Microstructure and tribological properties of CrAlTiN coating deposited via multi-arc ion plating

Abstract

Developments in engine technologies have led to reduction in engine volume and increase in engine power. Thus, valve seat ring components in engines should have high wear resistance. In this study, a high-performance coating on the surface of valve seat material was investigated. The CrAlTiN coating was prepared on the surface of vermicular graphite cast iron, a common material of valve seat ring, with a multi-arc ion plating technology. Experimental results showed that the distribution of crystal clusters was relatively uniform as bias voltage increased from − 100 V to − 400 V and large droplets appeared at low bias voltage. As bias voltage increased, the sizes and number of droplets decreased, and pits appeared. The increase of bias voltage was beneficial to the formation of new phase of CrAlTiN coating. At bias voltages of − 300 and − 400 V, the phase composition was mainly TiN, AlN, CrN, and small amounts of Al2O3, Cr2O3, Ti2O3, and Cr. The adhesion, nano-hardness, and elastic modulus of the coating increased and then decreased with increasing bias voltage. When the bias voltage was − 300 V, the maximum adhesion was 61 N, the nano-hardness was 26 GPa, and the elastic modulus was 268 GPa. Moreover, the lowest friction coefficient was observed (0.4). The wear mechanism of CrAlTiN at different bias voltages was abrasive wear.