Study on nanocrystalline Cr2O3 films deposited by arc ion plating: II. Mechanical and tribological properties

In this work, the influence of substrate bias voltage on the microhardness, adhesive strength, friction coefficient, and wear rate of AIP Cr₂O₃ films deposited on AISI 304 stainless steel substrates was investigated systematically. In the meantime, the wear failure mechanism of AIP Cr₂O₃ films in dry sliding contact was also analyzed and discussed. The results showed that the mechanical properties, adhesive behaviors, and tribological performance of AIP Cr₂O₃ films were greatly altered by applying a negative bias voltage. With increasing the bias voltage, the hardness, critical load, and tribological performance of AIP Cr₂O₃ films first were improved gradually, and then were impaired slightly again. When the bias voltage is − 100 V, the Cr₂O₃ film possessed the highest hardness, the strongest adhesion, and the best wear resistance. The essence of above phenomena was attributed to the variations of microstructure and defect density in the films induced by the substrate bias voltage increase. The main wear failure mechanism of AIP Cr₂O₃ films is crack initiation and propagation under the high contact stresses, inducing the local film with small area to flake off gradually, and eventually leading to the formation of a wear scar.