Effect of hydrogen charging on the mechanical characteristics and coating layer of CrN-coated aluminum alloy for light-weight FCEVs

Abstract

Abstract To commercialize fuel cell electric vehicles, it is essential to reduce the weight of the components and lower the manufacturing cost. In this study, the effect of hydrogen charging on the mechanical characteristics of aluminum alloys and CrN coating was also investigated through cathodic hydrogen charging, indentation and scratch experiments. The delamination of the CrN coating by hydrogen charging was observed through the experiments. In addition, as the hydrogen charging time increased, the hardness of the aluminum alloy increased by about 29.7%, whereas the hardness of the CrN coating decreased by about 42.8%. In particular, in the scratch experiments, it was found that hydrogen embrittlement and hydrogen blistering occurred at the interface between the CrN coating layer and the aluminum alloy due to hydrogen permeation and diffusion. Therefore, the adhesion strength of the CrN coating decreased significantly. However, the CrN coating was shown to suppress hydrogen permeation into the aluminum alloy.