scholarly journals Description of dynamic viscosity depending on the alloys composition and temperature using state diagrams

2018 ◽  
Vol 61 (9) ◽  
pp. 743-749
Author(s):  
V. P. Malyshev ◽  
A. M. Makasheva
Keyword(s):  
Factor Model ◽  
State Diagram ◽  
Liquidus Line ◽  
Boltzmann Distribution ◽  
Liquidus Curve ◽  
Pure Component ◽  
Thermal Barrier ◽  
Virtual Cluster ◽  
Pure Substances ◽  
Randomized Particles

The equilibrium nature of viscosity and fluidity is discovered on the basis of the Boltzmann distribution within the framework of the concept of randomized particles as a result of the virtual presence of crystal-mobile, liquid-mobile and vapor-mobile particles. It allows one to consider the viscosity and fluidity of solutions, in particular, melts of metal alloys, from the point of view of the equilibrium partial contributions of each component in the total viscosity and fluidity, despite the kinetic interpretation of natural expressions for these properties of the liquid. A linearly additive partial expression of viscosity is possible only for perfect solutions, in this case, for alloys with unrestricted mutual solubility of the components. Alloys with eutectics, chemical compounds and other features of the state diagram are characterized by viscosity dependencies that repeat the shape of liquidus curve over entire range of the alloy composition at different temperatures, with an increase in smoothness and convergence of these curves at increasing temperature. It was established that these features of viscosity temperature dependence are completely revealed within the framework of the concept of randomized particles and the virtual cluster model of viscosity in calculating the fraction of clusters determining the viscosity of the alloy. That viscosity of the alloy is found by the formula in which thermal energy RTcr at liquidus temperature is the thermal barrier of chaotization, characterizing the crystallization temperature of the melt Tcr, as well as the melting point of pure substances. On this basis, a method is proposed for calculating the alloys viscosity by phase diagrams using the temperature dependences of pure components viscosity to change the alloy’s viscosity in proportion to ratio of the clusters fractions at any temperature above liquidus line and for the pure component, taking into account the mole fraction of each component. As a result, a three-factor model of the liquid alloy viscosity has been obtained in which the thermal barrier of chaotization RTcr is used as variable for the first time. It determines the fraction of clusters for both pure substances (at RTcr  =  RTm ) and for alloys. This thermal barrier reflects the essence of the virtual cluster theory of liquid and adequacy of the concept of randomized particles.

Partial-cluster model of viscosity of copper-aluminum melt

2021 ◽  
pp. 59-65
Author(s):  
V. P. Malyshev ◽  
A. M. Malysheva
Keyword(s):  
Cluster Model ◽  
State Diagram ◽  
Liquidus Line ◽  
Viscosity Model ◽  
Analytical Determination ◽  
Heat Of Mixing ◽  
Al Alloy ◽  
Calculated Dependence ◽  
Wide Range ◽  
Copper Aluminum

The adequacy of the developed partial-cluster viscosity model with respect to melts of metal alloys was verified using the well-studied copper-aluminum system, for which the state diagram and viscosity isotherms are known in a wide range of compositions. Based on the literature on the thermodynamics of mixing copper and aluminum melts, it was found that this shift is accompanied by heat generation due to the formation of intermetallic compounds in the melt. The destruction of these compounds requires appropriate heat consumption, therefore, it should be taken into account in the partial-cluster viscosity model as an additional thermal barrier to randomization. On this basis, a refined and more generalized form of the partial-cluster model with the expression of the randomization energy of the melt in the form of the algebraic sum of the randomization heat along the liquidus line and the heat of destruction of any intermetallic formations is proposed ΔHch = RTliq – ΔHmix. Application of the generalized partial-cluster model to copper-aluminum melts ensured the repetition of the extreme form of empirical isotherms, even with the appearance of excess viscosity in the calculated dependence. A more detailed analysis of the heat of mixing according to its covalent and metal components showed that the second of them is already randomized and only the covalent component should be taken into account, which should be randomized and should be included in the total randomization barrier in the form ΔHch = RTliq – ΔcovH. Taking this component into account allowed us to obtain a more adequate calculated dependence of the viscosity of the Cu – Al alloy at a temperature of 1100 оC with a correlation coefficient of 0.986, which can be considered as a priority result in the description of viscosity isotherms according to state diagrams. This result is due to the analytical determination of the fraction of clusters in the melt based on the distribution of clusters proposed by the authors according to the number of particles included in the framework of the concept of randomized particles developed by the authors, which is directly related to the Boltzmann’s distribution.

