A honeycomb filter includes a pillar-shaped honeycomb structure having porous partition walls provided, surrounding a plurality of cells which serve as fluid through channels extending from an inflow end face to an outflow end face, and porous plugging portions provided either at the ends on the inflow end face or the outflow end face of the cells, wherein the plugging portions are composed of a porous material, the honeycomb structure has a central region and a circumferential region and a ratio of an area of the circumferential region with respect to that of the central region ranges from 0.1 to 0.5, and a plugging length L1 in the cell extending direction of a central plugging portion in the central region is smaller than a plugging length L2 of a circumferential plugging portion in the circumferential region, L1 ranges from 3 to 6 mm, and L2 from 7 to 9 mm.

A honeycomb filter includes a pillar-shaped honeycomb structure body having a porous partition wall disposed to surround a plurality of cells and a plugging portion provided at an open end on a first end face side or a second end face side of each of the cells, wherein the partition wall is composed of a material containing cordierite as a main component thereof, a number per unit area of pores which exist at a surface of the partition wall and which have equivalent circle diameters exceeding 3.0 μm is 1400 per mm.sup.2 or more, and, in a pore diameter distribution which indicates a cumulative pore volume of the partition wall, with a log pore diameter on a horizonal axis and a log differential pore volume (cm.sup.3/g) on a vertical axis, a half-value width of a first peak that includes a maximum value of the log differential pore volume is 0.30 or less.

A honeycomb filter includes a pillar-shaped honeycomb structure body having a porous partition wall disposed to surround a plurality of cells and a plugging portion provided at an open end on a first end face side or a second end face side of each of the cells, wherein the partition wall is composed of a material containing cordierite as a main component thereof, a number per unit area of pores which exist at a surface of the partition wall and which have equivalent circle diameters exceeding 3.0 μm is 1400 per mm.sup.2 or more, and, in a pore diameter distribution which indicates a cumulative pore volume of the partition wall, with a log pore diameter on a horizonal axis and a log differential pore volume (cm.sup.3/g) on a vertical axis, a half-value width of a first peak that includes a maximum value of the log differential pore volume is 0.30 or less.

A porous honeycomb heat storage structure including: a honeycomb structure which has a porous partition wall which defines a plurality of cells extending one end face to the other end face and allows a reaction medium to flow into the cells; and a heat storage portion which is configured by filling a heat storage material performing heat storage and heat dissipation by a reversible chemical reaction with the reaction medium or physical adsorption/desorption in at least a portion of each cells, wherein the heat storage portion has an area ratio in a range from 60% to 90% with respect to a cross sectional area of a honeycomb cross section orthogonal to an axial direction of the honeycomb structure.

A porous honeycomb heat storage structure including: a honeycomb structure which has a porous partition wall which defines a plurality of cells extending one end face to the other end face and allows a reaction medium to flow into the cells; and a heat storage portion which is configured by filling a heat storage material performing heat storage and heat dissipation by a reversible chemical reaction with the reaction medium or physical adsorption/desorption in at least a portion of each cells, wherein the heat storage portion has an area ratio in a range from 60% to 90% with respect to a cross sectional area of a honeycomb cross section orthogonal to an axial direction of the honeycomb structure.

A plugged honeycomb structure, including: a plurality of honeycomb segments, a bonding layer and a circumferential wall disposed to surround circumference of a honeycomb segment bonded body where the plurality of honeycomb segments are bonded, wherein in the bonding layer, the bonding layer at a part that bonds the honeycomb segments disposed in contact with the circumferential wall is a circumferential bonding layer, and the bonding layer at a part that bonds the honeycomb segment including a center of gravity in a cross section orthogonal to the extending direction of cells of the honeycomb segment bonded body or at a position closest to the center of gravity and another honeycomb segment adjacent to the honeycomb segment is a center bonding layer, and a bonding strength A1 of the circumferential bonding layer is larger than a bonding strength A2 of the center bonding layer.

A method of plugging channels of a honeycomb body and a honeycomb body including plugged channels. The method includes applying a shear force to a plugging mixture including a plurality of inorganic particles, clay, and a liquid vehicle to alter the viscosity of the plugging mixture from a first viscosity prior to the vibrating to a second viscosity which is less than the first viscosity. A honeycomb body is placed into contact with the plugging mixture such that a portion of the plugging mixture having the second viscosity flows into the plurality of channels. Application of the shear force is stopped or reduced to increase the viscosity of the portion of the plugging mixture in the plurality of channels to greater than the first viscosity.

A method of plugging channels of a honeycomb body and a honeycomb body including plugged channels. The method includes applying a shear force to a plugging mixture including a plurality of inorganic particles, clay, and a liquid vehicle to alter the viscosity of the plugging mixture from a first viscosity prior to the vibrating to a second viscosity which is less than the first viscosity. A honeycomb body is placed into contact with the plugging mixture such that a portion of the plugging mixture having the second viscosity flows into the plurality of channels. Application of the shear force is stopped or reduced to increase the viscosity of the portion of the plugging mixture in the plurality of channels to greater than the first viscosity.

A method for forming a plugged honeycomb article includes feeding a ceramic precursor material through an extrusion die, the extrusion die having a plurality of pins, a plurality of cavities bounded by adjacent pins, and alternating end-faces of the plurality of pins include extensions extending from an outlet of the extrusion die in an extrusion direction. The method further includes extruding the ceramic precursor material through the extrusion die to form a web structure comprising a plurality of cell walls and channels bounded by adjacent cell walls, supporting the web structure that has been extruded through the extrusion die, and providing movement between the extrusion die and the web structure in at least one direction substantially orthogonal to the extrusion direction while the extensions are positioned in at least a portion of the channels.

A method for forming a plugged honeycomb article includes feeding a ceramic precursor material through an extrusion die, the extrusion die having a plurality of pins, a plurality of cavities bounded by adjacent pins, and alternating end-faces of the plurality of pins include extensions extending from an outlet of the extrusion die in an extrusion direction. The method further includes extruding the ceramic precursor material through the extrusion die to form a web structure comprising a plurality of cell walls and channels bounded by adjacent cell walls, supporting the web structure that has been extruded through the extrusion die, and providing movement between the extrusion die and the web structure in at least one direction substantially orthogonal to the extrusion direction while the extensions are positioned in at least a portion of the channels.