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Artigos de revistas sobre o assunto "Copper crystalline phases"
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Semenov, A. P., Dmitriy Badma-Dorzhievich Tsyrenov e I. A. Semenova. "Sintez nanokompozitnykh pokrytiy TiN-Cu na printsipe sopryazheniya protsessov vakuumno-dugovogo ispareniya, magnetronnogo raspyleniya i raspyleniya ionnym puchkom". Микология и фитопатология, n.º 2 (15 de dezembro de 2023): 45–47. http://dx.doi.org/10.31857/s0869573323020064.
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Superhard TiN-Cu composite coatings have been obtained, the synthesis of which is based on the principle of coupling the operating modes of a vacuum arc evaporator a planar magnetron and a plasma ion source. The constitution, structure and properties of TiN-Cu composite coating do not depend on the type of hybrid methods of their synthesis. It is shown that the coatings have a characteristic homogeneous globular structure with crystallite sizes in the range of 20-50 nm and are textured along the plane (111). Copper does not form its own crystalline phase and is not in the crystal lattice of other phases, it is located at the boundaries of crystallites in an amorphous or X-ray amorphous state. The copper content throughout the coating profile is 5-10 at.%. The microhardness of the coatings is 38-42 GPa.
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Che Halin, Dewi Suriyani, Norainiza Saud e Haiza Haroon. "Microstructure Study on Cuprous Oxide Thin Films Deposited on n-Si Substrate via Sol-Gel Spin Coating Technique". Materials Science Forum 803 (agosto de 2014): 362–66. http://dx.doi.org/10.4028/www.scientific.net/msf.803.362.
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Cuprous oxide thin films were prepared by sol-gel method was successfully deposited onto n-Si substrate. Sol solutions were prepared by dissolving copper (II) acetate in isopropyl alcohol. Diethanolamine and glucopone were added into the sol solution to dissolve the copper (II) acetate rapidly to prevent the precipitation of blue copper (II) acetate. Crystalline phases are identified by X-ray diffraction (XRD) and the crystallite size is estimated by using Scherrer’s formula which indicates that the largest crystallite size is 41.84 nm with the lowest lattice parameter 4.25 Å. The optical band gap of the films is determined by optical absorption technique and the surface morphologies of films are analyzed by scanning electron microscopy (SEM). The SEM micrographs show that the particles agglomerate with different shapes and sizes.
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White, Rachel, Paul Thomas, Matthew R. Phillips, Ken Moran e Richard Wuhrer. "X-Ray Mapping and Scatter Diagram Analysis of the Discoloring Products Resulting from the Interaction of Artist's Pigments". Microscopy and Microanalysis 16, n.º 5 (31 de agosto de 2010): 594–98. http://dx.doi.org/10.1017/s143192761009375x.
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AbstractThe discoloring interaction between the artist's pigments cadmium yellow and the copper-containing malachite, an interaction that is conjectured to cause black spotting in oil paintings of the 19th and early 20th centuries, was examined using X-ray mapping and scatter diagram analysis. The application of these coupled techniques confirmed that copper sulfide phases were produced during discoloration reaction. Scatter diagram analysis indicated that two copper sulfide stoichiometries (CuS and Cu3S2) were present as reaction products where previously only crystalline CuS (covellite) had been identified by X-ray diffraction. The results demonstrate the potential of X-ray mapping coupled with scatter diagram analysis for the identification of both crystalline and X-ray amorphous phases produced by such complex heterogeneous interactions and their applicability to the investigation of interactions of artists' pigments.
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Wang, Xin. "Surface Crystallization in Mg-Based Bulk Metallic Glass during Copper Mold Casting". Advances in Materials Science and Engineering 2014 (2014): 1–4. http://dx.doi.org/10.1155/2014/798479.
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The localized crystallization of Mg54Cu28Ag7Y11bulk metallic glass (BMG) in the injection casting process using a copper mold was investigated. It has been found that several crystalline phases were formed close to the as-cast surface but did not exist in the internal part of the BMG plate. It is abnormal that the as-cast surface is partially crystallized with higher cooling rate than that of inside. Overheating of the melt and nucleation induced by the surface of copper mold play key roles in the abnormal crystallization. It is suggested that the function of copper mold to trigger heterogeneous nucleation cannot be totally ignored, although it provides the high cooling rate for the glass formation during casting.
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Wang, Yi Ming, Li Jing Zheng e Shu Jie Pang. "Formation and Mechanical Properties of Mg-Cu-Al-Gd Bulk Metallic Glass Composites". Materials Science Forum 650 (maio de 2010): 290–94. http://dx.doi.org/10.4028/www.scientific.net/msf.650.290.
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The effect of Al addition to Mg65Cu25Gd10 glassy alloy on the microstructure, thermal properties and mechanical properties were investigated. The Mg65Cu25-xAlxGd10 (x=1-7at. %) bulk metallic glass composites were formed by copper mold casting, and the fraction and size of the crystalline phases in the glassy matrix changed with the Al content. The Mg65Cu24Al1Gd10 glass composite consisted of a small amount of crystalline phases in the glassy matrix possesses high compressive strength up to about 850 MPa.
