Abstract: The present invention provides a needle-shaped ceramic body and needle-shaped ceramic catalyst body in which a base material is a high specific surface area porous cordierite body that is stable at high temperatures, and also provides methods of producing this needle-shaped ceramic body and needle-shaped ceramic catalyst body. The present invention relates to a needle-shaped ceramic body and needle-shaped ceramic catalyst body in which a base material is a high temperature-stable, high specific surface area porous cordierite body comprising a porous structure having a prescribed porosity and formed of a needle-shaped cordierite crystal phase, and further relates to methods of producing this needle-shaped ceramic body and needle-shaped ceramic catalyst body, and by using porous cordierite constituted of needle-shaped crystals as a catalyst-supporting honeycomb structure, the present invention is able to inhibit sintering-induced reduction in the specific surface area.

Abstract: A boron carbide based sintered body having a four-point flexural strength of at least 400 MPa and a fracture toughness of at least 2.8 MPa·m1/2, which has the following two preferred embodiments. (1) A boron carbide-titanium diboride sintered body obtained by sintering a mixed powder of a B4C powder, a TiO2 powder and a C powder while reacting them under a pressurized condition and comprising from 95 to 70 mol % of boron carbide and from 5 to 30 mol % of titanium diboride, wherein the boron carbide has a maximum particle diameter of at most 5 ?m. (2) A boron carbide-chromium diboride sintered body containing from 10 to 25 mol % of CrB2 in B4C, wherein the sintered body has a relative density of at least 90%, boron carbide particles in the sintered body have a maximum particle diameter of at most 100 ?m, and the abundance ratio (area ratio) of boron carbide particles of from 10 to 100 ?m to boron carbide particles having a particle diameter of at most 5 ?m, is from 0.02 to 0.6.

Abstract: A boron carbide based sintered body having a four-point flexural strength of at least 400 MPa and a fracture toughness of at least 2.8 MPa·m1/2, which has the following two preferred embodiments. (1) A boron carbide-titanium diboride sintered body obtained by sintering a mixed powder of a B4C powder, a TiO2 powder and a C powder while reacting them under a pressurized condition and comprising from 95 to 70 mol % of boron carbide and from 5 to 30 mol % of titanium diboride, wherein the boron carbide has a maximum particle diameter of at most 5 ?m. (2) A boron carbide-chromium diboride sintered body containing from 10 to 25 mol % of CrB2 in B4C, wherein the sintered body has a relative density of at least 90%, boron carbide particles in the sintered body have a maximum particle diameter of at most 100 ?m, and the abundance ratio (area ratio) of boron carbide particles of from 10 to 100 ?m to boron carbide particles having a particle diameter of at most 5 ?m, is from 0.02 to 0.6.

Abstract: A boron carbide based sintered body having a four-point flexural strength of at least 400 MPa and a fracture toughness of at least 2.8 MPa·m1/2, which has the following two preferred embodiments. (1) A boron carbide-titanium diboride sintered body obtained by sintering a mixed powder of a B4C powder, a TiO2 powder and a C powder while reacting them under a pressurized condition and comprising from 95 to 70 mol % of boron carbide and from 5 to 30 mol % of titanium diboride, wherein the boron carbide has a maximum particle diameter of at most 5 ?m. (2) A boron carbide-chromium diboride sintered body containing from 10 to 25 mol % of CrB2 in B4C, wherein the sintered body has a relative density of at least 90%, boron carbide particles in the sintered body have a maximum particle diameter of at most 100 ?m, and the abundance ratio (area ratio) of boron carbide particles of from 10 to 100 ?m to boron carbide particles having a particle diameter of at most 5 ?m, is from 0.02 to 0.6.

Abstract: The present invention provides a needle-shaped ceramic body and needle-shaped ceramic catalyst body in which a case material is a high specific surface area porous cordierite body that is stable at high temperatures, and also provides methods of producing this needle-shaped ceramic body and needle-shaped ceramic catalyst body. The present invention relates to a needle-shaped ceramic body and needle-shaped ceramic catalyst body in which a base material is a high temperature-stable, high specific surface area porous cordierite body comprising a porous structure having a prescribed porosity and formed of a needle-shaped cordierite crystal phase and further relates to methods of producing this needle-shaped ceramic body and needle-shaped ceramic catalyst body, and by using porous cordierite constituted of needle-shaped crystals as a catalyst-supporting honeycomb structure, the present invention is able to inhibit sintering-induced reduction in the specific surface area.

