Abstract: A method of manufacturing silicon nitride sintered bodies comprising the steps of preparing a powder consisting essentially of 100 parts by weight of silicon nitride, 2.about.15 parts by weight of a rare earth element, 0.5.about.15 parts by weight of a Zr compound and 0.3.about.5 parts by weight of SiC, molding the thus prepared powder and firing the resulting molding.

Abstract: A method of producing a porous ceramic filter, using a cordierite precursor or starting composition including a talc powder component and a silica powder component, such that particles of the talc powder component and the silica powder component whose size is not less than 150 .mu.m constitute not more than 3% by weight of the starting composition, while particles of the talc and silica powder components whose size is not more than 45 .mu.m constitute not more than 25% by weight of the starting composition. A green body for the porous ceramic honeycomb filter formed of this starting composition is fired to react the starting composition to form cordierite and produce the desired porous ceramic honeycomb filter.

Abstract: A ceramic turbo charger rotor having a bearing structure in which an inner race of an angular ball bearing and a spacer are assembled to a journal shaft as one unit in such a manner that one end of the spacer is assembled to a turbine-side connecting portion of the journal shaft by a pressure inserting manner and the other end of the spacer is assembled to a compressor-side connecting portion of the journal shaft by a clearance fitting manner. Therefore, the deviation between a center axis and a rotational axis of the rotor caused by the pressure insertion of the spacer is released at the compressor side and the amount of the unbalance before correcting of the rotor is remarkably reduced.

Abstract: Silicon nitride sintered bodies including Si.sub.3 N.sub.4 and at least one element selected from Y.sub.2 O.sub.3, MgO, ZrO.sub.2. In the silicon nitride bodies, a J phase solid solution is present in an intergranular phase, which satisfies a relation of 0.65x.ltoreq.y.ltoreq.x+2 wherein y is an amount of J phase solid solution and x is an amount of Y.sub.2 O.sub.3 as an additive.

Abstract: Cordierite honeycomb structural bodies having coefficients of thermal expansion of not more than 1.0x10.sup.-6, an improved thermal shock resistance, a very small leakage amount and an improved heat exchanging efficiency are provided by using very fine particles of kaolin and talc to restrict a total pore volume of a given pore diameter to a given range. The cordierite honeycomb structural bodies are useful in broader fields than conventional ones.

Abstract: In a shaft composite structure wherein a ceramic shaft integrally formed with a ceramic turbine rotor is fixed to a metal sleeve integrally formed with a metal rotary shaft of a compressor impeller, a connection edge is located at a position corresponding to a recess for seal ring, and a thickness of tip portion of the metal sleeve is made thin to reduce a stiffness.Therefore, a stress concentration at the connection edge can be eliminated effectively and thus a reliable shaft composite structure can be obtained.

Abstract: A cordierite honeycomb structural body to be used as a catalyst carrier, having excellent heat resistance, thermal shock resistance and coatability with a high specific surface area material and a catalyst is disclosed, which have a chemical composition consisting mainly of 42-56% by weight SiO.sub.2, 30-45% by weight of Al.sub.2 O.sub.3 and 12-16% by weight of MgO, having a crystal phase consisting mainly of cordierite, and having coefficients of thermal expansion of not higher than 0.3.times.10.sup.-6 /.degree.C. in the flow-passage direction of the honeycomb structure and not higher than 0.5.times.10.sup.-6 /.degree.C. in a direction perpendicular to the flow-passage of the honeycomb structure within the temperature range of 40.degree.-800.degree. C. A cordierite honeycomb-structural body, wherein a distribution of diameters of pores, relative to a total volume of pores having a diameter of 0.5-5 .mu.m is not less than 40% and the total volume of pores having a diameter of not smaller than 10 .mu.

