Friction and wear behavior of sialon/ (Ca,Mg)-sialon with lubrication by coated PbS nanoparticles as oil additives

The friction and wear behaviour of Sialon/(Ca,Mg)-Sialon with lubrication by liquid paraffin containing PbS nanoparticles coated with dialkyldithiophosphate or oleic acid as additives was investigated using an SRV ball-on-disc test rig. It was found that the addition of such nanoparticles reduced the friction coefficient of the friction couple irrespective of the concentration of the additive and the wear volume of (Ca, Mg)-Sialon, especially under relatively high loads such as 150 N or more. X-ray photoelectron spectroscopy and electron probe microanalysis revealed that a tribochemical film composed of PbSO₄, PbS₂O₃, PbSO₃, etc., was formed on the worn surface, and contributed to the lubricity of the PbS nanoparticles.