Search results for "Diffusion layer"
showing 5 items of 15 documents
Effective diffusion coefficient and diffusion-controlled reactions in insulating solids with defects
1995
Abstract The expressions for effective diffusion coefficient are obtained in the mean field approximation for two-phase system for spatial dimensions of 1, 2 and 3. The existence of potential barrier for diffusion on the phase boundary was taken into account via the boundary conditions. Obtained formulae could be applied in the theory of diffusion-controlled reactions and for interpreting the experimental data on defect diffusion in two-phase media.
Numerical Determination of Intrinsic Diffusion in Fe-Cr-Al Systems
2010
The intrinsic diffusion coefficients in diffusion aluminide coatings based on Fe-30Cr were determined at 1000oC. The diffusion fluxes were given by the Nernst Planck formulae and the Darken method for multicomponent systems was applied. This paper summarizes some numerical results to determine the composition dependent diffusivities in Fe-Cr-Al systems. The method presented in this study to obtain average intrinsic diffusion coefficients is as an alternative to the Dayananda method. Our method based on empirical parameters allowed us to predict the concentration profile during the interdiffusion process.
Numerical Determination of Intrinsic Diffusion Coefficient of Aluminide Coatings on Metals
2009
This paper presents a numerical method to determine the composition dependent diffusivities and to predict the concentration profile during the interdiffusion process. The intrinsic diffusion coefficients in diffusion aluminide coatings (Fe-Al) were determined at 1000oC. The obtained diffusion coefficient for iron in Fe3Al or FeAl is in the range 10-10 to 10-9 cm2.s-1. The aluminum diffusion coefficient varies from 10-11 to 10-7 cm2.s-1 in the same phases.The present approach also permits to model the reactive diffusion in the Fe-Al systems.
Diffusion and Migration
2003
The sections in this article are Introduction Fundamental Concepts Diffusion–migration Flux Equations Poisson Equation and the LEN Assumption Continuity Equation Ohm's Law and Migrational Transport Numbers Diffusion-conduction Flux Equation Diffusion Boundary Layer Faraday's Law and Integral Transport Numbers Nernst Equation and Concentration Overpotential Steady State Current–voltage Curves of Systems with One Active Species Integration of the Transport Equations Solutions of Homovalent Ions, |zi | =z Binary Electrolyte Solutions Ternary Electrolyte Solutions. The Supporting Electrolyte Weak Binary Electrolyte Steady State Current–overpotential Curves in the Presence of Supporting Electrol…
Scale dependent diffusion in latex films studied by photoinduced grating relaxation technique
2003
The transition from an aqueous dispersion of polyacrylate latices into a homogeneous polymer film on drying has been studied by monitoring the diffusion of hydrophobic and hydrophilic photochromic molecular probes with the help of a holographic grating relaxation (forced Rayleigh scattering) technique. Experiments with the hydrophobic probe in wet films result in an unusual spatial scale-dependence of the apparent diffusion coefficient that degenerates into a normal scale-independent diffusion coefficient as the film dries. Employment of a two-state diffusion model allows extracting the diffusion coefficients and mean displacements of the tracer in the polymer cores of the latex particles a…