Role of Graphite on Tribological Behaviour of Cast Iron(Machine Elements, Design and Manufacturing)

Abstract

Generally, it is known that graphite decreases friction and wear of cast iron. However, the literatures that logically explained this common sense are few. In this study, we observed the surface before and after friction test in lubricant test and dry test by SEM, EPMA and XPS to clarify the mechanism. In lubrication test and mild wear region of dry test, increase in the carbon content was confirmed on the top surface. However, it has decreased on the top surface in severe wear region of dry test. And, we proposed the wear mechanism that first, graphite in cast iron was extruded in cast iron matrix to the surface by plastic deformation, it was supplied to the top surface, it was rolled and extended on the surface, and ultra thin carbon film of about 2nm was formed on the surface.