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Phiri, Tina, Pritam Singh e Aleksandar Nikoloski. "Mineralogical Characterisation of Copper Slag and Phase Transformation after Carbocatalytic Reduction for Hydrometallurgical Extraction of Copper and Cobalt". Metals 14, n.º 10 (1 de outubro de 2024): 1119. http://dx.doi.org/10.3390/met14101119.
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Copper smelting slag is a significant potential resource for cobalt and copper. The recovery of copper and cobalt from copper slag could significantly augment the supply of these metals, which are essential to facilitating the transition to green energy while simultaneously addressing environmental concerns regarding slag disposal. However, the complex mineral composition of copper slag poses an enormous challenge. This study investigated the mineralogical and chemical characteristics of copper slag, which are vital for devising the most effective processing techniques. XRD and FESEM-EDS were employed to examine the morphologies of copper slag before and after the reduction process. The effects of borax and charcoal (carbocatalytic) reduction on phase transformation were evaluated. The XRD analysis revealed that the primary phases in the copper slag were Fe2SiO4 and Fe3O4. The FESEM-EDS analysis verified the presence of these phases and yielded supplementary details regarding metal embedment in the Fe2SiO4, Fe3O4, and Cu phases. The carbocatalytic reduction process expedited the transformation of copper slag microstructures from crystalline dendritic to amorphous and metallic phases. Finally, leaching experiments demonstrated the potential benefits of carbocatalytic reduction by yielding high extractions of Cu, Co, and Fe.
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Purvis, O. W., B. Pawlik-Skowrońska, G. Cressey, G. C. Jones, A. Kearsley e J. Spratt. "Mineral phases and element composition of the copper hyperaccumulator lichen Lecanora polytropa". Mineralogical Magazine 72, n.º 2 (abril de 2008): 607–16. http://dx.doi.org/10.1180/minmag.2008.072.2.607.
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AbstractMineral phases and element localization were investigated in the vivid turquoise-coloured lichen, Lecanora polytropa, sampled from a psammite boulder in a wall supporting mine spoil at the abandoned copper mine, Riddarhyttan Kopparverke, southern Sweden. Normally pale yellowish (usnic acid), the lichen is turquoise coloured internally with bluish inclusions. X-ray mapping shows that Cu occurs on and within the lichen and does not coincide with P or S, suggesting that it is indeed associated with carbon or other elements not detected (or reported) using X-ray mapping. Scanning electron microscopy in back-scatter mode confirmed that the greatest Cu concentrations occur in the form of crystalline aggregates in coloured inclusions below the major internal turquoise layer with smaller Cu contents. X-ray diffraction with a position-sensitive detector (XRD-PSD) confirmed coloured crystalline aggregates consisted of the copper oxalate, moolooite. The study confirms the value of XRD-PSD as a non-destructive tool to characterize small (~50 μm) metal oxalate inclusions obtained from within lichen samples.
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Ma, Minghong, e Yongqian Huang. "Impact of adding Na2SiF6 on the crystal phase and copper valence state in glass ceramics made from leftover granite for use as architectural ornamentation". Journal of Physics: Conference Series 2842, n.º 1 (1 de setembro de 2024): 012017. http://dx.doi.org/10.1088/1742-6596/2842/1/012017.
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Abstract The accumulation of granite waste can result in the occupation of a considerable amount of land resources. Using granite waste as glass ceramics for architectural decoration represents a potential solution to this issue. The microstructure, valence state, and crystalline phase of copper ions were examined by using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and X-ray diffraction (XRD). The findings demonstrated that the concentration of Na2SiF6 affects the valence condition of Cu ions in crystallized glass. The crystalline phases of the sample containing 1.84 wt% Na2SiF6 consisted of forsterite (MgSiO3) and diopside (CaMgSi2O6), and the Cu+ accounted for 39.9% of the total Cu ions in the sample which showed a grey-black color. For the sample containing 3.67 wt% Na2SiF6, the crystalline phases consisted of richterite (Na, F) syn (Na (Na, Ca) Mg5Si8O22F2), cuprite (Cu2O), and forsterite, its Cu+ accounted for 39.9%, and the sample appeared orange-red. With the increase of Na2SiF6 content, the percentage of Cu+ in the total Cu ions showed an increasing trend, and the corresponding red color of the samples gradually deepened.
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Maldivi, P., D. Guillon, A. M. Giroud-Godquin, J. C. Marchon, H. Abied, H. Dexpert e A. Skoukios. "Copper K edge EXAFS spectroscopy of the crystalline and columnar phases of copper (II) carboxylates". Journal de Chimie Physique 86 (1989): 1651–64. http://dx.doi.org/10.1051/jcp/1989861651.
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Dyakova, Vanya, Hristina Spasova, Yoanna Kostova, Yana Mourdjeva e Georgi Stefanov. "EFFECT OF CU AS МINORITY АLLOYING ЕLEMENT ON GLASS FORMING ABILITY AND CRYSTALLIZATION BEHAVIOR OF RAPIDLY SOLIDIFIED AL-SI-NI RIBBONS". ENVIRONMENT. TECHNOLOGIES. RESOURCES. Proceedings of the International Scientific and Practical Conference 3 (13 de junho de 2023): 69–73. http://dx.doi.org/10.17770/etr2023vol3.7200.
