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Auswahl der wissenschaftlichen Literatur zum Thema „Thermo precipitation“
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Zeitschriftenartikel zum Thema "Thermo precipitation"
1
Ding, Wen Hong, Bo Jiang, Chao Lei Zhang, Ya Zheng Liu, Li Sun, Tian Wu Liu, Zhi Qiang Zhang und Jin Pan. „Evolution of Carbides during Prestrain and Tempering“. Materials Science Forum 1016 (Januar 2021): 82–87. http://dx.doi.org/10.4028/www.scientific.net/msf.1016.82.
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The effect of thermo-mechanical treatment on the microstructural evolution of low carbon micro-alloyed high strength steel was studied by combining prestrain with tempering (PST) in this paper. It was found that the prestrain causes the dislocation to plug up around the grain boundary and carbide, resulting in carbide boundary fragmentation. Moreover, it breaks the thermo-dynamic equilibrium between the matrix and carbide, induces the dissolution of carbon in the high energy state, and then changes the distribution of carbon in the matrix. In the subsequent tempering process, the precipitation regularity of carbide was changed, which promoted the precipitation carbide at low temperature. The influence of carbide precipitation on dislocation can be divided into two stages: the first stage was precipitation induced creep, which promoted stress relaxation; the second stage was precipitation pinning dislocation, which improved material strength and inhibited stress relaxation.
2
Stechauner, G., und E. Kozeschnik. „Thermo-kinetic modeling of Cu precipitation in α-Fe“. Acta Materialia 100 (November 2015): 135–46. http://dx.doi.org/10.1016/j.actamat.2015.08.042.
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3
Vivas, J., C. Celada-Casero, D. San Martín, M. Serrano, E. Urones-Garrote, P. Adeva, M. M. Aranda und C. Capdevila. „Nano-precipitation Strengthened G91 by Thermo-mechanical Treatment Optimization“. Metallurgical and Materials Transactions A 47, Nr. 11 (06.06.2016): 5344–51. http://dx.doi.org/10.1007/s11661-016-3596-2.
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Joy, Jobin K., Alexandros Solomou, Theocharis Baxevanis, Ibrahim Karaman und Dimitris C. Lagoudas. „Micromechanical Modeling of Precipitation Hardened NiTiHf“. Materials Science Forum 915 (März 2018): 147–56. http://dx.doi.org/10.4028/www.scientific.net/msf.915.147.
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Actuation response of NiTiHf high temperature SMAs can be enhanced by means of suitable heat treatment on the material through precipitation hardening. Heat treatments can be chosen carefully to improve the performance of the NiTiHf SMAs in order to meet the requirements of targeted applications to design more robust and efficient high temperature solid-state actuator systems. The present work aims to develop a novel approach to model and predict the behavior of heat-treated NiTiHf SMAs. The predictions of the thermomechanical response of NiTiHf SMAs are based on Representative Volume Elements (RVEs). The precipitated NiTiHf SMA is modeled as a composite consist of of thermo-elastic non-transforming precipitates and a polycrystalline SMA matrix. The structural effect of precipitates and the effect of Hf-concentration gradient resulted from Hf depletion during precipitation are included. The composition distribution resulting from the elemental depletion and the transformation temperature distributions in the SMA matrix are related. In the present work, these relations are developed from experimental measurements on several NiTiHf compositions. Thermo-mechanical responses of Ni50.3Ti29.7Hf20heat-treated at 500°C for 48h at different loading conditions are predicted and the correlations with experimental results demonstrate the validity of the proposed framework.
5
Raynaud, G. M., und P. Guyot. „Coherent precipitation effect on thermo-power of AlCu alloys“. Acta Metallurgica 36, Nr. 1 (Januar 1988): 143–47. http://dx.doi.org/10.1016/0001-6160(88)90034-x.
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6
Ramesh Babu, Shashank, Matias Jaskari, Antti Jarvenpää, Thomas Paul Davis, Jukka Kömi und David Porter. „Precipitation Versus Partitioning Kinetics during the Quenching of Low-Carbon Martensitic Steels“. Metals 10, Nr. 7 (27.06.2020): 850. http://dx.doi.org/10.3390/met10070850.
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Low-carbon, low-alloy steels undergo auto-tempering and carbon partitioning to austenite during quenching to martensite. The microstructures of two such steels quenched at two cooling rates have been evaluated using electron microscopy to characterise lath and carbide precipitate morphologies, and the results have been compared with theoretical predictions based on the Thermo-Calc modules DICTRA and TC-Prisma. The modelling tools predicted the carbon depletion rates due to diffusion from the bcc martensite laths into austenite and the precipitation of cementite in the ferrite matrix. The predictions showed a satisfactory agreement with the metallographic results, indicating that the Thermo-Calc based software can aid in the design of new low-carbon martensitic steels.
7
Zhu, Yan, Hong Tao Li, Mei Zhang, Yong Zhong und Lin Li. „Hot Deformation Behavior of Nano-Precipitation Strengthening Steel“. Advanced Materials Research 1120-1121 (Juli 2015): 951–57. http://dx.doi.org/10.4028/www.scientific.net/amr.1120-1121.951.
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The hot deformation behavior of nanoprecipitation strengthening steel was studied using a Gleeble-3500 thermo-mechanical simulator. The results show that the peak stress reduces as the temperature increases, and increases as the strain rate increases. The dynamic recrystallization will more likely occur at higher deformation temperature and lower strain rate. The deformation activation energy of the tested steel at 950-1150οC is calculated to be 333.844kJ/mol by regression analysis. Flow stress equation of the tested steel is also established.
8
Mao, Bai Ping, Jun Peng Li und Jian Shen. „Effect of Thermo-Mechanical Heat Treatment on Microstructure and Mechanical Property of 2197 Al-Li Alloy“. Advanced Materials Research 284-286 (Juli 2011): 1621–25. http://dx.doi.org/10.4028/www.scientific.net/amr.284-286.1621.
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Effects of thermo-mechanical treatment on the mechanical properties and microstructure of 2197 alloy were studied through analyses of the mechanical properties by tensile tests and TEM observation of thermo-mechanical heat treated 2197 alloy plates of various states. Results show that the dominating precipitated phase of peak-aged 2197 alloy during thermo-mechanical heat treatment is T1 phase of which the size is 50~150nm. The precipitation and growth of T1 phase are accelerated due to the existed nucleation sites for heterogeneous nucleation of T1 phase offered by thermo-mechanical treatment, therefore, the time for 2197 alloy to reach the peak-aged state is shorten. The strength of 2197 alloy for peak-aged state is increased through thermo-mechanical treatment because the strengthening effect of T1 phase with higher aspect ratio is bigger than that of δ′ and θ′ phases.
9
Webel, Johannes, Adrian Herges, Dominik Britz, Eric Detemple, Volker Flaxa, Hardy Mohrbacher und Frank Mücklich. „Tracing Microalloy Precipitation in Nb-Ti HSLA Steel during Austenite Conditioning“. Metals 10, Nr. 2 (12.02.2020): 243. http://dx.doi.org/10.3390/met10020243.
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The microalloying with niobium (Nb) and titanium (Ti) is standardly applied in low carbon steel high-strength low-alloy (HSLA) steels and enables austenite conditioning during thermo-mechanical controlled processing (TMCP), which results in pronounced grain refinement in the finished steel. In that respect, it is important to better understand the precipitation kinetics as well as the precipitation sequence in a typical Nb-Ti-microalloyed steel. Various characterization methods were utilized in this study for tracing microalloy precipitation after simulating different austenite TMCP conditions in a Gleeble thermo-mechanical simulator. Atom probe tomography (APT), scanning transmission electron microscopy in a focused ion beam equipped scanning electron microscope (STEM-on-FIB), and electrical resistivity measurements provided complementary information on the precipitation status and were correlated with each other. It was demonstrated that accurate electrical resistivity measurements of the bulk steel could monitor the general consumption of solute microalloys (Nb) during hot working and were further complemented by APT measurements of the steel matrix. Precipitates that had formed during cooling or isothermal holding could be distinguished from strain-induced precipitates by corroborating STEM measurements with APT results, because APT specifically allowed obtaining detailed information about the chemical composition of precipitates as well as the elemental distribution. The current paper highlights the complementarity of these methods and shows first results within the framework of a larger study on strain-induced precipitation.
10
Wiehemeier, Lars, Timo Brändel, Yvonne Hannappel, Tilman Kottke und Thomas Hellweg. „Synthesis of smart dual-responsive microgels: correlation between applied surfactants and obtained particle morphology“. Soft Matter 15, Nr. 28 (2019): 5673–84. http://dx.doi.org/10.1039/c9sm00690g.
