Effect of the prior nitriding treatment on the adhesion and wear resistance of Cr/CrN coatings deposited over AISI 4140 steel

Abstract

Ceramic coatings improve the wear resistance of mechanical parts. However, adhesion of hard coatings to soft and ductile steel is usually poor because coating and substrate do not undergo similar deformations. In this work, coatings made of a Cr and a CrN layer deposited by cathodic arc PVD on plasma nitrided and untreated AISI 4140 steel were studied. Microstructure was examined by X-Ray Diffraction. Adhesion was analyzed by Rockwell C indentation and Scratch Test and wear resistance was evaluated by pin-on-disk test. The results show that the coatings deposited on nitrided steel exhibit better adhesion. The wear resistance of this system was found to be better than the non-nitrided and coated steel and the nitrided steel.