An exhaust gas filter purifies exhaust gas containing particulate matter emitted from an engine. The filter has cell walls and cells surrounded by the cell walls. Through pores formed in the cell walls, adjacent cells are communicated. The cells have open cells opening along an axial direction of the filter, and plugged cells. An upstream end part of the plugged cell is plugged by a plug member. On a cross section perpendicular to the axial direction, a flow-passage sectional area of the plugged cells is larger than a flow-passage sectional area of the open cells. A total length of the filter is not less than a first standard value and is not more than a critical length Lm determined by respective predetermined equations.

A honeycomb structure includes: a honeycomb structure body; and a convex part that protrudes outward from a part of circumference of the honeycomb structure body. The convex part surrounds the circumference of the honeycomb structure body like a ring. The convex part is of a tapered shape at least at one end having a tapered face. The convex part has a circumference coating layer making up the tapered face. The convex part has a maximum thickness of 1 to 20 mm, and a rough-face region on the tapered face, the rough-face region having surface roughness of 5 to 70 m. The rough-face region has a total of a rough-face region angle of 108 or more. An inclination angle formed between the tapered face and the extending direction of the cells is 10 to 80 degrees.

Disclosed is a honeycomb filter for collecting fine particles that includes a wall portion formed from a base material containing ceria-zirconia composite oxide and an inorganic binder. The wall portion has a gas permeability coefficient of 1.0 m.sup.2 or greater and 3.0 m.sup.2 or less.

A method of making SiC nanowires comprising: (a) mixing silicon powder with a carbon-containing biopolymer and a catalyst at room temperature to form a mixture; and (b) heating said mixture to a pyrolyzing temperature sufficient to react said biopolymer and said silicon power to form SiC nanowires.

A monolithic separation membrane structure comprises a porous monolithic substrate and a separation membrane. The monolithic substrate includes a first end surface, a second end surface and a plurality of through-holes respectively passing from the first end surface to the second end surface. The separation membrane is formed on an inner surface of the respective plurality of through-holes. The surface roughness Ra of the separation membrane is no more than 1 micrometer and the thickness of the separation membrane is no more than 5 micrometers.

The present invention is directed to a wall-flow filter. Said wall-flow filter contains a powder coating which increases the filtration efficiency only in the fresh state. An exhaust gas system comprising such a wall-flow filter is also claimed.

A honeycomb structure includes a pillar-shaped honeycomb structure body including porous partition walls defining and forming a plurality of cells which extend from an inflow end face to an outflow end face, and a porous outer wall surrounding the partition walls, a porous supporting bulge disposed to extend out from a circumference of the outer wall so that at least a part of the outer wall is exposed, and plugging portions arranged in open ends of the cells, and the supporting bulge has support portions and a side wall portion, and the partition walls and the outer wall of the honeycomb structure body and the support portions and the side wall portion of the supporting bulge are all formed monolithically by formation of a ceramic raw material.

Described herein is a cordierite membrane coated on a monolith substrate formed from cordierite. The membrane coating is formed from cordierite particles which have been processed to have a median particle size diameter of between 1 and 3 microns with a narrow particle size distribution suitable for forming a cordierite membrane on a cordierite monolith substrate. After the cordierite membrane is formed on the cordierite monolith substrate, the cordierite membrane monolith has a pore size of less than 1 micron.

A honeycomb structure includes a cordierite component, and has partition walls defining a plurality of cells which extend from one end face to the other end face and form through channels for a fluid, a thermal expansion coefficient in a central axis direction is 1.2 ppm/K or more and 3.5 ppm/K or less in a temperature change of 40 C. to 800 C., and a thermal expansion coefficient in a cross-sectional direction orthogonal to the central axis direction is 0.8 ppm/K or more and 2.5 ppm/K or less in the temperature range of 40 C. to 800 C.

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 m, a median pore diameter greater than or equal to about 10 m, a d.sub.f less than or equal to about 0.45, where d.sub.f=(d.sub.50d.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 m and at least one starch-based pore former having a median particle diameter greater than or equal to about 10 m. 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.