Abstract
To improve the tribological properties of titanium alloy at elevated temperatures, a multilayered lubricating coating was fabricated on the surface of Ti6Al4V alloy, involving an oxide ceramic coating deposited by PEO treatment, an electroplating Ag coating and a burnished MoS2 film. The tribological properties were evaluated by a ball-on-disk high temperature tribometer over a wide temperature range (RT-600°C). The results showed that the low friction coefficient and high wear resistance were exhibited at room and medium temperatures (<350°C) due to the effective lubrication of MoS2 and Ag layers and the high load supports provided by hard PEO coating. At high temperatures (>350°C), the oxidation of MoS2 topcoats and the adhesive wear of softened Ag led to the direct contact of Si3N4/exposed oxide underlayer giving rise to the rapid increase of friction coefficient. As the temperature increased to 600°C, the friction coefficient sharply decreased to a low level ~0.2, which was attributed to a combined effect of the diffused Ag from discharged reservoirs, the presence of high temperature lubricants (MoOx, Ag2MoO4) and the formation of lubricants/lubricating glaze layers contact.
Published Version
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