scholarly journals Investigation of the Liquidus Line on the Fe-B State Diagram

2018 ◽  
Keyword(s):  
Experimental Data ◽  
Free Energy ◽  
Crystallization Temperature ◽  
Boron Content ◽  
Chemical Potential ◽  
State Diagram ◽  
Liquidus Line ◽  
Structural Condition ◽  
Energy Potential ◽  
Eutectic Transformation

In this paper we determine the crystallization temperature of a melt of the Fe-B system depending on the boron content and. The thermodynamic properties of the boron-bearing phases are studied. The investigation was performed for alloys with the boron content of 2.0-4.2.0% (wt.), the rest is iron. The smelting of Fe-B system alloy was carried out in a furnace in alundum saggers in the argon atmosphere. The cooling rate of as-cast alloys was 10 K/s. To ascertain the structural condition of alloys we used the microstructure analysis, the differential thermal and the X-ray structural analyses. In the paper, based on experimental data for the Fe-B alloys, we determined the crystallization temperatures of alloys under consideration, depending on the content of boron in the alloy. In addition, we revealed that the γ-Fe+Fe2B eutectic transformation occurs at the temperature of 1441 K and at the boron content of 3.8% (wt.). To determine the thermodynamic functions of the phases we used the quasi-chemical method. With accounting for the contribution of the first degree approximation of the high-temperature expansion for the thermodynamic potential we derived expressions for the free energy of the melt of the binary Fe-B alloy, the boron-doped austenite and the Fe2B boride. The expressions obtained for the free energy potential and the chemical potential of the melt of the binary Fe-B alloy, the austenite and the Fe2B boride enable to obtain the Fe-В phase diagram liquidus boundaries. The calculations performed in this paper made it possible to obtain the numerical values of the crystallization temperature of the alloy, depending on the boron content, and to determine the temperature of the γ-Fe+Fe2B eutectic transformation and the boron content, at which this transformation takes place in the alloy. Such an approach allows describing most completely from the thermodynamic point of view the crystallization process and the eutectic transformation. The results of the calculations obtained in this paper are in good agreement with the experimental data.

scholarly journals Invariants of ratio of crystal-mobile, liquid-mobile, and vaporized chaotized particles in solid, liquid, and gas states of substance

2021 ◽  
Vol 104 (4) ◽  
pp. 69-78
Author(s):  
V.P. Malyshev ◽  
◽  
A.M. Makasheva ◽  
L.A. Bekbayeva ◽  
◽  
...  
Keyword(s):  
Atmospheric Pressure ◽  
Boltzmann Distribution ◽  
Self Organization ◽  
Qualitative And Quantitative Analysis ◽  
Qualitative And Quantitative ◽  
Heterogeneous Processes ◽  
State Of Matter ◽  
Solid Liquid ◽  
Mobile Liquid ◽  
Randomized Particles

The authors of the article have developed the concept of chaotic particles based on the Boltzmann distribution over the kinetic energy of the particles’ chaotic motion. This distribution allows to combine the solid, liquid, and gaseous states of matter with the help of energetic particles called crystal-mobile, liquid-mobile, and vapor-mobile. The ratio of the proportions of such randomized particles determines a certain state of matter aggregation. The sum of the shares of these particles in all combinations at any temperature is equal to unity. During the study it has identified that qualitative and quantitative analysis of states with a priority basic effect of a randomized component of a substance can be conducted. Certain regularities of states were discovered, independent of the specific type of substance and consistent with the physicochemical properties. The entropy of mixing of all three energy classes of chaotic particles was calculated for simple substances. It was characterized by a maximum in the interval of the boiling point of substances. This feature testifies to the unique variety of possibilities for the implementation of the most complex heterogeneous processes in terrestrial conditions at atmospheric pressure, which ultimately ensured the self-organization of life

Electron Microscopic Analysis of Myonecrosis Induced by a Pure Component Isolated From Rattlesnake Venom

1976 ◽  
Vol 34 ◽  
pp. 292-293
Author(s):  
Charlotte L. Ownby ◽  
David Cameron ◽  
Anthony T. Tu
Keyword(s):  
Gel Filtration ◽  
Microscopic Analysis ◽  
The United States ◽  
Exchange Chromatography ◽  
Pure Component ◽  
Electron Microscopic Level ◽  
Electron Microscopic ◽  
Mouse Muscle ◽  
Major Health Problem ◽  
Rattlesnake Venom

In the United States the major health problem resulting from snakebite poisoning is local tissue damage, i.e. hemorrhage and myonecrosis. Since commercial antivenin does not usually prevent such damage to tissue, a more effective treatment of snakebite-induced myonecrosis is needed. To aid in the development of such a treatment the pathogenesis of myonecrosis induced by a pure component of rattlesnake venom was studied at the electron microscopic level.The pure component, a small (4,300 mol. wt.), basic (isoelectric point of 9.6) protein, was isolated from crude prairie rattlesnake (Crotalus viridis viridis) venom by gel filtration (Sephadex G-50) followed by cation exchange chromatography (Sephadex C-25), and shown to be pure by electrophoresis. Selection of the myotoxic component was based on light microscopic observations of injected mouse muscle.

