Abstract: A cubic boron nitride complex polycrystal contains granular cubic boron nitride and tabular cubic boron nitride. The average grain size of the granular cubic boron nitride is 500 nm or less. The maximum value of a short side of the tabular cubic boron nitride is 10 nm or more to 10000 nm or less. Thereby, it is possible to provide a cubic boron nitride complex polycrystal having high hardness and a manufacturing method therefor, a cutting tool, a wire-drawing die and a grinding tool including the same.

Abstract: Single-crystal diamond is composed of carbon in which a concentration of a carbon isotope 12C is not lower than 99.9 mass % and a plurality of inevitable impurities other than carbon. The inevitable impurities include nitrogen, boron, hydrogen, and nickel, and a total content of nitrogen, boron, and hydrogen of the plurality of inevitable impurities is not higher than 0.01 mass %. In order to manufacture single-crystal diamond, initially, a hydrocarbon gas in which a concentration of the carbon isotope 12C is not lower than 99.9 mass % is subjected to denitrification.

Abstract: Polycrystalline diamond includes cubic diamond and hexagonal diamond, and a ratio of X-ray diffraction peak intensity of a (100) plane of the hexagonal diamond to X-ray diffraction peak intensity for a (111) plane of cubic diamond is not lower than 0.01%. In addition, a present method of manufacturing polycrystalline diamond includes the steps of preparing a non-diamond carbon material having a degree of graphitization not higher than 0.58 and directly converting the non-diamond carbon material to cubic diamond and hexagonal diamond and sintering the non-diamond carbon material, without adding any of a sintering agent and a binder, under pressure and temperature conditions at which diamond is thermodynamically stable.

Abstract: Nano polycrystalline diamond is composed of carbon, an element of different type which is an element other than carbon and is added to be dispersed in carbon at an atomic level, and an inevitable impurity. The polycrystalline diamond has a crystal grain size not greater than 500 nm. The polycrystalline diamond can be fabricated by subjecting graphite in which the element of different type which is an element other than carbon has been added to be dispersed in carbon at an atomic level to heat treatment within high-pressure press equipment.

Abstract: Nano polycrystalline diamond is composed of carbon and a plurality of impurities other than carbon. A concentration of each of the plurality of impurities is not higher than 0.01 mass %, and the nano polycrystalline diamond has a crystal grain size (a maximum length) not greater than 500 nm. The nano polycrystalline diamond can be fabricated by preparing graphite in which a concentration of an impurity is not higher than 0.01 mass % and converting graphite to diamond by applying an ultra-high pressure and a high temperature to graphite.

Abstract: Polycrystalline diamond includes cubic diamond and hexagonal diamond, and a ratio of X-ray diffraction peak intensity of a (100) plane of the hexagonal diamond to X-ray diffraction peak intensity for a (111) plane of cubic diamond is not lower than 0.01%. In addition, a present method of manufacturing polycrystalline diamond includes the steps of preparing a non-diamond carbon material having a degree of graphitization not higher than 0.58 and directly converting the non-diamond carbon material to cubic diamond and hexagonal diamond and sintering the non-diamond carbon material, without adding any of a sintering agent and a binder, under pressure and temperature conditions at which diamond is thermodynamically stable.

Abstract: The present invention provides a cutting tool that achieves cutting with high precision. The cutting tool of the present invention includes a cutting edge composed of a polycrystalline body including high-pressure-phase hard grains that contain one or more elements selected from the group consisting of boron, carbon, and nitrogen, the polycrystalline body being formed by subjecting a non-diamond carbon material and/or boron nitride, serving as a starting material, to direct conversion sintering under ultra-high pressure and high temperature without adding a sintering aid or a catalyst, in which letting the radius of curvature of the nose of the cutting edge of the cutting tool be R1, the sintered grains constituting the polycrystalline body have an average grain size of 1.2×R1 or less and a maximum grain size of 2×R1 or less.

