THE EFFECT OF PLASMA NITRIDING-BASE TREATMENTS ON THE ABSORPTION OF HYDROGEN BY IRON

Absorption of hydrogen by iron membranes modified by plasma nitriding, nitrocarburizing, sulphur-oxy-nitriding and oxy-nitrocarburizing was studied by the electrochemical permeation technique. Hydrogen was gene rated by cathodic polarization in 0.1 M NaOH at 25 degrees C. The perm eation rate of hydrogen through plasma treated membranes was by two or three orders of magnitude lower than that through an unmodified membr ane. Diffusivities and concentrations of hydrogen were determined for outer compound layers, inner diffusion layers, and an unmodified iron substrate. Contributions to the reduced hydrogen absorption were evalu ated for the hindrance of the hydrogen entry into the compound layers, and for the hindrance of hydrogen transport through the compound and diffusion layers.