The honeycomb structure body has a dense part at a part in axial direction including a center region of the inflow end face, the dense part having a change ratio of porosity calculated by the following Expression (1) that is 2 to 8%, and has an outside-diameter increasing part, and the honeycomb structure body has a change ratio of average diameter calculated by the following Expression (2) that is 0.2 to 3%,

(1−Px/Py)×100, Expression (1): in Expression (1), Px denotes the porosity (%) at the center region of the inflow end face, and Py denotes the porosity (%) of a circumferential region of the inflow end face.

(1−Dx/Dy)×100,   Expression (2): in Expression (2), Dx denotes the average diameter (mm) of the inflow end face, and Dy denotes the average diameter (mm) of the outflow end face.

The honeycomb structure body has a dense part having a change ratio of porosity calculated by the following Expression (1) that is 1 to 5%. The honeycomb structure body also has an outside-diameter decreasing part in which the outside diameter decreases from the inflow end face to the outflow end face. The honeycomb structure body has a change ratio of average diameter calculated by the following Expression (2) that is 0.2 to 3%.

(1−P.sub.x/P.sub.y)×100,  Expression (1): in Expression (1), P.sub.x denotes the porosity (%) at the center region of the outflow end face, and Py denotes the porosity (%) of a circumferential region of the outflow end face other than the center region.

(1−D.sub.x/D.sub.y)×100,  Expression (2): in Expression (2), D.sub.x denotes the average diameter (mm) of the outflow end face, and D.sub.y denotes the average diameter (mm) of the inflow end face.

A honeycomb structure has partition walls defining a plurality of hexagonal cells the partition walls are constituted by combining standard partition walls having a partition wall thickness in a range smaller than ±10% to an average partition wall thickness of the partition walls, wide partition walls having a partition wall thickness of +10% or more to the average partition wall thickness, and narrow partition walls having a partition wall thickness of −10% or less to the average partition wall thickness, and a non-standard partition wall ratio is in a range of 10% to 30% which is a ratio occupied by a subtotal number of non-standard partition walls obtained by adding the wide partition walls and the narrow partition walls in a total number of the partition walls which is obtained by adding the numbers of the standard partition walls, the wide partition walls and the narrow partition walls.

Disclosed is a ceramic honeycomb structure comprising a honeycomb body and a multilayered outer layer formed of a thick core layer applied and rapidly dried and a thin clad layer dried more gently to form a crack free dual skin layer. The core layer may have properties that are closer to those of the ceramic honeycomb body in service than the clad layer that may provide a tough outer shell to withstand handling and assembly.

A ceramic honeycomb body, suitable for use in exhaust gas processing, includes a honeycomb structure having a plurality of through-channels, a first portion of the plurality of through-channels have a first hydraulic diameter dh1, a second portion of the plurality of through-channels have a second hydraulic diameter that is smaller than the first hydraulic diameter dh1, the first hydraulic diameter dh1 is equal to or greater than 1.1 mm, and the first and second portions of through-channels, taken together, have a geometric surface area GSA greater than 2.9 mm.sup.−1. Diesel oxidation catalysts and methods of soot removal are also provided, as are other aspects.

A honeycomb structure includes a honeycomb segment bonded member including; a plurality of prismatic columnar shaped honeycomb segments; and a bonding layer bonding the segments, wherein one honeycomb segment has a bulge on one side face, extending in an axial direction, another honeycomb segment has a recess on one side face, extending in the axial direction, the one honeycomb segment and the another are disposed adjacent and bonded to each other via the bonding layer with the bulge inserted in the recess, length of the bulge is smaller than length of the one side face of the one honeycomb segment, length of the recess is smaller than length of the one side face of the another honeycomb segment, a base part of the bulge is defined with a bent side face, an angle between an imaginary bottom face and the bent side face of the bulge being 60° or more.

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 a porous ceramic honeycomb structure with a first end, a second end, and a plurality of walls having wall surfaces defining a plurality of inner channels. A highly porous layer is disposed on one or more of the wall surfaces of the honeycomb body. The highly porous layer has a porosity greater than 90%, and has an average thickness of greater than or equal to 0.5 μm and less than or equal to 10 μm. A method of making a honeycomb body includes depositing a layer precursor on a ceramic honeycomb body and binding the layer precursor to the ceramic honeycomb body to form the highly porous layer.

There is disclosed a plugged honeycomb structure. A plugged honeycomb structure includes a tubular honeycomb structure body having partition walls including a porous partition wall base material defining a plurality of cells which become through channels for a fluid and extend from a first end face to a second end face, and a porous trapping layer disposed on the surface of the partition wall base material; and plugging portions disposed in open ends of predetermined cells in the first end face and open ends of residual cells in the second end face, and the partition wall base material is constituted of a porous body including α-Al.sub.2O.sub.3 as a main phase and further including aluminum titanate and glass.

A honeycomb structure includes a pillar-shaped honeycomb structure body including porous partition walls defining and forming a plurality of cells which extend from an inflow end face to an outflow end face, and a porous outer wall surrounding the partition walls, a porous supporting bulge disposed to extend out from a circumference of the outer wall so that at least a part of the outer wall is exposed, and plugging portions arranged in open ends of the cells, and the supporting bulge has support portions and a side wall portion, and the partition walls and the outer wall of the honeycomb structure body and the support portions and the side wall portion of the supporting bulge are all formed monolithically by formation of a ceramic raw material.