A honeycomb structure includes porous partition walls defining cells which extend from a first end face to a second end face and which become through channels for a fluid, and a porous circumferential wall integrally formed with the partition walls to surround an outermost circumference of the partition walls, a thickness of the partition walls is from 101 to 381 m, porosities of the partition walls and the circumferential wall are both 48% or more, a porosity in a surface of the circumferential wall is higher than a porosity of an inner surface of the circumferential wall, and an average pore diameter in the surface of the circumferential wall is 10 m or more.

A ceramic honeycomb body having a skin that does not block partial cells extending from an inlet face to an outlet face at an outer periphery portion of the body. A method of making the ceramic honeycomb body having the skin includes disposing a sheet on an outer peripheral wall of a honeycomb core having an outer surface spaced apart from interiors of the partial cells and skinning the body having the sheet disposed thereon. Subsequent curing in the method bonds the skin to cell walls of the body spaced apart from interiors of the partial cells.

An article, includes a porous ceramic honeycomb body and a housing disposed on at least one of an outer periphery of the porous ceramic honeycomb body and opposing end faces of the porous ceramic honeycomb body, wherein the housing exerts a compressive force on the porous ceramic honeycomb body in at least one of radial direction and axial direction. A method of making the article, includes heating to greater than or equal to about 200 C the housing, crimping the housing tightly around the honeycomb body while the housing is greater than or equal to about 200 C, and cooling the housing. The housing exerts a compressive force on the porous ceramic honeycomb body in at least one of radial direction and axial direction by shrinking on cooling more than the honeycomb body.

A ceramic honeycomb body having a skin that does not block partial cells extending from an inlet face to an outlet face at an outer periphery portion of the body. A method of making the ceramic honeycomb body having the skin includes disposing a sheet on an outer peripheral wall of a honeycomb core having an outer surface spaced apart from interiors of the partial cells and skinning the body having the sheet disposed thereon. Subsequent curing in the method bonds the skin to cell walls of the body spaced apart from interiors of the partial cells.

There is provided a honeycomb structure where a crack at honeycomb segments, which constitute a honeycomb bonded assembly, is reduced. A honeycomb structure has a pillar-shaped honeycomb bonded assembly that has a plurality of pillar-shaped honeycomb segments having a porous partition wall defining a plurality of cells extending from an inflow end face as one end face to an outflow end face as another end face and becoming channels for a fluid, and a bonding layer bonding side surfaces of the plurality of honeycomb segments, and in the honeycomb bonded assembly, at 25 to 800 C., a thermal expansion coefficient of the bonding layer is larger than a thermal expansion coefficient of the honeycomb segment.

There is provided a honeycomb structure where a crack at a honeycomb substrate is reduced. A honeycomb structure has a honeycomb substrate that has a porous partition wall defining a plurality of cells extending from an inflow end face as one end face to an outflow end face as another end face and becoming channels for a fluid, and an outer circumference coating layer disposed at an outer circumference of the honeycomb substrate. At 25 to 800 C., a thermal expansion coefficient of the outer circumference coating layer is larger than a thermal expansion coefficient of the honeycomb substrate. The thermal expansion coefficients of the outer circumference coating layer and the thermal expansion coefficient at 25 to 800 C. preferably meet a relationship represented by the expression: 1.1<(the thermal expansion coefficient of the outer circumference coating layer/the thermal expansion coefficient of the honeycomb substrate)<40.

A circumferential coating material contains colloidal silica, silicon carbide, and titanium oxide different in particle diameters from silicon carbide, coats a circumferential surface of a honeycomb structure monolithically formed by extrusion, including as a main component, cordierite having a porosity of 50 to 75%, and forms a circumferential coating layer. A circumferentially coated honeycomb structure has a honeycomb structure comprising latticed porous partition walls defining and forming a plurality of polygonal cells forming through channels and extending from one end face to the other end face, and a circumferential coating layer formed by coating at least a part of a circumferential surface of the honeycomb structure with the circumferential coating material.

A honeycomb structure includes an outer peripheral side wall; a plurality of first cells having an opening on the first end surface and having a sealing portion on the second end surface; and a plurality of second cells having the sealing portion on the first end surface and having the opening on the second end surface, wherein the first cells and the second cells are arranged adjacent to each other with a partition wall interposed therebetween; wherein the sealing portion is composed of a ceramic containing MgO:9.0 to 13.4% by mass, Al.sub.2O.sub.3: 29.0 to 35.5% by mass, and SiO.sub.2: 50.0 to 58.0% by mass, and wherein an arithmetic average height Sa of the sealing portions on the first end surface and the second end surface is 18.0 m or less, respectively.

A honeycomb filter includes: a honeycomb substrate having porous partition walls disposed so as to surround cells extending from an inflow end face to an outflow end face, an outer peripheral coating layer disposed so as to surround an outer periphery of the honeycomb substrate, and plugging portions that are disposed at any one of ends on the inflow end face and ends on the outflow end face, of the cells, wherein, the outer peripheral coating layer has an inflection point at which thermal expansion in thermal expansion behavior of the outer peripheral coating layer turns to contraction and a temperature T1 of which is 1000 to 1500 C., and the outer peripheral coating layer has a porosity P1 of 36 to 48%, and a thermal expansion coefficient C1 between 40 to 800 C. of 2.5 to 3.510.sup.6/ C.