Ngk Insulators, Inc.

Toshiyuki Hamanaka

Takashi Harada

Shunichi Yamada

Seiichi Asami

Yutaka Ogawa

Kunikazu Hamaguchi

Fumio Hattori

Yasushi Noguchi

Keiichiro Watanabe

Kaname Fukao

Shigeru Mochida

Tadato Ito

Toshikazu Ito

Wataru Kotani

Kyoko Makino

Noboru Kondo

There is provided a honeycomb structure in which the structure is not segmented, or a smaller number of segments are integrated to suppress a local temperature rise and to reduce breakage by thermal stress at the time of use, and a method of manufacturing the structure. There is disclosed a honeycomb structurecomprising: a large number of cellspartitioned by cell wallsand extending through an axial direction. A flow channel separatoris formed in the honeycomb structure. There is disclosed a method of manufacturing the honeycomb structurein which the flow channel separatoris formed by extrusion. There is disclosed a method of manufacturing the honeycomb structurein which the flow channel separatoris formed by clogging.

Honeycomb structure and process for production thereof

A honeycomb filter includes a honeycomb-shaped filter base having a plurality of through holes and a sealing member fixed on end surfaces of the filter base in which the through holes are open. The through holes of the filter base are clogged with the sealing member in a checker flag form on each end surface so as to clog the through holes differently from the through holes sealed on the opposite end surface. The sealing member is a sheet-shaped fired body with a thickness of 3 mm or less, and a difference in coefficient of thermal expansion at temperatures of 40 to 800&#xb0; C. between said sealing member and said filter base is/&#xb0; C. or less. This honeycomb filter has high filtration efficiency, and very high thermal shock resistance and has high bonding strength between the sealing member and the filter base and a low pressure loss.

Honeycomb filter and method for manufacturing the same

A honeycomb filter for exhaust gas purification, possessing a honeycomb structure () having a plurality of through-holes which are separated from each other by porous partition walls and plugged alternately at the exhaust gas inlet face () and the exhaust gas outlet face (), wherein the honeycomb structure () has a slit () possessing an opening at least at the exhaust gas inlet face (), and the slit () is partially filled with a filler () in a depth of 3 to 25 times the width () of slit from the exhaust gas inlet face () toward a flow direction () of exhaust gas and a gap () is formed inside from a portion of the slit filled with the filler (). This honeycomb filter for exhaust gas purification has high purification ability, yet possesses high thermal shock resistance, and can be used continuously over a long period.

Honeycomb filter for exhaust gas purification

A honeycomb filter is composed mainly of silicon carbide or of metallic silicon and silicon carbide; the filter being formed by bonding a plurality of honeycomb segments each of which has a plurality of through-holes being partitioned by porous partition walls. The filter is plugged alternately at the exhaust gas inlet face and exhaust gas outlet face of honeycomb segments. Each two adjacent honeycomb segments are contacted with each other at each a portion of their sides facing each other. They are bonded with each other at least at part of each portion of said sides other than the contacted portion through a bonding material having a strength lower than that of a basal body of honeycomb segment. Thus, the thermal stresses generated among the respective portions constituting the filter is reduced. The generation of cracks, etc. can be also prevented considerably.

Honeycomb filter and process for production thereof

A ceramic honeycomb catalyst carrier wherein a porosity is 20% or less and an average surface roughness (Ra) of a partition wall of the carrier is 0.5 &mgr;m or more is obtained by forming ceramic raw materials to obtain a ceramic honeycomb formed body; drying the ceramic honeycomb formed body to obtain a ceramic honeycomb dried-up body; roughening a surface of the partition wall of the ceramic honeycomb dried-up body by exposing the ceramic honeycomb dried-up body in an airflow in which polishing powders are included; and sintering the ceramic honeycomb dried-up body after a surface treatment, or, by forming ceramic raw materials to obtain a ceramic honeycomb formed body; drying and sintering the ceramic honeycomb formed body to obtain a ceramic honeycomb sintered body; and roughening a surface of the partition wall of the ceramic honeycomb sintered body by exposing the ceramic honeycomb sintered body in an airflow or a water flow in which polishing powders are included.

Ceramic honeycomb catalyst carrier and method of producing the same

A production method of a honeycomb structure is provided. The production method of a thin wall cordierite honeycomb structure having cordierite as the main component of the crystalline phase includes: adding a forming auxiliary agent to a cordierite material to obtain a mixture, kneading the mixture to obtain a material batch, forming the material batch by extrusion to form a honycomb compact, drying the honeycomb compact to obtain a dried body, and firing the dried body. The cordierite material batch contains 65% by weight or more flat plate-like cordierite raw material including crystal water made from talc, kaolin and aluminum hydroxide with the BET specific surface areas for the cordierite raw materials being 7 to 18 m.sup.2 /g of talc, 14 to 22 m.sup.2 /g of kaolin and 6 to 18 m.sup.2 /g of aluminum hydroxide. The method can realize a thinner wall and a higher cell density and can improve the formability (in particular, the lubricity and the shape stability) at the time of extruding, the mechanical strength (hydrostatic pressure fracture strength), and the catalyst carrying characteristics.