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The influence of copper as a minority alloying element in the process of rapid solidification of Al-Si-Ni ribbons produced by Chill Block Melt Spinning (CBMS) was investigated. XRD and TEM analyses proved a completely amorphous structure of the alloys Al74Ni16Si10 and (Al74Ni16Si10)98Cu2. The crystallization behaviour of these alloys was studied by DSC analysis. It was found that the crystallization of the amorphous alloys (Al74Ni16Si10)100-xCux, x=0, 2 runs in two steps. The temperatures Tx1 and Tx2 of each of the crystallization steps were determined. It was proven that the addition of 2 at. % copper does not significantly change Tx temperatures. The temperature difference ΔTx was calculated and it showed that more thermally stable is the copper containing alloy. Crystalline analogues of the amorphous alloys were obtained by annealing of the melt-spun amorphous ribbons at a temperature which exceeded by 170°C the onset crystallization temperature. The type and size of separated crystalline phases were determined by XRD. It was found that the addition of 2 at. % Cu to Al74Ni16Si10 alloy causes a separation of new phases - Cu3.8Ni and (Al, Cu)Ni3 and 54%, 24% and 7% size increase of the phases Al, Al3Ni, NiSi2 respectively.
Teses / dissertações sobre o assunto "Copper crystalline phases"
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Riviere, Lucie. "Methyl chloride cracking and formation of coke during the methylchlorosilanes synthesis". Electronic Thesis or Diss., Lyon 1, 2024. http://www.theses.fr/2024LYO10189.
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Pendant la synthèse de Müller-Rochow, le silicium (Si) et le chlorure de méthyle (CH3Cl) réagissent pour former des méthylchlorosilanes (MCS) en présence d'un précurseur de cuivre et de promoteurs Zn et Sn. Le CH3Cl peut subir des réactions de craquage qui entraînent la formation de composés carbonés (coke) perturbant le fonctionnement des réacteurs industriels, ce qui entraîne une perte de production. L'objectif de cette thèse était d'étudier le craquage du CH3Cl et la formation de coke pendant l'étape d'activation de la synthèse des MCS et de trouver des solutions industrielles pour prévenir la formation de coke. Le chlorure de cuivre, généralement utilisé comme précurseur, peut soit former Cu3Si, actif pour la synthèse des MCS, soit être réduit en Cu, qui s'est révélé inactif pour la synthèse des MCS mais actif pour le craquage du CH3Cl. Dans ce travail, cette réaction secondaire est corrélée avec la formation de Cu(0), qui se produit dès le début de la synthèse des MCS et est favorisée par les promoteurs Zn et Sn. Cependant, il a été démontré que la cinétique de formation de Cu(0) est plus rapide que celle de Cu3Si, même en l'absence de promoteurs. Par conséquent, il est impossible d'éviter la formation de Cu(0) qui pourrait contribuer au craquage du CH3Cl. Une approche pour réduire la formation de coke a été de diminuer l'acidité en ajoutant des métaux alcalins : KCl et CsCl. Cela a donné des résultats favorables : il a été possible de réduire le taux de production de coke en diminuant la quantité de phase cristalline Cu(0) formée. Certaines explications ont été proposéesDuring the Müller-Rochow synthesis, Si and CH3Cl reacts to form methylchlorosilanes (MCS) in presence of a copper precursor, Zn and Sn promoters. CH3Cl can suffer from cracking reactions which results in the formation of carbonaceous compounds (coke) that disturbs the operation of industrial reactors, leading to a production loss. The purpose of this thesis was to study the CH3Cl cracking and the formation of coke during the activation step of the MCS synthesis and to find industrial solutions to prevent coke formation. Copper chloride which is generally used as precursor can either form Cu3Si, active for the MCS synthesis or be reduced into Cu(0) that was found to be inactive for the MCS synthesis but active for the CH3Cl cracking. In this work, this side reaction is correlated with Cu(0) formation which occurs from the beginning of the MCS synthesis and is enhanced by Zn and Sn promoters. However, Cu(0) formation kinetic was shown to be faster than Cu3Si even in the absence of promoters. Therefore, it is impossible to avoid Cu(0) formation which could contribute to CH3Cl cracking. An approach to reduce coke formation was to lower the acidity by adding alkali metals: KCl and CsCl. This provided favorable outcomes: it was possible to lower the coke production rate due to the reduction of the amount of Cu(0) crystalline phase formation. Some explanations were proposed
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Kokkaliaris, Stylianos. "Investigation of the vortex phase diagram and dynamics in single crystalline samples of the high temperature superconductor YBaâ†2Cuâ†3Oâ†7â†-â†#delta#". Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310294.
Texto completo da fonteCapítulos de livros sobre o assunto "Copper crystalline phases"
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LÓPEZ, Roberto, Jesús NAMIGTLE e Jorge MASTACHE. "Structural characterisation of copper oxide by X-ray diffraction". In Handbooks Engineering Science and Technology TIX, 70–96. ECORFAN, 2021. http://dx.doi.org/10.35429/h.2021.9.1.70.96.
