Fretting tribological performance of DLC, TiAlN and DLC/TiAlN coatings deposited on carburized 18CrNi4A steel

Abstract To improve the fretting wear performance of 18CrNi4A steel, DLC, TiAlN and DLC/TiAlN coatings were deposited on the surface of carburized 18CrNi4A steel, respectively. The microstructure morphologies, chemical compositions, and mechanical properties of these coatings were evaluated. The fretting tribological properties of pad/flat contact pairs for carburized 18CrNi4A steel, DLC, TiAlN and DLC/TiAlN coatings were investigated in different lubricant environments including dry sliding and #RIPP 7254 aviation grease. The results show that DLC, TiAlN and DLC/TiAlN coatings deposited on the carburized 18CrNi4A steel surface can improve surface roughness, hardness, fracture toughness and resistance to plastic deformation. DLC, TiAlN and DLC/TiAlN coatings deposited on the surface of carburized 18CrNi4A steel can make the surface of the substrate have excellent fretting wear properties. DLC and DLC/TiAlN coatings have lower coefficient of friction and better fretting wear resistance than TiAlN coatings in dry sliding condition, and DLC/TiAlN coatings have the lowest wear rate in #RIPP 7254 grease lubrication condition. In addition, the wear mechanisms of carburized 18CrNi4A steel, DLC, TiAlN and DLC/TiAlN coatings in dry sliding and #RIPP 7254 aviation grease conditions were analyzed.