Abstract: A ceramic honeycomb structure comprising large numbers of cells partitioned by porous cell walls, the cell walls having (a) porosity of 50-80%, and when measured by mercury porosimetry, (b) a median pore diameter being 25-50 ?m, (c) (i) a cumulative pore volume in a pore diameter range of 20 ?m or less being 25% or less of the total pore volume, (ii) a cumulative pore volume in a pore diameter range of more than 20 ?m and 50 ?m or less being 50% or more of the total pore volume, and (iii) a cumulative pore volume in a pore diameter range of more than 50 ?m being 12% or more of the total pore volume.

Abstract: A ceramic honeycomb structure comprising a ceramic honeycomb body having pluralities of longitudinal flow paths partitioned by square-lattice-cross-sectioned cell walls, and an outer peripheral wall formed on an outer periphery of the ceramic honeycomb body; the outermost peripheral cell wall of the ceramic honeycomb body having an outer peripheral surface shape reflecting the square lattice shapes of the cell walls; the thickness of the outer peripheral cell wall being larger than the thickness of the cell walls; and the outer peripheral wall being formed to cover an outer peripheral surface of the outer peripheral cell wall.

Abstract: A ceramic honeycomb structure comprising porous cell walls defining large numbers of flow paths, the cell walls having (a) porosity of 55% or more and less than 65%, and (b) 35,000/mm3 or more of substrate branches, wherein the number of substrate branches is defined by the number of branch points (including connecting points of 3 or more branches and connecting points of different-width branches) per a unit volume, in a network structure obtained by the skeletonization of the three-dimensional structure of cell wall substrates determined by X-ray CT.

Abstract: A method for producing a ceramic honeycomb structure comprising a ceramic honeycomb body having large numbers of longitudinal cells partitioned by porous cell walls having porosity of 50% or more, and a peripheral wall formed on a peripheral surface of the ceramic honeycomb body, comprising the steps of extruding moldable ceramic material to form a honeycomb-structured ceramic green body; machining a peripheral portion of the green body or a sintered body obtained from the green body to remove part of cell walls in the peripheral portion to obtain a ceramic honeycomb body having longitudinal grooves on a peripheral surface; applying colloidal metal oxide to a peripheral surface of the ceramic honeycomb body and drying it, and then applying a coating material comprising ceramic aggregate having an average particle size of 1 ?m or more to form the peripheral wall.

Abstract: A ceramic honeycomb structure having pluralities of flow paths partitioned by porous cell walls; (a) the cell walls having porosity of 50-60%; and (b) in a pore diameter distribution in the cell walls measured by mercury porosimetry, (i) pore diameters at cumulative pore volumes corresponding to particular percentages of the total pore volume being within specific ranges and having specific relationships; and (ii) the difference between a logarithm of the pore diameter at a cumulative pore volume corresponding to 20% of the total pore volume and a logarithm of the pore diameter at 80% being 0.39 or less, and its production method.

Abstract: A ceramic honeycomb structure having pluralities of flow paths partitioned by porous cell walls; (a) the cell walls having porosity of 50-60%; and (b) in a pore diameter distribution in the cell walls measured by mercury porosimetry, (i) pore diameters at cumulative pore volumes corresponding to particular percentages of the total pore volume being within specific ranges and having specific relationships; and (ii) the difference between a logarithm of the pore diameter at a cumulative pore volume corresponding to 20% of the total pore volume and a logarithm of the pore diameter at 80% being 0.39 or less, and its production method.

Abstract: A ceramic honeycomb structure including large numbers of flow paths partitioned by porous cell walls; (a) the cell walls having porosity of 55-65%; and (b) in a pore diameter distribution in the cell walls measured by mercury porosimetry, (i) a pore diameter at a cumulative pore volume corresponding to specific percentages of the total pore volume being within specific ranges and satisfying specific relationships; (ii) the difference of a logarithm of the pore diameter at a cumulative pore volume corresponding to 20% of the total pore volume and a logarithm of the pore diameter at 80% being 0.39 or less; and (iii) the volume of pores of more than 100 ?m being 0.05 cm3/g or less.

