An object of the present invention is to provide a honeycomb filter capable of achieving a combination of high collection efficiency and low pressure loss. The honeycomb filter comprises a ceramic honeycomb substrate in which a multitude of cells through which a fluid flows are disposed in parallel in a longitudinal direction and are separated by cell walls, each cell being sealed at an end section at either the fluid inlet side or the fluid outlet side, and a filter layer which, among the surfaces of the cell walls, is formed on the surface of the cell walls of those cells in which the end section at the fluid inlet side is open and the end section at the fluid outlet side is sealed by a sealing material, wherein the thickness of the filter layer increases gradually from the fluid inlet side toward the fluid outlet side.

A thermal shock resistant and asymmetric honeycomb ceramic wall-flow filter includes an inlet honeycomb ceramic surface and an outlet honeycomb ceramic surface. Inlet channels and outlet channels are provided on both the inlet honeycomb ceramic surface and the outlet honeycomb ceramic surface. The inlet channels are in communication with the outlet channels. Outlet ends of the inlet channels and inlet ends of the outlet channels are sealed. An inner diameter of the inlet channel is greater than that of the outlet channel. A cross-section of the inlet channel is a square, or two adjacent edges are connected by two connecting lines, or two adjacent edges are connected by two connecting lines or a circular arc located between the two connecting lines. The filter has good mechanical properties, low back pressure, and excellent thermal shock resistance.

Provided is a particulate filter in which a PM collection rate is stably increased. The particulate filter according to the present invention includes a substrate 10 having a wall flow structure having a porous partition wall 16 that partitions an inlet cell and an outlet cell, and a wash coat layer held on surfaces of internal pores of the partition wall. In addition, average filling rates A, B, and C of the wash coat layer measured for each predetermined pore diameter range in the internal pores satisfy specific relationships. Further, the wash coat layer is formed in a region that occupies 50% or more of a thickness of the partition wall, and an amount of a noble metal catalyst carried by the wash coat layer is 0 g/L or more but 0.2 g/L or less.

An exhaust gas purification filter that is suitable for arrangement in an exhaust passage of an internal combustion engine and for collecting particulate matter contained in exhaust gas, comprises: exhaust gas inflow passages and exhaust gas outflow passages that are arranged alternately; and porous partitions that separate the exhaust gas inflow passages and the exhaust gas outflow passages from each other. Each of the partitions is divided into a coated zone in which a surface of a partition base is coated with a coating layer having a smaller average pore diameter than an average pore diameter of the partition base and a non-coated zone that is located on a downstream side of the coated zone and in which a surface of the partition base is not coated with the coating layer.

A partial wall-flow filter has an inlet end, an outlet end, and a plurality of parallel channels disposed and configured to flow fluid from the inlet end to the outlet end. The channels are defined by a plurality of porous walls. A first portion of the channels have a first hydraulic diameter Dh1, a second portion of the channels have a second hydraulic diameter Dh2 smaller than the first hydraulic diameter Dh1, and the ratio of Dh1:Dh2 is in the range of 1.1 to 1.6. At least a portion of channels having hydraulic diameter Dh1 are plugged at the outlet end, and channels having hydraulic diameter Dh2 are flow-through channels.

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:

1.5≧T≧16×(100−P).sup.−1.4; and  Equation (1):

20≦P≦75.  Equation (2):

The invention relates to a wall-flow filter, to a method for the production and the use of the filter for reducing harmful exhaust gases of an internal combustion engine. The wall-flow filter was produced by exposing the filter at least twice successively to a powder-gas aerosol.

To provide an exhaust gas purification filter having a high capability of collecting particulate matter. The exhaust gas purification filter includes a filter base material having a wall flow structure and an exhaust gas purification catalyst. A wash coating amount of the exhaust gas purification catalyst ranges from 60 to 110 g/L or less. When the exhaust gas purification filter is divided into an upstream part, a middle part, and a downstream part, and average values of catalyst area ratios of the exhaust gas purification catalyst supported by surfaces of the partition walls are acquired at predetermined locations in cells on an inflow side and cells on an outflow side, a minimum value, among the average values, is 28% or greater. A maximum value, among sizes of pores in the partition walls after the exhaust gas purification catalyst is supported, is 14.6 μm or less.

A particulate filter having a porous ceramic honeycomb structure with a first end, a second end, and a plurality of walls having wall surfaces defining a plurality of inner channels. Filtration material deposits are disposed on one or more of the wall surfaces of the honeycomb body. The highly porous deposits provide durable high clean filtration efficiency with small impact on pressure drop through the filter.

electrically conductive honeycomb body that includes a porous honeycomb structure including a plurality of intersecting porous walls arranged to provide a matrix of cells, the porous walls including wall surfaces that define a plurality of channels extending from an inlet end to an outlet end of the structure. The porous walls include ceramic composite material that includes at least one carbide phase and at least one silicide phase, each carbide and silicide phase including one or more metals selected from the group consisting of Si, Mo, Ti, Zr and W.