Tribological characteristics of electroless Ni-P-MoS_2 composite coatings at elevated temperatures

摘要

Ni-P-MoS_2 composite coatings were deposited on AISI-1045 steel plate by electroless plating followed by a heat treatment at 300℃ for 2 h. The high-temperature tribological characteristics of the composite coatings were evaluated under dry sliding conditions in a tribometer with ball-on-disk configuration. The effect of the co-deposition of MoS_2 on the friction and wear behaviors of composite coatings at elevated temperature was investigated. Scanning electron microscopy was used to determine the morphology of the worn surface of composite coating. The chemical states of some typical elements on the worn surfaces were determined by X-ray photoelectron spectroscope. The results indicate that friction coefficient of the composite coatings decreases with the increase of test temperature up to 500℃, and the best tribological properties of Ni-P-MoS_2 composite coatings are achieved at 400 ℃. The worn surface of Ni-P-MoS_2 composite coatings are characterized by mild scuffing and deformation. The improvement of tribological properties of the composite coatings was attributed to the formation of the lubricious oxide film composed of oxides of Ni and Mo at high temperatures. With the test temperature increasing to 600℃, the tribological properties of the composite coating begin to deteriorate due to softening of the coating.