Abstract: A boron carbide based sintered body having a four-point flexural strength of at least 400 MPa and a fracture toughness of at least 2.8 MPa·m1/2, which has the following two preferred embodiments. (1) A boron carbide-titanium diboride sintered body obtained by sintering a mixed powder of a B4C powder, a TiO2 powder and a C powder while reacting them under a pressurized condition and comprising from 95 to 70 mol % of boron carbide and from 5 to 30 mol % of titanium diboride, wherein the boron carbide has a maximum particle diameter of at most 5 ?m. (2) A boron carbide-chromium diboride sintered body containing from 10 to 25 mol % of CrB2 in B4C, wherein the sintered body has a relative density of at least 90%, boron carbide particles in the sintered body have a maximum particle diameter of at most 100 ?m, and the abundance ratio (area ratio) of boron carbide particles of from 10 to 100 ?m to boron carbide particles having a particle diameter of at most 5 ?m, is from 0.02 to 0.6.

Abstract: A boron carbide based sintered body having a four-point flexural strength of at least 400 MPa and a fracture toughness of at least 2.8 MPa·m1/2, which has the following two preferred embodiments. (1) A boron carbide-titanium diboride sintered body obtained by sintering a mixed powder of a B4C powder, a TiO2 powder and a C powder while reacting them under a pressurized condition and comprising from 95 to 70 mol % of boron carbide and from 5 to 30 mol % of titanium diboride, wherein the boron carbide has a maximum particle diameter of at most 5 ?m. (2) A boron carbide-chromium diboride sintered body containing from 10 to 25 mol % of CrB2 in B4C, wherein the sintered body has a relative density of at least 90%, boron carbide particles in the sintered body have a maximum particle diameter of at most 100 ?m, and the abundance ratio (area ratio) of boron carbide particles of from 10 to 100 ?m to boron carbide particles having a particle diameter of at most 5 ?m, is from 0.02 to 0.6.

Abstract: The present invention relates to a chemical reaction system for efficiently excluding nitrogen oxides with low power consumption when excess oxygen is present in exhaust gas, to a method of use therefor, to an activation method therefor, and to a reaction method for oxidizing or reducing by the use of an oxidation-reduction reactor with high selectivity without the need to supply or exchange a reducing agent or oxidizing agent.

Abstract: The present invention provides a method of manufacturing a porous thick film of an oxide that has extremely few cracks and can be satisfactorily used as an oxygen partial pressure detecting part of an oxygen sensor.

Abstract: A boron carbide based sintered body having a four-point flexural strength of at least 400 MPa and a fracture toughness of at least 2.8 MPa·m1/2, which has the following two preferred embodiments. (1) A boron carbide-titanium diboride sintered body obtained by sintering a mixed powder of a B4C powder, a TiO2 powder and a C powder while reacting them under a pressurized condition and comprising from 95 to 70 mol % of boron carbide and from 5 to 30 mol % of titanium diboride, wherein the boron carbide has a maximum particle diameter of at most 5 ?m. (2) A boron carbide-chromium diboride sintered body containing from 10 to 25 mol % of CrB2 in B4C, wherein the sintered body has a relative density of at least 90%, boron carbide particles in the sintered body have a maximum particle diameter of at most 100 ?m, and the abundance ratio (area ratio) of boron carbide particles of from 10 to 100 ?m to boron carbide particles having a particle diameter of at most 5 ?m, is from 0.02 to 0.6.

Abstract: It is an object to provide an aluminum oxide-based sintered body and a manufacturing method thereof, according to which all of wear resistance, strength and fracture toughness can be exhibited to a high degree in a single sintered body, and there is provided a method of manufacturing a multi-layer aluminum oxide sintered body having high strength and wear resistance as well as high fracture toughness, that has a structure of at least two layers in which a surface layer is a high-strength wear-resistant layer comprising isometric crystals having a small grain size, and an inner part is a high-fracture-toughness layer constituted from anisotropic crystals, the method comprising the steps of (1) preparing a layered body by forming a layer of an aluminum oxide material that has a purity of at least 90% and contains a grain growth inhibiting agent and a layer of an aluminum oxide material that has a purity of at least 90% and contains a grain growth promoting agent, (2) carrying out setting such that the sintering

Abstract: The present invention provides a novel polishing material with which silicon nitride ceramic and sialon ceramic can be polished at high efficiency through a tribochemical reaction, and a method for manufacturing thereof, said material is used for polishing a silicon nitride ceramic or sialon ceramic as a material being polished, through a tribochemical reaction, and consists of a ceramic sinter containing an element that causes the ceramic being polished to undergo a dissolution reaction at the grain boundary of the sinter, within the particles thereof, and/or in pores thereof.

