The flow of H through this steel was strongly affected by surface reactions. An experimental investigation which was based upon pressure modulation techniques showed that macroscopic flow could be described by:
D (m2/s) = 7.3 x 10-7 exp[-6300/T]
and
P (mol/smPa½) = 8.1 x 10-7 exp[-8190/T]
plus a surface reaction of the form:
H2 (gas) → 2H (solid)
The rate constant for this reaction ranged over an order of magnitude at each temperature, and depended upon the surface preparation. The fastest reaction occurred on in situ H-ion beam-cleaned surfaces. The surface coefficient for this case was:
K (mol/sm2Pa) = 0.032 exp[-9710/T]
D.M.Grant, D.L.Cummings, D.A.Blackburn: Journal of Nuclear Materials, 1988, 152, 139-45
Table 102
Diffusivity of D in AISI 316
Temperature (K) | Pb-Li Layer | D (m2/s) |
518 | yes | 6.8 x 10-13 |
526 | yes | 1.2 x 10-12 |
526 | no | 2.4 x 10-12 |
540 | no | 2.3 x 10-12 |
547 | no | 4.6 x 10-12 |
548 | yes | 1.7 x 10-12 |
556 | yes | 2.0 x 10-12 |
556 | no | 3.7 x 10-12 |
570 | yes | 1.9 x 10-12 |
584 | yes | 2.1 x 10-12 |
586 | yes | 2.3 x 10-12 |
589 | yes | 3.2 x 10-12 |
589 | no | 6.0 x 10-12 |
600 | no | 6.8 x 10-12 |
625 | yes | 5.7 x 10-12 |
626 | yes | 5.0 x 10-12 |
626 | no | 9.6 x 10-12 |
629 | yes | 4.6 x 10-12 |
632 | no | 6.9 x 10-12 |
652 | no | 1.0 x 10-11 |
665 | yes | 8.5 x 10-12 |
667 | yes | 8.5 x 10-12 |
667 | no | 1.6 x 10-11 |
680 | no | 1.8 x 10-11 |