Abstract: Composite bodies comprise a metallic member and a ceramic member integrally joined together by joining a projection of the ceramic member to a recess of the metallic member. Their joining strength is improved by substantially limiting brazing metal to an interface between the outer peripheral surface of the projection of the ceramic member and the innner peripheral surface of the recess of the metallic member. The joining strength is also improved by forming a groove around the outer periphery of the metallic member at the joined end. The joining strength is also improved by providing a space or an intermediate member between a tip end surface of the projection and a bottom surface of the recess and attaining the relation: ##EQU1## in which G, L.sub.1, .alpha., .alpha.', T.sub.S and T.sub.

Abstract: Ceramic-metal composite bodies are disclosed, which are each formed by joining a projection on a ceramic member to a recess or a through hole formed in a metallic member together. A groove portion is provided substantially all around the outer periphery of the metallic member such that a fitting end of the metallic member is located in a position corresponding to the groove portion. A difference between a diameter of a bottom of the groove portion and an outer diameter of the projection of the ceramic member is 0.05 to 0.8 times as large as a difference between an outer diameter of the metallic member and the outer diameter of the projection of the ceramic member.

Abstract: A metal-ceramic composite body is produced by fitting a protruding portion of a ceramic member into a concave portion of an intermediate member and joining the intermediate member to a metallic member. In this case, a difference between the inner diameter in the concave portion of the intermediate member and the outer diameter in the protruding portion of the ceramic member is not less than 0.2% of the outer diameter in the protruding portion when the protruding portion is pulled out from the concave portion.

Abstract: Composite joined bodies are disclosed wherein, each includes constituent members and an intermediate member through which the constituent members are joined together. The intermediate member is designed in a honeycomb structure.

Abstract: A process is disclosed for producing silicon nitride sintered bodies. The process comprises the steps of molding a formulated starting material of silicon nitride, firing a thus obtained molding to obtain a fired body having a desired shape, and then thermally treating the fired body in such an atmosphere that has an oxygen partial pressure higher than that in a firing atmosphere and suppresses a weight increment in oxidation to not more than 0.1 mg/cm.sup.2. Working may be done to obtain the desired shape of the fired body after the firing but before the thermal treatment.

Abstract: A ceramic-metal composite body comprises a ceramic member with a projection formed thereon and a metallic member with a depression or through hole formed therein. The ceramic member and the metallic member are bonded together by fitting the projection of the ceramic member into the depression or through hole of the metallic member. The difference between the outer diameter of the projection of the ceramic member and the inner diameter of the depression or through hole of the metallic member when the projection of the ceramic member is extracted from the depression or through hole of the metallic member is not less than 0.2% of the outer diameter of the projection of the ceramic member.

Abstract: Silicon nitride sintered bodies are disclosed, which each consist essentially of Si, O, N, and at least two kinds of rare earth elements selected from Y, Er, Tm, Yb, and Lu the bodies comprising not less than 70% by weight of Si.sub.3 N.sub.4. The ratio of the molar amount of all the rare earth elements contained in the sintered body calculated as moles of Ln.sub.2 O.sub.3, Ln being a rare earth element selected from Y, Er. Tm, Yb and Lu divided by the molar amount of oxygen calculated as moles of SiO.sub.2 is within the range of from 0.4 to 1.3. The amount of oxygen calculated as moles of SiO.sub.2 is obtained by subtracting the amount of oxygen contained in all the Ln.sub.2 O.sub.3, all the rare earth elements contained in said sintered body being considered as molecules of Ln.sub.2 O.sub.3 from the amount of oxygen contained in the sintered body and converting the remaining amount of oxygen into moles of SiO.sub.2.

Abstract: Disclosed herein is a ceramic shape memory element containing zirconia. A ceramic article is also disclosed which contains at least one of tetragonal zirconia and monoclinic zirconia, and is subjected to plastic deformation through phase transformation caused by maintaining the article at a given temperature, and/or imposing a given stress thereupon. Methods of processing and joining the ceramic article by utilizing the shape memory phenomenon peculiar to such a ceramic article are also disclosed.

Abstract: A process for manufacturing a silicon nitride sintered body comprises molding a mixed powder of a silicon nitride starting material and a sintering aid and firing a thus obtained molding. The firing is carried out in an N.sub.2 atmosphere or a mixed atmosphere of N.sub.2 and an inert gas to which CO.sub.2 or a mixed gas of CO.sub.2 and CO is added. Thereby, an O.sub.2 partial pressure is increased to restrain the evaporation of SiO.sub.2 and nitriding of SiO.sub.2 during the firing. The silicon nitride sintered body suffers almost no deterioration of the fired surface resulting from the evaporation of SiO.sub.2 and the nitriding of SiO.sub.2, and exhibits substantially equal four point bending strength and oxidation resistance with respect to the fired surface and the inside thereof.

Abstract: Disclosed herein is a high durability zirconia porcelain which is high in thermal stability and free from degradation phenomena such as profile change and strength reduction, and is characterized in that change in length after the zirconia porcelain being maintained in hot water at 250.degree. C. for 50 hours is not more than 0.05%.

Abstract: A silicon nitride sintered body essentially consisting of compounds of Sr, Mg, Ce, Zr and Al in amounts of from 0.1 to 18% by weight when calculated as SrO, from 0.2 to 25% by weight when calculated as MgO, from 0.1 to 20% by weight when calculated as CeO.sub.2, from 0.1 to 15% by weight when calculated as ZrO.sub.2 and from 1 to 20% by weight when calculated as Al.sub.2 O.sub.3, respectively, and the balance being silicon nitride. A method of manufacturing the silicon nitride sintered body is also disclosed. The silicon nitride sintered body has a low thermal conductivity while high mechanical strength and high fracture toughness being maintained.

Abstract: A silicon nitride sintered body essentially consisting of compounds of Mg, Sr, Ce and Al in amounts of from 0.5 to 5% by weight when calculated as MgO, from 0.5 to 5% by weight when calculated as SrO, from 1 to 10% by weight when calculated as CeO.sub.2 and from 1 to 20% by weight when calculated as Al.sub.2 O.sub.3, respectively, and the balance being silicon nitride. A method of manufacturing the silicon nitride sintered body is also disclosed. The silicon nitride sintered body has a low thermal conductivity while high mechanical strength and high thermal shock resistance being maintained.

Abstract: An engine part comprises a plurality of ceramic members overlaid one on the other and including at least a first ceramic member with a front surface to be in contact with hot gas and a second ceramic member arranged behind the first member, each of the first member and the second member has a mechanical strength of more than 20 kg/mm.sup.2.

Abstract: A method for determining an amount of non-stabilized zirconia in a ceramic specimen involves subjecting the ceramic specimen to an environment having a controlled temperature and humidity and measuring mechanical and/or chemical properties of the specimen to determine if any deterioration of the specimen has occurred.