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In this work, the study of the structural characterization of copper oxide by the X-ray diffraction technique is presented. To obtain layers of copper oxide, sputtering and thermal oxidation techniques were combined. The average crystal size was calculated for the sputtered copper samples. For the copper oxide films obtained by thermal oxidation, both the crystal size and the texture coefficient were calculated. The crystalline quality was poor for layers obtained by sputtering. Thermal oxidation carried out on these films transformed its structure to the copper oxide phase known as cupric oxide.
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Kiose, Tatyana A., Tatyana L. Rakitskaya, Alim A. A. Ennan e Alla S. Truba. "Palladium-Copper Catalyst Supported on Carbon Fiber Material for Oxidation of Carbon Monoxide by Air Oxygen". In Environmental and Technological Aspects of Redox Processes, 167–87. IGI Global, 2023. http://dx.doi.org/10.4018/979-8-3693-0512-6.ch010.
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The phase composition, textural, protolytic properties, and activity of catalysts for the carbon monoxide low-temperature oxidation based on two series of non-woven carbon fiber material samples CFM-I and CFM-II, and K2PdCl4, Cu(NO3)2, KBr basic components were studied in this work. Catalysts and CFMs were studied by XRD, SEM, FTIR spectroscopy, nitrogen ad/desorption, pH-metric, and atomic absorption spectrophotometry methods. It has been found that the basic components K2PdCl4 and Cu(NO3)2 deposited on a microporous carbon surface undergo changes and form an X-ray amorphous Pd0 phase and a paratacamite – Cu2(OH)3Cl crystalline phase. The catalysts were tested in the range of carbon monoxide initial concentrations from 50 to 300 mg/m3 with an effective contact time of the catalyst with the gas-air mixture from 0.12 to 0.50 s. Catalysts provide air purification from CO to concentrations below MPCCO (20 mg/m3) and can be used in respiratory devices.
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Marzouki, Amira, Ameni Brahmia, Riadh Marzouki, Mosbah Jemmali, Ismat H. Ali e Mohamed Faouzi Zid. "Correlation between Structure, Electrical, and Magnetic Properties of Some Alkali-Oxide Materials". In Alkaline Chemistry and Applications. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.102322.
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In this chapter, the correlation between structure and electrical properties of Na2MP1.5As0.5O7 (MII = Co and Cu) are treated. The structural study shows that the cobalt and copper isotype materials can be crystallized in the tetragonal and monoclinic systems, respectively. The electrical study using impedance spectroscopy technique showed that these mixed diphosphate diarsenates are fast electrical conductors; however, the cobalt material exhibited more conductive property than the copper compound. In addition, the powder perovskite manganites La0.7M0.2M’0.1MnO3 (M = Sr, Ba and M’ = Na, Ag and K) have been prepared using the conventional solid-state reaction. The structural, magnetic, and magnetocaloric properties of these perovskite manganites compounds were studied extensively by means of X-ray powder diffraction (XRD) and magnetic measurements. These samples were crystallized in the distorted rhombohedral system with R3c space group. The variation of magnetization (M) vs. temperature (T) reveals that all compounds exhibit a second-order ferromagnetic to paramagnetic phase transition in the vicinity of the Curie temperature (TC). A maximum magnetic entropy change, ΔSMMax, of 4.07 J kg−1 K−1 around 345 K was obtained in La0.7Sr0.2Na0.1MnO3 sample upon a magnetic field change of 5 T. The ΔSMMax values of La0.7Ba0.2M’0.1MnO3 are smaller in magnitude compared to La0.7Sr0.2M’0.1MnO3 samples and occur at lower temperatures.
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Jemmali, Mosbah, e Lotfi Bessais. "Effect of M Substitution on Structural, Magnetic and Magnetocaloric Properties of R2Fe17-x Mx (R = Gd, Nd; M = Co, Cu) Solid Solutions". In Magnetic Skyrmions. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.96299.
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The structure, magnetic and magnetocaloric properties of Nd2Fe17−xCox (x = 0; 1; 2; 3, 4) and Gd2Fe17-xCux (x = 0, 0.5, 1 and 1.5) solid solutions have been studied. For this purpose, these samples were prepared by arc melting and subsequent annealing at 1073 K for a 7 days. Structural analysis by Rietveld method on X-ray diffraction (XRD) have determined that these alloys crystallize in the rhombohedral Th2Zn17-type structure (Space group R¯3 m) and the substitution of iron by nickel and copper leads to a decrease in the unit cell volume. The Curie temperature (TC) of the prepared samples depends on the nickel and copper content. Based on the Arrott plot, these analyses show that Nd2Fe17-xCox exhibits a second-order ferromagnetic to paramagnetic phase transition around the Curie temperature. These curves were also used to determine the magnetic entropy change ∆SMax and the relative cooling power. For an applied field of 1.5 T, ∆SMax increase from 3.35 J/kg. K for x = 0 to 5.83 J/kg. K for x = 2. In addition the RCP increases monotonously. This is due to an important temperature range for the magnetic phase transition, contributing to a large ∆SMax shape. Gd2Fe17-xCux solid solution has a reduction of the ferromagnetic phase transition temperature from 475 K (for x = 0) to 460 K (for x = 1.5) is due to the substitution of the magnetic element (Fe) by non-magnetic atoms (Cu). The magnetocaloric effect was determined in the vicinity of the Curie temperature TC. By increasing the Cu content, an increase in the values of magnetic entropy (∆SMax) in a low applied field is observed.
