Wear behaviour of steel-on-Si{sub}3N{sub}4 and Si{sub}3M{sub}4-on-Si{sub}3N{sub}4 systems with vapor phase lubrication of oleic acid and TCP

摘要

The wear property of Si{sub}3N{sub}4 under vapor phase lubrication of oleic acid and tricresylphosphate (TCP) in both steel-on-Si{sub}3N{sub}4 and Si{sub}3N{sub}4-on-Si{sub}3N{sub}4systems were investigated. The used oleic acid and TCP were fed into the evaporator simultaneouslywith two syringe pumps, and the vaporized lubricants were delivered by the carrier gas of nitrogen tothe ball pot of a modified four-ball wear tester. Tests were made using M50 tool steel ball orSi{sub}3N{sub}4 ball against Si{sub}3N{sub}4 discs at a load of 98 N and temperature of 370℃.Oleic acid, TCP and the combination of oleic acid with TCP as the vapor lubricants were evaluatedfor test time from 30 mm to 3 h. Results indicate that the oleic acid provides effective lubrication forsteel-on-Si{sub}3N{sub}4 system, and for the combination of oleic acid with TCP, the wear can beeven reduced. The wear of Si{sub}3N{sub}4 disc in steel-on-Si{sub}3N{sub}4 system is alwayslower as compared to that of in Si{sub}3N{sub}4-on-Si{sub}3N{sub}4 system. X-ray photoelectronspectroscopy (XPS) analyses of the rubbed surfaces suggest the formation of a film containingcarbonaceous deposits, iron phosphate, N-containing compounds and silicon oxides due to theoxidation of Si{sub}3N{sub}4.