Influence of CePO4 on high temperature anti-friction and anti-wear behaviors of nickel-based h-BN composite coatings

Solid lubricating coatings which offer and maintain anti-friction and anti-wear are urging to develop in the advanced technology applications over a wide range of temperatures. The h-BN composite coatings on the Inconel X750 superalloy is prepared by spark plasma sintering (SPS) technology to obtain low friction and wear over a broad temperature ranging from room temperature (RT) to 800 degrees C using a high temperature rotary tribometer. The influence of the contents of h-BN and CePO4 powders of the tribological properties of the composite coatings was studied systemically under different temperatures. The experimental results show that the composite coatings with 20 wt% h-BN show excellent high temperature anti-friction behaviors. Coefficient of friction (CoF) of the composite coatings with 20 wt% h-BN with CePO4 powder is lowest about 0.12 among the composite coatings at 800 degrees C. The CePO4 powders are helpful to improve the sintering behaviors and reduce the wear rate of the composite coatings at elevated temperature. The synergistic lubrication mechanism of h-BN and CePO4 of the composite coatings are investigated systematically. The high temperature anti-friction and antiwear mechanism of the composite coatings is due to the formation of a layered gradient lubrication film on the worn surface.