Study on tribological behavior of nanocopper lubricant additive by four-ball tester and its lubricating mechanism

The tribological characteristics of the base oil N68 and N68NT1 added 4% self-repairing nanocopper lubricant additive NT1 were investigated by MJ-100 four-ball friction and wear tester; the worn spot of steel ball surface and its constitute were respectively analyzed with Scan Electron Microscope (SEM) and Energy Disperse Spectrum (EDS); and the lubricating mechanism of self-repairing nanocopper lubricant additive on the steel/steel friction pairs was discussed. As the results, self-repairing nanocopper lubricant additive NT1 contributes to significantly increasing the anti-wear ability and load-carrying capacity of the base oil N68; the friction coefficients of steel ball/steel ball under lubricated by N68NT1 decrease respectively 33.8%, 39.4% and 55.5% compared with that of N68 under load of 296 N, 392 N and 490 N; the diameter of worn spot of steel ball decrease of 46.5%, 45.6% and 32.5% respectively. Mean while, the p_B value of N68NT1 is improved 33.3% compared with that of N68. This may be attributed to the synergetic effect of sediments on the worn steel surface.