoms temperatūroms.
Fluidized bed catalytic cracking catalyst waste is a zeolite material. Its unique properties are underused in cementitious materials production technology. Various additives, modifiers used in refractory castables are very expensive, so the use of catalyst waste as a modifying additive of castable properties has not only an ecological (waste recycling) but also an economical basis. Medium cement refractory castable was developed using 70 % and 40 % of aluminium oxide containing aluminate cement and catalyst waste additive, respectively 2,5 % and 5,0 %. The work also reveals an efficient effect of catalyst waste on alumina cement hydration, structure formation during cement solidification and after treatment at high temperature.

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39

Albert, Jacques. "Characterizations and design of planar optical waveguides and directional couplers by two-step K+ -Na+ ion-exchange in glass". Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=75759.

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Abstract (sommario):

Planar optical waveguides fabricated by K$ sp+$-Na$ sp+$ ion-exchange in soda-lime glass substrates are investigated.
Experimental characterizations of planar waveguide with respect to a wide range of fabrication conditions have been carried out, including detailed measurements of the refractive index anisotropy resulting from the large induced surface stresses.
Parallel to this, the non-linear diffusion process of ion-exchange was simulated numerically to provide, along with the results of the characterizations, a complete description of the refractive index profile from any set of fabrication conditions.
The magnitude of the maximum surface index change observed was shown theoretically to be almost entirely due to the induced stress at the surface of the substrate, arising from the presence of the larger potassium ions.
Finally, a novel class of single-mode channel waveguides, made by a "two-step" ion-exchange was analyzed. A simple model for these waveguides was developed and used in the design of two directional coupler structures which were fabricated and measured.
The two-step process was conceived because it relaxes waveguides' dimensional control, yielding single-mode guides of larger size, better suited for low-loss connections to optical fibers. It also provides an additional degree of freedom to adjust device properties.

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40

Rodrigues, Marcelo Acacio. "Uma contribuição para o estudo das deformações residuais proporcionadas pelo processo de usinagem por fresamento". Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/3/3152/tde-05082009-093850/.

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A operação de fresamento de faceamento tem como objetivo proporcionar superfícies planas isentas de deformação residual na seção transversal da peça usinada. Por outro lado, as evidências apresentadas neste trabalho demonstram que tal deformação existe e seu comportamento pode ser relacionado com grandezas tecnológicas como o tipo de ferramenta utilizada, a velocidade de avanço e de corte do processo além das propriedades mecânicas e metalúrgicas do material da peça.Foram realizados ensaios de fresamento de faceamento, em condições convencionais de usinagem, em duas superligas, sendo uma a base de níquel e outra a base de cobalto, além de uma liga de titânio. As relações de avanço por faca, ângulo de hélice e velocidade de corte foram manipuladas com o objetivo de se avaliar as deformações residuais sob diferentes taxas de deformação. Os corpos de prova foram avaliados em seu estado deformado e através de microscopia eletrônica de varredura, foi possível junto da modelagem matemática, concluir que a hipótese de deformação plana na seção transversal da peça é válida, e esta poderá ser avaliada através do uso da teoria de Slip Lines. O comportamento plástico do material foi avaliado através da teoria de Slip Lines com a implementação do modelo constitutivo Johnson-Cook, enquanto a estimativa de força no processo de usinagem foi feita com o uso da teoria da zona de planos de cisalhamentos paralelos modificada, conforme P.L.B Oxley e Lee e Shaffer. Os diversos pontos apresentados nesta tese que formam o conceito de contribuição foram identificados ao longo do texto, inclusive uma nova abordagem sobre a área de corte de uma fresa com canal helicoidal, bem como as críticas voltadas à definição do ângulo inicial do plano de cisalhamento e da temperatura para obtenção das tensões. A plasticidade do contínuo foi o principal aspecto tanto para estimar as tensões bem como para avaliar as deformações, seja no cavaco bem como na peça. O índice de plastificação do material se demonstrou como principal fator para uma reavaliação da proposta de P.L.B Oxley e, o entendimento de como as demais propriedades mecânicas associadas à este índice influenciam na deformação plana residual e demais condições de equilíbrio de tensões durante a usinagem são sugeridas para complementar o entendimento e uso desta contribuição.
The face milling operation purpose is providing flat machined surfaces free from residual strains at the cross section of the workpiece. On the other hand, the evidences presented in this thesis are enough to demonstrate that the strain exists and its behavior can be related to technical measurements such as the cutting tool helical profile, the feed rate, the cutting speed beyond the materials mechanical and metallurgical properties. Several face milling operation under conventional cutting conditions onto two super alloys have been performed. A nickel base alloy and a cobalt base were observed. A titanium base alloy has also been observed. The feed rate, the rake angle and the cutting speed were manipulated aiming the evaluation of the residual strains under different strain rates. The specimen has been evaluated in its strained condition throughout the use of scanning electronic microscopy. Furthermore with the mathematical modeling it has been possible to conclude that the residual strain at the cross sectional surface is supportable and the strained profile can be evaluated through the use of the Slip Line Field plasticity theory. The plastic behavior of the material has been evaluated with the Slip Line Field plasticity theory with the Johnson-Cook´s constitutive material´s model. The cutting force estimation has used the modified parallel shear plane zone machining model assured by P.L.B. Oxley and an ancient Slip Line solution presented by Lee and Shaffer. All of the details of this thesis which collaborate with the contribution concept have been pointed out along this research, especially the derivation of the helical area profile as well as the criticism related with the shear plane initial value definition and temperature estimation. The continuum plasticity has been the main aspect to evaluate the stresses and also the strains in the workpiece and also at the chip. The materials strain hardening index is main point for a new evaluation of the P.L.B Oxley machining model, and the understanding of how the mechanical properties related with this index influence the residual plane strain and the other convergence conditions of strain during the machining are suggested in order to build up the understanding of this contribution.

