Electrochemical methods were used to study diffusion in materials which contained 20wt% of polytetrafluoroethylene. It was found that the diffusivity decreased with increasing H content (table 112), and this was attributed to the porosity of the materials. An anomalous temperature dependence was attributed to structural changes.

O.A.Petrii, S.J.Vesina, I.I.Korobov, I.V.Kovrigina, K.N.Semenenko: Elektrokhimiya, 1985, 21[11], 1565-8. (Soviet Physics - Electrochemistry, 1985, 21[11], 1482-51)

 

Table 114

Permeability of H in GH761

 

Heat Treatment

Po (mol/msMPa½)

E (kJ/mol)

1090C,2h; w

0.000352

63.45

1090C,2h; w; 850,4h; a

0.000177

62.39

1090C,2h; w; 850,4h; a; 750C,24h; a

0.0000890

58.23

1090C,2h; w; 770,4h; a

0.000777

70.57

a: air-cooled, f: furnace-cooled, w: quenched