Abstract: A cylinder head has a ceramic precombustion chamber for an internal combustion engine. The cylinder head includes a part of the cylinder head made of a ceramic body having an injection aperture communicating with a main combustion chamber for jetting burning gases therethrough, a metal sleeve fitted on an outer circumference of the ceramic body and fitted in a precombustion chamber insert bore forming part of the cylinder head, and a head gasket interposed between the cylinder block forming the main combustion chamber and the ceramic body, the metal sleeve and the cylinder head. A surface of the ceramic body facing to the head gasket extends onto a side of the main combustion chamber beyond a surface of the ceramic body opening the injection aperture into the main combustion chamber.

Abstract: A process for producing a cordierite ceramic body by using a reclaimed cordierite composition for a cordierite ceramic article which has a composition similar to that of the cordierite ceramic body. The process includes the steps of: forming a desired formed body under a pressure by using a starting material which includes the recovered reclaimed cordierite composition, or a mixture of the reclaimed cordierite composition and a fresh cordierite composition; firing the formed body at a temperature between 1280.degree.-1330.degree. C. into a sample of the cordierite ceramic body; measuring a reaction ratio (R) between the amount of protoenstatite and cordierite crystals present in the sample; and formulating the starting material so that the reaction ratio (R) is 0.3 or less.

Abstract: Cordierite honeycomb structural bodies having excellent coatability for a material of high specific surface area and a catalyst thereon and low thermal expansion are disclosed. The cordierite honeycomb structural body as a chemical composition essentially consisting of from 42 to 56% of SiO.sub.2, from 30 to 45% of Al.sub.2 O.sub.3, and from 12 to 16% of MgO in terms of weight and contains cordierite as a main component of a crystalline phase. Porosity of the cordierite honeycomb structural body is from over 30% to not more than 42%. The total volume of pores having a diameter of from 0.5 to 5 .mu.m and the total volume of pores having a diameter of not less than 10 .mu.m are not less than 70% and not more than 10% of the total pore volume of the honeycomb structural body, respectively.

Abstract: Catalyst carriers made of cordierite honeycomb structures having low thermal expansion, porosities of not exceeding 30%, high strengths and thin partition walls with high cell density or low cell density are provided by using very fine particles of kaoline and talc which are considered heretofore disadvantageous for producing such catalyst carriers. The catalyst carriers are useful in a broader use field than conventional ones, particularly as catalyst carriers for purifying exhaust gases exited from automobile engines.

Abstract: A sintered aluminum titanate-mullite base ceramic having a chemical composition of not more than 0.8% of MgO, from 53 to 74% of Al.sub.2 O.sub.3, from 14 to 33% of TiO.sub.2, from 1.2 to 5% of Fe.sub.2 O.sub.3, from 6 to 20% of SiO.sub.2, and not more than 0.3% of (CaO+Na.sub.2 O+K.sub.2 O), and an amount of glass in mullite base matrices of the sintered body being not more than 5% when measured at a section of the sintered body. This aluminum titanate-mullite base ceramic is obtained by compounding from 40 to 65% of a starting material of aluminum titanate essentially consisting of from 45 to 62% of Al.sub.2 O.sub.3, from 34 to 50% of TiO.sub.2, from 3 to 7% of Fe.sub.2 O.sub.3, not more than 1% of SiO.sub.2 and not more than 0.3% of (CaO+Na.sub.2 O+K.sub.2 O) with from 35 to 60% of a starting material of mullite essentially consisting of from 18 to 32% of SiO.sub.2, from 68 to 82% of Al.sub.2 O.sub.3, and not more than 0.85% of (Fe.sub.2 O.sub.3 +TiO.sub.2 +CaO+MgO+Na.sub.2 O+K.sub.

Abstract: A ceramic honeycomb structural body having a high strength wherein the outer peripheral portion including an outer peripheral wall or a part extending from the end surface of the honeycomb body has a smaller porosity than the other portion. Such a ceramic honeycomb structural body is produced by filling pores in the above defined portion of the honeycomb body with a ceramic material having a smaller porosity than the ceramic honeycomb body material.

Abstract: Cordierite ceramic honeycomb structural bodies having a high thermal shock resistance and a high water absorption are produced by adding the defined amount of starch powder, a binder and water to a ceramic starting material to crystallize cordierite upon firing.