Hydrogen permeation barrier of carbon-doped TiZrN coatings by laser carburization

Abstract Hydrogen impermeability of carbon-doped TiZrN coatings was investigated in terms of carbon diffusion behavior and bonding states. The FFT pattern of a ring pattern and the inverse FFT with edge dislocations indicated formation of an amorphous phase and change in intergranular structure due to carbon diffusion through the grain boundaries of TiZrN. The diffused carbon followed Harrison Type-B behavior, because of localization at near-surface and increased compressive residual stress. The formation of amorphous carbon suggested the trapping at boundaries. The impermeability of the carbon-doped coatings was enhanced by 80 %, showing the contribution of amorphous carbon as a repellent.