The tribological properties of PPS-PTFE/SiO2 coating deposited on the textured surfaces processed by ultrasonic rolling

Abstract

In this paper, ultrasonic rolling textures were fabricated on 42CrMo steel substrates, and the polyphenylene sulfide-polytetrafluoroethylene/silicon dioxide (PPS-PTFE/SiO2) lubricating coatings were deposited on the textured surfaces to improve the tribological properties of the coating-substrate system. The influences of textures with different shapes (spiral, linear, wavy textures) and step distances (100, 150, 200, 250 μm) on the surface morphologies and strengthening effects of the substrates were investigated. The results showed the wavy texture with a step distance of 200 μm had the best strengthening effect, which increased the surface hardness and residual compressive stress by 126.1% and 5.1 times compared to the substrate, respectively. The influences of different textures on the friction and wear properties of lubricating coatings were studied by dry reciprocating friction testings. The results showed that the coating on the spiral textured surface with a step distance of 250 μm had the best tribological properties, and the average friction coefficient and wear rate were reduced by 45.5% and 49.5% compared to the coating on the substrate. The influence of ultrasonic rolling texture on the tribological properties of the lubricating coating was a combined result of the strengthening effect and texture structure. The strengthening effect provided a steady gain, while the texture structure provided either a gain or a deterioration.