Tribological properties of (Ti,Al)N coatings deposited at different bias voltages using the cathodic arc technique

A study was carried out to see the effect of substrate bias voltage on various tribological properties of (Ti,Al)N films deposited using the arc-PVD technique. Films were deposited at substrate biases of −30, −50, −100, −300 and −500 V. It has been found that the Al at.% decreases with an increase in bias voltage. The wear rate measured using a calo-wear test is at a minimum for the films deposited at −100 V bias voltage. Lattice strain and microhardness show a maxima at −100 V. It is observed that the number of macro particles on the surface increases with bias voltage for −30 and −50 V and decreases after −100 V. The Glancing-angle XRD shows the presence of the h-(Ti,Al)N phase at lower bias voltages. The color varies from bluish black (L=46.2, a*=−0.13, b*=−3.06) to brownish black (L=43.84, a*=2.39, b*=−1.53) as the bias voltage is increased. Oxidation and corrosion properties show marginal change with bias voltage.