The permeation through membranes prepared from various parts of nitrided specimens was investigated by using an electrochemical technique. The membranes were charged with H by galvanostatic cathodic polarization in 0.1M NaOH. Successive partial decay and build-up transients were analyzed in order to determine the diffusivities of H in the outer compound layer, the inner diffusion zone and the unmodified Fe substrate. The H transport in the diffusion zone was the most complex. It was found that H diffused mainly through the ferrite matrix, and by-passed the nitride precipitates. Therefore, the real diffusion paths in the diffusion zone had various lengths; and were greater than the membrane thickness.

Hydrogen Transport in Plasma Nitrided Iron. Z.Wolarek, T.Zakroczymski: Acta Materialia, 2004, 52[9], 2637-43