Wear mechanisms of Syalon ceramic tools when machining nickel-based materials

Abstract

The failure modes and the wear mechanisms operating at the tool faces, when machining Incoloy 901 with Syalon* ceramic tools, have been studied. It was observed that the tool life was controlled mainly by notching at the depth of cut and flank-face wear. A t very high speeds and feed rates fracture failure was also observed. Notching at the depth of cut was the dominant failure mode at slow speeds, and the use of various active and inert atmospheres suggests that it is caused by a chemical interaction between the chip and the tool. At high speeds, tool life was controlled by flank-face wear. The wear-mechanism analyses suggest that attrition, diffusion, and plastic deformation controlled the tool life. At slower speeds, attrition is the dominant wear mechanism, whereas at higher speeds diffusion followed by plastic deformation dominates. Where attrition occurs, either individual Syalon particles or aggregates of them are lifted off the tool faces, whereas with diffusion, transition elements (especially titanium and chromium) appear to react mainly with the primary phase (β' -crystals) causing the tools to wear.