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Surfactant-assisted precipitation polymerization of N-isopropylacrylamide (NIPAM) and acrylic acid (AAc) is used to make thermo- and pH-responsive copolymer microgels. The type of surfactant is found to have an impact on the particle properties.
Dissertationen zum Thema "Thermo precipitation"
1
Arnold, Lindsay G. „Engineering thermo-responsive affinity ligands for glycoprotein purification by affinity precipitation“. Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53493.
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Effective methods for isolation and purification of glycoproteins are of increasing significance to the rapidly growing biopharmaceutical and diagnostic industry. Glycoproteins represent the majority of therapeutic proteins on the market and are effectively used to treat immune disorders, infections, cancers, and other diseases. Targeting these glycoproteins is also critical to an emerging field of glycoproteomics aimed to understand structure-function relationships of glycans. Architecturally, these glycoproteins are proteins with covalently linked oligosaccharide chains of varying monosaccharide composition. Affinity chromatography has proven to be an excellent method of glycoprotein purification at the bench scale. However, chromatography in large scale production has its drawbacks. Column fowling, flowrate limitations, and diffusional constraints collectively hinder the effectiveness of the method. An alternative proposed in this dissertation is the use of affinity precipitation as a purification technique. The three main objectives are 1) develop and produce dual-functional, thermo-responsive affinity ligands from a biological host, 2) characterize and optimize the accompanying affinity precipitation method, and 3) apply the ligand and process to relevant, unmodified glycoproteins.
The design of the thermo-responsive affinity construct was comprised of two main functional domains. The binding capability was achieved by selection of small ligands with affinity to a specific monosaccharide moiety. Two different lectins, or sugar binding proteins, were used in the fusion design: a fucose binding lectin from Ralstonia solanacearum, and a sialic acid binding lectin from Vibrio cholera. The thermo-responsive functionality was obtained by use of an elastin-like peptide (ELP), which confers inverse solubility relationship properties to the fusion construct. A small library of varying ELP chain lengths were designed to find the optimal size fusion for both production and function. These dual functional ligands were cloned and expressed in the microbial host, E. coli. Furthermore, secretion of these constructs was achieved by employing the Tat secretion pathway in combination with an outer membrane lipoprotein deletion mutant with a leaky periplasm phenotype. This secretory mechanism allows for easy isolation, avoidance of inclusion bodies, and no additional protease inhibitors.
After successful production, the ligands were tested to confirm that dual functionality was preserved in fusion form. Once binding conditions and precipitation properties were ascertained, the purification ability was tested on model glycoproteins. Experimentation was carried out monitoring the purification yield, purity, and retained activity of the target enzymes. High contaminant solutions, such as cell lysates, were spiked with the model glycoproteins to mimic crude protein solutions. The purification ability of the constructs in these models was observed.
The method was then implemented on two relevant glycoprotein applications: 1) purification of soybean peroxidase from a crude protein extract and 2) targeting the therapeutic protein erythropoietin from albumin rich, used CHO cell media. By implementation of the fucose targeting fusion construct, the unmodified soybean peroxidase is isolated from a natural crude extract from the soybean hull, a by-product of the soybean industry. The affinity precipitation method parameters were optimized with respect to ratios, temperatures, recycle, and elution buffers to achieve successful isolation
of the low abundance enzyme. Under the optimized conditions, >95% recovery yield and a purification of 22.7 fold of an active, pure product was attainable.
The purification of erythropoietin led to additional experimentation with high-abundant glycoprotein solutions, as well as expansion of the affinity ligand platform. The concept of multi-lectin affinity precipitation, using the fucose and sialic acid binding lection sequentially, was introduced and tested for purification capability. An industrially relevant scheme involving isolation of the erythropoietin from used CHO cell media allowed for an achievable yield of about 60%, with a resulting albumin depletion of about 85%.
In addition to development of a pair of novel thermo-responsive affinity ligands for glycoprotein purification, this dissertation provides insight on possible improvements and future directions with respect to the thermo-responsive affinity ligand platform. This unique concept employs novel lectin fusions to target valuable glycoproteins using a method avoiding the major drawbacks associated with chromatography.
2
Zhou, Min. „Affinity precipitation using thermo-responsive, water-soluble polymers as matrix; synthetic studies toward the ageliferins“. Texas A&M University, 2003. http://hdl.handle.net/1969.1/1578.
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Isolated from marine sponges, many bromopyrrole alkaloids have become natural products of intense scientific interest. The oroidin-derived class of dimeric bromopyrrole alkaloids that include ageliferin, bromoageliferin, and dibromoageliferin exhibit interesting biological properties, including actomycin ATPase, antiviral and antibacterial activities.
As a prelude to the total synthesis of ageliferin, an intramolecular Diels-Alder (IMDA) reaction was explored as a means to introduce the three contiguous stereocenters. Toward this end, various IMDA precursors were synthesized, and several strategies for the synthesis of IMDA substrates were devised and explored.
Affinity chromatography is a powerful technique that enables the purification of a specific protein from a complex mixture. However, traditional affinity chromatography techniques are somewhat limited due to the solid state of the matrix. To overcome these limitations, the utility of a soluble polymer as an alternative affinity matrix was explored for the isolation of natural product receptors. This polymer displays physical properties that make it an ideal matrix for protein isolation and purification. The parent polymer is soluble in aqueous solution at 4 °C and precipitates once the mixture reaches 32 °C. Furthermore, employing this polymer for affinity chromatography may limit the nonspecific binding of proteins. It is also possible to determine the ligand loading using standard analytical techniques such as 1H and 13C NMR. For proof of concept, a dexamethasone-containing macroligand was synthesized to isolate the known glucocorticoid receptor. In addition, a cyclosporin A-containing macroligand was synthesized and employed to isolate the well known and more robust cyclophilins. In this work, it was demonstrated that indeed the ligand loading can be determined by 1H NMR technique. In addition, it was established, as expected, that the water solubility of the macroligands varies based on the hydrophilicity and hydrophobicity of the ligand and degree of ligand loading.
3
Gado, Moubarak. „Modèle par éléments discrets multi physique du comportement des matériaux métalliques sous sollicitations thermo mécaniques extrêmes“. Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0707/document.
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Les travaux de cette thèse concernent le développement d’un modèle par éléments discrets du comportement thermo-mécanique d’un alliage d’aluminium et de son évolution microstructurale lorsqu’il est soumis à des conditions de grandes déformations et/ou de grandes vitesses de déformation (soudage par friction-malaxageou FSW). Le procédé de « soudage par friction malaxage » (Friction Stir Welding,FSW) est un procédé de soudage récent, inventé en 1991 par « The Welding Institute (TWI) ». Ce procédé se distingue des autres par sa capacité à souder la matière à l’état visqueux, sans atteindre le point de fusion. Le principe est relativement simple et comparable à une opération de fraisage, si ce n’est que l’outil coupant est remplacé par un outil malaxant composé d’un pion et d’un épaulement. Ce procédé revêt un fort intérêt pour l’industrie aéronautique, car il offre la possibilité de souder des alliages d’aluminium des séries 2XXX et 7XXX, réputés difficiles à souder par d’autres procédés.Le soudage par friction-malaxage étant un procédé récent, il demeure encore un sujet de recherche actif, pour mieux appréhender certains points comme l’écoulement de la matière, l’influence des paramètres du procédé (vitesse de rotation, forme de l’outil, ...)et la modification de la microstructure. Ce dernier point est particulièrement important pour les alliages à durcissement structural comme ceux des séries 2XXX et 7XXX. Pour ces alliages d’aluminium, les propriétés mécaniques dépendent étroitement de leur état de précipitation, lui-même influencé par l’apport de chaleur généré lors du soudage.L’optimisation des paramètres de soudage par rapport aux propriétés mécaniques passe obligatoirement par la prédiction de l’état de la précipitation le long du joint soudé. Le travail de la thèse vise à mettre en place des modèles à l’échelle de la microstructure permettant de prévoir la modification des propriétés de la matière liées aux paramètres du procédéThe work of this thesis concerns the development of a model using the discrete element method, for the thermo-mechanical behavior of an aluminum alloy and its microstructural evolution when exposed to conditions of large deformations and/or high deformation rates (Friction StirWelding or FSW). Friction stir welding is a recent welding process invented in 1991 by "The welding Institute" (TWI). This process is different from the others by its ability to weld material in the viscous state, without reaching the melting point. The principle is relatively simple and similar to a milling process except that the cutting tool is replaced by a rotary tool composed of a pin and a shoulder. This process is of great interest in the aircraft industry because it offers the possibility to weld aluminum alloys 2XXX and 7XXX series, known to be difficult to weld by other processes. Since friction stir welding is a recent process, it still remains a subject of active research, to better understand certain issues such as material flow, influence of process parameters (rotation speed, tool shape, ...) and the modification of the microstructure. This last point is particularly important for structural hardening alloys such as those of the 2XXX and 7XXX series. For these aluminum alloys, the mechanical properties are highly dependent on their state of precipitation, which is itself influenced by the heat generated during thewelding. The optimization ofwelding parameters in order to obtain good mechanical properties requires the prediction of precipitation state along thewelded joint. Thework of this thesis is to develop required models at the scale of microstructure allowing to predict the modification of material properties related to the process parameters
4
Gabriel, Jindřich. „Optimalizace metody pro hodnocení špinivosti ETICS“. Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2021. http://www.nusl.cz/ntk/nusl-444260.
