Abstract: A ceramics shaped article having a large wall-thickness and having a complicated shape, which can not be monolithically produced by a conventional molding, can be easily produced through a monolithical molding by the use of a ceramic batch containing water as a plasticizing medium and a small amount of an organic binder as a plasticizer. The ceramic shaped article can be fired into a ceramic sintered article in high dimensional accuracy and yield.

Abstract: High density fine ceramic sintered bodies are disclosed, which have a maximum pore diameter of not more than 10 .mu.m and a porosity of not more than 0.5%. A process for producing such high density fine ceramic sintered bodies comprises the steps of mixing a ceramic raw material powder with a sintering aid, grinding the resultant, mixture granulating and shaping the mixture, and firing the shaped body. The granulated powder is once forcedly dried, and upon necessity is added with water and/or sieved to obtain a uniform granulated powder having a given amount of water.

Abstract: A high hardness silicon nitride sintered body which includes 10.about.50% of a .alpha.-Si.sub.3 N.sub.4 per total weight of silicon nitride and has a Knoop hardness of not less than 15.5 Gpa, and is use as a bearing material or the like.

Abstract: In a method of detecting defects formed in a surface or in the vicinity thereof of a ball of a bearing by means of an ultrasonic wave, the ball and a probe for projecting an ultrasonic wave toward the ball and receiving an ultrasonic wave reflected from the detects are arranged in water in such a manner that a center axis of the probe is deviated from a normal axis of the ball which passes through a center of the ball and extends in parallel with the center axis of the probe by such a displacement amount that the ultrasonic wave refracted by the ball propagates along the surface of ball. The ball is rotated about a horizontal axis perpendicular to the normal axis, and the ball and probe are rotated relative to each other about a center axis of the ball which is perpendicular both to the normal axis and horizontal axis of the ball, so that the whole surface of the ball is scanned automatically with the ultrasonic wave.

Abstract: A shaping mole including a container section which is to receive a water-containing ceramic composition and which is defined by a non-permeable mold or a combination of a non-permeable mold and a permeable mold. A part of a shaping surface of the non-permeable mold is made of a material having a contact angle of not less than 80.degree. for water. A process for shaping ceramic articles by using such a mold is also disclosed, which including, the steps of preparing a water-containing ceramic composition comprising a ceramic powder containing a sintering assistant, a shaping assistant, and water, pouring the water-containing ceramic material into the shaping mold, pressing the ceramic composition, and releasing the molding from the mold. The water-containing ceramic material is prepared by using at least a gelatinizable water-soluble binder as the shaping assistant.

Abstract: Heat-resisting phosphate based compound sintered bodies are disclosed, which each contain not less than 10% by weight of a crystalline phase of RZr.sub.4 (PO.sub.4).sub.6 in which R is an element in Group IIa of the Periodic Table. A weight-reduced percentage of the sintered body when being thermally treated at 1,400.degree. C. for 100 hours is not more than 10%. A process for producing such phosphate based compound sintered bodies is also disclosed.

Abstract: A direct injection-type diesel engine includes a piston head formed with a novel piston combustion chamber, with an inner wall surface composed essentially of ceramic material having a low thermal conductivity. The combustion chamber has a reduced opening diameter to enhance a squish air flow out of the clearance space between the piston and the cylinder head, and allows significant reduction of smoke, unburnt hydrocarbon and particulates in the exhaust gas, as well as minimization of thermal loss of the engine.

Abstract: A novel solid solution has a composition of R.sub.y Zr.sub.4 Si.sub.x P.sub.6-x O.sub.24 (R is at least one forming bivalent or trivalent element 0.ltoreq.x.ltoreq.2, 2/3.ltoreq.y.ltoreq.2). Furthermore, a heat-resistant sintered body and heat-resistant phosphate based compound sintered body comprises the above solid solution and has excellent heat resistance and high temperature stability. And also, a method of producing such sintered bodies is disclosed.

Abstract: A process for determining a relative temperature distribution at a surface of a high temperature member to be used in a gas containing oxygen at high temperatures is disclosed. The process comprises the step of determining the relative surface temperature distribution of the member by measuring concentrations of oxygen at the surface of the member, which surface is composed of silicon carbide or silicon nitride. The process may also include the step of quantitatively determining a distribution of temperatures at the surface of the member by measuring concentrations of oxygen at the surface of the member, determining a relationship between temperatures and concentrations of oxygen on a surface of a standard member, and comparing the measured oxygen concentrations at the surface of the member with those of a standard member with reference to this relationship.

Abstract: High density fine ceramic sintered bodies are disclosed, which have a maximum pore diameter of not more than 10 .mu.m and a porosity of not more than 0.5%. A process for producing such high density fine ceramic sintered bodies comprises the steps of mixing a ceramic raw material powder with a sintering aid, grinding the resulting mixture granulating and shaping the mixture, and firing the shaped body. The granulated powder is once forcedly dried, and upon necessity is added with water and/or sieved to obtain a uniform granulated powder having a given amount of water.

