Preparation and Friction and Wear Behavior of Waterborne Epoxy Resin-Based Bonded Solid Lubricant Coatings

Epoxy resin-based bonded solid lubricant coatings containing three types of solid lubricants (MoS2, graphite, and Sb2O3) were prepared using water as the dispersing medium. The epoxy resin-based bonded solid lubricant coatings were inexpensive, non-toxic, inflammable, and free of any volatile organic compounds (VOC), which made the coating environmentally friendly. An MFT-R 4000 type reciprocal friction and wear tester was used to evaluate the friction and wear behavior of the epoxy resin-based bonded solid lubricant coatings. The morphologies of the worn surfaces of the coatings and the transfer films on the counterpart steel surfaces were analyzed by using a scanning electron microscope, while the chemical states of Mo on the unworn and worn coating surface were analyzed by using an X-ray photoelectron spectrometer. And the wear mechanisms of the coatings were explored and discussed. It was found that the as-cured epoxy resin-based bonded MoS2-graphite-Sb2O3 coatings had better wear resistance and fatigue resistance than that of coatings with single and binary solid lubricants. Synergistic effects on anti-wear and anti-fatigue were found for two combinations, i.e. Sb2O3 and MoS2, graphite and MoS2. The synergistic effect of Sb2O3 and MoS2 was mainly related to mechanical interaction, and that of graphite and MoS2 was mainly due to reduced inter-layer interactions by adsorption of moisture on the surface of graphite. The failure of the bonded solid lubricant coatings was largely attributed to fatigue wear and micro-cracking induced by friction.