Provided are a method for producing a ceramic sintered body having improved light emission intensity, a ceramic sintered body, and a light emitting device. The method for producing a ceramic sintered body comprises preparing a molded body that contains a nitride fluorescent material having a composition containing: at least one alkaline earth metal element M.sup.1 selected from the group consisting of Ba, Sr, Ca, and Mg; at least one metal element M.sup.2 selected from the group consisting of Eu, Ce, Tb, and Mn; Si; and N, wherein a total molar ratio of the alkaline earth metal element M.sup.1 and the metal element M.sup.2 in 1 mol of the composition is 2, a molar ratio of the metal element M.sup.2 is a product of 2 and a parameter y and wherein y is in a range of 0.001 or more and less than 0.5, a molar ratio of Si is 5, and a molar ratio of N is 8, and wherein the nitride fluorescent material has a crystallite size, as calculated by X-ray diffraction measurement using the Halder-Wagner method, of 550 or less, and calcining the molded body at a temperature in a range of 1,600 C. or more and 2,200 C. or less to obtain a sintered body.

Disclosed are ceramic powder compositions that include Si, N, O, C, Mg, and/or Mn in tailored combinations of different crystalline phases for producing high temperature resistant and high strength ceramic products. In some aspects, a ceramic powder for producing high temperature-resistant and/or high mechanical strength materials comprises a silicon nitride (Si.sub.3N.sub.4) powder, comprising Si.sub.3N.sub.4 particles having a size within a range of 30 nm to 700 nm, wherein the Si.sub.3N.sub.4 powder include alpha and beta phase silicon nitride in an amount up to about 1-100% vol; and an impurity constituent intermixed with the Si.sub.3N.sub.4 powder within the ceramic powder, the impurity constituent comprising at least one of silicon (Si), nitrogen (N), oxygen (O), carbon (C), magnesium (Mg), or manganese (Mn), wherein the impurity constituent constitutes less than about 0.1% wt to 15% wt of the ceramic powder.

Disclosed are ceramic powder compositions that include Si, N, O, C, Mg, and/or Mn in tailored combinations of different crystalline phases for producing high temperature resistant and high strength ceramic products. In some aspects, a ceramic powder for producing high temperature-resistant and/or high mechanical strength materials comprises a silicon nitride (Si.sub.3N.sub.4) powder, comprising Si.sub.3N.sub.4 particles having a size within a range of 30 nm to 700 nm, wherein the Si.sub.3N.sub.4 powder include alpha and beta phase silicon nitride in an amount up to about 1-100% vol; and an impurity constituent intermixed with the Si.sub.3N.sub.4 powder within the ceramic powder, the impurity constituent comprising at least one of silicon (Si), nitrogen (N), oxygen (O), carbon (C), magnesium (Mg), or manganese (Mn), wherein the impurity constituent constitutes less than about 0.1% wt to 15% wt of the ceramic powder.

A turbine assembly includes an axial turbine with an axially arranged series of rotor sections and an external sheath providing structural support for the axial turbine, wherein the sheath is made from dense silicon nitride. Each rotor section includes an outer ring and rotor blades and the outer rings of the rotor sections connect to form a rotating outer casing, wherein the rotor sections are made from reaction bonded silicon nitride.

A ceramic according to the present invention includes, in mass %, BN: 20.0 to 55.0%, SiC: 5.0 to 40.0%, ZrO.sub.2 and/or Si.sub.3N.sub.4: 3.0 to 60.0%. The ceramic has a coefficient of thermal expansion at ?50 to 500? C. of 1.0?10.sup.?6 to 5.0?10.sup.?6/? C., is excellent in low electrostatic properties (10.sup.6 to 10.sup.14 ?.Math.cm in volume resistivity) and free-machining properties, and is thus suitable to be used for, for example, a probe guiding member for guiding probes of a probe card, and a socket for package inspection.

