It was found that very thin layers of the low-alloy steel, when implanted with very low concentrations of C ions, could exhibit modified H permeation kinetics. The C was implanted into one face of the samples so as to produce a concentration of about 0.8at% to a depth of 200nm. These samples exhibited more rapid H permeation kinetics with higher amounts of H. Thus, non-implanted samples had a diffusivity of 1.5 x 10-10m2/s, the implanted layers had a diffusivity of 7.1 x 10-16m2/s, and the diffusivity of the composite structure was 3.5 x 10-12cm2/s. The data were analyzed by using a new theory which permitted the design of layers, of various thicknesses, which had either an increased or decreased H permeability.

Hydrogen Permeation Behaviour of Carbon Ion Implanted HSLA Steel. M.A.Zampronio, A.Filevich, P.E.V.De Miranda: Journal of Materials Science Letters, 1996, 15[9], 810-1