Effect of SiC Addition to Al₂O₃ Ceramics Used in Cutting Tools

In this study, the effect of the addition of silicon carbide to alumina ceramics commonly used in cutting tool applications is addressed. Performance of Al₂O₃-SiC composite cutting inserts during the machining of hardened steels and ductile iron was compared to the results obtained for a cutting tool made out of 99 wt.% Al₂O₃, Al₂O₃-TiC, Al₂O₃-TiC-ZrO₂, and Al₂O₃-TiN. In almost all tests, the composite with silicon carbide demonstrated better wear resistance, longer tool lifetime, and the ability to cut at higher speeds. The enhanced properties of cutting tools with SiC can be attributed to the morphology and dimensions of the inclusions in the matrix as well as to the strength of the interphase boundaries, small porosity, and lack of high inner stresses in the volume.