This study investigates the effects of WO_3 formed by the heat treatment and its influence on the tribological behavior of W doped DLC (W-DLC) at elevated temperatures. The coatings were heat treated at 500°C and 600°C for one hour and air cooled. Pins made of 319 Al were tested against the heat treated coating in a pin-on-disk configuration at temperatures ranging from 25°C to 400°C. The 600°C heat treatment did not show any improvement in the tribological behavior of the W-DLC coating. However, the heat treatment at 500°C reduced the COF to 0.11 at 100°C compared to the as-deposited coating's COF at 100°C of 0.58. XPS and XRD analyses (i.e. XPS) along with microscopic (i.e. SEM, TEM) investigations showed that a WO_3 rich layer which was formed during the heat treatment was responsible for the low COF observed at 100°C.
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