Abstract: Polycrystalline diamond includes cubic diamond and hexagonal diamond, and a ratio of X-ray diffraction peak intensity of a (100) plane of the hexagonal diamond to X-ray diffraction peak intensity for a (111) plane of cubic diamond is not lower than 0.01%. In addition, a present method of manufacturing polycrystalline diamond includes the steps of preparing a non-diamond carbon material having a degree of graphitization not higher than 0.58 and directly converting the non-diamond carbon material to cubic diamond and hexagonal diamond and sintering the non-diamond carbon material, without adding any of a sintering agent and a binder, under pressure and temperature conditions at which diamond is thermodynamically stable.

Abstract: A diamond sintered body conventionally used in a cutting tool or the like includes an iron group metal element as a sintering aid, and therefore has a problem in heat resistance. A diamond sintered body not including the iron group metal, on the other hand, does not have sufficient mechanical strength to be used as a tool material, and also does not have conductivity, which makes electrical discharge machining impossible, and thus processing thereof is difficult. A diamond polycrystalline body having high heat resistance and mechanical strength and having conductivity enabling electrical discharge machining is obtained by using only an amorphous or fine graphite-type carbon material as a starting material, adding boron thereto and concurrently performing conversion into diamond and sintering in an ultra-high pressure and temperature condition.

Abstract: A diamond sintered body conventionally used in a cutting tool or the like includes an iron group metal element as a sintering aid, and therefore has a problem in heat resistance. A diamond sintered body not including the iron group metal, on the other hand, does not have sufficient mechanical strength to be used as a tool material, and also does not have conductivity, which makes electrical discharge machining impossible, and thus processing thereof is difficult. A diamond polycrystalline body having high heat resistance and mechanical strength and having conductivity enabling electrical discharge machining is obtained by using only an amorphous or fine graphite-type carbon material as a starting material, adding boron thereto and concurrently performing conversion into diamond and sintering in an ultra-high pressure and temperature condition.

Abstract: An object is to provide polycrystalline diamond applicable to diverse applications; and a water jet orifice, a stylus for gravure printing, a scriber, a diamond cutting tool, and a scribing wheel that include such polycrystalline diamond. This object is achieved by polycrystalline diamond obtained by converting and sintering non-diamond carbon under an ultrahigh pressure and at a high temperature without addition of a sintering aid or a catalyst, wherein sintered diamond grains constituting the polycrystalline diamond have an average grain diameter of more than 50 nm and less than 2500 nm and a purity of 99% or more, and the diamond has a D90 grain diameter of (average grain diameter+average grain diameter×0.9) or less.

Abstract: One object of the present invention is to provide a cutting tool excellent in strength and wear resistance. The cutting tool has a cutting blade formed using a highly hard diamond polycrystalline body made substantially only of diamond and produced by directly converting a raw material composition including a non-diamond type carbon material into diamond and sintering the diamond at an ultra high pressure and an ultra high temperature without adding a sintering aid or a catalyst, the polycrystalline body having a mixed construction including fine-grained diamond crystals with a maximum grain size of less than or equal to 100 nm and an average grain size of less than or equal to 50 nm and plate-like or particulate coarse-grained diamond crystals with a minimum grain size of greater than or equal to 50 nm and a maximum grain size of less than or equal to 10000 nm.

Abstract: One object of the present invention is to provide a wire drawing die excellent in strength and wear resistance. The wire drawing die has a core formed using highly hard diamond polycrystalline body made substantially only of diamond and produced by directly converting a raw material composition including a non-diamond type carbon material into diamond and sintering the diamond at an ultra high pressure and an ultra high temperature without adding a sintering aid or a catalyst, the polycrystalline body having a mixed construction including fine-grained diamond crystals with a maximum grain size of less than or equal to 100 nm and an average grain size of less than or equal to 50 nm and plate-like or particulate coarse-grained diamond crystals with a minimum grain size of greater than or equal to 50 nm and a maximum grain size of less than or equal to 10000 nm.

