Permeation of gases through solids

Critical assessments are made of reported measurements of the permeability Psub(m) to H and its isotopes of pure Ni and of several high Ni content alloys. For pure Ni Robertson's (1973) 'best value' is still appropriate. For Incoloys all measured Psub(m) lie within a factor 1.5 either way of Psub(m) = 4 .10-2 exp(-15 kcal.mol-1/RT) ccs (STP) cm-1 s-1 atmsup(-1/2). For Inconels 600, 617 and 625 all data are within a factor 1.5 either way of Psub(m) = 5.7 . 10-2 exp(-16/RT (same units), but Psub(m) for Inconel 718 is better represented by Psub(m) = 7.5 . 10-2 exp(-13.4/RT. For Hasteloy X, Psub(m) = 5.3 . 10-2 exp-15.66/RT, and the Psub(m) for Hasteloys N and B may be quite similar. It is evident that the permeabilities of these series of alloys are relatively insensitive to quite large composition changes. They are on average about 2 to 4 times larger than those of the austenitic stainless steels. In the same general range are the permeabilities of many other high Ni alloys, Nichrome, Kovar, Ceramvar, Niromet, Monel etc. Oxide layers on many of these alloys greatly impede permeation. (author)