Abstract: A honeycomb structure is made of cordierite and has a plurality of cells separated from each other by porous partition walls and functioning as fluid passages. The honeycomb structure has a thermal expansion coefficient of 0.25×10?6/° C. or less, an average pore diameter is 3 to 8 ?m, and a porosity of 25% or more. The honeycomb structure is made of cordierite excellent in thermal shock resistance even with large pore diameters and high porosity.

Abstract: There is provided a method for manufacturing a ceramic honeycomb structure comprising: a coating material adjustment step for obtaining a coating material by mixing at least water with a ceramic powder aggregate having only one peak in a particle size distribution, an average particle size of 23 to 39 ?m, and a particle size distribution width of 15 to 33, a coating material application step for applying the coating material to cover the outer periphery of a honeycomb structure having a plurality of cells separated by porous ceramic partition walls, and a coating material heat-drying step for forming an outer wall by heat-drying the coating material after the coating material application step. By the method, the outer periphery is covered with a coating material to form an outer wall to hardly generate, for example, crack generation and peeling upon drying the outer wall, and the coating material is provided.

Abstract: There is provided a method for manufacturing a ceramic honeycomb structure comprising: a coating material adjustment step for obtaining a coating material by mixing at least water with a ceramic powder aggregate having only one peak in a particle size distribution, an average particle size of 23 to 39 ?m, and a particle size distribution width of 15 to 33, a coating material application step for applying the coating material to cover the outer periphery of a honeycomb structure having a plurality of cells separated by porous ceramic partition walls, and a coating material heat-drying step for forming an outer wall by heat-drying the coating material after the coating material application step. By the method, the outer periphery is covered with a coating material to form an outer wall to hardly generate, for example, crack generation and peeling upon drying the outer wall, and the coating material is provided.

Abstract: There is provided a method for manufacturing a ceramic honeycomb structure comprising: a coating material adjustment step for obtaining a coating material by mixing at least water with a ceramic powder aggregate having only one peak in a particle size distribution, an average particle size of 23 to 39 ?m, and a particle size distribution width of 15 to 33, a coating material application step for applying the coating material to cover the outer periphery of a honeycomb structure having a plurality of cells separated by porous ceramic partition walls, and a coating material heat-drying step for forming an outer wall by heat-drying the coating material after the coating material application step. By the method, the outer periphery is covered with a coating material to form an outer wall to hardly generate, for example, crack generation and peeling upon drying the outer wall, and the coating material is provided.

Abstract: There is provided a method for manufacturing a ceramic honeycomb structure comprising: a coating material adjustment step for obtaining a coating material by mixing at least water with a ceramic powder aggregate having only one peak in a particle size distribution, an average particle size of 23 to 39 ?m, and a particle size distribution width of 15 to 33, a coating material application step for applying the coating material to cover the outer periphery of a honeycomb structure having a plurality of cells separated by porous ceramic partition walls, and a coating material heat-drying step for forming an outer wall by heat-drying the coating material after the coating material application step. By the method, the outer periphery is covered with a coating material to form an outer wall to hardly generate, for example, crack generation and peeling upon drying the outer wall, and the coating material is provided.

Abstract: A method for manufacturing a ceramic honeycomb structure includes the steps of: forming the outer periphery of a ceramic structure having a plurality of cells separated by ceramic porous partition walls into a predetermined shape; applying a coating material containing at least a ceramic powder, water, and a high-boiling additive having a higher boiling point than that of water on an outer periphery of the cell structure 2 so as to cover the outer periphery; and drying the coating material by heating to form an outer wall 3. The method provides a method for manufacturing a honeycomb structure having the outer wall formed by covering the outer periphery with a coating material and hardly having a crack and a defect such as peeling and a coating material.

Abstract: There is disclosed a honeycomb structure having excellent thermal shock resistance. The honeycomb structure contains cordierite as a main component, and has an average pore diameter of 4 ?m or more and 10 ?m or less, a total pore volume of 0.18 cm3/g or more and 0.22 cm3/g or less, and Young's modulus of 4 GPa or more and 6 GPa or less.

Abstract: A honeycomb structure is made of cordierite and has a plurality of cells separated from each other by porous partition walls and functioning as fluid passages. The honeycomb structure has a thermal expansion coefficient of 0.25×10?6/° C. or less, an average pore diameter is 3 to 8 ?m, and a porosity of 25% or more. The honeycomb structure is made of cordierite excellent in thermal shock resistance even with large pore diameters and high porosity.

