“…The excellent intrinsic mechanical, thermal and chemical properties of the ceramic tool materials make them the most promising and competitive tool materials for machining the difficult-to-cut materials such as the hardened steel and nickel based alloys [1,2]. However, the intrinsic brittleness of the Al 2 O 3 ceramics and the characteristics of Si 3 N 4 ceramics (such as the relatively lower hardness, wear resistance and fracture toughness) have limited their applications to be the tool materials [3][4][5].…”