Tribological behavior of polyimideiepoxy resin-polytetrafluoroethylene bonded solid lubricant coatings filled with in situ-synthesized silver nanoparticles

Polyimide/epoxy resin-polytetrafluoroethylene (denoted as PI/EP-PTFE) bonded solid lubricant coatings filled with silver nanoparticles synthesized in situ were prepared. The phase composition and grain size of the Ag nanoparticles were analyzed by X-ray diffraction and field-emission scanning electron microscopy, respectively. A micro-hardness tester was employed to determine the micro-hardness of the as-fabricated PI/EP-PTFE lubricant coatings, and a ring-on-block test rig was selected to evaluate the tribological behavior of the lubricant coatings under dry friction and RP-3 aviation kerosene lubrication conditions. The worn surfaces of the lubricant coatings were observed with a scanning electron microscope. Results indicate that the silver citrate precursor was decomposed to generate Ag nanoparticles during the curing process of PI/EP-PTFE lubricant coatings. Resultant in situ-synthesized Ag nanoparticles with a size of about 100 nm were homogeneously dispersed in the lubricant coatings, thereby significantly increasing the micro-hardness, reducing the friction coefficient and enhancing the wear life of the lubricant coatings. Particularly, the lubricant coating filled with 5% Ag nanoparticles exhibited the lowest friction coefficient and the longest wear life. Moreover, due to the excellent lubrication and cooling effect of RP-3 aviation kerosene, the lubricant coating achieved better friction-reducing and anti-wear abilities under RP-3 aviation kerosene lubrication than that under dry friction. (C) 2017 Published by Elsevier B.V.