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A.H. Alzahrani, Hassan. "CuO and MWCNTs Nanoparticles Filled PVA-PVP Nanocomposites: Morphological, Optical, Dielectric, and Electrical Characteristics". In Carbon Nanotubes - Recent Advances, New Perspectives and Potential Applications [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.105810.
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Copper dioxide (CuO) nanoparticles and multiwall carbon nanotubes (MWCNTs)-filled poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) (PVP) blend matrix (50/50 wt%)-based polymer nanocomposites (PNCs) have been prepared employing the solution-cast method. The X-ray diffraction explores the semicrystalline morphologies of these PNCs. The FTIR, SEM, and AFM measurements of PNCs expose the development of the miscible mix, polymer-polymer and polymer-nanoparticle interactions, and the influence of CuO and MWCNTs nanofillers on the morphology aspects on the main chain of PVA/PVP blend. The nanofiller loading for x = 14 wt% in the PVA–PVP blend matrix significantly enhances the crystalline phase, diminishing the optical energy gap to 2.31 eV. The DC conductivity is found to be maximum for x = 14 wt% loading concentration. The dielectric and electrical characteristics of these PNCs are investigated for an applied frequency range from 1 kHz to 1 MHz. The dielectric permittivity values increase substantially, owing to the decrease in the nano-confinement phenomenon at low frequency. The rise in applied frequency reduces dielectric permittivity and impedance values and enhances AC electrical conductivity. These PNCs having good dielectric and electrical characteristics can be used as frequency tunable nano-dielectric material in electronic devices.
Trabalhos de conferências sobre o assunto "Copper crystalline phases"
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Soylu, E., e G. Tranell. "Melting behaviour investigation of municipal solid waste incineration fly ash samples from different incineration technologies for metal recovery – an integrated experimental and thermodynamic modelling". In 12th International Conference of Molten Slags, Fluxes and Salts (MOLTEN 2024) Proceedings, 1631–42. Australasian Institute of Mining and Metallurgy (AusIMM), 2024. http://dx.doi.org/10.62053/sqtv9191.
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Municipal solid waste incineration fly ash (MSWI FA) is an important waste product that holds considerable potential for valourisation. In addition to major phases such as CaSO4, CaCO3, NaCl, KCl, and silicates, these ashes contain significant amounts of valuable elements like copper (Cu), zinc (Zn), lead (Pb), and others, where the specific composition depends on the source of the waste and the incineration process used. This study aims to investigate the melting behaviour of municipal MSWI FA samples from various incineration technologies, including rotary kiln, grate furnace, and circular fluidised bed, as a background for pyro/hydrometallurgical metal extraction. The experimental study was designed to research the effect of salt composition on the melting temperature and phase formations of different ash types, as well as metal migration between phases, using a sessile drop furnace. As a complimentary approach to the experimental study, thermodynamic modelling (FactSage™ ver 8.3, by Thermfact/CRCT and GTT-Technologies) was used to predict the phase formations of different fly ashes using Scheil-Gulliver cooling of molten ash. The observed melting point of the samples varied between 1000–1400°C depending on the ash type, without any trend of salt composition effect on the melting point. Upon solidification, there were three distinct phases observed in the samples: a metallic phase, a crystalline, non-metallic phase with inhomogeneous shape pattern, and an amorphous matrix phase. The findings indicate that the predominant component in the matrix phase was Ca-O-Si, implying the formation of calcium silicate slag. Elemental mapping showed metallic droplets consisting of primarily Fe-P phases, while the crystalline non-metallic phase is concentrated in Ca and S. The furnace atmosphere (Ar versus CO) had no significant impact on the phase formations. Thermodynamic modelling results were in good agreement with the experimental study, except for P-rich metallic phases, showing the formation of non-metallic and complex silicate slag phase formations.
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Yevdokymenko, Yuriy, Mykola Iefimov, Gennadii Frolov e Kateryna Iefimova. "Properties of HVAF-coatings from Al-Cu-Fe quasicrystalline alloy". In IXth INTERNATIONAL SAMSONOV CONFERENCE “MATERIALS SCIENCE OF REFRACTORY COMPOUNDS”. Frantsevich Ukrainian Materials Research Society, 2024. http://dx.doi.org/10.62564/m4-yy1802.
