Ngk Insulators, Inc.

Takehiko Watanabe

Yasushi Noguchi

Hiroyuki Suenobu

Yukari Nakane

Yuji Katsuda

Satoshi Yamazaki

Takeshi Tokunaga

Atsushi Watanabe

Seiichiro Hayashi

Wataru Kotani

Kazuhiko Hamatsuka

Kyoko Makino

Daniel Yukichi Kitaguchi

Yohei Ono

Akira Nishikawa

A manufacturing method of the honeycomb structure has a forming step of forming a honeycomb formed body having partition walls defining a plurality of cells; a convex end portion forming step of forming a convex end portion including a convex end face in the obtained honeycomb formed body; a mounting step of directing downward one end face on which the convex end portion is formed and mounting the honeycomb formed body on a shelf plate; a firing step of firing the honeycomb formed body mounted on the shelf plate to form a honeycomb fired body; and an end face grinding step of grinding one end face of the honeycomb fired body to remove the convex end portion.

Manufacturing method of honeycomb structure, and honeycomb formed body

A raw setter has a plate shape, is made of the same material as in a honeycomb formed body, and has a chamfered portion in which a circumferential portion of one end face is chamfered in an oblique direction and whose has a tapered cross-sectional shape by reducing a diameter of an end face portion to an outer diameter, a ratio of an area of a flat portion to an end face area is from 10 to 85%, an angle formed between the flat portion and the chambered portion is from 3 to 50&#xb0;, a flatness of each of the flat portion of the one end face and a flat portion of the other end face is 0.3 mm or less, and a thickness of cell partition walls is 0.1 mm or less.

Raw setter, and firing method of honeycomb formed body

A die has two surfaces, in a forming material supplying surface which is one surface, a plurality of back holes to introduce a forming material of a honeycomb formed body into the die are formed, and in a honeycomb formed body extruding surface which is the other surface, lattice-shaped slits corresponding to cell partition walls are formed, the back holes communicate with the slits in slit intersecting portions of the slits, polygonal cell blocks defined by the slits include chamfered portions in which parts of corner portions and the like are chamfered at a chamfering angle &#x3b8; of 1.0 to 8.0&#xb0; to the extruding direction, from the honeycomb formed body extruding surface toward a slit depth direction, and straight portions which are not chamfered, and a ratio of a length L of the straight portion to a slit depth D is from 20 to 60%.

Honeycomb formed body extruding die

A process for producing a honeycomb structure includes: a mixing step where forming raw materials including a ceramic raw material are mixed to obtain a forming blended material, a kneading step where the forming blended material is kneaded to obtain kneaded clay, a forming step where the kneaded clay is formed into a honeycomb shape to obtain a honeycomb formed article, and a firing step where the honeycomb formed article is fired to obtain a honeycomb structure. The ceramic raw material is a cordierite forming raw material, and a magnetic powder contained in the kneaded clay is at a ratio of 400 ppm or less with respect to solid content conversion mass of the whole kneaded clay. There is provided a honeycomb structure capable of improving trapping efficiency, in particular, initial trapping efficiency by reducing the number of coarse pores in the partition walls.

Process for producing honeycomb structure

There is disclosed a ceramic structure which comprises a material having a controlled pore distribution and including cordierite as the main crystal phase. In the pore distribution, the volume of pores having pore diameters smaller than 20 &#x3bc;m accounts for 15% or less of the total pore volume, and the volume of pores having pore diameters of 20 to 100 &#x3bc;m accounts for 70% or more of the total pore volume. This ceramic structure is suitable for realizing a ceramic catalyst body which has excellent purification efficiency, is reduced in pressure loss, and is mountable even in a limited space.

Ceramic structure and process for producing the same

A method of producing cordierite ceramic where the degree of stacking faults and the particle diameter of kaolinite used as a component of a cordierite-forming raw material are appropriately adjusted so that microcracks having an average width of 0.3 &#x3bc;m or more are introduced into the resulting cordierite ceramic to produce a high-quality cordierite ceramic that includes a cordierite crystal oriented in a specific direction and has a porosity of 25% or more and a coefficient of thermal expansion of 0.30&#xd7;10/&#xb0; C. or less.

Cordierite ceramic and method of producing the same

A process for producing a honeycomb structure by obtaining clay from a cordierite-forming raw material containing an alumina source, a silica source, and a magnesia source; and forming the clay into a honeycomb shape, wherein a material having, in its volume particle size distribution, a 50 volume % particle size (V50) [&#x3bc;m] of 1 to 25 &#x3bc;m is used, as each of alumina source, silica source, and magnesia source; and a material having, in the volume particle size distribution of the whole cordierite-forming raw material, a ratio of 90 volume % particle size (V90) [&#x3bc;m] to 10 volume % particle size (V10) [&#x3bc;m] [a volume particle size distribution ratio (V90/V10)] of 10 or less and a difference (V90&#x2212;V10) between 90 volume % particle size (V90) [&#x3bc;m] and 10 volume % particle size (V10) [&#x3bc;m] of 25 &#x3bc;m or less is used, as the cordierite-forming raw material.

There are newly provided an index which quantitatively indicates shapes of kaolin particles, and a method of measuring the index. There is also provided a method of manufacturing a low-thermal-expansion honeycomb structure suitable for an application such as a car exhaust gas purifying catalyst carrier by use of the kaolin particles whose index is not less than a predetermined value. A certain amount of kaolin particlesare pressed and filled into a container, peak intensities of the kaolin particlesin (200), (020), and (002) faces are measured by X-ray diffraction, respectively, and a cleavage index of the kaolin particlesis calculated from the resultant measured values by the following equation (1):Cleavage index=(002)/[(200)+(020)+(002)]&#x2003;&#x2003;(Equation 1),wherein (200), (020), and (002) denote values of the peak intensities of the kaolin particles measured in the (200), (020), and (002) faces by the X-ray diffraction, respectively.

Method of manufacturing cordierite honeycomb structure including measuring cleavage index of kaolin particles

There is provided a method for manufacturing a porous ceramic structure, including: firing a formed body containing ceramic particles and a combustible powder functioning as a pore former, and burning off the combustible powder to obtain the porous ceramic structure. The combustible powder has an exothermic rate of 0 to 35 &#x3bc;V&#xb7;min./mg, which is obtained from a differential thermal analysis. The method for manufacturing a porous ceramic structure can inhibit a crack from being generated during firing even without slowing down the temperature rise rate at the combustion range of the pore former or without lowering an oxygen content in the firing atmosphere.

Method for manufacturing porous ceramic structure

There is provided a method for manufacturing a porous ceramic structure, including: firing a formed body containing ceramic particles and a combustible powder functioning as a pore former, and burning off the combustible powder to obtain the porous ceramic structure. As the combustible powder, porous resin particles having an average particle diameter of 10 to 50 &#x3bc;m and a porosity of 50 to 90% are used. The method for manufacturing a porous ceramic structure can inhibit the combustible powder functioning as a pore former from being smashed upon mixing/kneading a forming raw material and suppressing an excess heat generation upon firing and can manufacture a porous ceramic structure having a stable porosity with a good yield.

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Nagoya, Japan

Takehiko Watanabe