Preparation And Study Of Self-Lubricating Ceramic Coating On Surface Of Aluminium Alloy

Self-lubricating composite had inherent superiorities in mechanical design and simplification, and carried excellent tribological behaviour under special surroundings, which was one of the importance hot research topic on the realm of tribology and material science. In this paper, the antifriction and wearable self-lubricating ceramic coating was successfully prepared on the surface of LY12 aluminium alloy by micro-arc oxidation (MAO) and coating technology. The effects of technology parameter, additive, adding amount of solid lubricate and coating PTFE on the friction and wear properties of ceramic coatings were detailedly studied. According to phase compositions, surface morphologies of ceramic and friction pair, the self-lubrication processing of ceramic coating was discussed.The phase compositions of ceramic coating was investigated by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The element compositions and distributing were analysed by Electron probe microanalysis (EPMA) and Energy spectrum (EDS). The morphologies of ceramic coating and wear scar were observed by Scanning electron microscopy (SEM). The sliding friction and wear properties of ceramic coating were tested by ball on disc tester and reciprocating friction and wear testing machines, respectively. The morphology of wear scar was observed by optical microscope. The results showed that technical parameters had direct influence on the friction and wear properties of ceramic coating prepared in aluminate solution.The ceramic had good friction and wear properties under technical parameters of current density as 8 A/dm2, electrolyte concentration as 8 g/L and processing time as 60 minutes. When NaF was added to the electrolyte, the surface of ceramic coating becomes smooth and friction and wear properties became better. The proper adding amount is 2 g/L. Self-lubricating ceramic coating was prepared by suspending appropriate amount solid lubricant in solution, which could notably decrease friction coefficient and weight loss of ceramic coating. Coated PTFE on the surface, ceramic coating could hold antifriction and wearable self-lubrication property. Weight loss of the ceramic coating, which coated PTFE, was 0 mg under 5 N low load wearing 20 minutes.At surrounding of air and room temperature, when coated PTFE film, the ceramic coating without solid lubricant sharply decreased the friction coefficient and weight loss, and the ceramic coating with solid lubricant had low coefficient increasing trend.According to the morphologies of wear scar and friction pair, the processing mechanism of self-lubricating ceramic coating was proposed. Meanwhile, the cycle process of self-lubricating film, which underwent forming, destroyed, shed and regenerating, was analyzed.