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Alloys of Al-Cu-Fe system containing quasicrystalline ψ-phase are perspective as thermal barrier, wear-resistant, corrosion-resistant and anti-adhesion coatings. Typically, such alloys are compositions of quasicrystalline and crystalline metallic phases, making them similar to metal ceramics [1]. Until now, high quality thermal spraying coatings from alloys containing ψ-phase more than 70 %(mass) have not been obtained due to its low plasticity at temperatures up to 500°C, phase transition to λ-phase and β-phase at 880°C and narrow area of existence in the diagram of states. The spraying was carried out by HVAF spraying method with liquid fuel burner GVO-RV with flow rate control of two-phase flow parameters, developed in IPMS of NASU [2]. The burner provides spraying powder with temperature 700-1000°C and velocity at least 500 m/s. In this mode the formation of coatings occurs from solid particles due to their plastic deformation. This allows to avoid typical for traditional technologies heating of particles above Tm=1080°С leading to oxidation and evaporation of aluminum resulting in the alloy composition leaving the limits of the existence of ψ-phase. The coatings were sprayed from water atomized Al63Cu25Fe12 powders [3] of fractions +20/-40 µm, +40/-63 µm, +63/-80 µm with the content of ψ-phase 65-75 %(mass). The content of ψ-phase in the coatings was ±5 % compared to powder; in some cases it came to 90 %. The thickness of the coatings is a controllable parameter and may reach 1000 µm. The porosity of coatings on substrates from copper, titanium, steels, aluminum alloys is 4-8 %. The adhesive/cohesive strength of coatings on 1044 steel substrates, determined by the pin method equals to 31±3 MPa. The thermal conductivity coefficient of Al-Cu-Fe coatings increases from 1.9±0.15 W/(m×K) at 20°C to 2.2±0.2 W/(m×K) at 800°C. The resistance of coatings to erosion at jet-abrasive processing is at the level of an HVAF-coating made of stainless steel AISI 301.
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Patel, Sanjay, e K. K. Pant. "Hydrogen Production for PEM Fuel Cells via Oxidative Steam Reforming of Methanol Using Cu-Al Catalysts Modified With Ce and Cr". In ASME 2006 4th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2006. http://dx.doi.org/10.1115/fuelcell2006-97209.
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The performance of Cu-Ce-Al-oxide and Cu-Cr-Al-oxide catalysts of varying compositions prepared by co-precipitation method was evaluated for the PEM fuel cell grade hydrogen production via oxidative steam reforming of methanol (OSRM). The limitations of partial oxidation and steam reforming of methanol for the hydrogen production for PEM fuel cell could be overcome using OSRM and can be performed auto-thermally with idealized reaction stoichiomatry. Catalysts surface area and pore volume were determined using N2 adsorption-desorption method. The final elemental compositions were determined using atomic absorption spectroscopy. Crystalline phases of catalyst samples were determined by X-ray diffraction (XRD) technique. Temperature programmed reduction (TPR) demonstrated that the incorporation of Ce improved the copper reducibility significantly compared to Cr promoter. The OSRM was carried out in a fixed bed catalytic reactor. Reaction temperature, contact-time (W/F) and oxygen to methanol (O/M) molar ratio varied from 200–300°C, 3–21 kgcat s mol−1 and 0–0.5 respectively. The steam to methanol (S/M) molar ratio = 1.4 and pressure = 1 atm were kept constant. Catalyst Cu-Ce-Al:30-10-60 exhibited 100% methanol conversion and 152 mmol s−1 kgcat−1 hydrogen production rate at 300°C with carbon monoxide formation as low as 1300 ppm, which reduces the load on preferential oxidation of CO to CO2 (PROX) significantly before feeding the hydrogen rich stream to the PEM fuel cell as a feed. The higher catalytic performance of Ce containing catalysts was attributed to the improved Cu reducibility, higher surface area, and better copper dispersion. Reaction parameters were optimized in order to maximize the hydrogen production and to keep the CO formation as low as possible. The time-on-stream stability test showed that the Cu-Ce-Al-oxide catalysts subjected to a moderate deactivation compared to Cu-Cr-Al-oxide catalysts. The amount of carbon deposited onto the catalysts was determined using TG/DTA thermogravimetric analyzer. C1s spectra were obtained by surface analysis of post reaction catalysts using X-ray photoelectron spectroscopy (XPS) to investigate the nature of coke deposited.
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El Hasadi, Yousef M. F., e J. M. Khodadadi. "Numerical Simulation of Solidification of Colloidal Suspensions Inside a Differentially-Heated Cavity". In ASME 2013 Heat Transfer Summer Conference collocated with the ASME 2013 7th International Conference on Energy Sustainability and the ASME 2013 11th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/ht2013-17594.
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Development of the solid-liquid interface, distribution of the particle concentration field, as well as the development of thermo-solutal convection during solidification of colloidal suspensions in a differentially-heated cavity is investigated. The numerical model is based on the one-fluid-mixture approach combined with the single-domain enthalpy-porosity model for phase change. The linear dependence of the liquidus concentration of the nanoparticles was assumed. A colloidal suspension consisting of water and copper, and alumina nanoparticles were considered. In the current investigation, the nanoparticle size selected was 2 nm. The suspension was solidified unidirectionally inside a square differentially-heated cavity that was cooled from the left side. It was found that the solid-liquid interface changed its morphology from a planar shape to a dendritic one as the solidification process proceeds in time, due to the constitutional supercooling that resulted from the increased concentration of particles at the solid-liquid interface rejected from the crystalline phase. Initially, the flow consisted of two vortices rotating in opposite directions. However, at later times only one counter clockwise rotating cell survived. Changing the material of the particle to alumina results in crystallized phase with a higher concentration of particles if it is compared to that of the solid phase resulted from freezing the copper-water colloidal suspension. Decreasing the segregation coefficient destabilize the solid-liquid interface, and increase the intensity of the convection cell with respect to that of the case of no particle rejection. At slow freezing rates, the crystal phase resulted consisted of lower particle content if it is compared to that resulted from higher freezing rate.
