The phenomenon of occurrence of a hydrodynamic oil film on the bearing system is analyzed. A theoretical model of the radial slide bearing system that takes into account the normal and static ...stresses as well as the deformations is proposed. The values of stress and deformation in the contact area are established. They are compared with the values obtained using the Hertz model. Moreover, the results of the analysis of the bearing system in thermodynamic equilibrium are presented. In this case, the journal and the bushing are separated by an oil layer.
In this paper, the reactive diffusion in Ni80C20r?Ti ternary system is discussed at 1173K. The diffusion couple was prepared and annealed for 100 h. The two intermetallic phases and two two-phase ...zones occurred, namely: Ti2Ni, TiNi, TiNi+Cr, and TiNi3+Cr. Based on the experimental results (molar fractions, thicknesses of the intermetallic phases), the intrinsic diffusion coefficients of all components in each phase were numerically approximated. The Wagner method was used in the pure intermetallic phases. In the two phase zones the approximation was based on the generalized Darken and Wagner methods. The presented methods allowed for determination of the effective diffusion coefficients in each presented phase.
In the present work, a performance of ASTM A439 Austenitic Ductile Iron type D5S at high temperature in the oxidizing environment was investigated. The obtained results revealed that exposure at ...temperatures 800?C, 850?C, and 900?C resulted in relatively high mass gain and an extensive oxide scale spallation from the samples? surfaces during cooling. However, the material exposed at 950?C revealed a better oxidation resistance and no oxide scale spallation. The material exposed at 1000?C showed the best oxidation resistance among the studied samples. The surfaces and cross-sectional investigation revealed that the material exposed at 950?C formed mostly Ni/Cr/Mn-mixed protective oxide scale and local formation of Fe-rich nodules. In comparison with the sample exposed at 1000?C, a smaller amount of Fe-rich nodules per area unit was observed and most of the surface was covered by Ni/Cr/Mn-mixed protective scale. The latter was explained by the change in the calculated diffusion coefficients in the alloy for Ni and Fe, namely up to 900?C the diffusion coefficient for Fe was much higher than for Ni, while above 900?C the diffusion coefficient for Ni becomes higher than for Fe. This phenomenon was correlated with a phase transformation from ?-Fe into ?-Fe resulting in the diffusion coefficient change.
The simple phenomenological model and analytical approach of electromigration in the two-phase alloy (solder) under combined influence of the Kirkendall effect, backstress and sedimentation is ...presented. It is compared with electromigration in pure metal under condition of quasi-equilibrium vacancies (unlimited power of vacancy sinks-sources) and electromigration in pure metal with account of nonequilibrium vacancies.
The Nernst–Planck–Poisson (NPP) model is used to numerically simulate electrochemical impedance spectra (EIS) of ion-selective electrodes (ISEs). By using the Hierarchical Genetic Strategy with real ...number encoding (HGS(FP)) the reverse problem is solved. The NPP–HGS(FP) method allows estimation of physicochemical parameters of ISEs with plastic membranes, which is illustrated here by using NPP–HGS(FP) for obtaining the values of the diffusion coefficients of ions in the ISE membrane phase. The NPP–HGS(FP) method allows calculation of the most accurate solution of the inverse problem and can be effectively used to facilitate the process of finding the parameters for optimal ISE performance. The method presented here not only allows for interpretation of the EIS spectra but also for accounting for the mechanism of the processes occurring at the interface in terms of physicoelectrochemically valid concepts.
We present the first simple analytical description of the interdiffusion process where the competition between the Kirkendall shift and the backstress is considered. It is shown that two diffusion ...subzones are formed; these sections are linked to the fast and slow diffusing component. During the interdiffusion process, the stress effect does not vanish.
The evolution of the understanding of the mass transport phenomena in solids and liquids allows for the unification of phenomenological models. The central Darken problem is considered from the ...choice of the coordinate axes for diffusion, i.e. the definition of this mode of motion and the method of diffusion displacement is defined and measured. Euler's and Liouville theorems are used extensively in the analysis. The formula is derived for volume density conservation, i.e. the volume continuity equation. This fundamental formula defines the volume-fixed frame of reference in the multicomponent solid, gas and liquid solutions. The volume-fixed frame of reference is self-consistent with the foundations of linear irreversible thermodynamics, except that is recognises the need to add volume density to the usual list of extensive physical properties undergoing transport in every continuum. Proposed modifications are self-consistent with the literature dating back to Onsager, the experiments of Kirkendall, their interpretation by Darken and recent generalized formulations. It will be shown that the method can be used in mechano-chemistry and electro-mechano-chemistry.
In the present paper the sedimentation process in Cu–Sn alloy is discussed in two ways: by experimental and numerical approach. The sedimentation process was executed at the following conditions ...— the rotation speed 35,000 RPM, the radii was between 88 and 93 mm, temperature 180 °C and time 2 h. During the experiment the separation of the Cu3Sn and Cu6Sn5 phase was observed. The sedimentation process clearly influenced the morphology of the alloy. Moreover, the model based on the bi-velocity method is presented. The model allow for determination of the phase fraction when centrifugal force acting on the sample.
•The sedimentation in two-phase zone.•Phase separation in Cu–Sn alloy.•Phase fraction determination by bi-velocity model.
In this paper it is shown that the small voids, cracks or inclusions may act as sinks for vacancies or sources for interstitial atoms if the density is very close to equilibrium by numerical ...simulations. The two dimensional model is presented based on the generalized Darken concept. The void radius is estimated and compared with experimental results in Fe–Pd and β-NiAl–Cu systems. During the studies the following question arises: where is the most favorable place of the void formation. This question will be discussed.
•Voids growth due to the drift velocity and vacancy migration.•Experimental results in Fe–Pd and β-NiAl–Cu systems are shown.•Radius of the void is estimated.•Two-dimensional approach is proposed.
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