Abstract: There are provided sufficiently strong, hard, and heat resistant, dense and homogenous polycrystalline diamond applicable to cutting tools, dressers, dies and other working tools and excavation bits and the like, and a cutting tool having a cutting edge of the polycrystalline diamond. The polycrystalline diamond is formed substantially only of diamond formed using a composition of material containing a non diamond type carbon material, the composition of material being converted directly into diamond and sintered at ultra high pressure and ultra high temperature without aid of a sintering aid or a catalyst, and has a mixed microstructure having a fine crystal grain of diamond having a maximal grain size of at most 100 nm and an average grain size of at most 50 nm and a coarse crystal grain of diamond in the form of one of a platelet and a granule having a grain size of at least 50 nm and at most 10,000 nm.

Abstract: Various types of diamond tools are provided by utilizing the fact that a synthetic single crystal diamond for use in a tool having a nitrogen content of 3 ppm or less exhibits an enhanced hardness in a (100) plane in a <111> direction and simultaneously the reduction in defects. The above synthetic single crystal diamond is synthesized by the temperature difference method under an ultra high pressure at high temperature and contains, in its crystals, nickel introduced by atomic substitution or boron and nickel introduced by atomic substitution.

Abstract: A diamond sintered body conventionally used in a cutting tool or the like includes an iron group metal element as a sintering aid, and therefore has a problem in heat resistance. A diamond sintered body not including the iron group metal, on the other hand, does not have sufficient mechanical strength to be used as a tool material, and also does not have conductivity, which makes electrical discharge machining impossible, and thus processing thereof is difficult. A diamond polycrystalline body having high heat resistance and mechanical strength and having conductivity enabling electrical discharge machining is obtained by using only an amorphous or fine graphite-type carbon material as a starting material, adding boron thereto and concurrently performing conversion into diamond and sintering in an ultra-high pressure and temperature condition.

Abstract: Various types of diamond tools are provided by utilizing the fact that a synthetic single crystal diamond for use in a tool having a nitrogen content of 3 ppm or less exhibits an enhanced hardness in a (100) plane in a <111> direction and simultaneously the reduction in defects. The above synthetic single crystal diamond is synthesized by the temperature difference method under an ultra high pressure at high temperature and contains, in its crystals, nickel introduced by atomic substitution or boron and nickel introduced by atomic substitution.

Abstract: A method of manufacturing n-type semiconductor diamond by the present invention is characterized in producing diamond incorporating Li and N by implanting Li ions into, so that 10 ppm thereof will be contained in, single-crystal diamond incorporating 10 ppm or more N, or else, in doping single-crystal diamond with Li and N ions, by implanting the ions so that ion-implantation depths at which the post-implantation Li and N concentrations each are 10 ppm or more will overlap, and thereafter annealing the diamond in a temperature range of from 800° C. or more to less than 1800° C. to electrically activate the Li and N and restore the diamond crystalline structure. In the present invention, n-type semiconductor diamond incorporates, from the surface of the crystal to the same depth, 10 ppm or more of each of Li and N, wherein its sheet resistance is 107 ?/? or less.

Abstract: A thermoelectric material has an average crystal particle size of at most 50 nm and has a relative density of at least 85%. A method of manufacturing a thermoelectric material includes the steps of preparing a fine powder and sintering or compacting the fine powder under a pressure of at least 1.0 GPa and at most 10 GPa.

Abstract: The object of the present invention is to provide a cutting tool consisting of fine grain cBN free from a binder and having a grain size of at most 1 &mgr;m and having a high hardness, high strength and excellent heat resistance. The feature thereof consists in a cutting tool compring, as an edge part, a cubic boron nitride sintered compact containing cubic boron nitride having an average grain diameter of at most 1 &mgr;m, in which the cubic boron nitride sintered compact has, at the said edge part, an I(220)/I(111) of (220) diffraction intensity (I(220)) to (111) diffraction intensity (I(111)) ratio of at least 0.05 in X-ray diffraction of arbitrary direction and impurities are substantially not contained in the grain boundaries.