Microstructure, mechanical, and tribological properties of hydrogenated amorphous carbon film deposited on Ti6Al4V alloy under different substrate bias voltage

The aim of this work is to find how substrate bias affect the microstructure, mechanical, and tribological properties of the a-C/H films deposited on Ti6Al4V by magnetron sputtering. In order to attain this purpose, the structure of the deposited a-C/H film was investigated by scanning electron microscopy. Chemical bonding was examined by Raman spectroscopy techniques. Mechanical and tribological properties were evaluated using nanoindentation, scratch, internal stress, and ball-on-disk friction testing. The results showed that the sp 2 content in a-C/H films increased as the bias voltage increased from − 400 to − 1200 V, indicating the graphitization of the films. The hardness (H) decreased from 29 to 18 GPa and the adhesion strength ranged from 13.1 to 25.3 N with increasing bias substrate. The average friction coefficient decreased at a bias voltage of − 300 V and increased when the bias voltage increased to − 1200 V. The best tribological performance was reached at − 600 V bias voltage. Reasons for the changing of structures, mechanical and tribological properties of a-C/H films were proposed.