Abstract: A ceramic heat transmission type or regenerative heat exchanger, including a plurality of matrix segments bonded together with a bonding material. A difference in coefficient of thermal expansion between the matrix segments and the bonding material is not more than 0.02% at 800.degree. C., and a Young's modulus of the bonding material is not less than 0.4 times to not more than 1.8 times that of the matrix segment. A process for producing the ceramic heat exchangers includes the steps of extruding and firing honeycomb structural segments in which a crystalline phase is mainly composed of cordierite and a coefficient of thermal expansion in an extending direction of flow channels is not more than 0.06% at 800.degree. C., machining an outer periphery of each of the segments, coating a bonding material around the outer periphery of each of the segments, bonding the segments together, and drying and firing the bonded segments.

Abstract: Cordierite honeycomb structural bodies having coefficients of thermal expansion of not more than 1.0.times.10.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: 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 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: Highly gas-tight rotary cordierite heat regenerator is formed of a honeycomb structural body having a porosity of 20-45% and mainly consisting of cordierite, and open pores of the partition walls defining channels of the honeycomb structural body are sealed with a filler thereto, the difference of thermal expansion between the honeycomb structural body and the filler being less than 0.1% at 800.degree. C. The honeycomb structural body is made by preparing fired segments thereof, sealing the open pores of the partition walls with the filler thereof, bonding the segments with a ceramic bonding material, and firing the bonded segments.

Abstract: A ceramic material for a honeycomb structure is formed from a mixture of raw materials comprising, per 100 parts by weight of the mixture, 20 to 80 parts by weight of cordierite powder and 20 to 80 parts by weight of powder having a crystalline phase consisting mainly of a solid solution of SiO.sub.2 --Al.sub.2 O.sub.3 --Fe.sub.2 O.sub.3 --TiO.sub.2 --MgO. The mixture consists essentially of 15.7 to 44.0% by weight of SiO.sub.2, 29.8 to 41.0% by weight of Al.sub.2 O.sub.3, 0.9 to 8.3% by weight of Fe.sub.2 O.sub.3, 7.0 to 35.9% by weight of TiO.sub.2 and 4.9 to 16.1% by weight of MgO.

Abstract: A ceramic material for a honeycomb structure is prepared from a mixture of raw materials comprising per 100 parts by weight of the mixture 40 to 90 parts by weight of cordierite powder and 10 to 60 parts by weight of crystalline glass powder having a crystalline phase consisting mainly of a solid solution of .beta.-spodumene. The mixture consists essentially of 51.5 to 64.4% by weight of siO.sub.2, 24.8 to 33.7% by weight of Al.sub.2 O.sub.3, 5.5 to 12.4% by weight of MgO and 0.4 to 2.7% by weight of Li.sub.2 O. It may further contain up to 5.1% by weight of TiO.sub.2 and up to 1.8% by weight of ZrO.sub.2.

Abstract: The disclosed method seals preselected open ends of channels of a ceramic honeycomb structural body with cordierite-forming sealing material batch, and fires the honeycomb structural body with the thus sealed ends, so as to convert the sealing material batch into cordierite.

Abstract: The disclosed method seals preselected open ends of channels of a ceramic honeycomb structural body by attaching a film to that end surface of the honeycomb structural body which is to be selectively sealed while boring holes on the film at positions corresponding to desired open ends of the channels to be sealed, dipping the end surface in a sealing material containing slurry, pressing sealing material mixture body in the desired channels open ends, and then firing the ceramic honeycomb structural body with the sealing materials applied thereto.

Abstract: Highly gas-tight rotary cordierite heat regenerator is formed of a honeycomb structural body having a porosity of 20-45% and mainly consisting of cordierite, and open pores of the partition walls defining channels of the honeycomb structural body are sealed with a filler thereto, the difference of thermal expansion between the honeycomb structural body and the filler being less than 0.1% at 800.degree. C. The honeycomb structural body is made by preparing fired segments thereof, sealing the open pores of the partition walls with the filler thereof, bonding the segments with a ceramic bonding material, and firing the bonded segments.