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41

Kirabira, John Baptist. "Properties of Ugandan minerals and fireclay refractories". Doctoral thesis, KTH, Materials Science and Engineering, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-225.

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Development of products which can be produced from a country’s natural resources is very important as far as the industrialization of a nation and saving foreign exchange is concerned. Presently, industries in Uganda and the other states in the Lake Victoria region import all refractory-related-consumables, as the demand cannot be met locally. Based on the abundance of ceramic raw materials for high temperature applications in the region and the demand for refractories by industries it is pertinent to develop and manufacture firebricks by exploiting the locally available raw materials.

This thesis thus, concerns the characterisation of ceramic raw mineral powders from the Lake Victoria region, more particularly, Uganda, with the aim of developing firebrick refractories from the minerals. Two main deposits of kaolin and a ball clay deposit were investigated to assess their potential in the manufacture of refractory bricks. Raw- and processed sample powders were investigated by means of X-ray diffraction (XRD), thermal analysis (DTA-TG) and Scanning Electron Microscopy (SEM). In addition, the chemical composition, particle size distribution, density, and surface area of the powders were determined.

A comprehensive study on beneficiation of Mutaka kaolin was carried out using mechanical segregation of particles. The aim of the study was to explore other potential applications like in paper filling and coating. The beneficiation process improves the chemical composition of kaolin to almost pure, the major impurity being iron oxide.

A general production process scheme for manufacturing fireclay bricks starting with raw powder minerals (Mutaka kaolin and Mukono ball clay) was used to make six groups of sample fireclay brick. Experimental results from the characterization of formulated sample bricks indeed revealed the viability of manufacturing fireclay bricks from the raw minerals. Based on these results, industrial samples were formulated and manufactured at Höganäs Bjuf AB, Sweden. Kaolin from the Mutaka deposit was used as the main source of alumina while ball clay from Mukono was the main plasticizer and binder material. The formulated green body was consolidated by wet pressing and fired at 1350°C in a tunnel kiln. Characterization of the sintered articles was done by X-ray diffraction, scanning electron microscopy, and chemical composition (ICP-AES). In addition, technological properties related to thermal conductivity, thermal shock, alkali resistance, water absorption, porosity, shrinkage, permanent linear change (PLC), linear thermal expansion, refractoriness under load (RUL), and cold crushing strength were determined. The properties of the articles manufactured from the selected naturally occurring raw minerals reveal that the produced articles compare favourably with those of parallel types. Thus, the raw materials can be exploited for industrial production.

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42

Luchini, Bruno [Verfasser], Christos G. [Akademischer Betreuer] Aneziris, Christos G. [Gutachter] Aneziris e Victor C. [Gutachter] Pandolfelli. "Processing and properties of bulk and cellular carbon-bonded refractory materials / Bruno Luchini ; Gutachter: Christos G. Aneziris, Victor C. Pandolfelli ; Betreuer: Christos G. Aneziris". Freiberg : Technische Universität Bergakademie Freiberg, 2019. http://d-nb.info/1220636509/34.