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Ratnawulan, Ahmad Fauzi e Sukma Hayati AE. "Effect of calcination temperature on phase transformation and crystallite size of copper oxide (CuO) powders". In THE 4TH INTERNATIONAL CONFERENCE ON RESEARCH, IMPLEMENTATION, AND EDUCATION OF MATHEMATICS AND SCIENCE (4TH ICRIEMS): Research and Education for Developing Scientific Attitude in Sciences And Mathematics. Author(s), 2017. http://dx.doi.org/10.1063/1.4995173.
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Umbelino Gomes, Uilame, Kívia Fabiana Galvão de Araújo, Maria José Santos Lima, Vitor Manoel Silva Fernandes De Souza, Cléber da Silva Lourenço e Rafael Alexandre Raimundo. "Study Of The Influence Of Milling Time On The Synthesis Temperature Of Monoclinic And Orthorhombic Nanostructured Cunb2o6 Via High-Energy Milling". In Euro Powder Metallurgy 2023 Congress & Exhibition. EPMA, 2023. http://dx.doi.org/10.59499/ep235765398.
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Copper niobate (CuNb2O6) has been studied for technological and environmental applications, such as in solar cells and photocatalysts, for example. And to make the application of CuNb2O6 even more feasible, in this study, therefore, high-energy milling was applied in its synthesis process with variation in the milling time, from the precursor powders Nb2O5 and CuO. The calcination occurred in a muffle with temperatures in the range of 500 °C to 1000 °C, for 3 h and heating rate of 5 °/min. Then, the powders were characterized by XRD, SEM, EDS and Raman. The powders showed crystallite sizes smaller than 80 nm, good homogeneity and high purity. The particle morphologies and the Raman spectrum are coherent with the literature. It was also verified that the increase in milling time reduced the initial formation temperature of the monoclinic phase and the calcination time for the complete formation of the orthorhombic phase.
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Wang, Yana, Jane H. Davidson e Lorraine F. Francis. "Scaling in Polymer Tubes Used in Solar Water Heating Systems". In ASME 2004 International Solar Energy Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/isec2004-65056.
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An experimental study of the growth of calcium carbonate (commonly termed scaling) on copper, nylon 6,6, semiaromatic high temperature nylon, polypropylene, polybutylene, and Teflon tubes exposed to hard water is presented. The objective of the study is to gain qualitative information on the scaling of polymer tubes in nonisothermal, flowing conditions expected in heat exchangers and solar absorbers. The 89-cm long tubes were placed in tube-in-shell heat exchangers. Water prepared from 10 °C tap water with a total calcium concentration of 4×10−3 M, and a pH of 9.0 was pumped through the tubes at 4 cm/s. A 50 percent propylene glycol solution at 60 °C was maintained on the shell-side of the heat exchanger. The experiment was carried out for 540 hours with these conditions. Sections of the tubes were removed periodically to determine the extent of scaling. Results include scanning electron microscope images of the tube surfaces before and after exposure to the flowing water, X-ray diffraction to determine the crystalline phase content of the observed deposits, and chemical analysis to determine the mass of calcium carbonate per unit surface area and to estimate the scaling rate. A model of the scaling process is presented to help interpret the data. The data show conclusively that polymer tubes are prone to scaling. With the exception of nylon 6,6, the scaling rate on the polymers is about the same as that on copper. The nylon 6,6 substrate appears to enhance scaling.
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Fan, Jinsheng, David Gonzalez, Jose Garcia, Brittany Newell e Robert A. Nawrocki. "The Effects of Additive Manufacturing and Electric Poling Techniques on PVdF Thin Films: Towards 3D Printed Functional Materials". In ASME 2020 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/smasis2020-2245.
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Abstract Mechanical flexibility, faster processing, lower fabrication cost and biocompatibility enable poly (vinylidene fluoride) (PVdF) to have a wide range of applications. This work investigated the use of a piezoelectric polymeric material, PVdF, in combination with 3D printing, to explore new strategies for the fabrication of smart materials with embedded functions, namely sensing. The motivation behind this research was to design and fabricate PVdF thin films that will be used to build pressure sensors with applications in active intelligent structures. In this work, 3D printed PVdF thin films with thickness values in the range of 250 to 350 μm were poled under high direct current electrical fields, which were varied from 0.4 to 12 MV/m and temperatures from 80 to 140 °C. Copper electrodes were applied, forming a standard capacitor layered structure, to facilitate poling and to collect piezoelectric output voltage. The poling process enabled the piezoelectric crystalline phase transition of printed PVdF films to transfer from the non-active a α-phase to the piezoelectric active β-phase and rearranged the dipole alignments of the β-phase. The efficiency of poling was evaluated through the piezoelectric constant calculated from measured calibration curves. These calibration curves demonstrated the PVdF sensing device have a positive linear correlation between mechanical input and voltage output. We found that a peak value in piezoelectric constant correlated with poling voltages and temperatures. The highest piezoelectric constant achieved through contact poling was 32.29 pC/N poled at 750 V and 120 °C, and temperature was deemed the most important factors to influence piezoelectric constant. We believe that the present work demonstrates a path towards fully 3D printed smart, functional materials.
