The honeycomb filter of the present invention includes a honeycomb fired body that includes multiple cells serving as channels of exhaust gas; and porous cell partition walls defining the cells, the cells including exhaust gas introduction cells whose ends on an exhaust gas inlet side are open and whose ends on an exhaust gas outlet side are plugged, and exhaust gas emission cells whose ends on the exhaust gas outlet side are open and whose ends on the exhaust gas inlet side are plugged, wherein the honeycomb fired body contains ceria-zirconia composite oxide particles and alumina particles, when the pore size of the cell partition walls of the honeycomb fired body is measured by mercury porosimetry, and the measurement results are presented as a pore size distribution curve with pore size (μm) on the horizontal axis and log differential pore volume (mL/g) on the vertical axis, the volume of micropores having a pore size of 1 to 100 μm accounts for 80 vol % or more of the total pore volume, and a value obtained by dividing the half width (μm) of the maximum peak in the pore size range of 1 to 100 μm by the mode size (μm) is 0.5 or less.

Method of identifying a valid flow path includes: performing fluid analysis of a porous body, which is ought to have inflow surface and outflow surface, based on structure data representing a 3-dimentional structure of the porous body to generate data indicating at least a pressure distribution of a fluid in a flow path in the porous body; and identifying a valid flow path that allows the fluid to flow from the inflow surface to the outflow surface based on a gradient of pressure values along a flow direction of the fluid in the flow path.

Method of identifying a valid flow path includes: performing fluid analysis of a porous body, which is ought to have inflow surface and outflow surface, based on structure data representing a 3-dimentional structure of the porous body to generate data indicating at least a pressure distribution of a fluid in a flow path in the porous body; and identifying a valid flow path that allows the fluid to flow from the inflow surface to the outflow surface based on a gradient of pressure values along a flow direction of the fluid in the flow path.

A honeycomb structure according to at least one embodiment of the present invention includes: partition walls defining cells each extending from a first end surface of the honeycomb structure to a second end surface thereof to form a fluid flow path; and an outer peripheral wall. The partition walls and the outer peripheral wall are each formed of ceramics containing silicon carbide and silicon. A surface of the silicon has formed thereon an oxide film having a thickness of from 0.1 μm to 5.0 μm.

A honeycomb structure according to at least one embodiment of the present invention includes: partition walls defining cells each extending from a first end surface of the honeycomb structure to a second end surface thereof to form a fluid flow path; and an outer peripheral wall. The partition walls and the outer peripheral wall are each formed of ceramics containing silicon carbide and silicon. A surface of the silicon has formed thereon an oxide film having a thickness of from 0.1 μm to 5.0 μm.

A porous honeycomb structure including cordierite, having a plurality of cell channels which pass through an interior of the porous honeycomb structure and are partitioned by porous partition walls, wherein the porous partition walls have a porosity of 45 to 60% as measured by a mercury intrusion method, wherein in a volume-based cumulative pore diameter distribution measured by the mercury intrusion method, the porous partition walls have a cumulative 10% pore diameter (D10) and a cumulative 50% pore diameter (D50) calculated from a small pore side, and satisfy a relationship of 0.45≤(D50−D10)/D50, and 3 μm≤D50≤10 μm.

A separator element comprising a porous rigid single-piece substrate (2) presenting firstly, at its periphery, a perimeter wall (2.sub.1) that is continuous between an inlet (4) for the fluid medium for treatment at one end of the porous substrate and an outlet (5) for the retentate at the other end of the porous substrate, and secondly, internally, a surface covered by a separator layer (6) and defining an open structure made up of empty spaces (3) for passing a flow of the fluid medium for treatment. The empty spaces (3) are arranged in the porous substrate so as to create within the porous substrate a first flow network (R1) for the fluid medium for treatment, having at least two interconnected flow circuits (R1.sub.1, R1.sub.2) for the fluid medium between the inlet (4) and the outlet (5) of the porous substrate.

Disclosed are a honeycomb structure body, a honeycomb structure filter and an extrusion molding die for a honeycomb structure body, which belong to the field of vehicle exhaust purification materials. The honeycomb structure body includes a honeycomb body and a skin layer around the honeycomb body, the honeycomb body including axially-extending channels defined by a porous wall, wherein a radial path of a radial section of the honeycomb body from a central axis to the skin layer consists of a porous wall inner section and a porous wall outer section in sequence, an average wall thickness of inner porous walls provided in the porous wall inner section is smaller than an average wall thickness of outer porous walls provided in the porous wall outer section, and a length of the porous wall inner section in the radial path accounts for 71%-95%. The arrangement of the specific structure of the honeycomb structure body of the present application not only increases the strength of the honeycomb structure body, but also ensures good thermal shock resistance and small back pressure of the honeycomb structure body; and the honeycomb structure body of the present application is prepared by integral molding, thereby achieving high production efficiency and low preparation cost.

Disclosed are a honeycomb structure body, a honeycomb structure filter and an extrusion molding die for a honeycomb structure body, which belong to the field of vehicle exhaust purification materials. The honeycomb structure body includes a honeycomb body and a skin layer around the honeycomb body, the honeycomb body including axially-extending channels defined by a porous wall, wherein a radial path of a radial section of the honeycomb body from a central axis to the skin layer consists of a porous wall inner section and a porous wall outer section in sequence, an average wall thickness of inner porous walls provided in the porous wall inner section is smaller than an average wall thickness of outer porous walls provided in the porous wall outer section, and a length of the porous wall inner section in the radial path accounts for 71%-95%. The arrangement of the specific structure of the honeycomb structure body of the present application not only increases the strength of the honeycomb structure body, but also ensures good thermal shock resistance and small back pressure of the honeycomb structure body; and the honeycomb structure body of the present application is prepared by integral molding, thereby achieving high production efficiency and low preparation cost.

A honeycomb filter includes a pillar-shaped honeycomb structure having porous partition walls provided, surrounding a plurality of cells which serve as fluid through channels extending from an inflow end face to an outflow end face, and porous plugging portions provided either at the ends on the inflow end face or the outflow end face of the cells, wherein the plugging portions are composed of a porous material, the honeycomb structure has a central region and a circumferential region, and a ratio of an area of the circumferential region with respect to that of the central region ranges from 0.1 to 0.5, a plugging length L1 in the cell extending direction of a central plugging portion in the central region is larger than a plugging length L2 of a circumferential plugging portion in the circumferential region, L1 ranges from 7 to 9 mm, and L2 from 3 to 6 mm.