HYDROGEN PERMEATION AND DIFFUSION IN BERYLLIUM

A precise hydrogen permeation experiment for beryllium was conducted at a temperature ranging from 735 to 1000 K under hydrogen gas pressure of 10(1) to 10(3) Pa. Diffusion coefficient and permeation coefficient were determined from the steady slate permeation and time transient permeation independently. The steady state permeation rate was proportional to the square root of H-2 pressure and the time sequence of permeation rate agreed well with theoretical one, indicating that the permeation controlled by bulk diffusion. The temperature dependencies of the permeation coefficients (Phi) and diffusion coefficients (D) were respectively, Phi=(1.0+/-0.1)x10(-6) exp[-73+/-20(kJ/mol)/RT] (mol . m(-1). s(-1). Pa--1/2), D=(1.3+/-0.1)x10(-7) exp[-59+/-20(kJ/mol)/RT] (m(2) . s(-1)). Solubility calculated from the relation Phi=DS was S=7.1 exp[-14(kJ/mol)/RT] (mol . m(-3). Pa--1/2).