Effect of rare earth cerium on the synthesis and wear-resistance of electroless Ni-P-PTFE coatings

By adding various concentrations of rare earth cerium into the acidic hypophosphite plating baths, electroless Ni-P-PTFE coatings have been successfully deposited on the surface of shaft made of mild steel. Surface morphology, microhardness and interfacial adhesion of the coatings were characterized by scanning electron microscope equipped with energy dispersive spectrometer, vicker microhardness meter and WS-92 scrape instrument, respectively. Ring-plate wear test was applied to study the friction coefficient and wear resistance of Ni-P-PTFE coating. Results revealed that Ni-P-PTFE coatings deposited with 10ppm or 20ppm cerium in the plating baths show low friction coefficient and high interfacial adhesion, leading to its perfect wear resistance. However, both the interfacial adhesion and wear resistance of the Ni-P-PTFE coatings were decreased drastically as the cerium concentration in the plating baths was exceeds 50ppm.