Fractionation of polymethylene chains: An electron crystallographic investigation

1986 ◽  
Vol 44 ◽  
pp. 794-795
Author(s):  
Douglas L. Dorset
Keyword(s):  
Cross Section ◽  
Binary Systems ◽  
Linear Chain ◽  
Pure Component ◽  
Organic Substrates ◽  
Crystallographic Investigation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Molecular Sizes ◽  
The Stability

A variety of linear chain materials exist as polydisperse systems which are difficultly purified. The stability of continuous binary solid solutions assume that the Gibbs free energy of the solution is lower than that of either crystal component, a condition which includes such factors as relative molecular sizes and shapes and perhaps the symmetry of the pure component crystal structures.Although extensive studies of n-alkane miscibility have been carried out via powder X-ray diffraction of bulk samples we have begun to examine binary systems as single crystals, taking advantage of the well-known enhanced scattering cross section of matter for electrons and also the favorable projection of a paraffin crystal structure posited by epitaxial crystallization of such samples on organic substrates such as benzoic acid.

Characterization of thermal barrier coatings formed by electon-beam physical vapor deposition (EB-PVD)

1989 ◽  
Vol 47 ◽  
pp. 426-427
Author(s):  
Ozer Unal
Keyword(s):  
Thermal Barrier Coatings ◽  
Physical Vapor Deposition ◽  
Ceramic Coating ◽  
High Vacuum ◽  
Ceramic Coatings ◽  
High Energy ◽  
Thermal Barrier ◽  
Protective Oxide ◽  
Barrier Coatings ◽  
Energy Beam

Interest in ceramics as thermal barrier coatings for hot components of turbine engines has increased rapidly over the last decade. The primary reason for this is the significant reduction in heat load and increased chemical inertness against corrosive species with the ceramic coating materials. Among other candidates, partially-stabilized zirconia is the focus of attention mainly because ot its low thermal conductivity and high thermal expansion coefficient.The coatings were made by Garrett Turbine Engine Company. Ni-base super-alloy was used as the substrate and later a bond-coating with high Al activity was formed over it. The ceramic coatings, with a thickness of about 50 μm, were formed by EB-PVD in a high-vacuum chamber by heating the target material (ZrO2-20 w/0 Y2O3) above its evaporation temperaturef >3500 °C) with a high-energy beam and condensing the resulting vapor onto a rotating heated substrate. A heat treatment in an oxidizing environment was performed later on to form a protective oxide layer to improve the adhesion between the ceramic coating and substrate. Bulk samples were studied by utilizing a Scintag diffractometer and a JEOL JXA-840 SEM; examinations of cross-sectional thin-films of the interface region were performed in a Philips CM 30 TEM operating at 300 kV and for chemical analysis a KEVEX X-ray spectrometer (EDS) was used.

Psychometrical Properties of a French Version of the General Self-Efficacy Short Scale (ASKU)

2020 ◽  
Vol 79 (1) ◽  
pp. 15-25
Author(s):  
Jean Philippe Décieux ◽  
Philipp Emanuel Sischka ◽  
Anette Schumacher ◽  
Helmut Willems
Keyword(s):  
Self Efficacy ◽  
Factor Model ◽  
German Version ◽  
French Version ◽  
Context Variable ◽  
Confirmatory Factor ◽  
French Speaking ◽  
German Speaking ◽  
Valid Instrument ◽  
General Self Efficacy

Abstract. General self-efficacy is a central personality trait often evaluated in surveys as context variable. It can be interpreted as a personal coping resource reflecting individual belief in one’s overall competence to perform across a variety of situations. The German-language Allgemeine-Selbstwirksamkeit-Kurzskala (ASKU) is a reliable and valid instrument to assess this disposition in the German-speaking countries based on a three-item equation. This study develops a French version of the ASKU and tests this French version for measurement invariance compared to the original ASKU. A reliable and valid French instrument would make it easy to collect data in the French-speaking countries and allow comparisons between the French and German results. Data were collected on a sample of 1,716 adolescents. Confirmatory factor analysis resulted in a good fit for a single-factor model of the data (in total, French, and German version). Additionally, construct validity was assessed by elucidating intercorrelations between the ASKU and different factors that should theoretically be related to ASKU. Furthermore, we confirmed configural and metric as well as scalar invariance between the different language versions, meaning that all forms of statistical comparison between the developed French version and the original German version are allowed.

