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, wherein the partition wall is composed of a material containing cordierite as a main component thereof, porosity of the partition wall measured by a mercury press-in method is 60 to 68%, an average pore diameter of the partition wall measured by a mercury press-in method is 8 to 12 and in a pore diameter distribution which indicates a cumulative pore volume of the partition wall measured by a mercury press-in method, with a pore diameter (μm) on an abscissa axis and a log differential pore volume (cm.sup.3/g) on an ordinate axis, a first peak that includes a maximum value of the log differential pore volume has a pore diameter value of 10 μm or less, the pore diameter value corresponding to a ⅓ value width of the maximum value.

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, wherein the partition wall is composed of a material containing cordierite as a main component thereof, porosity of the partition wall measured by a mercury press-in method is 60 to 68%, an average pore diameter of the partition wall measured by a mercury press-in method is 13 to 18 μm, and in a pore diameter distribution indicating a cumulative pore volume of the partition wall measured by a mercury press-in method, with a pore diameter (μm) on an abscissa axis and a log differential pore volume (cm.sup.3/g) on an ordinate axis, a first peak including a maximum value of the log differential pore volume has a pore diameter value of 15 μm or less, the pore diameter value corresponding to a ⅓ value width of the maximum value.

A honeycomb structure, including: a plurality of pillar shaped honeycomb segments, each of the pillar shaped honeycomb segments including a partition wall and a plugged portion; and a joining layer arranged so as to join side surfaces of the pillar shaped honeycomb segments to each other. The honeycomb structure satisfies the following equations (1) to (3):

y≤1000  (1);

y≤717.92x.sup.−0.095  (2); and

y≥462.4x.sup.−0.153  (3),

in which y is a maximum temperature (° C.) at which the use of the honeycomb structure is accepted, and x is a thermal conduction factor represented by the following equation:

thermal conduction factor=(thermal conductivity of the partition wall×thermal conductivity of the joining layer)/(average thickness of the joining layer×porosity of the partition wall).

A honeycomb body having intersecting porous walls which includes first through fourth cells, wherein the cells extend from inlet to outlet face and are plugged to define a repeating structural unit with three inlets and one outlet channel. Repeating structural unit includes a first channel including length L.sub.1, width W.sub.2, and area A.sub.1, a second channel including length L.sub.2, the width W.sub.2, and area A.sub.2, a third channel including the length L.sub.1, width W.sub.1, and area A.sub.3, and a fourth channel including the length L.sub.2, the width W.sub.1, and A.sub.4, wherein the first through third channels are inlets and the fourth channel is a rectangular outlet and at least one of W.sub.1≥W.sub.2 and L.sub.1≠L.sub.2, i.e. W.sub.1≥W.sub.2, or L.sub.1≠L.sub.2, or W.sub.1≥W.sub.2 and L.sub.1≠L.sub.2. Repeating structural unit has a quadrilateral outer perimeter. Particulate filters including the honeycomb body, honeycomb extrusion dies, and methods of manufacturing the honeycomb body are provided.

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 honeycomb structure body has cell walls, inner cells and outer cells, and a boundary partition wall. The inner cells are arranged in a high cell density area and the outer cells are arranged in a low cell density area. A cell density of the high cell density area is higher than a cell density of the low cell density area. Cell reinforced parts are formed at a first intersection part at which the cell walls intersect each other. Boundary reinforced parts are formed at a second intersection part at which the cell walls and the boundary partition wall intersect each other. The honeycomb structure body satisfies a relationship of Sb>Sc, where Sb indicates an average value of a cross sectional area of the overall boundary reinforced parts, and Si indicates an average value of a cross sectional area of the overall inner cell reinforced parts.

A honeycomb structure includes a pillar-shaped honeycomb structure body having porous partition walls surrounding a plurality of cells which extend from a first to a second end face and which form flow channels of a fluid, and a circumferential wall enclosing the partition walls, wherein, specific cell of the cells is provided with a pair of projection which projects into the cell from the partition wall, the projection projects, in at least a pair of opposed partition walls among the partition walls constituting the cell, into the cell from a first and a second side, and which is provided continuously in a direction the cell extends, and in the case where the width of a top part of the projection is denoted by W1, and the width of a bottom part of the projection is denoted by W2, W1>W2 holds, and W2/W1 is 0.5 to 0.9.

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.

A coated ceramic honeycomb body comprising a honeycomb structure comprising a matrix of intersecting porous walls forming a plurality of axially-extending channels, at least some of the plurality of axially-extending channels being plugged to form inlet channels and outlet channels, wherein a total surface area of the outlet channels is greater than a total surface area of the inlet channels, and wherein a catalyst is preferentially located within the outlet channels, and preferentially disposed on non-filtration walls of the outlet channels. Methods and apparatus configured to preferentially apply a catalyst-containing slurry to the outlet channels and non-filtration walls are provided, as are other aspects.

An exhaust gas purification filter includes a cell assembly including cells and a partition wall, seal members, and a skin member. The partition wall has a porosity of 50% to 70%. The skin member has a thickness T of 0.3 mm to 1.0 mm. The partition wall includes crossing portions, each cell has at least one part of an outer periphery defined by a corresponding one of the crossing portions, the at least one part of the outer periphery is rounded to have a value of radius of curvature R being 0.02 mm to 0.6 mm A degree of distortion δ being a degree of change in the external dimensions of the filter in axial direction, is greater than 0 and is 1.5 mm or less. A value of a structural variable X, expressed by Equation 1 below, is 0.05 to 6, X=T×R/δ . . . Equation 1.