Abstract: Disclosed herein is a method of manufacturing a ceramic honeycomb structural body and a die for extruding a ceramic honeycomb structural body wherein the die includes molding slits having a profile corresponding to a sectional profile of a ceramic honeycomb structural body and ceramic raw batch material supply holes through which a ceramic raw batch material is supplied to the molding slits. The pitch ratio between a short side and a long side of the molding slits is substantially 1:.sqroot.3.

Abstract: Cordierite series dense and low expansion ceramics have excellent thermal shock resistance property, being airtight, heat resistant and having high dimensional stability at high temperatures can be achieved by incorporating 2-10% by weight of P.sub.2 O.sub.5 in the cordierite ceramic and acid treating the fired or sintered body to selectively remove P.sub.2 O.sub.5 to primarily result in an amount of 0.1% by weight of P.sub.2 O.sub.5 remaining in the sintered body.

Abstract: A process for dewaxing a ceramic molded body is disclosed, the process includes heating an injection molded body made from ceramic material and a wax-series binder, said heating occurring upon a porous ceramic body.

Abstract: The disclosed ceramic heat exchanger has a stress relief layer disposed in the proximity of joint between a hollow hub and a honeycomb structural body integrally joined to the outer circumference of the hub, the stress relief layer having the difference in thermal expansion of not greater than 0.1% at 800.degree. C. relative to the hub.

Abstract: Disclosed herein is a ceramic honeycomb structural body which has cells of a rectangular section in which the pitch ratio between the short side and the long side of the cells is substantially 1:.sqroot.3. A method of manufacturing a ceramic honeycomb structural body and a die for extruding a ceramic honeycomb structural body are also disclosed. The die comprises molding slits having a profile corresponding to a sectional profile of a ceramic honeycomb structural body and ceramic raw batch material supply holes through which a ceramic raw batch material is supplied to the molding slits, wherein the pitch ratio between the short side and the long side of the molding slits is substantially 1:.sqroot.3. Further, a rotary regenerator type ceramic heat exchanger composed of the ceramic honeycomb structural body is disclosed.

Abstract: Ceramic honeycomb type recuperative heat exchangers having a large number of parallel channels formed of partition walls are disclosed, in which fluids to be heat-exchanged are passed through respective channels that are produced by extruding a ceramic raw batch material into a honeycomb structural body, drying the shaped honeycomb structural body, prior to or after firing step cutting off partition walls in the given rows of the honeycomb structural body in the axial direction of the channels to a given depth from the end surface of the honeycomb structural body and sealing only the end surfaces of said rows.

Abstract: A ceramic shaped body having an improved mechanical strength which is useful for a structural material, such as engine parts, is produced by coating a slip which is substantially the same in the chemical composition as the ceramic shaped body and is very small in the difference of the thermal expansion coefficient at 800.degree. C. from the shaped body, on the surface of the shaped body, drying the coated shaped body, subjecting the thus treated shaped body to a hydrostatic press and firing such a shaped body.

Abstract: Ceramic honeycomb type recuperative heat exchangers having a large number of parallel channels formed of partition walls are disclosed, in which fluids to be heat-exchanged are passed through respective channels that are produced by extruding a ceramic raw batch material into a honeycomb structural body, drying the shaped honeycomb structural body, prior to or after firing step cutting off partition walls in the given rows of the honeycomb structural body in the axial direction of the channels to a given depth from the end surface of the honeycomb structural body and sealing only the end surfaces of said rows.

Abstract: A thermal stress-resistant rotary regenerator type ceramic heat exchanger comprising a plurality of ceramic honeycomb structural matrix segments bonded by a ceramic binder is produced by extruding a plurality of ceramic honeycomb structural matrix segments, firing the segments, bonding the segments with one another by application of a ceramic binder, said ceramic binder after the subsequent sintering having substantially the same mineral composition as said ceramic matrix segments and the thickness of 0.1 to 6 mm, and a difference in thermal expansion being not greater than 0.1% at 800.degree. C. relative to the ceramic matrix segments, drying the bonded segments, and firing the dried bonded segments.

Abstract: The invention relates to low-expansion ceramics, the chemical composition of which consists of 1.2 to 20% by weight of magnesia (MgO), 6.5 to 68% by weight of alumina (Al.sub.2 O.sub.3), 19 to 80% by weight of titanium in terms of titanium oxide (TiO.sub.2), 1 to 20% by weight of silica (SiO.sub.2), and 0.5 to 20% by weight of iron in terms of ferric oxide (Fe.sub.2 O.sub.3); the major component of crystalline phase thereof is a solid solution of magnesium oxide-aluminum oxide-titanium dioxide-silicon oxide-iron oxide; the ceramics have a coefficient of thermal expansion of not more than 20.times.10.sup.-7 (1/.degree.C.) in a temperature range of 25.degree. C. to 800.degree. C., a four-point flexural strength of not smaller than 50 kg/cm.sup.2 at room temperature, and a melting point of not lower than 1,500.degree. C.