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43

Memarpour, Arashk. "A study on the Submerged Entry Nozzels (SEN) respecting clogging and decarburization". Licentiate thesis, KTH, Tillämpad processmetallurgi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-25110.

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The submerged entry nozzle (SEN) has been used to transport the molten steel from tundish to the mould. The main purpose of the SEN usage is both to prevent oxygen and nitrogen pick-up by molten steel and to achieve the desired flow condition in the mould. Therefore, the SEN can be considered as a vital factor for a stable casting process and the steel quality. Furthermore, the steelmaking processes occur at high temperatures around 1873 K so the interaction between the refractory materials of the SEN and molten steel is unavoidable. Therefore, the knowledge of the SEN behaviors during pre-heating and casting is necessary for the design of the steelmaking processes. The internal surfaces of modern SENs are coated with a glass/silicon powder layer to prevent the SEN graphite oxidation during pre-heating. The effects of the interaction between the coating layer and the SEN base refractory materials on clogging were studied in supplement 1. The results of the study indicated the penetration of the formed alkaline-rich glaze into the Alumina/graphite base refractory during pre-heating. More specifically, the alkaline-rich glaze reacts with graphite to form carbon monoxide gas. Thereafter, dissociation of CO at the SEN/molten metal interface takes place. This leads to reoxidation of dissolved REM (Rare Earth Metal), which form the “In Situ” REM oxides at the interface between the SEN and the REM alloyed molten steel. Also, the interaction of the penetrated glaze with alumina in the SEN base refractory materials leads to a formation of a high-viscous alumina-rich glaze during the SEN pre-heating process. This in turn, creates a very uneven surface at the SEN internal surface. The “In Situ” formation of the REM oxides together with the uneven internal surface of the SEN may facilitate the accumulation of the primary inclusions. Supplement 1 revealed the disadvantages of the glass/silicon powder layer. On the other hand the carbon oxidation is a main industrial problem for un-coated Alumina/Graphite Submerged Entry Nozzles (SEN) during pre-heating. This led to the proposal of a new refractory material for the SEN. In supplement 2, the effect of ZrSi2 antioxidant and the coexistence of antioxidant additive and (4B2O3 ·BaO) glass powder on carbon oxidation were investigated at simulated non-isothermal heating conditions in a controlled atmosphere. Also, the effect of ZrSi2 antioxidant on carbon oxidation was investigated at isothermal temperatures at 1473 K and 1773 K. The specimens’ weight losses and temperatures were plotted versus time and compared to each others. The thickness of the oxide areas were measured and also examined using XRD, FEG-SEM and EDS. The coexistence of 8 wt% ZrSi2 and 15 wt% (4B2O3 ·BaO) glass powder of the total alumina/Graphite base refractory materials, presented the most effective resistance to carbon oxidation. The 121% volume expansion due to the Zircon formation during heating and filling up the open pores by (4B2O3 ·BaO) glaze during green body sintering led to an excellent carbon oxidation resistance. In supplement 3, decarburization behaviors of Al2O3-C, ZrO2-C and MgO-C refractory materials constituting a commercial Submerged Entry Nozzle (SEN), have been investigated in different gas atmosphere consisting of CO2, O2 and Ar. The (CO2/O2) ratio values were kept the same as it is in propane combustion flue gas at Air Fuel Ratio (AFR) values equal to 1.5 and 1 for both Air-fuel and Oxygen-fuel combustions. Laboratory experiments were carried out non-isothermally in the temperature range 873 K to 1473 K at 15 K/min followed by isothermal heating at 1473 K for 60 min. The decarburization ratio (α) values of the three refractory types were determined by measuring the weight losses of the samples. The results showed that the decarburization ratio (α) values of the MgO-C refractory became 3.1 times higher for oxygen-fuel combustion compared to air-fuel combustion both at AFR equal to 1.5 in the temperature range 873 K to 1473 K. The decarburization ratio (α) values for Al2O3-C samples were the same as for the isothermal heating at 1473 K and non-isothermal heating in the temperature range 473 to 1773 K with a 15 K/min heating rate. It substantiates the SEN preheating advantage at higher temperatures for shorter holding times instead of heating at lower temperatures for longer holding times. Jander’s diffusion model was proposed for estimating the decarburization rate of Al2O3-C refractory in the SEN. The activation energy for Al2O3-C samples heated at AFR equal to 1.5, for air-fuel and oxygen-fuel combustions were found to be 84.5 KJ/mol and 95.5 KJ/mol respectively during non-isothermal heating in the temperature range 873 K to 1473 K.
QC 20101008

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44

Wang, Huijun. "A Study on the Reaction between MgO Based Refractories and Slag-Towards the Development of Carbon-free Lining Material". Doctoral thesis, KTH, Mikro-modellering, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-214420.

