Permeation and mass spectroscopy techniques were used to determine H diffusion coefficients in 3N-purity single crystals and polycrystals (table 192). It was found that the diffusion coefficients were independent of the H concentration. Overall, the results for temperatures of 400 to 1200C could be described by:

D (cm2/s) = 6 exp[-24.7(kcal/mol)/RT]

A.P.Kakharov, V.M.Sharapov, E.I.Evko: Fiziko-Khimicheskaya Mekhanika Materialov, 1973, 9[2], 29-33

 

 

 

Table 192

Diffusivity of H in W

 

Temperature (C)

D (cm2/s)

400

6.43 x 10-8

600

4.22 x 10-6

800

5.99 x 10-5

1000

3.67 x 10-4

1200

1.38 x 10-3