Abstract
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.
Highlights
Diamond-like carbon (DLC) coatings have been widely researched during the past decade
We investigated the structural changes in the sp2 and sp3 configuration with increasing bias voltage, by Raman spectroscopy and x-ray photoelectron spectroscopy (XPS)
Si-doped DLC coatings deposited with increasing bias voltages ranging from 65 to 85 V have been studied
Summary
Diamond-like carbon (DLC) coatings have been widely researched during the past decade. The wide range of applications of these films arises from their remarkable properties, such as low friction and high wear resistance, chemical inertness, nano-smoothness, or even anti-bacterial properties [5, 6]. These coatings have some limitations complicating their wider application, such as the low thermal stability, dependence on the sliding environment, or the adhesion strength [7,8,9,10]. The sliding environment has been reported to affect greatly the surface chemistry of these films, reporting large differences in COF in dry environments and humid, as well as between those coatings deposited with hydrogenated precursors and without them [7, 17, 18]
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