Abstract: [Problem] This invention aims to provide a production method of a fine grain polycrystalline diamond compact which is suitable for finishing cutting tool materials and/or ultra-precision machining tool materials. In the method, a freeze-drying process for preventing the growth of secondary particle formation is unnecessary, and an aid does not need to be mixed in advance. [Means for Resolution] Disclosed is a following production method of a fine grain polycrystalline diamond compact. Each of carbonate and a C—H based organic compound which is a solid at room temperature, is sandwiched between diamond powder layers to stack them up in layers in a Ta capsule. Particle size of the diamond powder is 4 ?m or less in average; and the organic compound is preferably one or more selected from among polyethylene, polypropylene and polystyrene. The layers in the capsule are sintered under the conditions of a pressure of 7.7 GPa or higher and a temperature of 2000° C. or higher.

Abstract: A method for producing a highly uniform and highly dense sintered cubic boron nitride compact having high hardness by sintering at a milder condition without a binder, is provided. The method includes deflocculating secondary particles in cubic boron nitride starting powders by dispersing the starting powders in a solution of a deflocculant; molding the green compact after removing the solution of the deflocculant from the starting powders; and then sintering the green compact in the presence of a supercritical fluid source in a supercritical state by pressing and heating the green compact together with the supercritical fluid source. The supercritical fluid source can be one or more selected from a group consisted of polyvinylidene chloride, polyvinyl chloride, polyethylene, polypropylene, polystyrene, a polyester and an ABS resin. In the sintering, the pressure is 5 GPa or higher, and the temperature is 1400° C. or higher.

Abstract: A cutting tip for a drilling tool includes a cemented carbide cutting base, a diamond element supported by the cutting base, and a bonding layer formed between the cutting base and the diamond element in order to bond them. The bonding layer includes diffusion layers and in which one or two or more metals selected from a group consisting of Fe, Ni, Co, Ti, Zr, W, V, Nb, Ta, Cr, Mo, and Hf diffuses into at least one of the diamond or the cement carbide.

Abstract: The present invention is to provide a diamond sintered compact having good conductivity together with the characteristics, such as hardness, thermal conductivity, thermal resistance, chemical stability, almost equal to those of a natural diamond. A boron-doped diamond sintered compact having good conductivity and high thermal resistance is produced by a sintering process, in which 90 to 99.9 wt. % of a boron-doped diamond powder and 0.1 to 10% wt. % of a powder comprising, one or more of carbonates including Mg, Ca, Sr or Ba, and/or one or more of composite carbonates composed by two or more of these elements, as a bonding phase component, are sintered together under Ht/HP conditions, and the bonding phase component melts and then fills into the space between the boron-doped diamond powder particles.

Abstract: [Problem] This invention aims to provide a production method of a fine grain polycrystalline diamond compact which is suitable for finishing cutting tool materials and/or ultra-precision machining tool materials. In the method, a freeze-drying process for preventing the growth of secondary particle formation is unnecessary, and an aid does not need to be mixed in advance. [Means for Resolution] Disclosed is a following production method of a fine grain polycrystalline diamond compact. Each of carbonate and a C—H based organic compound which is a solid at room temperature, is sandwiched between diamond powder layers to stack them up in layers in a Ta capsule. Particle size of the diamond powder is 4 ?m or less in average; and the organic compound is preferably one or more selected from among polyethylene, polypropylene and polystyrene. The layers in the capsule are sintered under the conditions of a pressure of 7.7 GPa or higher and a temperature of 2000° C. or higher.

Abstract: A method for producing a highly uniform and highly dense sintered cubic boron nitride compact having high hardness by sintering at a milder condition without a binder, is provided. The method includes deflocculating secondary particles in cubic boron nitride starting powders by dispersing the starting powders in a solution of a deflocculant; molding the green compact after removing the solution of the deflocculant from the starting powders; and then sintering the green compact in the presence of a supercritical fluid source in a supercritical state by pressing and heating the green compact together with the supercritical fluid source. The supercritical fluid source can be one or more selected from a group consisted of polyvinylidene chloride, polyvinyl chloride, polyethylene, polypropylene, polystyrene, a polyester and an ABS resin. In the sintering, the pressure is 5 GPa or higher, and the temperature is 1400° C. or higher.

Abstract: The present invention is to provide a diamond sintered compact having good conductivity together with the characteristics, such as hardness, thermal conductivity, thermal resistance, chemical stability, almost equal to those of a natural diamond. A boron-doped diamond sintered compact having good conductivity and high thermal resistance is produced by a sintering process, in which 90 to 99.9 wt. % of a boron-doped diamond powder and 0.1 to 10% wt. % of a powder comprising, one or more of carbonates including Mg, Ca, Sr or Ba, and/or one or more of composite carbonates composed by two or more of these elements, as a bonding phase component, are sintered together under Ht/HP conditions, and the bonding phase component melts and then fills into the space between the boron-doped diamond powder particles.

Abstract: A cutting tip for a drilling tool includes a cemented carbide cutting base, a diamond element supported by the cutting base, and a bonding layer formed between the cutting base and the diamond element in order to bond them. The bonding layer includes diffusion layers and in which one or two or more metals selected from a group consisting of Fe, Ni, Co, Ti, Zr, W, V, Nb, Ta, Cr, Mo, and Hf diffuses into at least one of the diamond or the cement carbide.

Abstract: A cutting tip for a drilling tool includes a cemented carbide cutting base 11, a diamond element 12 supported by the cutting base 11, and a bonding layer formed between the cutting base 11 and the diamond element 12 in order to bond them. The bonding layer 13 includes diffusion layers S1 and S2 in which one or two or more metals selected from a group consisting of Fe, Ni, Co, Ti, Zr, W, V, Nb, Ta, Cr, Mo, and Hf diffuses into at least one of the cemented carbide or the diamond.