Development of Al₂O₃-SiC composite tool for machining application

Al₂O₃-SiC composites containing up to 30 wt.% of dispersed SiC particles (∼280 nm) were fabricated via hot-pressing and machined as cutting tools. The Al₂O₃-SiC particulate composites exhibit higher hardness than their unreinforced matrix because of the inhibited grain growth by adding SiC and the presence of hard secondary phase (SiC). The fracture toughness of the composites remains constant up to 10 wt.% loading of SiC. For machining heat-treated AISI 4144140 steel, the Al ₂O₃-10 wt.% SiC composite tool showed the longest tool life, seven times longer than a commercial tool made of Al₂O ₃-TiC composite, while the composite tool with 5 wt.% SiC showed the longest tool life for machining gray cast iron. The improved performance of the Al₂O₃-SiC composite tools attributes to the transformation of fracture mode from intergranular fracture for Al ₂O₃ to intragranular fracture for Al₂O ₃-SiC composites.