Microstructure and properties of CrN coating via multi-arc ion plating on the valve seat material surface

• CrN coating applied to engine valve seat ring was prepared by multi-arc ion plating. • The CrN coating with high bonding force, hardness and low friction coefficient. • The surface roughness and three-dimensional topography of the coating were tested by white light interferometer. • The three-dimensional morphologies of wear scars were observed. The multi-arc ion plating technology is used to prepare CrN coating on the valve seat material surface. Results show that the surface grains gradually increase in size and becomes less uniform with the increase of the Cr target current. At different Cr target currents, the main phases of the CrN coating are Cr, CrN, and Cr 2 N. The critical load of the coating and matrix is 49.2 N. When the Cr target current is 65 A, the nano-hardness is maximum (18.84 GPa), and Young ’s modulus is 255.41 GPa. The CrN coating can reduce the friction coefficient of the valve seat material from 0.62 to 0.48, thereby improving the wear-resistance behavior. The main wear mechanism is abrasive wear.