Tribological behavior of molybdenum disulfide bonded solid lubricating coatings cured with organosiloxane-modified phosphate binder

Abstract

Hydroxyl-polysiloxane prepolymers were prepared via refluxing methyltriethoxysilane (METS) and dimethoxydimethylsilane (MSDS) at 75 °C in the presence of hydrochloric acid as the reactant. As-obtained prepolymers were used to modify aluminum chromium phosphate binder; and the modified aluminum chromium phosphate binder was adopted to fabricate bonded solid lubricating coatings with MoS₂ and Sb₂O₃ as the solid lubricants. The structure of the modified aluminum chromium phosphate binder was investigated by infrared spectrometry and X-ray photoelectron spectroscopy. The corrosion behavior of the organosiloxane-modified phosphate solid lubricating coatings was examined by salt spray test. Moreover, an MM-200 friction and wear tester and an Optimol SRV-IV oscillating friction and wear tester were performed to evaluate the tribological behavior of the solid lubricating coatings at room temperature and 500 °C. The worn surfaces of the solid lubricating coatings were observed and analyzed with a scanning electron microscope. It was found that P–O–Si bond was formed in the organosiloxane-modified aluminum chromium phosphate binder, which confirmed that there occurs chemical reaction between hydroxyl-polysiloxane prepolymer and the aluminum chromium phosphate binder. As a result, the flexible organic structure bonded in the aluminum chromium phosphate binder favored to improve the toughness, corrosion resistance and tribological behavior of the molybdenum disulfide bonded solid lubricating coatings.