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This diploma thesis deals with the issue of adhesion of pollution to the final surface treatments of the ETICS system. The theoretical part deals with important factors and processes that affect the degree of adhesion of pollution. The practical part of the diploma thesis follows the diploma thesis of Ing. Jakub Krejčík. Optimization of test methods for simulation of artificial pollution on tested samples was proposed. These samples were then evaluated in the laboratory and also compared with plasters that were exposed to real pollution from the natural environment.
5
Nicol, Alison. „Aspects of copper precipitation and irradiation hardening in Fe-Cu alloys“. Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325841.
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6
Cavasotto, Thiago. „Obtenção e caracterização de óxido de cério, obtido a partir da decomposição térmica do tris(8-hidroxiquinolinato)cério(III)“. Universidade Tecnológica Federal do Paraná, 2015. http://repositorio.utfpr.edu.br/jspui/handle/1/1503.
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CAPESNo presente trabalho foi estudado a influência do pH final de precipitação, tempo e modo de agitação, onde foi avaliado o modo de agitação mecânico e por ultrassom na obtenção do dióxido de cério. Para a otimização do processo, fez-se o uso de uma ferramenta chamada Planejamento Fatorial, na qual, a partir dos dados experimentais fornece uma estimativa para melhores condições levando em consideração uma variável resposta. As variáveis resposta adotadas no trabalho foram Temperatura Final de Decomposição e Tamanho médio de Partícula. O dióxido de cério foi obtido a partir da decomposição térmica do complexo tris(8-hidroxiquinolinato)cério(III), que foi sintetizado por meio da técnica de precipitação química, empregando o quelante 8-hidroxiquinolina e caracterizado por meio de espectroscopia na região do infravermelho (FTIR) e microscopia eletrônica de varredura (MEV), foi também realizado o estudo do comportamento térmico do complexo, com auxílio da térmogravimetria (TG), térmogravimetria derivada (DTG) e análise térmica diferencial (DTA); o dióxido de cério foi caracterizado por meio de FTIR e difratometria de raios X (DRX), a partir dos dados de DRX foi calculado o tamanho médio de partículas com o auxílio da fórmula de Scherrer. O Planejamento Fatorial indicou para variável resposta Temperatura Final de Decomposição, que para ambos modos de agitação as melhores condições de síntese são para maiores valores de pH´s finais de precipitação, o tempo de agitação não teve influência significativa a 95% de significância, dentro da faixa estudada. Para variável resposta Tamanho Médio de Partícula, o teste mostrou para os dois modos de agitação, que nenhuma das variáveis teve influência significativa a 95% de significância, dentro da faixa estudada, atribuindo então o tamanho médio de partículas somente ao método de síntese. Não houve diferença significativa entre os modos de agitação também.
In the present work, it was investigated the influence of the final pH of precipitation, agitation time and mode of agitation, which assessed the mechanical agitation mode and ultrasound to obtain the cerium dioxide. For process optimization, it was used a tool called Planning Factor, which provides an estimative of better conditions, considering a response variable from the experimental data. The responsible variable adopted in this work was Decomposition Final Temperature and Particle Average Size. The cerium dioxide was obtained from the thermal decomposition of the complex tris (8-hydroxyquinolinate) cerium (III), synthesized by chemical precipitation using 8-hydroxyquinolinechelator and characterized by infrared spectroscopy (FTIR) and scanning electronic microscopy (SEM). In addition, it was performed the study of the complex thermal behavior with assistance of thermogravimetry (TG), derivative thermogravimetry (DTG) and differential thermal analysis (DTA); The cerium dioxide was characterized by FTIR and X-ray diffraction (XRD), in which it was based to the determination of the particle average size using Scherrer's formula. The Factorial design pointed out to response variable Decomposition Final temperature that, for both modes of agitation, the best synthesis conditions are for higher values of final pH's precipitation. Also, the stirring time had no significant influence when used the 95% significance studied range. For response variable Average Size, the test pointed out to both ways of stirring, when none of the variables had significant influence at 95% significance within the studied range, assigning the average particle size only to the method of synthesis. Thereby, there was no significant difference between the stirring modes.
7
Marinin, Aleksandr. „Synthesis and characterization of superparamagnetic iron oxide nanoparticles coated with silica“. Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-121520.
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Multifunctional superparamagnetic iron oxide nanoparticles (SPIONs) coated with silica are a promising research field for lots of biomedical applications. The scope of this work is a preparation of SPIONs and coating them with silica to form core-shell structured nanoparticles for nanomedicine applications. SPIONs were synthesized by two chemical methods – co-precipitation and thermal decomposition of organic iron precursor. Prepared nanoparticles were carefully characterized –average size, size distribution, morphology, crystallinity, colloidal stability and magnetic properties were studied. After comparing SPIONs synthetized by two routes the most suitable method for biomedical applicable nanoparticles preparation is determined. The nanomedicine requires nanoparticles of the highest quality. The next step was coating SPIONs with silica shell. For this purpose inverse microemulsion method was chosen. TEOS was used as a silica precursor. Mean size, size distribution, magnetic properties, structure of silica shell were studied.
8
Grosset, Lisa. „Développement et validation d’un modèle de vieillissement thermique d’alliages d’aluminium pour application aéronautique“. Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEM010.
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Les exigences des clients du secteur aéronautique imposent aux entreprises de prendre en compte pour le dimensionnement les effets de la température sur toute la durée de vie du produit. Cependant, aucune loi ne permet actuellement de prévoir l’impact du vieillissement thermique sur le comportement des matériaux. Ce travail a pour objectif de comprendre le mécanisme de vieillissement thermique des alliages d’aluminium et son impact sur les propriétés mécaniques, mais surtout d’acquérir un outil performant capable d’obtenir rapidement des données matériaux après vieillissement.Au cours de cette étude, de nombreuses analyses microstructurales et mécaniques ont été réalisées sur trois alliages d’aluminium à durcissement structural. Différentes combinaisons temps-température de vieillissement ont été testées afin de disposer d’une large base de données sur ces matériaux (caractéristiques mécaniques statiques Rm, Rp0,2 et dureté et tailles des précipités durcissants). Ces données ont ensuite été compilées dans un modèle de vieillissement basé sur les théories classiques de durcissement structural, de croissance et de coalescence des précipités.Le modèle de vieillissement créé répond au besoin initial et prédit de façon conservative le comportement mécanique des alliages ayant subi un vieillissement thermique isotherme. Des axes d’amélioration sont envisagés pour ce modèle évolutif, comme l’intégration de la prévision du comportement en fatigue ainsi que le traitement de cas anisothermes pour une représentation plus réelle des conditions de service des pièces aéronautiquesIn aeronautics, customers ask companies to consider the effects of temperature over the entire life of the product in structural requirements. Indeed, aircraft parts are demanded to last longer (up to 90 000 hours) and operate at higher temperatures (up to 250°C). No laws enable to predict the impact of thermal ageing on materials behavior. Current practices are to perform mechanical testing after ageing in ovens at various temperatures, but they are expensive and incompatible with the development schedules. This work aims to understand the thermal aging mechanism of aluminum alloys and its impact on mechanical properties, but especially to acquire a powerful tool able to quickly obtain material data after aging.During this study, many microstructural and mechanical analyses were conducted on three precipitation hardened aluminum alloys. Different combinations of aging time and temperature were tested to get a large database of these materials (static mechanical characteristics Rm, Rp0,2 and hardness and sizes of hardening precipitates). These data were then compiled into a computing aging model based on the classical theories of precipitation hardening, growth and coarsening of precipitates.The created aging model responds to the initial need and can conservatively predict the mechanical behavior of aluminum alloys under isothermal aging. Improvement areas are considered for this evolutionary model, such as the integration of fatigue behavior prediction and the inclusion of thermal cycles for a more realistic representation of service conditions of aircraft parts
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Vural, Irem. „Synthesis Of Zirconium Tungstate And Its Use In Composites With Tunable Thermal Expansion Coefficient“. Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12612973/index.pdf.
