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 filter including a ceramic honeycomb structure having large numbers of flow paths partitioned by porous cell walls, and plugs disposed in the flow paths alternately on the exhaust gas inlet or outlet side, to remove particulate matter from an exhaust gas passing through the porous cell walls; the porous cell walls having porosity of 45-75%, the median pore diameter A (?m) of the cell walls measured by mercury porosimetry, and the median pore diameter B (?m) of the cell walls measured by a bubble point method meeting the formula of 35<(A?B)/B×100?70, and the maximum pore diameter of the cell walls measured by a bubble point method being 100 ?m or less.

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) pore diameters at cumulative pore volumes 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 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 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 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 having a large number of flow paths partitioned by porous cell walls, the cell walls meeting the conditions; (a) the cell walls having porosity of 55-80%, (b) the cell walls having a median pore diameter D50 (measured by mercury porosimetry) of 5-27 ?m, (c) pores open on cell wall surfaces having an opening area ratio of 20% or more, (d) pores open on cell wall surfaces having a median opening diameter d50 (determined from equivalent circle diameters on an area basis) of 10-45 ?m, (e) the density of pores open on cell wall surfaces having equivalent circle diameters of 10 ?m or more and less than 40 ?m being 350/mm2 or more, (f) the maximum inclination of a curve of a cumulative pore volume relative to a pore diameter (determined from a pore distribution measured by mercury porosimetry) being 1.6 or more, and (g) a ratio D50/d50 of the median pore diameter D50 to the median opening diameter d50 being 0.65 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 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) pore diameters at cumulative pore volumes 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 having a large number of flow paths partitioned by porous cell walls, the cell walls having porosity of 40-60%; pores opening on the cell wall surface having an opening area ratio (total opening area of pores opening on cell wall surface per unit area) of 15% or more; the median opening diameter of the opening pores being 10 ?m or more and less than 40 ?m, when the opening diameter of each pore opening on the cell wall surface is expressed by an equivalent circle diameter (diameter of a circle having the same area as the opening area of each pore); the density of pores having equivalent circle diameters of 10 ?m or more and less than 40 ?m being 350/mm2 or more; and the average circularity of pores having equivalent circle diameters of 10 ?m or more and less than 40 ?m being 1-2.

Abstract: A method for producing a ceramic honeycomb structure having a large number of paths partitioned by porous cell walls, the cell walls having thickness of 0.17-0.45 mm and porosity of 40% or more, comprising the steps of preparing a moldable material comprising a ceramic material powder, a binder, a pore-forming material and water, extruding the moldable material to form a honeycomb-shaped green body, and drying and sintering the green body, the pore-forming material having a melting point of 40-110° C., being solid in the moldable material, and being melted in the drying step so that 25% or more thereof is removed from the green body in the drying step.

Abstract: A ceramic honeycomb structure having a large number of flow paths partitioned by porous cell walls, the cell walls having porosity of 40-60%; pores opening on the cell wall surface having an opening area ratio (the total opening area of pores opening on the cell wall surface per a unit area) of 15% or more; the median opening diameter of the opening pores being 10 ?m or more and less than 40 ?m, when the opening diameter of each pore opening on the cell wall surface is expressed by an equivalent circle diameter (a diameter of a circle having the same area as the opening area of each pore); the density of pores having equivalent circle diameters of 10 ?m or more and less than 40 ?m being 350/mm2 or more; and the average circularity of pores having equivalent circle diameters of 10 ?m or more and less than 40 ?m being 1-2.

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 filter including a ceramic honeycomb structure having large numbers of flow paths partitioned by porous cell walls, and plugs disposed in the flow paths alternately on the exhaust gas inlet or outlet side, to remove particulate matter from an exhaust gas passing through the porous cell walls; the porous cell walls having porosity of 45-75%, the median pore diameter A (?m) of the cell walls measured by mercury porosimetry, and the median pore diameter B (?m) of the cell walls measured by a bubble point method meeting the formula of 35<(A?B)/B×100?70, and the maximum pore diameter of the cell walls measured by a bubble point method being 100 ?m or less.

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 filter comprising a ceramic honeycomb structure having large numbers of flow paths partitioned by porous cell walls, and plugs disposed in the flow paths alternately on the exhaust gas inlet or outlet side, to remove particulate matter from an exhaust gas passing through the porous cell walls; the porous cell walls having porosity of 45-75%, the median pore diameter A (?m) of the cell walls measured by mercury porosimetry, and the median pore diameter B (?m) of the cell walls measured by a bubble point method meeting the formula of 35<(A?B)/B×100?70, and the maximum pore diameter of the cell walls measured by a bubble point method being 100 ?m or less.