Effect of deposition mode and pulse parameters on the mechanical and tribological properties of magnetron sputtered TiBx films

Abstract

The structural, mechanical and tribological properties of TiB_x films deposited by high-power impulse magnetron sputtering (HiPIMS) were characterized to understand the effect of pulse parameters, including pulse length (7‒170 μs) and peak target current density (0.44‒1.1 A cm^‒2), on the film properties. For comparison, the films are also obtained in direct current (dcMS) and mid-frequency (mfMS) sputtering modes. The films are deposited on WC-Co substrates from a TiB₂ target at an Ar pressure of 0.2 Pa, average discharge power of 500 W, substrate bias voltage of ‒65 V and a substrate temperature of 420 °C. The phase composition, mechanical (hardness, elastic modulus), and tribological (friction coefficient and wear rate) properties of TiB_x films were measured. The adhesion of the films was assessed using the scratch and Rockwell C indentation tests. It is shown that HiPIMS is a preferred technique for depositing high quality TiB_x films with improved mechanical and tribological properties and that the pulse parameters significantly influence the properties of the deposited films. TiB_x films deposited using optimal HiPIMS parameters (pulse length of 100 μs and peak target current density of 0.44 A cm^‒2) outperform those produced using dcMS and mfMS in terms of hardness and friction coefficient. All TiB_x films exhibit low wear rates (about 2 × 10^‒6 mm³H^‒1m^‒1) and good adhesion to the WC-Co substrate, regardless of the sputtering mode.