Effects of bias voltage and temperature on mechanical properties of Ti-Si-N coatings deposited by a hybrid system of arc ion plating and sputtering techniques

Ti-Si-N coatings were deposited on WC-Co substrates by a hybrid coating system of arc ion plating (AIP) and sputtering techniques. Effects of deposition temperature and substrate bias voltage on the microstructure and mechanical properties, such as microhardness, indentation elastic modulus of Ti-Si-N coatings were systematically investigated in this work. As the deposition temperature increased up to 300 °C, microhardness and indentation elastic modulus of the Ti-Si-N coating steadily increased. Higher temperature above 350 °C, however, caused the microhardness to decrease due to grain growth. The substrate bias voltage had an effect on the Si content in Ti-Si-N coating. Applying a small substrate bias voltage of -100 V in Ti-Si-N coatings induced compressive residual stress into the coating and modified its microstructure toward denser one due to ion bombardment effect. However, much higher substrate bias voltage of -400 V caused the diminution of Si content by re-sputtering phenomenon, which could result in a decline of nanocomposite characteristics of Ti-Si-N. The superior mechanical properties of the Ti-Si-N coatings were obtained at the deposition condition of 300 °C, -100 V.