An alternative approach to the tribological analysis of Si-doped DLC coatings deposited with different bias voltages using Raman spectroscopy mapping

A series of diamond-like carbon (DLC) coatings were deposited with increasing bias voltage using magnetron sputtering techniques. Structural changes were observed in the sp2-configuration across the films which were accompanied by a slight increase in the sp3 fraction. With an increasing bias voltage, the thermal stability of the coatings increased from 300 to 450 °C. Oxygen diffusion was observed through the coating as a result of the high-temperature annealing and found to slow down with increasing bias voltage. Coefficients of friction (COF) remained stable with temperature for the individual coatings, with the softer films reporting the lowest COF. Our approach employed Raman spectroscopy to map the wear tracks at different temperatures, providing a deeper understanding of the coating performance and suggested maximum flash temperatures endured during testing.