Abstract: A ceramic honeycomb structure comprising large numbers of cells partitioned by porous cell walls, the cell walls having (a) porosity of 50-80%, and when measured by mercury porosimetry, (b) a median pore diameter being 25-50 ?m, (c) (i) a cumulative pore volume in a pore diameter range of 20 ?m or less being 25% or less of the total pore volume, (ii) a cumulative pore volume in a pore diameter range of more than 20 ?m and 50 ?m or less being 50% or more of the total pore volume, and (iii) a cumulative pore volume in a pore diameter range of more than 50 ?m being 12% or more of the total pore volume.

Abstract: A ceramic honeycomb structure having pluralities of flow paths partitioned by porous cell walls, (a) the cell walls having porosity of 50-63%; and (b) in a pore diameter distribution in the cell walls measured by mercury porosimetry, (i) pore diameters at cumulative pore volumes corresponding to particular percentages of the total pore volume being within specific ranges and having specific relationships; (ii) the difference between a logarithm of the pore diameter at a cumulative pore volume corresponding to 20% of the total pore volume and a logarithm of the pore diameter at 80% being 0.39 or less; and (iii) the volume of pores of more than 100 ?m being 0.03 cm3/g or less.

Abstract: A method for producing a ceramic honeycomb body having large numbers of longitudinal cells partitioned by cell walls, with its peripheral portion removed by machining, includes rotatably holding the ceramic honeycomb body on a main axis of a lathe, and rotating the ceramic honeycomb body around the main axis, to remove its peripheral portion by machining with a tool; the lathe comprising a first fixing jig on the main axis, and a second fixing jig substantially opposing the first fixing jig; each of the first and second fixing jigs having an abutting end portion opposing each other, the abutting end portion having a smaller outer shape than that of the end surface of the ceramic honeycomb body, and the abutting portion having a substantially flat abutting end surface perpendicular to the main axis.

Abstract: A ceramic honeycomb structure comprising porous cell walls defining large numbers of flow paths, the cell walls having (a) porosity of 55% or more and less than 65%, and (b) 35,000/mm3 or more of substrate branches, wherein the number of substrate branches is defined by the number of branch points (including connecting points of 3 or more branches and connecting points of different-width branches) per a unit volume, in a network structure obtained by the skeletonization of the three-dimensional structure of cell wall substrates determined by X-ray CT.

Abstract: A method for producing a ceramic honeycomb structure comprising a ceramic honeycomb body having large numbers of longitudinal cells partitioned by porous cell walls having porosity of 50% or more, and a peripheral wall formed on a peripheral surface of the ceramic honeycomb body, comprising the steps of extruding moldable ceramic material to form a honeycomb-structured ceramic green body; machining a peripheral portion of the green body or a sintered body obtained from the green body to remove part of cell walls in the peripheral portion to obtain a ceramic honeycomb body having longitudinal grooves on a peripheral surface; applying colloidal metal oxide to a peripheral surface of the ceramic honeycomb body and drying it, and then applying a coating material comprising ceramic aggregate having an average particle size of 1 ?m or more to form the peripheral wall.

Abstract: A ceramic honeycomb structure having pluralities of flow paths partitioned by porous cell walls; (a) the cell walls having porosity of 50-60%; and (b) in a pore diameter distribution in the cell walls measured by mercury porosimetry, (i) pore diameters at cumulative pore volumes corresponding to particular percentages of the total pore volume being within specific ranges and having specific relationships; and (ii) the difference between a logarithm of the pore diameter at a cumulative pore volume corresponding to 20% of the total pore volume and a logarithm of the pore diameter at 80% being 0.39 or less, and its production method.

Abstract: A ceramic honeycomb structure comprising large numbers of cells partitioned by porous cell walls, the cell walls having (a) porosity of 50-80%, and when measured by mercury porosimetry, (b) a median pore diameter being 25-50 ?m, (c) (i) a cumulative pore volume in a pore diameter range of 20 ?m or less being 25% or less of the total pore volume, (ii) a cumulative pore volume in a pore diameter range of more than 20 ?m and 50 ?m or less being 50% or more of the total pore volume, and (iii) a cumulative pore volume in a pore diameter range of more than 50 ?m being 12% or more of the total pore volume.

