An exhaust gas purification filter is used so as to support a NO.sub.X purification catalyst. The exhaust gas purification filter includes a honeycomb structure portion and a plug portion. The honeycomb structure portion includes a partition wall and cells. Numerous pores are formed in the partition wall. The cells are partitioned by the partition walls and form a flow path for an exhaust gas. The plug portion alternately seals an inflow end surface or an outflow end surface for the exhaust gas in the cells. The partition wall has a gas permeability coefficient that is equal to or greater than 0.35×10.sup.−12 m.sup.2, a pore volume ratio of pore diameters of 9 μm or less that is equal to or less than 25%, and an average pore diameter that is equal to or greater than 12 μm.

A honeycomb structure includes a pillar-shaped honeycomb structure body having a porous partition wall so as to surround a plurality of cells extending from a first end face to a second end face, and a circumferential coating layer composed of a circumferential coating material coated on at least a part of circumference of the honeycomb structure body, wherein the circumferential coating layer has a printing area for printing on the surface thereof, the printing area has a lightness (L*) in L*a*b* color space (CIE1976) defined by International Commission on Illumination (CIE) of 35 or more, and the printing area has a surface roughness Ra of 30 μm or less.

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 μm in a longitudinal direction.

A pillar-shaped honeycomb structure including an outer peripheral side wall, a plurality of first cells provided on an inner peripheral side of the outer peripheral side wall, the first cells extending from a first end surface to a second end surface, each opening on the first end surface and having a sealing portion with an average void ratio of 4% or less on the second end surface, and a plurality of second cells provided on the inner peripheral side of the outer peripheral side wall, the second cells extending from the first end surface to the second end surface, each having a sealing portion with an average void ratio of 4% or less on the first end surface and opening on the second end surface, the first cells and the second cells being alternately arranged adjacent to each other with a partition wall interposed therebetween.

A honeycomb structure comprising a pillar-shaped honeycomb structure body having a porous partition wall disposed so as to surround a plurality of cells, wherein let that A denotes an absolute value of open frontal area (%) in a plane of the honeycomb structure body orthogonal to the extending direction of the cells and P denotes an absolute value of porosity (%) of the partition wall, the honeycomb structure has a value represented by the following expression (1) that is 0.05 to 0.12, let that D denotes an average pore diameter (m) of the partition wall and G denotes a geometric surface area (mm.sup.2/mm.sup.3) of the partition wall, the honeycomb structure has a value represented by the following expression (2) that is 8 to 50 (μm×mm.sup.2/mm.sup.3), and the honeycomb structure has a hydraulic diameter of the cells that is 1.1 mm or more,

(1−A/100)×(1−P/100),  Expression (1)

D×G.  Expression (2)

Provided is an exhaust gas purification device that ensures an improved purification performance and a suppressed pressure loss. An exhaust gas purification device of the present disclosure includes a honeycomb substrate and an inflow cell side catalyst layer. disposed on a surface on the inflow cell side in an inflow side region of the partition wall. When a gas permeability coefficient of an inflow side partition wall portion including the inflow side region of the partition wall and the inflow cell side catalyst layer is Ka and a gas permeability coefficient of an outflow side partition wall portion including an outflow side region at least from the predetermined position to an outflow side end of the partition wall is Kb, a ratio Ka/Kb of the gas permeability coefficients is within a range of 0.4 or more and 0.8 or less.

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.

The present disclosure relates to porous ceramic articles and a method of making the same. The porous ceramic articles have a porosity (P) as a fraction in a range of about 0.3 to about 0.7; a permeability factor PQ>0.025, wherein PQ is (K.sub.bulk)/(P.Math.d.sub.50.sup.2), K.sub.bulk being bulk permeability in Darcy, and d.sub.50 being the mean pore size in micrometers (m); a tortuosity in a range of about 1.8 to 3; and a median pore size diameter d.sub.50 in a range of about 10 m to about 35 m. The porous ceramic articles can have an interconnected bead microstructure comprising beads and bead connections, PQ is directly proportional to bead size, and wherein in a random cross section through the body, the beads appear as globular portions.

A joining material used for joining side surfaces of a plurality of silicon carbide-based honeycomb segments to each other to produce a silicon carbide-based honeycomb structure. The joining material contains from 0.1 to 50% by mass of processed powder generated in the production of the silicon carbide-based honeycomb segments and/or the silicon carbide-based honeycomb structure. The joining material has an average particle diameter D50 of from 0.5 to 60 m.

A honeycomb structure including a plurality of porous honeycomb block bodies bound via joining material layers A. Each of the porous honeycomb block bodies includes a plurality of porous honeycomb segments bound via joining material layers B, each of the porous honeycomb segment includes: partition walls that defines a plurality of cells to form flow paths for a fluid, each of cells extending from an inflow end face that is an end face on a fluid inflow side to an outflow end face that is an end face on a fluid outflow side; and an outer peripheral wall located at the outermost periphery. At least a part of the joining material layers A has higher toughness than that of the joining material layers B.