Abstract: A honeycomb structure is made of cordierite and has a plurality of cells separated from each other by porous partition walls and functioning as fluid passages. The honeycomb structure has a thermal expansion coefficient of 0.25×10?6/° C. or less, an average pore diameter is 3 to 8 ?m, and a porosity of 25% or more. The honeycomb structure is made of cordierite excellent in thermal shock resistance even with large pore diameters and high porosity.

Abstract: An exhaust gas purifying filter for removing carbon particles from combustion exhaust gas, having a honeycomb structural body, flow passages that are sealed alternately at both ends by means of sealing portions to form checkerboard patterns. In the exhaust gas purifying filter according to the invention, lengths of the sealing portions formed in the flow passages of the honeycomb structural body vary randomly. An exhaust gas purifying apparatus utilizing the exhaust gas purifying filter according to the invention is also disclosed.

Abstract: An imaginary plane dividing a profile of a rough surface of a filter into halves with equal volume is defined as a mean plane. Assuming cutting the filter with the mean plane, a ratio of the total cross-sectional area of the recesses appearing to the whole area of the mean plane is defined as a Valley Level. An exhaust gas filter having a surface with a Valley Level of at most 20%, a porosity of 40% to 55% and an average pore diameter of 5 .mu.m to 50 .mu.m effectively collects fine particles contained in exhaust gases discharged from internal combustion engines, such as diesel engines, with little pressure loss, and has an improved releasability of deposited fine particles and can be readily regenerated by flow of blowback air, with high efficiency. When the filter has a specified two-layer structure, the Valley Level is readily controllable.

Abstract: An exhaust gas filter is provided, including a honeycomb structure having a plurality of partition walls defining through-holes extending along an axial direction. The through-holes include first and second groups. The first group is plugged via first sealing members at a second axial end of the honeycomb structure, while the second group is plugged via second sealing members at the first axial end of the honeycomb structure. The first group of through-holes is adapted to receive exhaust gas, and trap therein fine particles. The first sealing members have a three-dimensional micropore structure that includes interconnected pores to allow blowback air to pass therethrough. The blowback air flows through both the first sealing members and the partition walls defining the second through-holes so as to remove the fine particles that have collected in the first through-holes.

Abstract: Cordierite honeycomb ceramics comprises a cordierite phase as a main ingredient. A value of [Fe.sub.2 O.sub.3 wt %/(MgO wt %+Fe.sub.2 O.sub.3 wt %)].times.100 is 2-10, where a ferric component is calculated as Fe.sub.2 O.sub.3. A thermal expansion coefficient of the cordierite honeycomb ceramics is less than 0.5.times.10.sup.-6 /.degree. C. within a temperature range of 40.degree.-800.degree. C. in a direction parallel to a flow passage of a honeycomb body. In the cordierite honeycomb ceramics including a ferric component, a ferric component is added from a talc as raw materials. The cordierite honeycomb ceramics having a low thermal expansion coefficient is obtained by mixing raw materials for cordierite generation to obtain a batch, extruding the batch into a honeycomb formed body, drying the honeycomb formed body, and firing the dried honeycomb formed body at a temperature range of 1350.degree.-1450.degree. C. After that, the sintered honeycomb body is immersed in an acid solution if necessary.

Abstract: A porous ceramic filter has properties such that a porosity of the filter is more than 45% and less than 60%, a volume of pores having a pore size of less than 40 .mu.m is more than 60% of total volume of pores of the ceramic filter and an inequality of 1000M+85N.gtoreq.530 is satisfied, wherein M (m.sup.2 /g) is a specific surface of total pores continued from a surface to an inner portion of the filter and N (.mu.m) is a surface roughness of a surface of the filter. Preferably, the porous ceramic filter has a thermal expansion coefficient of less than 0.5.times.10.sup.-6 /.degree.C. within a temperature range of 40.degree..about.800.degree. C. in a direction parallel to a flow passage of the filter. The porous ceramic filter according to the invention is preferably used for eliminating soots in an exhaust gas from a diesel engine, and has a long operating time and requires less frequent filter regenerations.

Abstract: A machining apparatus comprises a mounting base, a tuning fork secured to the mounting base at the root thereof, a driver associated with the forward end of one of the oscillating legs of the tuning fork for driving the tuning fork so as to cause resonant oscillation of the tuning fork, and a machining member fixed to the forward end of the other oscillating leg of the tuning fork for acting on a workpiece.