In order to elucidate hydrogen transport through non-dilute alloy membranes, an extensive series of absorption and flux measurements was performed for three V-Ni alloys over a range of pressures and temperatures. Alloy disks of three compositions (V95Ni5, V90Ni10, V85Ni15) were sliced from arc-melted ingots and coated on each side with a Pd dissociation catalyst. Hydrogen absorption and desorption isotherms were calculated using the Sieverts method, and the hydrogen flux was measured using the constant-pressure permeation method. The pressure–concentration relationships of these alloys were non-ideal; particularly at high hydrogen concentrations. The diffusion coefficients for each alloy consequently exhibited a significant hydrogen concentration dependence, which illustrated the non-applicability of Fick’s first law to these alloys. A strong dependence upon Ni content was also observed. During permeation the hydrogen concentration gradient increased with increasing distance from the feed surface.

Diffusion of Atomic Hydrogen through V-Ni Alloy Membranes under Non-Dilute Conditions. M.D.Dolan, K.G.McLennan, J.D.Way: Journal of Physical Chemistry C, 2012, 116[1], 1512-8

 

Table 187

Thermotransport of D and H in V

 

Material

Migrating Species

H (kJ/mol)

Nb

H

9.4

Nb

D

16.3

V

H

1.8

V

D

6.1

V-10at%Cr

H

4.8

V-10at%Cr

D

9.2

V-20at%Cr

H

5.8

V-20at%Cr

D

10.0

V-10at%Nb

H

8.5

V-10at%Nb

D

12.5

V-25at%Nb

H

13.1

V-25at%Nb

D

16.5

V-50at%Nb

H

15.8

V-50at%Nb

D

18.8

V-75at%Nb

H

16.9

V-75at%Nb

D

20.0

V-90at%Nb

H

15.8

V-90at%Nb

D

20.4

V-1at%Ti

H

3.5

V-1at%Ti

D

7.6

V-5at%TI

H

7.7

V-5at%Ti

D

10.9

V-10at%Ti

H

10.4

V-10at%Ti

D

13.4

V-20at%Ti

H

12.2

V-20at%Ti

D

14.2

V-30at%Ti

H

12.1

V-30at%Ti

D

13.2

 

Figure 39

Diffusivity of D in V-Cr and V-Ti

(squares: V, triangles: V0.96Cr0.04, circles: V0.9Cr0.1, stars: V0.97Cr0.03, crosses: V0.92Cr0.08)