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Thermal mismatch between different components of a system could be sources of problems like residual stress induced cracking, thermal fatigue or even optical misalignment in certain high technology applications. Use of materials with tailored thermal expansion coefficient is a counter-measure to overcome such problems. With its negative thermal expansion coefficient zirconium tungstate (ZrW2O8) is a candidate component to be used in synthesis of composites with controlled thermal expansion coefficient (CTE).
ZrW2O8 is typically produced by solid-state reaction between zirconium oxide and tungsten oxide at 1200oC. However, it has been demonstrated that ZrW2O8 can also be synthesized using wet chemical techniques, which provide a superior chemical homogeneity that often extents down to the atomic scale, and the convenient means of controlling nucleation and growth of the primary crystallites. With the commonly adopted wet chemical approaches, it is possible to crystallize particles with sizes in the submicrometer range at temperatures as low as 600 oC or even lower. In these studies, precursors are aged either below 100 oC (7 days &ndash3 weeks), or at 160-180 oC under hydrothermal conditions (1&ndash
2 days). Besides the obvious disadvantage in the ageing steps, use of tungsten sources with high cost in all approaches, constitutes the other disadvantage. Production of composites with tunable controlled thermal expansion (CTE) has been achieved by blending negatively and positively expanding materials in different proportions. In majority of these studies composites have been produced by conventional sintering methods. Spark Plasma Sintering (SPS) is a recent technique
in which sintering can be achieved at relatively low temperatures in short durations. There is only one study made by Kanamori and coworkers on the use of SPS in sintering of a composite, in which ZrW2O8 is one of the constituents [1]. This study aims the synthesis of ZrW2O8 particles and composites that possess tunable or zero CTE. A novel precursor recipe for ZrW2O8 synthesis was developed. In preparation of the precursor a total of 2 days of ageing and a temperature less than 100 oC was used. It was developed using a cost-effective tungsten source, namely tungstic acid and its final pH was lower than 1. The particles obtained from &lsquo
unwashed&rsquo
procedure had sizes in micrometer range, while those obtained from &lsquo
washed&rsquo
case had sizes in the range of 400-600 nm. These precursors could readily be crystallized at 600 oC, which in turn provided the desired particle sizes for composite applications. Experimental details on the precursor development are hereby presented with a discussion on the effects of solution parameters (i.e. solubility of tungstic acid, adjustment of the stoichiometry, ageing time) on the phase purity of the fired product. Zirconium oxide (ZrO2) has positive vi thermal expansion, therefore ZrW2O8/ZrO2 was selected as the composite system, and for their synthesis both conventional and spark plasma sintering methods were experimented. Composition ranges that provide composites with almost zero CTE&rsquo
s were determined. The composite having a composition of containing 35% ZrW2O8, 65% ZrO2, and 35 w/o Al2O3 and sintered at 1200 oC for 24 hours had an expansion coefficient of 0.20 x 10-6/K for conventional method, while the one having a composition of 55% ZrW2O8, 45% ZrO2 and sintered at 1000 oC for 5 minutes had an expansion coefficient of 0.94 x 10-6/K for spark plasma sintering method. For characterization of the products X-ray diffraction (XRD), scanning electron microscopy (SEM), photon correlation spectroscopy (PCS), and thermal and dilatometer analyses (DTA/TGA/DMA) were used.
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Maphangwa, Khumbudzo Walter. „Lichen thermal sensitivities, moisture interception and elemental accumulation in an arid South African ecosystem“. Thesis, University of the Western Cape, 2010. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_7139_1307950118.
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Elevated temperatures accompanying climate warming are expected to have adverse effects on sensitive lichen species. This premise was examined by measuring the sensitivity of different lichen species to elevated temperatures in the laboratory and in the field. Laboratory studies involved the exposure of nine hydrated lichen species (Xanthoparmelia austro-africana, X. hyporhytida, Xanthoparmelia sp., Xanthomaculina hottentotta, Teloschistes capensis, Ramalina sp., Flavopuntelia caperata, Lasallia papulosa, Parmotrema austrosinensis) collected from sites of different aridity and mean annual temperature for 2 hourly intervals to temperatures ranging from 24º
C to 48º
C in a forced daft oven and measuring their respiration rates and maximum quantum yield of PSII. Field studies involved simultaneous hourly measurements of ground surface air temperatures and Lichen effective quantum yield of PSII of hydrated lichen species populations under ambient and artificially modified environmental conditions.
Bücher zum Thema "Thermo precipitation"
1
Emerson, Douglas G. A heat and water transfer model for seasonally frozen soils with application to a precipitation-runoff model. Washington, D.C: U.S. G.P.O., 1994.
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2
Ellis, David L. Precipitation strengthened high strength, high conductivity Cu-Cr-Nb alloys produced by chill block melt spinning. [Washington, D.C.]: National Aeronautics and Space Administration, 1989.
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3
Räisänen, Jouni. Future Climate Change in the Baltic Sea Region and Environmental Impacts. Oxford University Press, 2017. http://dx.doi.org/10.1093/acrefore/9780190228620.013.634.
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The warming of the global climate is expected to continue in the 21st century, although the magnitude of change depends on future anthropogenic greenhouse gas emissions and the sensitivity of climate to them. The regional characteristics and impacts of future climate change in the Baltic Sea countries have been explored since at least the 1990s. Later research has supported many findings from the early studies, but advances in understanding and improved modeling tools have made the picture gradually more comprehensive and more detailed. Nevertheless, many uncertainties still remain.In the Baltic Sea region, warming is likely to exceed its global average, particularly in winter and in the northern parts of the area. The warming will be accompanied by a general increase in winter precipitation, but in summer, precipitation may either increase or decrease, with a larger chance of drying in the southern than in the northern parts of the region. Despite the increase in winter precipitation, the amount of snow is generally expected to decrease, as a smaller fraction of the precipitation falls as snow and midwinter snowmelt episodes become more common. Changes in windiness are very uncertain, although most projections suggest a slight increase in average wind speed over the Baltic Sea. Climatic extremes are also projected to change, but some of the changes will differ from the corresponding change in mean climate. For example, the lowest winter temperatures are expected to warm even more than the winter mean temperature, and short-term summer precipitation extremes are likely to become more severe, even in the areas where the mean summer precipitation does not increase.The projected atmospheric changes will be accompanied by an increase in Baltic Sea water temperature, reduced ice cover, and, according to most studies, reduced salinity due to increased precipitation and river runoff. The seasonal cycle of runoff will be modified by changes in precipitation and earlier snowmelt. Global-scale sea level rise also will affect the Baltic Sea, but will be counteracted by glacial isostatic adjustment. According to most projections, in the northern parts of the Baltic Sea, the latter will still dominate, leading to a continued, although decelerated, decrease in relative sea level. The changes in the physical environment and climate will have a number of environmental impacts on, for example, atmospheric chemistry, freshwater and marine biogeochemistry, ecosystems, and coastal erosion. However, future environmental change in the region will be affected by several interrelated factors. Climate change is only one of them, and in many cases its effects may be exceeded by other anthropogenic changes.
4
Norrgård, Stefan. Changes in Precipitation Over West Africa During Recent Centuries. Oxford University Press, 2017. http://dx.doi.org/10.1093/acrefore/9780190228620.013.536.
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Water, not temperature, governs life in West Africa, and the region is both temporally and spatially greatly affected by rainfall variability. Recent rainfall anomalies, for example, have greatly reduced crop productivity in the Sahel area. Rainfall indices from recent centuries show that multidecadal droughts reoccur and, furthermore, that interannual rainfall variations are high in West Africa. Current knowledge of historical rainfall patterns is, however, fairly limited. A detailed rainfall chronology of West Africa is currently only available from the beginning of the 19th century. For the 18th century and earlier, the records are still sporadic, and an interannual rainfall chronology has so far only been obtained for parts of the Guinea Coast. Thus, there is a need to extend the rainfall record to fully understand past precipitation changes in West Africa.The main challenge when investigating historical rainfall variability in West Africa is the scarcity of detailed and continuous data. Readily available meteorological data barely covers the last century, whereas in Europe and the United States for example, the data sometimes extend back two or more centuries. Data availability strongly correlates with the historical development of West Africa. The strong oral traditions that prevailed in the pre-literate societies meant that only some of the region’s history was recorded in writing before the arrival of the Europeans in the 16th century. From the 19th century onwards, there are, therefore, three types of documents available, and they are closely linked to the colonization of West Africa. These are: official records started by the colonial governments continuing to modern day; regular reporting stations started by the colonial powers; and finally, temporary nongovernmental observations of various kinds. For earlier periods, the researcher depends on noninstrumental observations found in letters, reports, or travel journals made by European slave traders, adventurers, and explorers. Spatially, these documents are confined to the coastal areas, as Europeans seldom ventured inland before the mid-1800s. Thus, the inland regions are generally poorly represented. Arabic chronicles from the Sahel provide the only source of information, but as historical documents, they include several spatiotemporal uncertainties. Climate researchers often complement historical data with proxy-data from nature’s own archives. However, the West African environment is restrictive. Reliable proxy-data, such as tree-rings, cannot be exploited effectively. Tropical trees have different growth patterns than trees in temperate regions and do not generate growth rings in the same manner. Sediment cores from Lake Bosumtwi in Ghana have provided, so far, the best centennial overview when it comes to understanding precipitation patterns during recent centuries. These reveal that there have been considerable changes in historical rainfall patterns—West Africa may have been even drier than it is today.