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Swalla, Dana R., e Richard W. Neu. "Role of Misorientation in Assessing Fretting Damage". In World Tribology Congress III. ASMEDC, 2005. http://dx.doi.org/10.1115/wtc2005-63313.
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The primary focus of the current work is to develop quantifying measures that can describe the evolution of fretting damage at the microstructural scale in a dual phase Ti-6Al-4V as well as two single phase materials: commercially pure titanium (CP-Ti), which consists of pure alpha-phase titanium, and a near alpha Ti-5Al-2.5Sn. It is important to understand deformation behavior at the microstructural scale in heterogeneous materials because features at this scale, such as grain size, crystallographic orientation, and phase distribution, strongly influence crack development and are dimensionally of the same magnitude as the fretting damage volume. In Ti-6Al-4V, the size, distribution, and crystallographic orientation of the alpha-phase, which has an HCP crystalline structure, is particularly significant in fretting crack formation. Recent studies have linked an increase in average intra-grain misorientation (AMIS) measured using electron backscatter diffraction (EBSD) to increasing strain in medium to high stacking fault metals such as titanium, nickel, copper, and aluminum. A high AMIS value in the near surface layers of specimens subjected to procedures that may induce surface damage has been shown to correlate with a reduction in low-cycle fatigue life. Furthermore, AMIS may be used to estimate plastic strain accumulation when calibrated to specimens tested at a known plastic strain. In the current study, the effect of slip displacement amplitude and number of fretting cycles on the evolution of fretting damage is quantified using AMIS. Additional supporting evidence of significant plastic strain accumulation in the near surface layers of the fretted specimens obtained using nanoindentation and energy dispersive X-ray analysis (EDX) will also be presented. An opportunity exists to directly link microstructural damage measures such as AMIS with life prediction procedures, and therefore, remaining challenges in developing such methods will be discussed.
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Kapat, Jay, Umit Kursun, George Wayne Finger, William McDonald, Jose Solomon, Ashok Kumar, Deepak Srivastava e Meyya Meyyappan. "Nanoscale Thermal Management With Gas-Cooling". In ASME 2007 5th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2007. http://dx.doi.org/10.1115/icnmm2007-30161.
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Nanoscale thermal management (NSTM) will become imperative as power density of IC’s increases further or as 3-dimensional IC’s are introduced. Such NSTM solutions must be integrated with the IC’s to be effective. It can be envisioned that an ideal NSTM solution will involve two-phase flow, liquid flow and gas flow. This paper focuses on gas flow, both as a fundamental thermal management technique in any future NSTM solution, and also as a basis for understanding more complex liquid and two-phase flow techniques that may also be involved in any NSTM solution. Heat removal by gaseous flow in any NSTM solution may be broken up in four fundamental processes: (1) bulk flow through micro-scale ducts where there may or may not be any heat transfer through the side-walls, (2) interaction of gaseous molecules with duct walls which may be at the same or a different temperature, (3) interaction between gas molecules and any enhanced surfaces such as carbon nanotubes (CNTs) as pin fins, and (4) thermal conduction and distribution in the device substrate. This paper touches upon all four fundamental process of heat removal by gaseous flow in an NSTM solution. Preliminary results from the first three processes are presented whereas a preliminary design and fabrication solution is presented for the fourth process. Preliminary computational results for pressure-driven flow of helium as the coolant gas through a micro-channel duct with a backward facing step are presented as an example for the first process. Backward facing step simulates any change in flow cross-section that may be unavoidable or desirable in any practical NSTM solution. Computation is based on direct simulation Monte Carlo (DSMC), where statistical noise due to low-speed flow is greatly eliminated through the use of the IP technique. Pressure boundary conditions are used in this simulation as they would be more realistic to represent an NSTM application. Preliminary results for computation of tangential momentum accommodation coefficient (TMAC) for helium-wall collisions are presented as an example for the second process. Molecular dynamics (MD) simulation of collisions between helium atoms and copper atoms in a crystallographically perfect copper wall are performed for different ratios between kinetic energy of helium atoms and Lenard-Jones energy of He-Cu interactions. The results are compared to limited experimental results that are available. Preliminary computational results for energy transfer between hydrogen molecules/atoms and a single wall carbon nanotube (SWNT) are presented as an example for the third process. Here MD simulation is employed where high temperature hydrogen molecules are allowed to collide with a SWNT that is initially at a lower temperature. As time progresses, the amount of net energy transfer from the hydrogen molecules to the SWNT is monitored. The result is normalized with the nominal surface area of the SWNT and the driving temperature differential to form coefficient for thermal energy transport (CTET). The values obtained are compared against macroscopic correlations. Deposition of nano-crystalline diamond is proposed as a solution for thermal spreading in the fourth process. Some examples of deposition and the corresponding atomic structure are presented.