The steady-state permeation rates of H through 2N8-purity foils which were 6.7μ to 1.83mm in thickness were determined by using a pressure gradient of 760torr. The permeation rates were inversely proportional to the thickness of the foil. Over the temperature range of 423 to 1000K, the rate could be described by:

r (mol/cm2s) = (7.22 x 10-7 exp[-52400/RT])/d(cm),

where d was the foil thickness. The diffusion coefficients were determined by using the time-lag method, and calculations which were based upon steady-state permeation and H solubility data. The led to the expression:

D (cm2/s) = 5.39 x 10-3 exp[-4.00(kJ/mol)/RT]

It was concluded that the permeation of H was governed by volume diffusion.

W.Fischer: Zeitschrift für Naturforschung A, 1967, 22, 1581-72