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In present thesis, the fundamental studies on the reaction between MgO based refractories and slag were undertaken for the development of a carbon-free bonding MgO lining material. Alumina was selected as a potential binder material. Due to MgO-Al2O3 chemical reaction, the developed refractory was bonded by MgO·Al2O3 spinel phase. To begin with, an investigation of the dissolution process of dense MgO and MgO·Al2O3 spinel in liquid slag was carried out. To obtain reliable information for dissolution study, a new experimental method was therefore developed. In this method, a cylinder was rotating centrally in a special designed container with a quatrefoil profile. This method also showed a good reliability in revealing the dissolution mechanism by quenching the whole reaction system. The experimental results showed that the dissolution process of MgO and spinel was controlled by both mass transfer and chemical reaction. It was found that the rapid dissolution of spinel was mainly because of its larger driving force. To improve the resistance against slag penetration, two aspects were studied to develop carbon-free MgO refractory. First, colloidal alumina was used and the effect of its addition into MgO matrix was investigated. The use of colloidal alumina was to form bonding products in the grain boundary of MgO. The results showed that the alumina addition greatly improved the resistance of MgO based refractory against slag penetration in comparison with the decarburized MgO-carbon refractory. It was found that the improvement of resistance was mainly related to the spinel-slag reaction products of CaO·Al2O3 and CaO·MgO·Al2O3 solid phases at the grain boundaries. Second, the effect of particle size distribution on the penetration resistance of MgO was investigated. The most profound improvement against the slag penetration was obtained by using a proper particle size distribution. The results highlighted the importance of considering the refractory structure. Experiments were undertaken to investigate the dissolution mechanism of different types of MgO based refractories in liquid slag. It was observed that the dissolution of spinel bonded MgO refractory was much slower than the decarburized MgO-carbon refractory. The primary dissolution in spinel bonded MgO refractory occurred at the slag-penetrated layer, and the removal of this layer by peeling off enhanced the dissolution rate rapidly.

QC 20170918

European RFCS LEANSTORY project

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45

SANTOS, WILSON N. dos. "Contribuicao ao estudo da condutividade termica do material ceramico concreto refratario utilizando a tecnica de fio quente com ajustes por regressao nao linear". reponame:Repositório Institucional do IPEN, 1988. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9901.

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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

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46

Friček, Jakub. "Sledování vlivu keramické vazby na vlastnosti izolačních žáromateriálů". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-225890.

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Thermal insulating refractories are an integral part of each thermal unit since they reduce its energy consumption. The current phenomenon of saving in both environmental and financial aspects reflects in searching for such possibilities to produce at lower manufacturing and material costs. One of the possible ways is to valorise waste materials. The theoretical part then deals with the division of refractory materials, classification of thermal insulation refractory materials and manufacturing technologies. The experiment is focused on the production of insulating refractory materials made from plastic dough with a possibility of using sawdust and materials made by pressing mixture moist, with a focus on coal bottom ash. Both of these technologies will be tested for the possibility of modification by using mixed clays and of increasing the strength by using clays with lower sintering temperature.

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47

MACHADO, GLAUSON A. F. "Recobrimentos à base de mulita em refratário de carbeto de silício obtidos a partir de PMSQ [POLI (METILSILSESQUIOXANO)] e alumínio". reponame:Repositório Institucional do IPEN, 2017. http://repositorio.ipen.br:8080/xmlui/handle/123456789/27969.

