Effects of Varying Power and Argon Gas Flux on Tribological Properties and High-Speed Drilling Performance of Diamond-Like Carbon Coatings Deposited using High-Power Impulse Magnetron Sputtering System

This study examines the effects of different pulse powers and gas fluxes on the mechanical and tribological properties and high-speed drilling performance of diamond-like carbon coatings deposited on tungsten carbide substrates by high-power impulse magnetron sputtering. It is shown that an appropriate pulse power is essential in improving the mechanical and tribological properties of the coatings. Specifically, coatings deposited with a pulse power of 5 kW possess a high hardness and good tribological properties, as evidenced by a high hardness-to-elastic modulus ratio. The optimal deposition parameters are determined to be a pulse power of 5 kW and an argon flux of 80 sccm. The resulting coating (designated as C80/5) has the highest hardness (24.95 GPa) of the various coatings and wear rates 11.1, 7.3 and 6.2 times better than those of the bare WC substrate under loads of 6 N, 10 N and 14 N, respectively. Moreover, the coating has low coefficient of friction values of 0.086, 0.098 and 0.062 under loads of 6 N, 10 N and 14 N, respectively. The micro-drilling tests show that the drill coated with C80/5 has a lifetime three times longer than that of an uncoated micro-drill.