A cBN sintered compact comprising a cubic boron nitride and a ceramic binder phase, wherein a cubic C-containing Ta compound in an amount of 1.0 to 15.0 vol % is dispersed in the ceramic binder phase and has a mean particle diameter of 50 to 500 nm.

A cBN-based ultra-high pressure sintered body contains cBN particles and a binder phase. The binder phase contains at least one of a nitride or oxide of Al or a nitride, carbide, or carbonitride of Ti, and a metal boride having an average particle diameter of 20 to 300 nm is dispersed in an amount of 0.1 to 5.0 vol % in the binder phase. The metal boride includes a metal boride (B) containing at least one of Nb, Ta, Cr, Mo, and W as a metal component and containing no Ti and a metal boride (A) containing only Ti as a metal component. In a case where a ratio (vol %) of the metal boride (A) in the metal boride is represented by V.sub.a and a ratio (vol %) of the metal boride (B) is represented by V.sub.b, a ratio of V.sub.b/V.sub.a is 0.1 to 1.0.

A cubic boron nitride sintered material comprises 30% by volume or more and 99.9% by volume or less of cubic boron nitride grains and 0.1% by volume or more and 70% by volume or less of a binder phase, the cubic boron nitride grain having a carbon content of 0.08% by mass or less, the cubic boron nitride sintered material being free of free carbon.

Disclosed is a composition having nanoparticles or particles of a refractory metal, a refractory metal hydride, a refractory metal carbide, a refractory metal nitride, or a refractory metal boride, an organic compound consisting of carbon and hydrogen, and a nitrogenous compound consisting of carbon, nitrogen, and hydrogen. The composition, optionally containing the nitrogenous compound, is milled, cured to form a thermoset, compacted into a geometric shape, and heated in a nitrogen atmosphere at a temperature that forms a nanoparticle composition comprising nanoparticles of metal nitride and optionally metal carbide. The nanoparticles have a uniform distribution of the nitride or carbide.

A cubic boron nitride sintered material includes: more than 80 volume % and less than 100 volume % of cubic boron nitride grains; and more than 0 volume % and less than 20 volume % of a binder phase. The binder phase includes: at least one selected from a group consisting of a simple substance, an alloy, and an intermetallic compound selected from a group consisting of a group 4 element, a group 5 element, a group 6 element in a periodic table, aluminum, silicon, cobalt, and nickel. A dislocation density of the cubic boron nitride grains is more than or equal to 3×10.sup.17/m.sup.2 and less than or equal to 1×10.sup.20/m.sup.2.

A long-term ablation-resistant nitrogen-containing carbide ultra-high temperature ceramic with an ultra-high melting point is prepared as follows: preparing the HfC powder and the HfN powder according to a mass ratio of HfC:HfN=(1-7):1; uniformly mixing the HfC powder and the HfN powder with the carbon powder and the carbon nitride powder to obtain a mixed powder, wherein the amount of the carbon powder and the amount of the carbon nitride powder do not exceed 8.0 wt. % and 5.0 wt. %, respectively, of the mixed powder mass; and performing spark plasma sintering on the mixed powder to produce the ceramic with the ultra-high melting point, a density ≥98%, and a uniform C/N content distribution. The ultra-high temperature ceramic is suitable for ultra-high temperature ablation-resistant protection at ≥3000° C. The ceramic maintains a close to zero ablation rate and a continuously stable oxidation-resistant protective structure after ablation for 300 s.

A cubic boron nitride sintered material comprises 30% by volume or more and 80% by volume or less of cubic boron nitride grains and 20% by volume or more and 70% by volume or less of a binder phase, the cubic boron nitride grains having a dislocation density of 3×10.sup.17/m.sup.2 or more and 1×10.sup.20/m.sup.2 or less.

A ceramic containing, in mass %: Si.sub.3N.sub.4: 20.0 to 60.0%, ZrO.sub.2: 25.0 to 70.0%, at least one selected from SiC and AlN: 2.0 to 17.0%, where AlN is 10.0% or less, at least one selected from MgO, Y.sub.2O.sub.3, CeO.sub.2, CaO, HfO.sub.2, TiO.sub.2, Al.sub.2O.sub.3, SiO.sub.2, MoO.sub.3, CrO, CoO, ZnO, Ga.sub.2O.sub.3, Ta.sub.2O.sub.5, NiO and V.sub.2O.sub.5: 5.0 to 15.0%, wherein Fn calculated from the following equation (1) satisfies 0.02 to 0.40. This ceramic can be laser machined with high efficiency.

Fn=(SiC+3AlN)/(Si.sub.3N.sub.4+ZrO.sub.2)  (1)

The invention relates to an item made of a material consisting of a plurality of ceramic phases, said material including: a majority ceramic phase comprising nitrides and/or carbonitrides of one or more element(s) selected from among Ti, Zr, Hf, V, Nb, and Ta, said majority ceramic phase being present in a percentage by weight comprised between 60 and 98%, at least one minority ceramic phase, with either one single minority ceramic phase formed of zirconium and/or aluminium silicide, or several minority ceramic phases formed respectively of carbides of one or more element(s) selected from among Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and W and of zirconium oxides and/or aluminium oxides, said at least one minority ceramic phase being present in its entirety in a percentage by weight comprised between 2 and 40%.

The present invention also relates to the method for manufacturing this item.

A cubic boron nitride sintered material comprising cubic boron nitride grains, a binder phase, and a void, in which a percentage of the cubic boron nitride grains based on the total of the cubic boron nitride grains and the binder phase is 40 vol % to 70 vol %, a percentage of the binder phase based on the total of the cubic boron nitride grains and the binder phase is 30 vol % to 60 vol %, the binder phase includes 10 vol % to 100 vol % of aluminum oxide grains, an average grain size of the aluminum oxide grains is 50 to 250 nm, the cubic boron nitride sintered material comprises 0.001 vol % to 0.100 vol % of one or more first voids, and at least one portion of each of the first voids is in contact with the aluminum oxide grains.