Abstract:
The tribological behavior of polyimide (PI) boned solid lubricating coatings filled with nanometer lanthanum fluoride (LaF_3) sliding against SAE2100 steel was examined on an MHK-500 friction and wear tester, using the PI-based coating without nano-LaF_3 as a control. The corrosion resistance of the coatings was evaluated according to GB 10125-88. Thus the effect of nano-LaF_3 as the filler on the antiwear ability and corrosion resistance of the coatings was highlighted. It was found that the coating with l%~2% nano-LaF_3 showed the best antiwear ability, but it recorded a friction coefficient almost the same as that of the coating without the nano-LaF_3 filler. Moreover, the incorporation of 2% nano-LaF_3 filler led to a significant increase in the corrosion resistance of the coating, and the corrosion resistance of the PI-based bonded solid lubricating coatings were related to the water contact angles. Namely, the PI-based coating containing 4% nano-LaF_3 had a smaller water contact angle, which corresponded to the poorer corrosion resistance of the coating. The improvement in the wear resistance and corrosion resistance of the PI-based bonded solid lubricating coatings by the incorporation of the nano-LaF_3 filler was attributed to the strengthened interfacial bonding among the nano filler and the polymeric matrix and various other fillers. However, the PI-based coating of a too high mass fraction of the nano filler had increased surface and interface defects, which led to the worsening of the wear resistance and corrosion resistance of the coating.