A simple theory for maximum H inventory and release: A new transport parameter

A simplified theory of hydrogen transport in materials is presented. The problem is formulated in terms of a dimensionless transport parameter, W = R(phiK0)sup(1/2)/D where R is the projected range, phi is the incident penetrating flux, K0 is a phenomenological recombination coefficient and D is the diffusion coefficient for hydrogen in the material. Using this parameter, equations which describe recycle times, maximum hydrogen inventory and maximum hydrogen permeation are derived. This treatment yields simple analytic expressions for these quantities which are shown to be excellent approximations to the behavior obtained from exact numerical solutions. This transport parameter further results in a natural classification of the different types of behavior of hydrogen in materials. (orig.)