Effect of hydrogen charging on the wear resistance of CrN-coated Al alloy for hydrogen valve of fuel cell electric vehicles

In this research, wear resistance of chromium nitride (CrN) coated aluminum alloy with hydrogen charging was investigated. Delamination rates of the CrN coating layer after 6 and 12 h of hydrogen charging were measured to be 42.37% and 86.96%, respectively. In particular, damage by hydrogen attack was observed in the exposed area of aluminum alloy. Increasing in applied load and hydrogen charging time decreased the friction coefficient, and when the two factors interacted, a significantly higher increasing rate of wear damage was observed. The increasing rate in wear depth due to hydrogen charging was greater at the applied of 1 N than at 5 N. This is because hydrogen permeation affects the wear resistance of the CrN coating layer and aluminum alloy in the depth direction. In addition, re-transfer and re-adhesion of the CrN coating, whose adhesion strength had decreased due to hydrogen charging, actively occurred.