Fabrication and hydrogen permeation resistance of dense CrN coatings

Hydrogen embrittlement has become a hot research topic due to the rapid development of hydrogen energy and coating technology is regarded as the most efficient method to mitigate hydrogen embrittlement. However, the grain gaps in coatings frequently serve as paths for hydrogen permeation thus decreasing the protecting effects. In this work, ion bombardment is performed during magnetron sputtering deposition of dense CrN coatings to decrease the formation of grain gaps. The compactness of the CrN coatings is improved by disrupting the growth of grains using energetic ion bombardment. Hydrogen permeation tests reveal that the apparent hydrogen diffusion coefficient and hydrogen permeability of the dense CrN coating 52.6 and 24.1 times less than those of the unprotected substrate. The tensile test also reveals excellent hydrogen embrittlement resistance compared to the X70 substrate and conventional coatings.