Improved mechanical and tribological properties of diamond-like carbon films by adjusting pulsed substrate bias

In order to obtain super-hard films with excellent mechanical and tribological properties, diamond-like carbon (DLC) films were prepared on ultra-fine grained cemented carbide substrates by linear magnetic filtered arc ion plating (AIP) under different negative pulsed bias voltages. The result indicated that the pulsed bias voltage had a strong effect on the structure and properties of DLC films. The as-deposited films showed very smooth surfaces because of the magnetic filtration system. Upon increasing the bias voltage from 0 to-1000 V, the fraction of sp3 bonds first increased and then decreased, while the ratio ID/IG exhibited the opposite tendency. The maximum sp3 bond fraction of 74.4 % was determined at-200 V, resulting in the highest hardness, elastic modulus, and elastic recovery of the films. Furthermore, the films exhibited excellent tribological properties with the lowest friction coefficient of 0.073 at-200 V, which was associated with the super-high hardness and low surface roughness. The improved mechanical and tribological properties of DLC films could be achieved by using the appropriate pulsed bias voltage.