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Nash, David. Changes in Precipitation Over Southern Africa During Recent Centuries. Oxford University Press, 2017. http://dx.doi.org/10.1093/acrefore/9780190228620.013.539.
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Precipitation levels in southern Africa exhibit a marked east–west gradient and are characterized by strong seasonality and high interannual variability. Much of the mainland south of 15°S exhibits a semiarid to dry subhumid climate. More than 66 percent of rainfall in the extreme southwest of the subcontinent occurs between April and September. Rainfall in this region—termed the winter rainfall zone (WRZ)—is most commonly associated with the passage of midlatitude frontal systems embedded in the austral westerlies. In contrast, more than 66 percent of mean annual precipitation over much of the remainder of the subcontinent falls between October and March. Climates in this summer rainfall zone (SRZ) are dictated by the seasonal interplay between subtropical high-pressure systems and the migration of easterly flows associated with the Intertropical Convergence Zone. Fluctuations in both SRZ and WRZ rainfall are linked to the variability of sea-surface temperatures in the oceans surrounding southern Africa and are modulated by the interplay of large-scale modes of climate variability, including the El Niño-Southern Oscillation (ENSO), Southern Indian Ocean Dipole, and Southern Annular Mode.Ideas about long-term rainfall variability in southern Africa have shifted over time. During the early to mid-19th century, the prevailing narrative was that the climate was progressively desiccating. By the late 19th to early 20th century, when gauged precipitation data became more readily available, debate shifted toward the identification of cyclical rainfall variation. The integration of gauge data, evidence from historical documents, and information from natural proxies such as tree rings during the late 20th and early 21st centuries, has allowed the nature of precipitation variability since ~1800 to be more fully explored.Drought episodes affecting large areas of the SRZ occurred during the first decade of the 19th century, in the early and late 1820s, late 1850s–mid-1860s, mid-late 1870s, earlymid-1880s, and mid-late 1890s. Of these episodes, the drought during the early 1860s was the most severe of the 19th century, with those of the 1820s and 1890s the most protracted. Many of these droughts correspond with more extreme ENSO warm phases.Widespread wetter conditions are less easily identified. The year 1816 appears to have been relatively wet across the Kalahari and other areas of south central Africa. Other wetter episodes were centered on the late 1830s–early 1840s, 1855, 1870, and 1890. In the WRZ, drier conditions occurred during the first decade of the 19th century, for much of the mid-late 1830s through to the mid-1840s, during the late 1850s and early 1860s, and in the early-mid-1880s and mid-late 1890s. As for the SRZ, markedly wetter years are less easily identified, although the periods around 1815, the early 1830s, mid-1840s, mid-late 1870s, and early 1890s saw enhanced rainfall. Reconstructed rainfall anomalies for the SRZ suggest that, on average, the region was significantly wetter during the 19th century than the 20th and that there appears to have been a drying trend during the 20th century that has continued into the early 21st. In the WRZ, average annual rainfall levels appear to have been relatively consistent between the 19th and 20th centuries, although rainfall variability increased during the 20th century compared to the 19th.
6
Farmakis, Dimitrios, John Parissis und Gerasimos Filippatos. Acute heart failure: epidemiology, classification, and pathophysiology. Oxford University Press, 2015. http://dx.doi.org/10.1093/med/9780199687039.003.0051.
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Acute heart failure is defined as the rapid development or change of symptoms and signs of heart failure that requires urgent medical attention and usually hospitalization. Acute heart failure is the first reason for hospital admission in individuals aged 65 or more and accounts for nearly 70% of the total health care expenditure for heart failure. It is characterized by an adverse prognosis, with an in-hospital mortality rate of 4-7%, a 2-3-month post-discharge mortality of 7-11%, and a 2-3-month readmission rate of 25-30%. The majority of patients have a previous history of heart failure and present with normal or increased blood pressure, while about half of them have a preserved left ventricular ejection fraction. A high prevalence of cardiovascular or non-cardiovascular comordid conditions is further observed, including coronary artery disease, arterial hypertension, atrial fibrillation, diabetes mellitus, renal dysfunction, chronic lung disease, and anaemia. Different classification systems have been proposed for acute heart failure, reflecting the clinical heterogeneity of the syndrome; the categorization to acutely decompensated chronic heart failure vs de novo acute heart failure and to hypertensive, normotensive, and hypotensive acute heart failure are among the most widely used and clinically relevant classifications. The pathophysiology of acute heart failure involves several pathogenetic mechanisms, including volume overload, pressure overload, myocardial loss, and restrictive filling, while several cardiovascular and non-cardiovascular causes or precipitating factors lead to acute heart failure through a single of these mechanisms or a combination of them. Regardless of the underlying mechanism, peripheral and/or pulmonary congestion is the hallmark of acute heart failure, resulting from fluid retention and/or fluid redistribution. Myocardial injury and renal dysfunction are also involved in the precipitation and progression of the syndrome.
7
Christensen, Ole Bøssing, und Erik Kjellström. Projections for Temperature, Precipitation, Wind, and Snow in the Baltic Sea Region until 2100. Oxford University Press, 2018. http://dx.doi.org/10.1093/acrefore/9780190228620.013.695.
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The ecosystems and the societies of the Baltic Sea region are quite sensitive to fluctuations in climate, and therefore it is expected that anthropogenic climate change will affect the region considerably. With numerical climate models, a large amount of projections of meteorological variables affected by anthropogenic climate change have been performed in the Baltic Sea region for periods reaching the end of this century.Existing global and regional climate model studies suggest that:• The future Baltic climate will get warmer, mostly so in winter. Changes increase with time or increasing emissions of greenhouse gases. There is a large spread between different models, but they all project warming. In the northern part of the region, temperature change will be higher than the global average warming.• Daily minimum temperatures will increase more than average temperature, particularly in winter.• Future average precipitation amounts will be larger than today. The relative increase is largest in winter. In summer, increases in the far north and decreases in the south are seen in most simulations. In the intermediate region, the sign of change is uncertain.• Precipitation extremes are expected to increase, though with a higher degree of uncertainty in magnitude compared to projected changes in temperature extremes.• Future changes in wind speed are highly dependent on changes in the large-scale circulation simulated by global climate models (GCMs). The results do not all agree, and it is not possible to assess whether there will be a general increase or decrease in wind speed in the future.• Only very small high-altitude mountain areas in a few simulations are projected to experience a reduction in winter snow amount of less than 50%. The southern half of the Baltic Sea region is projected to experience significant reductions in snow amount, with median reductions of around 75%.
8
Dunlop, Storm. 4. Water in the atmosphere. Oxford University Press, 2017. http://dx.doi.org/10.1093/actrade/9780199571314.003.0004.
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Among the planets in the Solar System, Earth is unique in possessing large quantities of water, and water’s properties are highly significant in determining weather. This is because water readily exists in three different phases (ice, liquid water, and water vapour) at temperatures frequently encountered on Earth. ‘Water in the atmosphere’ explains humidity and saturation: the number of molecules of water vapour in the air is determined solely by temperature. Unstable conditions lead to the formation of cumuliform clouds and precipitation is created by either glaciation or coalescence. There are three groups of clouds—cumuliform, stratiform, and cirriform—with ten types of cloud identified based on their altitude and structure.
9
Gao, Yanhong, und Deliang Chen. Modeling of Regional Climate over the Tibetan Plateau. Oxford University Press, 2017. http://dx.doi.org/10.1093/acrefore/9780190228620.013.591.
