Analysis of geometrical and surface effects on experimental data extracted from a hydrogen permeation test: Consequences of an oxide layer

摘要

To understand a metal susceptibility to Hydrogen Embrittlement (HE), it is importantrnto quantify the diffusion of hydrogen through a metallic membrane. Electrochemicalrnpermeation tests are the most common methods for experimentally determining the diffusionrncoefficient of a metal. However the parameters directly accessible from experiments are therntime required for a stream to be observed and the flux saturation corresponding to a steadyrnstate. The literature offers different models to obtain the diffusion coefficient from theserncurves. But this diffusion coefficient is not that of the membrane alone because it also takesrninto account the surface state and the kinetics of trapping. For some thicknesses of membranernand surface coatings (oxide) this approximation cannot be considered fair. We propose tornsimulate numerically the influence of the oxide thickness on the effective diffusion coefficientrntaking into account the trapped hydrogen. This study should enable us to correct thernexperimental data to provide value of lattice diffusion and hydrogen solubility.