Quartz Addition Effects on Microstructure and Friction Wear Properties of Enamel Coating

Enamel coatings with the quartz addition amount of 0%, 4%, 8% and 12% were prepared by the single dipping method. The tribological properties of the coating were tested by HSR-2M high-speed reciprocating friction tester. In order to analyze the wear mechanism, scanning electron microscope was used to characterize the microstructure and the wear morphology of enamel coatings. Results showed that when the addition amounts of quartz were 0% and 4%, the enamel coatings had high porosity and low pore density. Microcracks tended to extend along the shortest distance among the pores, and the hard abrasives transferred to the worn surface during the friction process, which made sharp grooves at the bottom of the sliding wear track. The main wear mechanisms were abrasive wear and brittle fracture. While the addition amounts of quartz were up to 8% and 12%, the enamel coatings had low porosity and high pore density. And the size distribution of pores for 8% quartz coating was uniform, and the wear rate and wear track depth were only one third of that of 0% quartz coating. Small pores with uniform diameter increased the energy barrier for crack propagation during the friction process, and a dense self-lubrication accumulation layer of wear debris formed on the worn surface because of the interception of the small uniform pores in enamel coating. The wear mechanism was mainly abrasive wear.