Abstract: A method for the production of a high-strength high-toughness silicon nitride sinter includes the steps of mixing a silicon nitride powder with a sintering additive, adding to the resultant mixture as seed particles 0.1 to 10% by volume, based on the amount of the mixture, of elongated single crystal .beta.-silicon nitride particles having a larger minor diameter than the average particle diameter of the silicon nitride powder and having an aspect ratio of at least 2, forming the resultant mixture so as to orient the elongated single crystal .beta.-silicon nitride particles as seed particles in a specific direction, and heating the green body to density it and simultaneously induce epitaxial growth of single crystal .beta.-silicon nitride particles, and a high-strength, high-toughness silicon nitride sinter obtained by the method.

Abstract: A method for the production of a high-strength high-toughness silicon nitride sinter includes the steps of mixing a silicon nitride powder with a sintering additive, adding to the resultant mixture as seed particles 0.1 to 10% by volume, based on the amount of the mixture, of elongated single crystal .beta.-silicon nitride particles having a larger minor diameter than the average particle diameter of the silicon nitride powder and having an aspect ratio of at least 2, forming the resultant mixture so as to orient the elongated single crystal .beta.-silicon nitride particles as seed particles in a specific direction, and heating the green body to density it and simultaneously induce epitaxial growth of single crystal .beta.-silicon nitride particles, and a high-strength, high-toughness silicon nitride sinter obtained by the method.

Abstract: A sintered ceramic article formed mainly of alumina, having a chemical composition of from 1 to 10% by weight of La.sub.2 O.sub.3, from 0.01 to 0.1% by weight of SiO.sub.2, and the balance of Al.sub.2 O.sub.3 and containing these components in the form of corundum (.alpha.-Al.sub.2 O.sub.3) and lanthanum .beta.-alumina (La.sub.2 O.sub.3.llAl.sub.2 O.sub.3) and a method for the production of a sintered ceramic article formed mainly of alumina, comprising the steps of shaping a mixture of Al.sub.2 O.sub.3, La.sub.2 O.sub.3, and SiO.sub.2, calcining the shaped mixture in the air at a temperature in the range of from 600.degree. C. to 1000.degree. C., and further firing the calcined shaped mixture to a temperature in the range of from 1400.degree. C. to 1800.degree. C.

Abstract: A sintered silicon oxynitride composition comprises as an amount of starting material the combination of (a) a silicon component comprising silicon nitride(Si.sub.3 N.sub.4) and silicon oxide(SiO.sub.2) in a mol ratio of SiO.sub.2 /Si.sub.3 N.sub.4 being 0.7 to 1.2, and (b) at least one second component selected from an aluminum oxide, an aluminum nitride, a rare earth oxide, and a rare earth nitride, said second component being in an amount of from about 0.1 to 10 mol per 100 mol of said silicon component.

Abstract: An alumina silica sintered ceramic that is produced by the normal sintering method and which has bending strength of at least 300 MPa at room temperature and at least 400 MPa at an elevated temperature, for example, 1,300.degree. C. is disclosed.This sintered ceramic is produced by a process comprising the following steps: providing a chiefly amorphous starting powder that consists of 62-73 wt % Al.sub.2 O.sub.3 and correspondingly 38-27 wt % SiO.sub.2 ; calcining this starting powder to make a calcined product that is chiefly composed of a crystalline phase and which contains oxides of an alkali metal and an alkaline earth metal in a total amount of no more than 1,500 ppm; pressing the ground particles of the calcined product into a compact; and sintering the compact at 1,500.degree.-1,750.degree. C. and at atmospheric pressure.

Abstract: A shaped article of superplastic ceramic composed of zirconia toughened ceramic containing, or not containing, fine alumina powder is produced by deforming the ceramic under the action of stress at a temperature in the range of superplastic temperatures thereof.