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O carbeto de silício (SiC) é um material que apresenta baixa expansão térmica, altas resistências mecânica e ao choque térmico e alta condutividade térmica. Em razão disto é empregado na confecção de mobília de fornos de sinterização. O SiC no entanto sofre degradação a altas temperaturas quando submetido a atmosferas agressivas. A utilização de recobrimentos protetores evita a exposição direta da superfície do material à atmosfera dos fornos; a mulita pode ser um recobrimento protetor apropriado em razão de sua alta estabilidade em temperaturas elevadas e seu coeficiente de expansão térmica compatível com o do SiC (4x10-6/°C e 5,3x10-6/°C, respectivamente). No presente trabalho foi estudada a obtenção de recobrimento de mulita, para refratário de SiC, a partir da utilização de polímero precursor cerâmico e alumínio particulado. Foram preparadas composições com 10, 20, 30 e 50% (vol.) de alumínio adicionado ao polímero, sendo utilizados pós de alumínio de diferentes distribuições de tamanhos de partículas. As composições foram submetidas a diversos ciclos térmicos para determinação da condição mais adequada à obtenção de alto teor de mulita. A composição que apresentou melhor resultado foi a contendo 20% do pó de Al de menor tamanho de partículas. A partir desta, foi preparada e aplicada suspensão para ser aplicada sobre o refratário de SiC. A suspensão aplicada, após seca, reticulada e tratada termicamente a 1580°C, originou um recobrimento de mulita. Foram realizados ciclos de choque térmico em amostras com e sem recobrimento para comparação, num total de 26 ciclos. As condições foram 600°C/30 min. seguida de resfriamento ao ar até a temperatura ambiente. Após cada choque térmico, as amostras foram caracterizadas por microscopia óptica e eletrônica e determinado o módulo de elasticidade. Os recobrimentos apresentaram boa adesão e não foram detectados danos significativos após os choques térmicos.
Tese (Doutorado em Tecnologia Nuclear)
IPEN/T
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

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48

Magnusson, Lena. "On the Nucleation and Inoculation of Metals". Doctoral thesis, Stockholm : Royal Institute of Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3893.

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49

Collignon, Brice. "Séchage des bétons réfractaires : expérimentation, modélisation et influence d'un ajout de fibres polymère". Thesis, Vandoeuvre-les-Nancy, INPL, 2009. http://www.theses.fr/2009INPL051N/document.

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Les matériaux réfractaires non façonnés dense (MRNF) prennent une part de plus en plus importante aussi bien en cimenterie, fonderie, sidérurgie, ... Principalement constitués d’agrégats à base d’alumine, de magnésie, de spinelle, … ils constituent des matériaux de faible perméabilité contenant une teneur résiduelle en eau de 4 à 6 %. Leur séchage avant leur première utilisation est une opération critique qui conditionne leur durée de vie. D’une part, mal conduit, il peut du fait des endommagements occasionnés, réduire considérablement la durée de vie des installations. D’autre part, certaines conditions de séchage conduisent à une véritable destruction de nature explosive du matériau correspondant à une élévation brutale de la pression interne (accompagnant l’élévation de la pression de vapeur saturante de l’eau avec la température). Le travail a permis de se familiariser avec les matériaux réfractaires non-façonnés à l’aide d’une caractérisation thermomécanique complète menée entre la température ambiante et 500 °C, de comprendre les mécanismes mis en jeu lors de leur séchage, d’une part, par une expérimentation et, d’autre part, en les reproduisant en s’appuyant sur un transfert simultané de chaleur et de masse en milieu poreux. Et enfin, il a permis d’étudier l’impact d’un ajout de fibres polymère sur une caractéristique qui gère l’évacuation de l’eau, la perméabilité, et plus généralement sur le séchage
Castable refractories take a more and more important place in various industries: cement factory, casting, iron and steel making. They consist mainly of aggregates of high-alumina and ultra-low cement. Their permeability is very low and they contain before the first heat-up a residual water content of 4 to 6 % (dry basis). Drying during the first heat-up is a crucial step which sharply influence the refractory in-service performances. On one hand, damaging can occur, and as a consequence will reduce drastically the life time of the plants. On the other hand, particular drying conditions can lead to an explosive spalling of the refractory corresponding to an internal gas pressure steep raise linked to the water saturated vapour pressure raise with temperature. First, a complete thermomechanical characterization between ambient temperature and 500 °C of the unshaped refractory materials has been conducted. Then the mechanisms involved during their drying, on one hand, by an experiment and, on the other hand, by using a simultaneous heat and mass transfer model in porous media have been studied. And last, the impact of adding polymer fibers has been analysed both on the concrete permeability as well as their influence on drying

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COSTA, FRANCINE A. da. "Sintese e sinterizacao de pos compositos do sistema W-Cu". reponame:Repositório Institucional do IPEN, 2004. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11176.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
FAPESP:00/00255-9

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