In one aspect, a material structure is disclosed, which includes a macroscopic porous substrate configured to receive a flow of a medium for passage of at least a portion thereof through the porous substrate. At least one porous coating is disposed on at least a portion of an inner surface of the porous substrate, wherein the porous coating comprises a matrix having a plurality of interconnected passages. The porous substrate and the coating are configured to treat at least one contaminant, if any, present in the flowing medium.

In a porous composite, a base material has a honeycomb structure whose inside is partitioned into a plurality of cells. In the plurality of cells, a plurality of first cells whose one ends in the longitudinal direction are sealed, and a plurality of second cells whose other ends in the longitudinal direction are sealed are arranged alternately. A collection layer covers inner surfaces of the plurality of first cells. An overall Sa that is an arithmetical mean height Sa indicating a surface roughness of a surface of the collection layer in the plurality of first cells is greater than or equal to 0.1 μm and less than or equal to 12 μm. An overall mean thickness that is a mean thickness of the collection layer in the plurality of first cells is greater than or equal to 10 μm and less than or equal to 40 μm.

A honeycomb filter includes a pillar-shaped honeycomb substrate having a porous partition wall disposed so as to surround a plurality of cells serving as a fluid through channel extending from a first end face to a second end face; and a plugging portion provided at an open end on the first end face side or the second end face side of each of the cells, wherein the partition wall constituting the honeycomb substrate is composed of a ceramic porous material, a ratio of a volume of pores having a pore diameter of 10 μm or less with respect to a total pore volume of the partition wall measured by a mercury press-in method is 85 to 95%, and an average pore diameter of the partition wall measured by the mercury press-in method is 4 to 10 μm.

A ceramic honeycomb filter has (a) cross section areas of intake flow paths being larger than those of discharge flow paths; (b) the intake and discharge flow paths having octagonal cross section shapes with four-fold rotation symmetry each obtained by cutting off four corners from a square; (c) the intake and discharge flow paths being alternately arranged in a first direction and a second direction perpendicular to the first direction, such that their opposing sides are parallel; (d) the opening ratio of the intake flow paths being 45-60%; (e) the number of the flow paths per cm.sup.2 being 30-60; (f) the thickness t1 of a cell wall between an intake flow path and a discharge flow path adjacent to that intake flow path being 0.150-0.260 mm; and (g) the thickness t2 of a cell wall between adjacent intake flow paths meeting 1.175<t2/t1<1.6.

A honeycomb structure has a plurality of cells formed by a plurality of partition walls. The partition walls are formed of a porous material composed predominantly of cordierite. Each partition wall includes surface layer portions having a porosity of 50% or more and an inside portion having a porosity of 50% or more, the surface layer portions being portions ranging respectively from opposite surfaces to a depth corresponding to 25% of the thickness of the partition wall, and the inside portion being the other portion. The surface layer portions and the inside portion both include pores having axial pore widths of less than 30 μm and pores having axial pore widths of 30 μm or more. A mean axial pore width in the surface layer portions is smaller than a mean axial pore width in the inside portion.

Ceramic honeycomb bodies and methods for then manufacture are provided. The ceramic honeycomb body comprises a bulk density of less than 210 g/L, a geometric surface area (GSA) greater than 93 in.sup.−1 (3.66 mm.sup.−1), a mechanical integrity factor (MIF) greater than 0.28%, and a back pressure factor (BPF) greater than 0.4 mm.sup.2.

An exhaust gas purification filter includes a plurality of cells extending in a filter axial direction, a porous partition separating and defining the plurality of cells, and a sealing section sealing the plurality of cells alternately at both filter ends. The partition has a void volume of a reduced dale, Vvv, and a material volume of a reduced peak, Vmp, as volume parameters determined in noncontact surface roughness measurement on a surface of the partition, with their total value being more than 1.3 μm.sup.3/μm.sup.2 and 1.7 μm.sup.3/μm.sup.2 or less. The partition has a mean pore size of 12 μm or more and 20 μm or less. The partition also has a porosity of 50% or more and 75% or less.

The present invention provides an exhaust purification filter with which pressure loss can be reduced, the filter having high exhaust purification performance and granular-substance-filtering performance. The exhaust purification filter comprises a filter base material having a wall flow structure, and an exhaust purification catalyst supported on a dividing wall of the filter base material, the exhaust purification filter being such that: a median pore diameter (D50) of the filter base material according to a volumetric basis is 15 μm or greater; and the exhaust purification catalyst is unevenly supported on a high-density layer, in which the density of the exhaust purification catalyst is relatively high, and a low-density layer, in which the density of the exhaust purification catalyst is relatively low.

A ceramic honeycomb structure having a web structure including a plurality of intersecting channel walls forming channels. The ceramic honeycomb structure has a total porosity greater than or equal to about 55%, an average channel wall thickness less than or equal to about 150 μm, a median pore diameter greater than or equal to about 10 μm, a d.sub.f less than or equal to about 0.45, where d.sub.f=(d.sub.50−d.sub.10)/d.sub.50, and a strength (MOR/CFA) greater than or equal to about 900 psi. A method of manufacturing a ceramic honeycomb structure by mixing a ceramic precursor batch composition having a median particle diameter less than or equal to about 10 μm and at least one starch-based pore former having a median particle diameter greater than or equal to about 10 μm. The method also includes forming a mixture of ceramic precursor batch composition and a starch-based pore former into a green ceramic structure having a web structure, and firing the green ceramic structure to yield a ceramic honeycomb structure.

An exhaust gas purification filter includes a cell assembly including cells each having a quadrangular cross-sectional shape and a partition wall, seal members, and a skin member. The partition wall has a porosity P1 of 50% to 70%, and the skin member has a porosity P2 of 50% to 70%, the porosity P1 and the porosity P2 satisfy a relationship P1<P2. A difference between the porosity P2 and the porosity P1 is 20% or less. 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 is rounded to have a radius of curvature R, each cell has a radius r of a hydraulic diameter, the radius of curvature R and the radius r of the hydraulic diameter satisfy a relationship 0.2<R [mm]/r [mm]<1.