As part of a study of surface protection, tracer techniques were used to monitor S penetration of oxide scales. It was found that, when the sulfidizing agent was 35S vapour at a pressure of 10-6atm, the S diffusivity was equal to 10-13cm2/s. When the sulphidizing agent was labeled-H2S at a pressure of 10-6atm, the diffusivity was 6 x 10-13cm2/s.

Heterodiffusion of Sulfur in Polycrystalline Alumina Protecting an Alloy from Sulfidizing Corrosion-Diffusion Model. J.P.Larpin, P.A.Mari, J.M.Chaix, J.C.Colson: Solid State Ionics, 1984, 12, 459-65