Disclosed are a silicon nitride ceramic sintered body and preparation method thereof. The silicon nitride ceramic sintered body includes a sintered bulk and a hard surface layer having a thickness of 10-1000 m, formed on a surface of the sintered bulk, wherein the sintered bulk comprises a first silicon nitride crystalline phase and a first grain boundary phase; the hard surface layer comprises a second silicon nitride crystalline phase and a second grain boundary phase; the first grain boundary phase comprises a metal tungsten phase being tungsten elementary substance and/or a tungsten alloy; the second grain boundary phase comprises tungsten carbide particles; tungsten element in the metal tungsten phase accounts for 80-100 wt % of total tungsten element in the first grain boundary phase; and tungsten element in the tungsten carbide particles accounts for 60-100 wt % of total tungsten element in the second grain boundary phase.

Disclosed are a silicon nitride ceramic sintered body and a-preparation method thereof. The silicon nitride ceramic sintered body includes a sintered bulk and a hard surface layer having a thickness of 10-1000 m, formed on a surface of the sintered bulk, wherein the sintered bulk comprises a first silicon nitride crystalline phase and a first grain boundary phase; the hard surface layer comprises a second silicon nitride crystalline phase and a second grain boundary phase; the first grain boundary phase comprises a metal tungsten phase being tungsten elementary substance and/or a tungsten alloy; the second grain boundary phase comprises tungsten carbide particles; tungsten element in the metal tungsten phase accounts for 80-100 wt % of total tungsten element in the first grain boundary phase; and tungsten element in the tungsten carbide particles accounts for 60-100 wt % of total tungsten element in the second grain boundary phase.

Provided are a method for producing a ceramic composite material that has a high light emission intensity, a ceramic composite material, and a light emitting device. The method for producing a ceramic composite material, includes: preparing a green body containing a nitride fluorescent material having a composition represented by the following chemical formula (I) and aluminum oxide particles mixed with each other; and performing primary sintering the green body at a temperature in a range of 1,250 C. or more and 1,600 C. or less to provide a first sintered body:

M.sub.wLn.sup.1.sub.xA.sub.yN.sub.z(I)

wherein in the chemical formula (I), M represents at least one element selected from the group consisting of Ce and Pr; Ln.sup.1 represents at least one element selected from the group consisting of Sc, Y, La, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; A represents at least one element selected from the group consisting of Si and B; and w, x, y, and z each satisfy 0<w1.0, 2.5x3.5, 5.5y6.5, and 10z12.

Provided are a method for producing a ceramic composite material that has a high light emission intensity, a ceramic composite material, and a light emitting device. The method for producing a ceramic composite material, includes: preparing a green body containing a nitride fluorescent material having a composition represented by the following chemical formula (I) and aluminum oxide particles mixed with each other; and performing primary sintering the green body at a temperature in a range of 1,250 C. or more and 1,600 C. or less to provide a first sintered body:

M.sub.wLn.sup.1.sub.xA.sub.yN.sub.z(I)

wherein in the chemical formula (I), M represents at least one element selected from the group consisting of Ce and Pr; Ln.sup.1 represents at least one element selected from the group consisting of Sc, Y, La, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; A represents at least one element selected from the group consisting of Si and B; and w, x, y, and z each satisfy 0<w1.0, 2.5x3.5, 5.5y6.5, and 10z12.

A polymer-derived composition and method for providing a ceramic-based precursor coating on a metal surface are disclosed. The composition comprises one or more preceramic polymers admixed with one or more metal particulates. The composition is integrally disposed on and within the metal surface of a metal part through pressure-assisted pyrolysis of a metal particulate-filled preceramic polymer under appropriate conditions, thereby providing a corrosion-resistant and oxidation-resistant metal surface. The precursor coating composition is applied and dried onto the metal surface. The coated steel material is then hot stamped at a pre-defined temperature under a time and pressure conditions sufficient to pyrolyze precursor coating composition to form a protective coating on the surface of the steel. The coated steel material is then cooled. Further, the hot stamping is performed in a period of no more than 1 minute and at a temperature controlled at 400-800? C.