Production method of thin wall cordierite honeycomb structure

Ceramic materials to be insert-cast are disclosed, which each contain not less than 65% by volume of aluminum titanate as a crystalline phase, and have an average particle diameter of crystals thereof being not less than 10 .mu.m, Young's modulus of 50 to 2,000 kgf/mm.sup.2, compression strength of 5 to 40 kgf/mm.sup.2, and porosity of 5 to 35%. Ceramic port liners are also disclosed, which are free from cracking due to compression force during insert-casting, peeling-off during use, and facilitate insert-casting. To attain this, a reinforcement which meets either one or both of requirements that differences in coefficient of thermal expansion at 800.degree. C. and Young's modulus between the reinforcement and a material constituting the port liner body are in a range of .+-.0.1% and in a range of .+-.1,000 kgf/mm.sup.2, respectively, is filled into a depressed portion at an outer peripheral surface of the port liner body to form an integrated structure with a flat or swelled surface. Alternatively, the outer peripheral surface of the port liner body is worked to give uneven portions at a joining surface of the port liner body to a metal to insert-cast the port liner. Another alternative is to utilize a stress-releasing slit formed in a wall of the port liner body. Further, the outer peripheral surface of the ceramic port liner body may be covered with a ceramic sheet which is irreversively expandable by heating.

Ceramicm port liners

A porous ceramic honeycomb filter having a chemical composition consisting of, as main components, 42-56 wt % SiO.sub.2, 30-45 wt % Al.sub.2 O.sub.3, and 12-16 wt % MgO and containing cordierite as a main component of a crystalline phase. The porous ceramic honeycomb filter has a porosity of at least 40% and not greater than 55%. The volume of pores having a diameter not larger than 2 .mu.m in the filter is not larger than 0.015 cc/g to thereby improve the collecting time with low pressure loss and high collecting efficiency.

Porous ceramic honeycomb filter and method of producing the same

A ceramic material for use in insert-casting, which contains not less than 65% by volume of aluminum titanate as a crystalline phase. The average particle diameter of crystals of the aluminum titanate is not less than 10 .mu.m, and not more than 20% by volume of a glass phase containing a rare earth element in an amount of 0.5 to 16% by weight when calculated in the form of an oxide is contained. Young's modulus is 50 to 2,000 kgf/mm.sup.2. A process for producing the same is also disclosed, which includes the steps of preparing a powder by mixing a material, as an Al.sub.2 O.sub.3 source material, containing not more than 96% by weight of Al.sub.2 O.sub.3 and having an average particle size of not less than 3 .mu.m, a material having an average particle diameter of not more than 3 .mu.m as a TiO.sub.2 source material, and a given rare earth element in an amount of 1.8% by weight when calculated in the form of an oxide, shaping the powder, and drying and firing the shaped body. The ceramic material has an actual break strain of not less than 6.times.10.sup.-3. The process for producing such a ceramic material includes a step of cooling the shaped body at a rate of at least not less than 500.degree. C./hr in a temperature range not less than 200.degree. C. during and/or after the firing.

Ceramic materials for use in insert-casting and processes for producing

Ceramic materials to be insert-cast

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.

Method of producing a cordierite honeycomb structural body

In a method for effectively producing ceramic manifolds for thermally insulating exhaust channels, an intermediate product is first formed by drain casting which includes a main ceramic pipe having a plurality of branch pipes extending therefrom whose ends are connected together by elongated connection members in the form of thin plates or bars. Thereafter, the intermediate product is fired and the ends of the branch pipes are then cut off together with the connection members. In this manner, even ceramic pipes complicated in shape readily can be produced by preventing strains and deformations which would otherwise occur during firing of the intermediate product.

Method of proudcing ceramic manifolds for thermally insulating exhaust

Novel processes have been developed by the present invention for producing hollow ceramic articles. Such ceramic articles are produced by using a water-absorbable mold having water non-permeable faces on an inner surface of the mold at locations corresponding to valve holes. The thickness of a ceramic layer deposited on the inner surface of the mold is controlled by measuring an amount of a lowered liquid surface level of the slurry near a slurry-pouring opening of the mold. Open ends of a hollow ceramic article are formed by cutting corresponding closed ends after deposition of the slurry and firing. A uniform thickness of a slurry deposited onto the inner surface of the mold can be attained by rotating the mold around an arbitrary rotary axis at a rotation speed of 1 to 60 rpm. All ceramic material contained in the slurry fed inside the mold may be deposited on the inner surface of the mold while the mold is being rotated or swung.

Process for producing hollow ceramic articles

A heat insulating ceramic insert-cast article for an internal combustion engine, comprising a ceramic liner and a metallic member enclosing an outer periphery of the ceramic liner. The ceramic liner is adapted to contact exhaust gases. A joint boundary between the ceramic liner and the metallic member is constituted by contact faces at which the ceramic liner contacts the metallic member and heat insulating air layers at which the ceramic liner and the metallic member do not contact each other. A process for producing such a heat insulating ceramic insert-cast article is also disclosed. First, the outer periphery of the ceramic liner is covered with the heat insulating layer which is partially formed with cuts, and then the ceramic liner is enclosed with a molten metal in the state that the ceramic liner is covered with the layer. Thus, the metal flows into the cuts and solidifies therein to form contact faces between the ceramic liner and the metal, while portions at which the metal does not flow inside due to the pressure of the layer are converted to heat insulating layers.

Heat insulating ceramic insert-cast articles for use in exhaust channels

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. The bonding material has a coefficient of thermal expansion different from that of the matrix segments after the firing by not more than 0.02% at 800.degree. C., and a Young's modulus of the bonding material being not less than 0.4 time to not more than 1.8 times that of the matrix.

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Suzuka, Japan

Toshiyuki Hamanaka