An object of the present invention is to provide a honeycomb filter having low pressure loss and high collection efficiency. The honeycomb filter of the present invention 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 filter layer comprises spherical ceramic particles, and the average particle size of the spherical ceramic particles increases gradually from the fluid inlet side toward the fluid outlet side.

Methods for producing porous carbon product utilize template material in the form of template particles containing macropores and a polymerizable carbon precursor substance. The macropores of the template are infiltrated with the precursor substance in dissolved or melted form. After carbonization of the infiltrated precursor substance, the template is removed to form the porous carbon product. In order to obtain a carbon structure with hierarchical porosity having a high fraction of mesopores having pore sizes in the range of 2 to 50 nm, after the infiltration and before carbonization, the precursor substance within the macropores of the template is subjected to a treatment at a foaming temperature at which the precursor substance foams under polycondensation and fills the macropores as substantially mesoporous foam, in which at least 70% of the pores have pore sizes in the range of 10 to 150 nm.

A honeycomb structure includes a honeycomb structure body having a partition wall which is constituted of a porous body. The porous body includes a refractory aggregate and a bonding material. The porous body constituting includes the bonding material at a mass proportion of 20 to 35 mass %. In an observation of a cross section of the partition wall with an electron microscope, when observing any given ten visual fields meeting a following condition (1), the number of refractory aggregates meeting a following condition (2) is five pieces or more in all of the ten visual fields. Condition (1): a proportion of an area occupied by the bonding material is 30% or more. Condition (2): the refractory aggregate has a particle diameter of 5 μm or more, and 60% or more of an outer circumference of the refractory aggregate is surrounded by the bonding material.

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):

A vehicular exhaust filter (2) comprising a porous substrate having an inlet face and an outlet face with the porous substrate comprising inlet channels extending from the inlet face and outlet channels extending from the outlet face is disclosed. The inlet channels and the outlet channels are separated by a plurality of filter walls having a porous structure. The vehicular exhaust filter (2) is loaded with a refractory powder having a tapped density before loading of less than 0.10 g/cm.sup.3 and the vehicular exhaust filter has a mass loading of the refractory powder of less than 10 g/l.

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.

A porous ceramic laminate, which can reduce pressure loss of a fluid, includes a first porous layer and a second porous layer. The second porous layer is laminated on, in contact with or via air, the first porous layer. A part of the second porous layer is laminated on, in contact with, the first porous layer. Each of the first porous layer and the second porous layer contains a metal oxide. A ratio Da/Db of an average pore diameter Da of the first porous layer relative to an average pore diameter Db of the second porous layer is 10 or more. A proportion of a portion in which a distance between the first porous layer and the second porous layer is smaller than 1 μm is 70% or less.

A pillar shaped honeycomb structure, including: an outer peripheral wall; and a porous partition wall disposed inside the outer peripheral wall, the a porous partition wall defining a plurality of cells, each of the cells extending from one end face to other end face to form a flow path, wherein a surface of the porous partition wall in the cells comprise a collecting layer having an average pore diameter lower than that of the porous partition wall; and wherein magnetic particles having a Curie point of 700° C. or higher are provided either or both between the surfaces of the porous partition wall and the collecting layer, and on the collecting layer.

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.