Optimization of tribological and mechanical properties of epoxy through hybrid filling

In the present work, epoxy based quaternary composites were produced by filling lubricant oil-loaded microcapsules, surface grafted nano-SiO2 and discontinuous carbon fibers. Through orthographic tests, the optimal contents of the fillers were determined for achieving significantly improved tribological properties. The lowest specific wear rate and friction coefficient of the composite can be 9.8 × 10−7 mm3/N m and 0.12, respectively, much lower than those of unfilled epoxy, i.e. 1.3 × 10−4 mm3/N m and 0.56. In addition, mechanical properties, especially the maximal loading ability, of the quaternary composite were evidently higher than those of the binary composite with oil-loaded microcapsules. The oil released from the broken microcapsules during sliding wear mainly accounted for the lubrication, while nano-SiO2 and carbon fibers serve as both solid lubricant and reinforcement. As a result, positive synergetic effect appeared and the proposed quaternary composites might be applicable in practice.