Diffusion Phenomena in Slabs of Finite Thickness

A mathematical model of coatings of finite thickness is developed. Diffusion into a virgin region occurs for a specified time; diffusion out from the nonuniformly contaminated region then takes place for another specified time. The amount of contamination is given as a function of time and position, and the integrated contamination is given as a function of time. Curves are presented to make the model useful for the experimental determination of the diffusion coefficient.