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The modeling of climate over the Tibetan Plateau (TP) started with the introduction of Global Climate Models (GCMs) in the 1950s. Since then, GCMs have been developed to simulate atmospheric dynamics and eventually the climate system. As the highest and widest international plateau, the strong orographic forcing caused by the TP and its impact on general circulation rather than regional climate was initially the focus. Later, with growing awareness of the incapability of GCMs to depict regional or local-scale atmospheric processes over the heterogeneous ground, coupled with the importance of this information for local decision-making, regional climate models (RCMs) were established in the 1970s. Dynamic and thermodynamic influences of the TP on the East and South Asia summer monsoon have since been widely investigated by model. Besides the heterogeneity in topography, impacts of land cover heterogeneity and change on regional climate were widely modeled through sensitivity experiments.In recent decades, the TP has experienced a greater warming than the global average and those for similar latitudes. GCMs project a global pattern where the wet gets wetter and the dry gets drier. The climate regime over the TP covers the extreme arid regions from the northwest to the semi-humid region in the southeast. The increased warming over the TP compared to the global average raises a number of questions. What are the regional dryness/wetness changes over the TP? What is the mechanism of the responses of regional changes to global warming? To answer these questions, several dynamical downscaling models (DDMs) using RCMs focusing on the TP have recently been conducted and high-resolution data sets generated. All DDM studies demonstrated that this process-based approach, despite its limitations, can improve understandings of the processes that lead to precipitation on the TP. Observation and global land data assimilation systems both present more wetting in the northwestern arid/semi-arid regions than the southeastern humid/semi-humid regions. The DDM was found to better capture the observed elevation dependent warming over the TP. In addition, the long-term high-resolution climate simulation was found to better capture the spatial pattern of precipitation and P-E (precipitation minus evapotranspiration) changes than the best available global reanalysis. This facilitates new and substantial findings regarding the role of dynamical, thermodynamics, and transient eddies in P-E changes reflected in observed changes in major river basins fed by runoff from the TP. The DDM was found to add value regarding snowfall retrieval, precipitation frequency, and orographic precipitation.Although these advantages in the DDM over the TP are evidenced, there are unavoidable facts to be aware of. Firstly, there are still many discrepancies that exist in the up-to-date models. Any uncertainty in the model’s physics or in the land information from remote sensing and the forcing could result in uncertainties in simulation results. Secondly, the question remains of what is the appropriate resolution for resolving the TP’s heterogeneity. Thirdly, it is a challenge to include human activities in the climate models, although this is deemed necessary for future earth science. All-embracing further efforts are expected to improve regional climate models over the TP.
10
Cook, Kerry H. Climate Change Scenarios and African Climate Change. Oxford University Press, 2018. http://dx.doi.org/10.1093/acrefore/9780190228620.013.545.
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Accurate projections of climate change under increasing atmospheric greenhouse gas levels are needed to evaluate the environmental cost of anthropogenic emissions, and to guide mitigation efforts. These projections are nowhere more important than Africa, with its high dependence on rain-fed agriculture and, in many regions, limited resources for adaptation. Climate models provide our best method for climate prediction but there are uncertainties in projections, especially on regional space scale. In Africa, limitations of observational networks add to this uncertainty since a crucial step in improving model projections is comparisons with observations. Exceeding uncertainties associated with climate model simulation are uncertainties due to projections of future emissions of CO2 and other greenhouse gases. Humanity’s choices in emissions pathways will have profound effects on climate, especially after the mid-century.The African Sahel is a transition zone characterized by strong meridional precipitation and temperature gradients. Over West Africa, the Sahel marks the northernmost extent of the West African monsoon system. The region’s climate is known to be sensitive to sea surface temperatures, both regional and global, as well as to land surface conditions. Increasing atmospheric greenhouse gases are already causing amplified warming over the Sahara Desert and, consequently, increased rainfall in parts of the Sahel. Climate model projections indicate that much of this increased rainfall will be delivered in the form of more intense storm systems.The complicated and highly regional precipitation regimes of East Africa present a challenge for climate modeling. Within roughly 5º of latitude of the equator, rainfall is delivered in two seasons—the long rains in the spring, and the short rains in the fall. Regional climate model projections suggest that the long rains will weaken under greenhouse gas forcing, and the short rains season will extend farther into the winter months. Observations indicate that the long rains are already weakening.Changes in seasonal rainfall over parts of subtropical southern Africa are observed, with repercussions and challenges for agriculture and water availability. Some elements of these observed changes are captured in model simulations of greenhouse gas-induced climate change, especially an early demise of the rainy season. The projected changes are quite regional, however, and more high-resolution study is needed. In addition, there has been very limited study of climate change in the Congo Basin and across northern Africa. Continued efforts to understand and predict climate using higher-resolution simulation must be sustained to better understand observed and projected changes in the physical processes that support African precipitation systems as well as the teleconnections that communicate remote forcings into the continent.
Buchteile zum Thema "Thermo precipitation"
1
Yasuhara, H., N. Kinoshita, H. Kurikami, S. Nakashima und K. Kishida. „Evolution of Permeability in Siliceous Rocks by Dissolution and Precipitation Under Hydrothermal Conditions“. In Thermo-Hydromechanical and Chemical Coupling in Geomaterials and Applications, 457–64. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118623565.ch46.
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2
Huan, Li, Zhu Tianle, Tang Ping und Xing Xuan. „Gaseous Elemental Mercury Oxidation by Non-thermal Plasma“. In Electrostatic Precipitation, 699–703. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-89251-9_146.
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3
Oda, Tetsuji, Hikaru Kuramochi und Ryo Ono. „Non-thermal Plasma Processing for Dilute VOCs Decomposition Combined with the Catalyst“. In Electrostatic Precipitation, 638–43. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-89251-9_132.
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4
Chen, Ming-Gong, Adrian Mihalcioiu, Kazunori Takashima und Akira Mizuno. „Catalyst Size Impact on Non-Thermal Plasma Catalyst Assisted deNO x Reactors“. In Electrostatic Precipitation, 681–84. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-89251-9_142.
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5
Inbakumar, S., und A. Anukaliani. „Surface Modification of Polestar Fabrics by Non-thermal Plasma for Improving Hydrophilic Properties“. In Electrostatic Precipitation, 718–22. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-89251-9_150.
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6
Robson, Joseph D. „Modelling Dispersoid Precipitation in Scandium Containing Aluminium Alloys“. In THERMEC 2006, 386–91. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-428-6.386.
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7
Jun, Hyun J., Raghavan Ayer, Thirumalai Neeraj und Russell Steel. „Friction Stir Welding of Precipitation Hardened Ni Based Alloys“. In THERMEC 2006, 3763–68. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-428-6.3763.
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8
Perez, Michel, Eglantine Courtois, Daniel Acevedo Reyes, Thierry Epicier und Philippe Maugis. „Precipitation of Niobium Carbonitrides: Chemical Composition Measurements and Modeling“. In THERMEC 2006, 4196–201. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-428-6.4196.
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9
Ide, Shinsuke, Yoshimasa Funakawa, Yasushi Kato und Osamu Furukimi. „Retardation of 20%Cr Steel Oxidation with Laves Phase Precipitation“. In THERMEC 2006, 4887–90. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-428-6.4887.
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10
Xu, W., D. San Martin, Pedro E. J. Rivera Díaz del Castillo und Sybrand van der Zwaag. „Modelling Chi-Phase Precipitation in High Molybdenum Stainless Steels“. In THERMEC 2006 Supplement, 531–36. Stafa: Trans Tech Publications Ltd., 2006. http://dx.doi.org/10.4028/0-87849-429-4.531.
Der volle Inhalt der QuelleKonferenzberichte zum Thema "Thermo precipitation"
1
Cox, Austin, Theocharis Baxevanis und Dimitris Lagoudas. „Numerical Evaluation of the Effect of Ni4Ti3 Precipitates on the Overall Thermo-Mechanical Response of NiTi Shape Memory Alloys“. In ASME 2013 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/smasis2013-3183.
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The effect of precipitation on the thermo-mechanical properties of Ni-rich near-equiatomic NiTi Shape Memory Alloys (SMAs) is investigated via the finite element method. The thermo-mechanical response is simulated using a Representative Volume Element (RVE), which takes into account the structural effect of the precipitates, as well as the effect of the Ni-concentration gradient in the matrix. The Ni-distribution profile is evaluated using Fick’s law for diffusion. The obtained results reproduce several of the experimentally observed precipitation-induced changes on the transformation behavior characteristics of these materials.
2
Dong, Xianping, Lin Zhao, Feng Sun und Lanting Zhang. „Strengthening of an Al-Containing Austenitic Stainless Steel at High Temperature“. In ASME Turbo Expo 2013: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gt2013-95494.
