Sliding Wear Behavior of HVOF-sprayed Cr3C2–NiCr/CeO2 Composite Coatings at Elevated Temperature up to 800 °C

Abstract

Four types of Cr3C2–NiCr coatings containing different fractions of CeO2 additive were deposited using high velocity oxy-fuel spraying. Hardness tester, X-ray diffractometer, contact surface profiler, and scanning electron microscope equipped with energy dispersive spectrometer were employed to characterize the microhardness, phase composition, surface roughness, and microstructure of as-sprayed coatings. At the same time, the friction and wear behavior of the as-sprayed coatings sliding against Si3N4 ball at room temperature and elevated temperature of 400 or 800 °C under unlubricated condition was evaluated using an oscillating friction and wear tester. The worn surfaces of the composite coatings and Si3N4 counterpart balls were analyzed by means of scanning electron microscopy, X-ray diffraction, and three dimensional non-contact surface profiler. The friction and wear mechanisms of the coatings with and without CeO2 additive were comparatively discussed. Results show that the composite coatings doped with CeO2 had better wear-resistance than that without CeO2, and the coating containing 4 wt% CeO2 showed the best wear-resistant property. The improved wear-resistant properties of the composite coatings doped with CeO2 were attributed to the refined microstructure and improved mechanical properties induced by CeO2.