Tribological Reaction Generated on Ceramic – Steel Couples Under Boundary Lubrication

Abstract

The effect of ZnDTP on Al2 O3 , Si3 C, and Si3 N4 surface was investigated with ceramic-steel couples under lubricated conditions. Metal transfer to the ceramic surfaces was found to increase with load and surface roughness, depending on the kind of ceramic. P, S, and Zn as atomic constituent elements of ZnDTP were measured on the ceramic surface in all three types of ceramic-steel couple. The amount of each of these elements deposited increased as the Fe content transferred onto the surfaces increased. Measurements of hardness and fracture toughness were conducted on SiC and Si3 N4 in SiC - and Si3 N4 -steel couples with and without additive to determine changes in mechanical properties of the ceramic surfaces. Further investigations were conducted to determine the effect of the gases, O2 and N2 , on friction and wear properties of the Si3 N4 -steel couple. Saturation of the lubricant oil with O2 and N2 was found to cause an increase of the wear rate at about 100 N in this couple.