Lubrication by Components of Engine Exhaust — A New Concept of Solid Lubrication

Exhaust gases from internal combustion engines contain appreciable quantities of various hydrocarbons and carbon monoxide. Solid carbon formed by decomposition of these gases on tribosurfaces could replace circulating lubricating oil, especially in low heat rejection engines. Experiments with silicon nitride in a pin-on-disc tribometer operating at 520°C, 2.2GPa contact pressure and 4.4cm/s sliding speed have demonstrated that friction and wear can be reduced by over 90% of their unlubricated values when ethylene, acetylene, and carbon monoxide and hydrogen are directed into the contacts. The lubricating deposit composition and morphology have been evaluated and compared in terms of effectiveness.