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Three Al-containing austenitic steels with slightly different contents of Nb, V and C in the Fe-19.95Ni-14.19Cr-2.25Al-2.46Mo-1.95Mn-0.15Si-0.01B (wt.%) system were designed to study the effect of precipitations on creep/rupture resistance. After induction melting, alloys were cast into a metal mold followed by thermo-mechanical treatment. A continuous Al-rich oxide scale was formed on the surface after exposure at 800°C for 146 hrs in air. By decreasing the C content from 0.07 to 0.04%, coarse NbC precipitates in the as-cast microstructure could be removed during annealing treatment. Thermo-mechanical treatment enabled nano-scale precipitation of NbC in the alloys containing 0.04% C. Although the yield strength of the alloy with 0.07% C was relatively high at 750°C, its creep/rupture life was 164 hrs at 700°C/150 MPa. Alloys having low carbon content formed a uniform fine MC precipitation around 10–20 nm and showed a creep/rupture life between 1002 and 1530 hrs at 700°C/150 MPa. This is comparable with that of super304H tested under the same condition. Fe2(Mo,Nb) Laves phase was found in the microstructure after creep/rupture testing. NiAl precipitated in alloys after creep/rupture testing for more than 1000 hrs. However, strengthening effect from these two phases is not obvious, indicating that nano-scale NbC precipitates are the major source of strengthening during creep/rupture at high temperature. In addition, nano-scale (Nb,V)C was found in V containing alloy corresponding to the longest creep/rupture life.
3
Bardel, Didier, Michel Perez, Daniel Nelias, Thibaut Chaise, Jerôme Garnier und Florent Bourlier. „Evolution of Mechanical Behavior of 6XXX Aluminium Alloy due to the Precipitation State During a Thermo-Mechanical Process“. In ASME 2013 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/pvp2013-97426.
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The aim of this research is to link the microstructural state and the mechanical properties of an age hardening alloy during a fast heat treatment such as encountered during welding. A coupled model between precipitation state and mechanical properties is used to predict the yield strength and hardening behavior that can be observed experimentally. The method permits the identification of the kinematic and isotropic contributions in the hardening model. The methodology is applied to a 6061-T6 aluminium alloy which is used in the Jules Horowitz reactor vessel. The general idea of this methodology is to couple an efficient microstructural model to a mechanical one based on the dislocation theory and ad’hoc experiments. The theoretical background is based on the work of Kampmann and Wagner, known as the KWN model, to account for nucleation, growth/dissolution and coarsening of precipitates. This analysis requires transient thermo-mechanical experimental data. The efficiency of these models and their coupling are shown for a serie 6XXX aluminium alloy which contains β″ and β′ precipitates. Ultimately these models are coupled to a FEA model and allows to predict the distribution of precipitates within each element of the mesh, and subsequently its mechanical behavior.
4
Nielsen, O̸yvind, Harald Laux und Anne Lise Dons. „Modeling of Macrosegregation and Secondary Phase Precipitation During Solidification of Binary Alloys“. In ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-32890.
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A multiphase volume-averaged model describing macrosegregation in an alloy that solidifies by the formation and growth of a primary and a secondary solid phase has been formulated. The model is based on the work presented by Ni and Beckermann (Metall. Trans. 22B, 1991, p. 349), but is extended to account for secondary phase precipitation. A CFD model has been developed by implementation of the mathematical model in a commercial CFD code. Macrosegregation due to thermo-solutal convection in binary alloys with a stationary solid phase (primary and secondary solids) has been simulated. The predictions compare fairly well to experimental results and simulations previously reported in the literature.
5
Chen, Bo, Michael W. Spindler, David J. Smith und Peter E. J. Flewitt. „Effect of Thermo-Mechanical History on Reheat Cracking in 316H Austenitic Stainless Steel Weldments“. In ASME 2010 Pressure Vessels and Piping Division/K-PVP Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/pvp2010-25088.
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Reheat cracking has been observed in the heat affected zone of the 316H austenitic stainless steel thick section weldments during service at a temperature of ∼500°C. This has been attributed to the creep dominated relaxation of the highly triaxial residual stresses. Here the role of thermo-mechanical variables that contribute to the susceptibility of thick section 316H austenitic stainless steel weldments is briefly reviewed. The influence of the plastic strain, carbide precipitation and impurity element segregation on the subsequent creep deformation behaviour and the susceptibility to creep cavitation damage is discussed. A systematically designed experiment which includes these parameters has been undertaken for a 316H austenitic stainless steel. In addition, residual stress profiles have been introduced into cylindrical pre-treated specimens and the relaxation of these profiles with heat treatment has been measured by neutron diffraction. The experimental results are considered with respect to the effect of the microstructure on subsequent creep deformation and stress relaxation. The susceptibility to intergranular brittle fracture is discussed and an attempt is made to correlate the microstructure and stress state factors encountered in the HAZ with the accumulation of the creep cavitation associated with reheat cracking.
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Bremer, Sandrine, Volker Flaxa und Franz M. Knoop. „A Novel Alloying Concept for Thermo-Mechanical Hot-Rolled Strip for Large Diameter HTS (Helical Two Step) Line Pipe“. In 2008 7th International Pipeline Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/ipc2008-64678.
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One of the major priorities of the research and development department of the Salzgitter Group is placed on the product and process optimisation of both approved conventional steel grades for line pipe application and novel high strength alloying concepts. With respect to reduced wall-thicknesses and higher operating pressures for gas transportation pipelines, the requirements for hot wide strip material are steadily increasing. Material strength can be increased either by grain refinement of the ferritic-pearlitic phase in combination with precipitation hardening or by replacing the ferrite-pearlite by an intermediate microstructure, so-called acicular ferrite. A low carbon content supports the formation of the microstructure desired and results in an improvement of the carbon equivalent. This acicular ferrite does not only raise the material strength but also improve low temperature toughness, weldability and workability. New processing routes based on the demands of novel alloying concepts have been developed in order to achieve the intermediate microstructure. In the following paper, two different alloying and processing strategies and the resulting mechanical properties and microstructures are described and illustrated.
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Blaizot, Jérôme, Thibaut Chaise, Daniel Nelias und Michel Perez. „Characterization and Modelling of Tensile Flow Behavior of Ni Base Alloy 690 at Various Temperatures and Strain Rates“. In ASME 2014 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/pvp2014-28775.
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Pressurized Water Reactor components are welded by Gas Tungsten Arc Welding (GTAW). To achieve good corrosion resistance and mechanical properties, Ni base alloy 690 is used to manufacture these components. The understanding of physical phenomena involved during welding and the prediction of induced residual stresses are crucial to guarantee high quality of these components. Welding induces drastic changes in the microstructure of the molten zone and heat-affected zone of metallic alloys especially for multi-pass welding. These changes may deteriorate the mechanical properties of the assembly. In order to reproduce the complex thermo-mechanical loading occurring within the heat affect zone, experiments on a thermo-mechanical simulator Gleeble 3500 have been carried out. In order to characterize the base alloy, isothermal tensile tests have been performed at various strain rates and temperatures (from 25 to 1100°C). A constitutive law has been proposed to predict the mechanical properties under different strain rates and temperatures. Tensile tests have also been performed after several thermal cycles to understand the effect of welding on mechanical properties of Ni alloy 690. In parallel, grain size evolution and carbide precipitation have been characterized and correlated to measured mechanical properties.
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Gontcharov, Alexandre B., Paul Lowden, Ashutosh Jena, Sunyong Kwon und Mathieu Brochu. „Weldability and Properties of Newly Developed LW4280 High Gamma Prime Nickel Based Superalloy for 3D AM and Repair of Turbine Engine Components“. In ASME Turbo Expo 2021: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/gt2021-58851.
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Abstract Chemical composition, structure, mechanical and oxidation properties of welds produced utilizing laser direct energy deposition process of a newly developed LW4280 welding powder will be presented. Crack-free and high-density specimens were fabricated for manufacturing standard and subsized tensile test samples as per ASTM E-8. Optical and scanning electron microscopy revealed the formation of epitaxial grain growth during solidification of the welding pool followed by precipitation of fine gamma prime phase during the reheating from the subsequent weld layers. A sub-solvus primary aging temperature determined using Thermo-Calc software followed by secondary aging resulted in precipitation of above 49% of cuboidal γ′ phase. Excellent ultimate tensile strength of 1310 MPa (190 ksi), 0.2% yield strength of 855 MPa (124 ksi), and elongation of 18.7% were measured at ambient temperature. At 926°C (1700°F), the tensile testing yielded of 579 MPa (84 ksi), 0.2% yield strength of 462 MPa (67 ksi), and elongation of 18.8%. Cyclic oxidation resistance of the LW4280 weld material at 1120°C (2048°F) was superior to Rene 80 and Mar M247 while slightly below Rene 142.
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Tachibana, Shunichi, Yota Kuronuma, Tomoyuki Yokota, Shinji Mitao, Hitoshi Sueyoshi, Yutaka Wada, Keizou Yabumoto, Yutaka Moriya und Moriyasu Nagae. „Development of TMCP Type Alloy625/X65 Clad Steel Plate for Pipe“. In 2014 10th International Pipeline Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/ipc2014-33150.
