A particulate filter, including: a pillar-shaped honeycomb structure portion having a plurality of first cells extending from a first end face to a second end face, the first end face being open and the second end face being plugged, and a plurality of second cells extending from the first end face to the second end face, the first end face being plugged and the second end face being open, in which the first cells and the second cells are alternately arranged adjacent to each other with porous partition walls interposed therebetween; and a low thermal conductive layer covering a part or the whole of an outer peripheral side surface of the pillar-shaped honeycomb structure portion, the thermal conductivity in a thickness direction of the low thermal conductive layer being 0.6 W/(m.Math.K) or less.

An outer periphery coating material being coated onto an outer peripheral surface of a ceramic honeycomb structure to form an outer periphery coated layer. The outer periphery coating material comprises: a particle mixture containing cordierite particles and amorphous silica particles in a mass ratio of from 40:60 to 80:20; and from 10 to 30% by mass of crystalline inorganic fibers in an outer percentage relative to the particle mixture. An average particle diameter of the cordierite particles is different from an average particle diameter of the amorphous silica particles.

The honeycomb structure includes a pillar-shaped honeycomb structure body, and a circumferential coating layer disposed to surround a circumference of the honeycomb structure body, and cells which are formed at an outermost circumference of the honeycomb structure body and in which peripheries of the cells are defined by the partition walls without any lacks are defined as outermost circumference complete cells, and in a cross section of the honeycomb structure body which is perpendicular to an extending direction of the cells a minimum distance T (mm) among distances from the outermost circumference complete cells to the surface of the circumferential coating layer and a porosity P (%) of the circumferential coating layer satisfy relations of Equation (1) and Equation (2) as follows:
1.5T16(100P).sup.1.4; andEquation (1):
20P75Equation (2).

Honeycomb bodies and methods for treating a honeycomb bodies that include a skin surrounding a matrix of cells, the skin and the matrix of cells comprising a porous inorganic material. Methods include applying a buffer solution to only the porous inorganic material of the skin and coating the porous inorganic material of the skin with an oxide slurry. The oxide slurry includes an oxide or a precursor of the oxide configured to increase the isostatic strength of the honeycomb body. After treatment, the honeycomb body may be dried.

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 honeycomb structure includes a honeycomb substrate having a porous partition wall that defines a plurality of cells that extend from an inlet end face as an inlet side for a fluid to an outlet end face as an outlet side for the fluid, and a porous circumferential wall that is monolithically formed with the partition wall, and a coat layer that is disposed on at least a part of the outer surface of the circumferential wall. Here, a part of the coat layer penetrates into the pores of the circumferential wall, and a thickness of the part of the coat layer that penetrates into the pores of the circumferential wall is from 1 to 90% of the thickness of the circumferential wall.

An exhaust system includes an exhaust gas treatment article having a porous ceramic honeycomb body mounted in a housing. The exhaust gas treatment article includes a thermal barrier disposed at the outer peripheral surface of the honeycomb body, wherein the thermal barrier comprises blocked peripheral cell channels adjacent to and around the entire peripheral surface and/or a thermal barrier skin.

A method to form a laminar integral skin of a honeycomb structure is provided. The method includes extruding a ceramic precursor batch through a die with feedholes in entry side and slots in exit face of the die to form the honeycomb structure. In a region on the periphery of the die configured to form the cell matrix, a series of concentric slots around the matrix in the exit face of the die are configured to feed skin onto the matrix. Ring sections between concentric slots are angled away from the center and a mask is disposed on top of the periphery producing a channel for extruded skin to meet and bond to extruded matrix. Optionally, slots in the skin-forming ring sections enhance knitting between laminar skin layers. The die and honeycomb body having uniform integral skin are also provided.

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 circumferential coating material to be applied to a circumferential surface of a honeycomb structure made of ceramics formed by extrusion, the circumferential coating material including a ceramic raw material that forms a circumferential coating layer, wherein the ceramic raw material contains: a ceramic mixture of first ceramic particles having particulate shapes, and second ceramic particles having particulate shapes and an average particle diameter different from an average particle diameter of the first ceramic particles; and a fiber material having an elongated strip-like shape, wherein the ceramic mixture has particle size distribution including at least two local maximum values, and the fiber material has an average fiber length ranging from 30 to 100 m in a longitudinal direction.