Abstract: A cutting tool blank formed of material having a composition comprising of 0.1 to 20 wt % of BaCO.sub.3 and/or MgCO.sub.3, and/or 0.05 to 10 wt % of CaMg(CO.sub.3).sub.2 or CaCO3, the balance being preferably substantially diamond forming a matrix is heated and maintained at a temperature of 800.degree. to 1400.degree. C. in a vacuum to change, by chemical reaction, the above BaCO.sub.3 and/or MgCO.sub.3, and/or CaMg(CO.sub.3).sub.2 or CaCO.sub.3 into 0.05 to 13% of BaO and/or MgO and/or 0.02 to 5% of CaO, and to form pores. In this manner, a cutting tool formed of a diamond-based ultra-high-temperature-sintered material having a structure in which BaO, MgO and/or CaO are distributed finely and uniformly in a diamond matrix is obtained.

Abstract: A wear resistant C-BN-based cutting tool superior in toughness includes a specified amount of at least one of a Ti carbide/nitride component, a compound including at least one of Ti and Al, tungsten carbide, Al.sub.2 O.sub.3, and the balance being C-BN and incidental impurities.

Abstract: A TiCN-based cermet cutting insert superior in toughness with improved wear resistance includes a binding phase and at least two hard dispersion phases. One hard dispersion phases includes a core of TiCN while the other hard dispersion phases includes a core of a carbonitride solid solution of Ti and one of a V,Hf,Cr, Ta,Nb, Zr, W and Mo.

Abstract: The ceramics of the present invention comprises a composition having a bonding phase constituent component, a dispersed phase constituent component, and unavoidable impurities. The bonding phase constituent component has one or more of titanium and aluminum carbide, nitride and carbonitride compounds including oxygen, and 20% to 48% by volume of decomposed reaction phase cubic crystal boron nitride. The dispersed phase constituent component comprises cubic crystal boron nitride, and the decomposed reaction phase comprises one or more of titanium carbide, titanium nitride and titanium carbonitride, and one or more of aluminum oxide and aluminum nitride, as well as titanium boride. The crystal grain sizes in the bonding phase comprising the decomposed reaction phase, and the crystal grain sizes in the dispersed phase comprising the cubic boron nitride are all substantially less than 1 micron. The titanium and aluminum carbide compound is preferably Ti.sub.

Abstract: A cubic boron nitride-based very high pressure-sintered material very excellent in both toughness and wear resistance and adapted to be employed in cutting tools for milling hard steels and like machining purposes. The very high pressure-sintered material consists essentially of: 1-20 percent at least one compound selected from the group consisting of titanium carbide and titanium carbo-nitride; 1-20 percent at least one compound selected from the group consisting of CoAl, NiAl, and (Co, Ni)Al; and 75-97 percent cubic boron nitride and inevitable impurities. The very high pressure-sintered material may further contain 1-10 percent at least one metal selected from the group consisting of cobalt and nickel.