%0 Journal Article
%T Hydrogen diffusion and uptake in nickel Alloy 625 under cathodic protection conditions.
%A Lu X
%A Johnsen R
%J Heliyon
%V 10
%N 13
%D 2024 Jul 15
%M 39050476
%F 3.776
%R 10.1016/j.heliyon.2024.e33924
%X Hydrogen diffusion and uptake in nickel Alloy 625 under cathodic protection potential (-1050 mVAg/AgCl) and temperature (10 °C) were studied using electrochemical permeation tests. It is the first time hydrogen permeation of nickel alloy at a temperature lower than room temperature was investigated. The results revealed that the effective diffusivity of hydrogen  D eff   at -1050 mVAg/AgCl varied from 1.81 to 2.86 × 10-15 m2/s across the temperature range of 10-23 °C. The effective subsurface hydrogen concentration  C s u b    was influenced by both the applied temperature and overpotential. Particularly, the change in  C sub   at 10 °C is dependent on the hydrogen absorption efficiency affected by the surface coverage fraction of hydrogen. Furthermore, the hydrogen fugacity on the sample surface  f H 2    , the applied overpotential, and the temperature have been successfully cross correlated to interpret hydrogen evolution and adsorption. It was demonstrated that  f H 2    primarily changed with the applied overpotential, while the temperature affected the gradient of  f H 2    during the potential increment. The current study provides valuable insights for industries, assisting in the prediction of hydrogen absorption and hydrogen-assisted failures in subsea nickel alloy components.