Failure of ceramic-and diamond-coated cutting tool when turning carbon-graphite phase sintered carbons

Sintered carbons used for mechanical seals contain carbon and graphite in order to give high strength and adequate lubrication. In this paper, the wear pattern and the wear rate of CVD ceramic and CVD diamond cutting tool are described comparing with those of cemented carbide, alumina-based ceramic and sintered diamond, when turning carbon-graphite phase materials. In addition, the machinability of sintered carbons is discussed in terms of physical and mechanical properties. CVD ceramic shows the same behavior as cemented cart-ride rather than alumina-based ceramic. CVD diamond displays the best cutting performance. Wear rate of cemented carbide and coated cutting tools has a good correlation to the physical characteristics rather than the mechanical properties.