Abstract: A method for producing a diamond single crystal includes implanting an ion other than carbon into a surface of a diamond single crystal seed substrate and thereby decreasing the transmittance of light having a wavelength of 800 nm, the surface having an off-angle of 7 degrees or less with respect to a {100} plane, and homoepitaxially growing a diamond single crystal on the ion-implanted surface of the seed substrate using a chemical vapor synthesis under synthesis conditions where the ratio NC/NH of the number of carbon-containing molecules NC to the number of hydrogen molecules NH in a gas phase is 10% or more and 40% or less, the ratio NN/NC of the number of nitrogen molecules NN to the number of carbon-containing molecules NC in the gas phase is 0.1% or more and 10% or less, and the seed substrate temperature T is 850° C. or more and less than 1000° C.

Abstract: Provided are a diamond polycrystalline body having a longer life than conventional diamond polycrystalline bodies when it is slid, a method for manufacturing the same, and a tool. In a diamond polycrystalline body, at least one element whose oxide has a melting point of less than or equal to 1000° C. is added thereto, and crystal grains have an average grain size of less than or equal to 500 nm. Thereby, wear of diamond can be suppressed, and the diamond polycrystalline body can have a longer life when it is slid.

Abstract: Provided are a diamond polycrystalline body having a longer life than conventional diamond polycrystalline bodies when it is slid, a method for manufacturing the same, and a tool. In a diamond polycrystalline body, at least one element whose sulfide or chloride has a melting point of less than or equal to 1000° C. is added thereto, and crystal grains have an average grain size of less than or equal to 500 nm. Thereby, wear of diamond can be suppressed, and the diamond polycrystalline body can have a longer life when it is slid.

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, 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: A method for producing a diamond single crystal includes implanting an ion other than carbon into a surface of a diamond single crystal seed substrate and thereby decreasing the transmittance of light having a wavelength of 800 nm, the surface having an off-angle of 7 degrees or less with respect to a {100} plane, and homoepitaxially growing a diamond single crystal on the ion-implanted surface of the seed substrate using a chemical vapor synthesis under synthesis conditions where the ratio NC/NH of the number of carbon-containing molecules NC to the number of hydrogen molecules NH in a gas phase is 10% or more and 40% or less, the ratio NN/NC of the number of nitrogen molecules NN to the number of carbon-containing molecules NC in the gas phase is 0.1% or more and 10% or less, and the seed substrate temperature T is 850° C. or more and less than 1000° C.

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: 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: 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: 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: 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 polycrystalline diamond body contains diamond particles. The diamond particles have a mean particle size of 50 nm or less. As a result of measurement of a knoop hardness under a test load of 4.9 N at 23° C.±5° C., the polycrystalline diamond body has a ratio of a length B of a shorter diagonal line with respect to a length A of a longer diagonal line of diagonal lines of a knoop indentation, expressed as a B/A ratio, of 0.080 or less. This polycrystalline diamond body is tough and has a small particle size.

Abstract: Provided are a diamond polycrystalline body having a longer life than conventional diamond polycrystalline bodies when it is slid, a method for manufacturing the same, and a tool. In a diamond polycrystalline body, at least one element whose sulfide or chloride has a melting point of less than or equal to 1000° C. is added thereto, and crystal grains have an average grain size of less than or equal to 500 nm. Thereby, wear of diamond can be suppressed, and the diamond polycrystalline body can have a longer life when it is slid.

Abstract: Provided are a diamond polycrystalline body having a longer life than conventional diamond polycrystalline bodies when it is slid, a method for manufacturing the same, and a tool. In a diamond polycrystalline body, at least one element whose oxide has a melting point of less than or equal to 1000° C. is added thereto, and crystal grains have an average grain size of less than or equal to 500 nm. Thereby, wear of diamond can be suppressed, and the diamond polycrystalline body can have a longer life when it is slid.

Abstract: A cubic boron nitride polycrystal includes cubic boron nitride, the cubic boron nitride having an average grain size of not more than 150 nm, a ratio b/a being not more than 0.085 in measurement of Knoop hardness at 23° C.±5° C. under a test load of 4.9 N, the ratio b/a being a ratio between a length a of a longer diagonal line and a length b of a shorter diagonal line of a Knoop indentation.

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: Polycrystalline diamond having excellent resistance to crack propagation is provided. The polycrystalline diamond includes layered diamond and granular diamond. The layered diamond is formed by laminating plate-like diamond layers. When the polycrystalline diamond is observed in an arbitrary cross section, the layered diamond appearing at an observation visual field in the cross section occupies an area of more than or equal to 90% of the total area of the polycrystalline diamond in the observation visual field.

Abstract: A single crystal diamond (10) is provided as a single crystal diamond into which a defect portion (11) is introduced. The defect portion (11) can be detected by a phase difference occurring when the single crystal diamond (10) is irradiated with circularly polarized light. In the single crystal diamond (10), a maximum value of average values of the phase differences measured within a measurement region (M) formed in a shape of a square having a side length of 1 mm is 30 nm or more.

Abstract: A single crystal diamond has a surface. In the single crystal diamond, a measurement region is defined in the surface, the measurement region includes a portion exhibiting a transmittance that is highest in the single crystal diamond and a portion exhibiting a transmittance that is lowest in the single crystal diamond, the measurement region has a plurality of square regions that are continuously arranged and each have a side having a length of 0.2 mm, and an average value of transmittances in each of the plurality of square regions is measured, wherein assuming that the average value of the transmittances in one square region is defined as T1 and the average value of the transmittances in another square region adjacent to the one square region is defined as T2, a relation of ((T1?T2)/((T1+T2)/2)×100)/0.2?20 (%/mm) is satisfied throughout the measurement region.

Abstract: A method for producing a diamond single crystal includes implanting an ion other than carbon into a surface of a diamond single crystal seed substrate and thereby decreasing the transmittance of light having a wavelength of 800 nm, the surface having an off-angle of 7 degrees or less with respect to a {100} plane, and homoepitaxially growing a diamond single crystal on the ion-implanted surface of the seed substrate using a chemical vapor synthesis under synthesis conditions where the ratio NC/NH of the number of carbon-containing molecules NC to the number of hydrogen molecules NH in a gas phase is 10% or more and 40% or less, the ratio NN/NC of the number of nitrogen molecules NN to the number of carbon-containing molecules NC in the gas phase is 0.1% or more and 10% or less, and the seed substrate temperature T is 850° C. or more and less than 1000° C.