Exploring the Multidimensional Facets of Authoritarianism: Authoritarian Aggression and Social Dominance Orientation

2008 ◽  
Vol 67 (1) ◽  
pp. 51-60 ◽  
Author(s):  
Stefano Passini
Keyword(s):  
Social Dominance ◽  
Factor Model ◽  
Three Dimensional ◽  
Social Dominance Orientation ◽  
Model Fit ◽  
Regression Analyses ◽  
One Dimensional ◽  
Confirmatory Factor ◽  
The One ◽  
Better Than

The relation between authoritarianism and social dominance orientation was analyzed, with authoritarianism measured using a three-dimensional scale. The implicit multidimensional structure (authoritarian submission, conventionalism, authoritarian aggression) of Altemeyer’s (1981, 1988) conceptualization of authoritarianism is inconsistent with its one-dimensional methodological operationalization. The dimensionality of authoritarianism was investigated using confirmatory factor analysis in a sample of 713 university students. As hypothesized, the three-factor model fit the data significantly better than the one-factor model. Regression analyses revealed that only authoritarian aggression was related to social dominance orientation. That is, only intolerance of deviance was related to high social dominance, whereas submissiveness was not.

A Psychometric Study of the Quality Perception Questionnaire

2012 ◽  
Vol 71 (2) ◽  
pp. 101-106 ◽  
Author(s):  
Raffaele Cioffi† ◽  
Anna Coluccia ◽  
Fabio Ferretti ◽  
Francesca Lorini ◽  
Aristide Saggino ◽  
...  
Keyword(s):  
Structural Equation ◽  
Factor Model ◽  
Equation Modeling ◽  
Fit Indices ◽  
Quality Perception ◽  
Italian Survey ◽  
Confirmatory Factor ◽  
Instrument Measuring ◽  
Hospital Structures

The present paper reexamines the psychometric properties of the Quality Perception Questionnaire (QPQ), an Italian survey instrument measuring patients’ perceptions of the quality of a recent hospital admission experience, in a sample of 4400 patients (Mage = 56.42 years; SD = 19.71 years, 48.8% females). The 14-item survey measures four factors: satisfaction with medical doctors, nursing staff, auxiliary staff, and hospital structures. First, we tested two models using a confirmatory factor analysis (structural equation modeling): a four orthogonal factor and a four oblique factor model. The SEM fit indices and the χ² difference suggested the acceptance of the second model. We then did a simulation using a bootstrap with 1000 replications. Results confirmed the four oblique factor solution. Third, we tested whether there were significant differences with respect to age or sex. The multivariate general linear model showed no significant differences in the factors with respect to sex or age.

Question Wording Effects in the Assessment of Global Self-Esteem

2000 ◽  
Vol 16 (1) ◽  
pp. 13-19 ◽  
Author(s):  
Martin Dunbar ◽  
Graeme Ford ◽  
Kate Hunt ◽  
Geoff Der
Keyword(s):  
Reading Ability ◽  
Factor Model ◽  
Self Esteem ◽  
Reading Scores ◽  
Poor Reading ◽  
Method Effect ◽  
Two Samples ◽  
Positive Item ◽  
Method Effects ◽  
Best Fit

Summary: Marsh (1996) produced evidence that method effects associated with negatively worded items might be responsible for the results of earlier factor analytic studies that reported finding positive and negative self-esteem factors in the Rosenberg Global self-esteem scale ( Rosenberg, 1965 ). He analyzed data collected from children using a 7-item self-esteem measure. This report details attempts to replicate Marsh 's analysis in data collected from two samples of adults who completed the full 10-item Global Self-Esteem (GSE) scale. The results reported here are similar to those given by Marsh in so much as a correlated uniquenesses model produced a superior fit to the data than the simple one factor model (without correlated uniquenesses) or the often reported two factor (positive and negative self-esteem) model. However, whilst Marsh reported that the best fit was produced by allowing negative item uniquenesses to correlate with each other, the model that produced the best fit to these data was one that contained correlated positive item uniquenesses. Supporting his claim that differential responding to negative and positive self-esteem items reflects a method effect associated with reading ability, Marsh also showed that factors associated with negative and positive items were most distinct among children who had poor reading scores. We report a similar effect among a sample of older adults where the correlation between these factors was compared across two groups who were selected according to their scores on a test of verbal reasoning.

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