Abstract: A method for producing a ceramic honeycomb structure comprising a ceramic honeycomb body having large numbers of longitudinal cells partitioned by porous cell walls having porosity of 50% or more, and a peripheral wall formed on a peripheral surface of the ceramic honeycomb body, comprising the steps of extruding moldable ceramic material to form a honeycomb-structured ceramic green body; machining a peripheral portion of the green body or a sintered body obtained from the green body to remove part of cell walls in the peripheral portion to obtain a ceramic honeycomb body having longitudinal grooves on a peripheral surface; applying colloidal metal oxide to a peripheral surface of the ceramic honeycomb body and drying it, and then applying a coating material comprising ceramic aggregate having an average particle size of 1 ?m or more to form the peripheral wall.

Abstract: A ceramic honeycomb structure having pluralities of flow paths partitioned by porous cell walls, (a) the cell walls having porosity of 50-63%; and (b) in a pore diameter distribution in the cell walls measured by mercury porosimetry, (i) pore diameters at cumulative pore volumes corresponding to particular percentages of the total pore volume being within specific ranges and having specific relationships; (ii) the difference between a logarithm of the pore diameter at a cumulative pore volume corresponding to 20% of the total pore volume and a logarithm of the pore diameter at 80% being 0.39 or less; and (iii) the volume of pores of more than 100 ?m being 0.03 cm3/g or less.

Abstract: A ceramic honeycomb structure having pluralities of flow paths partitioned by porous cell walls; (a) the cell walls having porosity of 50-60%; and (b) in a pore diameter distribution in the cell walls measured by mercury porosimetry, (i) pore diameters at cumulative pore volumes corresponding to particular percentages of the total pore volume being within specific ranges and having specific relationships; and (ii) the difference between a logarithm of the pore diameter at a cumulative pore volume corresponding to 20% of the total pore volume and a logarithm of the pore diameter at 80% being 0.39 or less, and its production method.

Abstract: A method for producing a honeycomb-shaped ceramic structure by extrusion-molding a moldable material including a cordierite-forming material and a pore-forming material, wherein the cordierite-forming material contains 15-25% by mass of silica having an average particle size of 20-30 ?m, with 5% or less by mass of particles having particle sizes of 10 ?m or less and 5% or less by mass of particles having particle sizes of 100 ?m or more, a particle size distribution deviation SD of 0.5 or less, and sphericity of 0.5 or more, and wherein the pore-forming material is present in an amount of 5-40% by mass based on the cordierite-forming material and has an average particle size of 15-50 ?m, with 10% or less by mass of particles having particle sizes of 5 ?m or less and 5% or less by mass of particles having particle sizes of 80 ?m or more.

Abstract: A cordierite-type ceramic honeycomb structure having large numbers of flow paths partitioned by porous cell walls; the cell walls having (a) porosity of more than 65% and 75% or less, (b) in a pore diameter distribution measured by mercury porosimetry, (i) a pore diameter d10 at a cumulative pore volume corresponding to 10% of the total pore volume being less than 50 ?m, a pore diameter (median pore diameter) d50 at 50% being 18-27 ?m, a pore diameter d90 at 90% being 10 ?m or more, and (d10?d90)/d50 being 2.3 or less; (ii) ? [=log(d20)?log(d80)] being 0.

Abstract: A ceramic honeycomb structure comprising a ceramic honeycomb body having pluralities of longitudinal flow paths partitioned by square-lattice-cross-sectioned cell walls, and an outer peripheral wall formed on an outer periphery of the ceramic honeycomb body; the outermost peripheral cell wall of the ceramic honeycomb body having an outer peripheral surface shape reflecting the square lattice shapes of the cell walls; the thickness of the outer peripheral cell wall being larger than the thickness of the cell walls; and the outer peripheral wall being formed to cover an outer peripheral surface of the outer peripheral cell wall.