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Demand for CRAs (Corrosion Resistant Alloys) clad steel is getting increased for pipeline application of oil and gas industry because of economic advantage over solid CRAs. CRAs clad steel consists of a CRAs layer for corrosion resistance and a carbon steel for mechanical properties. Nickel based Alloy625 is known to be suitable for harsh environmental condition such as high temperature and high pressure H2S (hydrogen sulfide) condition. In this paper, the corrosion resistance of Alloy625/X65 clad steel plate for pipe produced by TMCP (Thermo-Mechanical Control Process) was investigated. TTP (Time - Temperature - Precipitation) and TTS (Time - Temperature - Sensitization) diagram of Alloy625 indicated precipitation nose, e.g. M6C and M23C6 which would cause deterioration of corrosion resistance. TMCP enable Alloy625 to avoid long time exposure to the precipitation nose. In Huey test, the corrosion rate in TMCP was almost the same as that of solution treated Alloy625 and smaller than that in Q-T (Quench and Temper). In ferric chloride pitting test, no pitting was observed in Alloy625 layer of TMCP type clad steel. In addition, the corrosion test simulating service environment using autoclave apparatus was conducted under the condition of 0.39MPa H2S - 0.53MPa CO2 - Cl− solution at 200°C. Alloy625 clad steel produced by TMCP showed neither SSC (Sulfide stress corrosion cracking) nor crevice corrosion. All the mechanical properties of base carbon steel satisfied API 5L grade X65 specification by optimizing TMCP conditions. It is notable that 85% SATT of DWTT was below −10 °C. Thus, Alloy625/X65 clad steel plate for pipe produced by TMCP with both superior corrosion resistance and low temperature toughness has been developed.
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Okatsu, Mitsuhiro, Kenji Oi, Koichi Ihara und Toshiyuki Hoshino. „High Strength Linepipe With Excellent HAZ Toughness“. In ASME 2004 23rd International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2004. http://dx.doi.org/10.1115/omae2004-51143.
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The API 5L-X65 steel plates for low temperature service were produced using the thermo-mechanical control process (TMCP) with the optimum micro-alloying addition. Featuring of the additions are as low amount of titanium, calcium, niobium, and vanadium as possible, for high heat affected zone (HAZ) toughness and strength. Controlling titanium and nitrogen and the Ti/N ratio, a large number of TiN dispersed finely are formed in steel and the austenite grain size near a weld fusion line is refined remarkably owing to strong pinning effect of TiN. Calcium addition promotes ferrite nucleation, so that increase in fine polygonal ferrites makes microstructure of HAZ much finer. Niobium and vanadium content are reduced, because carbide precipitates are formed when the coarse grain HAZ is reheated around 700 degree C and the precipitation hardening deteriorates HAZ toughness. The trial manufacturing of the 19.5mm, 26.9mm and 31.4mm thick X65 grade UOE pipes was finalized with the satisfactory results. The toughness of longitudinal submerged-arc welds was more than 50 J in Charpy V-notch impact test at −30°C.
Berichte der Organisationen zum Thema "Thermo precipitation"
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Reis, J. Oil recovery improvement through profile modification by thermal precipitation. Office of Scientific and Technical Information (OSTI), Januar 1991. http://dx.doi.org/10.2172/6374690.
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2
Clausen, Jay, Michael Musty, Anna Wagner, Susan Frankenstein und Jason Dorvee. Modeling of a multi-month thermal IR study. Engineer Research and Development Center (U.S.), Juli 2021. http://dx.doi.org/10.21079/11681/41060.
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Inconsistent and unacceptable probability of detection (PD) and false alarm rates (FAR) due to varying environmental conditions hamper buried object detection. A 4-month study evaluated the environmental parameters impacting standoff thermal infra-red(IR) detection of buried objects. Field observations were integrated into a model depicting the temporal and spatial thermal changes through a 1-week period utilizing a 15-minute time-step interval. The model illustrates the surface thermal observations obtained with a thermal IR camera contemporaneously with a 3-d presentation of subsurface soil temperatures obtained with 156 buried thermocouples. Precipitation events and subsequent soil moisture responses synchronized to the temperature data are also included in the model simulation. The simulation shows the temperature response of buried objects due to changes in incoming solar radiation, air/surface soil temperature changes, latent heat exchange between the objects and surrounding soil, and impacts due to precipitation/changes in soil moisture. Differences are noted between the thermal response of plastic and metal objects as well as depth of burial below the ground surface. Nearly identical environmental conditions on different days did not always elicit the same spatial thermal response.
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Jiang, Chao, Yongfeng Zhang und Enrique Martinez. Low length scale modeling of Cr precipitation in FeCrAl under thermal aging conditions. Office of Scientific and Technical Information (OSTI), August 2017. http://dx.doi.org/10.2172/1471740.
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Reis, J. Oil recovery improvement through profile modification by thermal precipitation. Annual report, October 1, 1991--September 30, 1992. Office of Scientific and Technical Information (OSTI), Dezember 1992. http://dx.doi.org/10.2172/10130131.
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Reis, J. C. Oil recovery improvement through profile modification by thermal precipitation. Final report, October 1, 1991--August 27, 1993. Office of Scientific and Technical Information (OSTI), April 1994. http://dx.doi.org/10.2172/10151518.
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6
Yang, Ying. Development of Computational Tools for Modeling Thermal and Radiation Effects on Grain Boundary Segregation and Precipitation in Fe-Cr-Ni-based Alloys. Office of Scientific and Technical Information (OSTI), August 2017. http://dx.doi.org/10.2172/1394351.
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Douglas, Thomas, Merritt Turetsky und Charles Koven. Increased rainfall stimulates permafrost thaw across a variety of Interior Alaskan boreal ecosystems. Engineer Research and Development Center (U.S.), Juni 2021. http://dx.doi.org/10.21079/11681/41050.
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Earth’s high latitudes are projected to experience warmer and wetter summers in the future but ramifications for soil thermal processes and permafrost thaw are poorly understood. Here we present 2750 end of summer thaw depths representing a range of vegetation characteristics in Interior Alaska measured over a 5-year period. This included the top and third wettest summers in the 91-year record and three summers with precipitation close to mean historical values. Increased rainfall led to deeper thaw across all sites with an increase of 0.7 ± 0.1 cm of thaw per cm of additional rain. Disturbed and wetland sites were the most vulnerable to rain-induced thaw with ~1 cm of surface thaw per additional 1 cm of rain. Permafrost in tussock tundra, mixed forest, and conifer forest was less sensitive to rain-induced thaw. A simple energy budget model yields seasonal thaw values smaller than the linear regression of our measurements but provides a first-order estimate of the role of rain-driven sensible heat fluxes in high-latitude terrestrial permafrost. This study demonstrates substantial permafrost thaw from the projected increasing summer precipitation across most of the Arctic region.
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G.D. LeCain, N. lu und M. Kurzmack. Use of Thermal Data to Estimate Infiltration in Pagany Wash Associated with the winter of 1997-1998 El Nino Precipitation, Yucca Mountain, Nevada. Office of Scientific and Technical Information (OSTI), Januar 2000. http://dx.doi.org/10.2172/840693.
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Day, Christopher M., Hiromal Premachandra und Darcy M. Bullock. Characterizing the Impacts of Phasing, Environment, and Temporal Factors on Pedestrian Demand at Traffic Signals. Purdue University, 2011. http://dx.doi.org/10.5703/1288284317352.
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There is a need for more and higher quality data on pedestrian demand patterns for a number of applications in planning, transportation engineering, public health, and other areas. It is particularly desirable to better characterize the influence of daily, weekly, and annual variations; the impact of weather and special events; and the effects of changes in pedestrian phasing. This paper proposes and demonstrates a methodology for quantifying the relative demand for pedestrian service at a signalized intersection by using the percent of signal cycles per hour in which the pedestrian phase was actuated. Although this performance measure does not by itself provide a pedestrian count, it can be used as a surrogate to characterize how pedestrian volumes vary due to operating conditions. More importantly, since this technique does not require new sensors, the data can be collected at thousands of intersections across the nation where pedestrian push buttons are in use. This paper documents findings from over a year of data collection at a signalized intersection on a college campus. The effects of daily/weekly/annual variations, special events, weather (temperature and precipitation), seasonal changes in activity patterns, and changes in pedestrian signal phasing are documented. A Tobit model is used to account for the influences of these variables and understand how they co-influence pedestrian activity. The implementation of an exclusive pedestrian phase is associated with a 9% increase in pedestrian phase utilization at the intersection. This change is associated with a decrease in user cost relative to performing midblock crossings. The modeled impact of snowfall events adds further insight by showing that as the user cost of making midblock crossings increases, pedestrian activity at the intersection increases.