The present invention is directed to a porous pre-densified CeO.sub.2-stabilized ZrO.sub.2 ceramic having a density of 50.0 to 95.0%, relative to the theoretical density of zirconia, and an open porosity of 5 to 50% as well as to a densified CeO.sub.2-stabilized ZrO.sub.2 ceramic having a density of 97.0 to 100.0%, relative to the theoretical density of zirconia, and wherein the grains of the ceramic have an average grain size of 50 to 1000 nm, methods for the preparation of the pre-densified and densified ceramics and their use for the manufacture of dental restorations.

A honeycomb filter includes a pillar-shaped honeycomb structure body having a porous partition wall disposed to surround a plurality of cells which serve as fluid through channels 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 is composed of a material containing cordierite as a main component thereof, and a number per unit area of pores which exist at a surface of the partition wall and which have equivalent circle diameters exceeding 3.0 μm is 600 per mm.sup.2 or more.

A honeycomb filter includes a pillar-shaped honeycomb structure body having a porous partition wall disposed to surround a plurality of cells which serve as fluid through channels 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 is composed of a material containing cordierite as a main component thereof, and a number per unit area of pores which exist at a surface of the partition wall and which have equivalent circle diameters exceeding 3.0 μm is 600 per mm.sup.2 or more.

A manufacturing method of a honeycomb filter includes a kneaded material preparation process, a forming process, and a firing process, wherein the cordierite forming raw material contains porous silica as an inorganic pore former, in a cumulative particle size distribution of the cordierite forming raw material, particle diameters (μm) of 10% by volume, 50% by volume, and 90% by volume of the total volume from a small diameter side, are denoted by D.sub.(a) 10, D.sub.(a) 50 and D.sub.(a) 90, respectively, and a particle diameter (μm) of 50% by volume of the total volume from the small diameter side is denoted by D.sub.(b) 50 in a cumulative particle size distribution of the organic pore former, and the cordierite forming raw material and the organic pore former satisfy given expressions.

A manufacturing method of a honeycomb filter includes a kneaded material preparation process, a forming process, and a firing process, wherein the cordierite forming raw material contains porous silica as an inorganic pore former, in a cumulative particle size distribution of the cordierite forming raw material, particle diameters (μm) of 10% by volume, 50% by volume, and 90% by volume of the total volume from a small diameter side, are denoted by D.sub.(a) 10, D.sub.(a) 50 and D.sub.(a) 90, respectively, and a particle diameter (μm) of 50% by volume of the total volume from the small diameter side is denoted by D.sub.(b) 50 in a cumulative particle size distribution of the organic pore former, and the cordierite forming raw material and the organic pore former satisfy given expressions.

An apparatus contains at least one pressure-rated apparatus shell and at least one modular framework system containing ceramic fiber composite materials and arranged within the apparatus shell. A modular lining apparatus includes the modular framework system and. refractory bricks. The apparatus can be used for high-temperature reactors, especially electrically heated high-temperature reactors.

An apparatus contains at least one pressure-rated apparatus shell and at least one modular framework system containing ceramic fiber composite materials and arranged within the apparatus shell. A modular lining apparatus includes the modular framework system and. refractory bricks. The apparatus can be used for high-temperature reactors, especially electrically heated high-temperature reactors.

A method includes forming a ceramic member that has a plurality of closed pores within a ceramic matrix. The forming includes compacting a ceramic powder to form intra-particle pores between particles of the ceramic powder, and sintering the compacted ceramic powder to cause diffusion of the ceramic powder and formation of the ceramic matrix. The diffusion does not fill the intra-particle pores and leaves the closed pores.

A method includes forming a ceramic member that has a plurality of closed pores within a ceramic matrix. The forming includes compacting a ceramic powder to form intra-particle pores between particles of the ceramic powder, and sintering the compacted ceramic powder to cause diffusion of the ceramic powder and formation of the ceramic matrix. The diffusion does not fill the intra-particle pores and leaves the closed pores.

The present invention relates to an agglomerate abrasive grain made up of a plurality of individual abrasive grains which are bonded into an inorganic or organic binder matrix, wherein, based on the total weight of the agglomerate abrasive grain, at least 8% by weight of the abrasive grains which are bonded into the matrix are fused alumina-based polycrystalline alumina abrasive grains with a percentage of more than 97% by weight of alpha-alumina, and wherein the polycrystalline alumina abrasive grains, in turn, are made up of a plurality of Al.sub.2O.sub.3 primary crystals with a crystal size of between 20 μm and 100 μm. The agglomerate abrasive grain has a closed macroporosity with a pore volume of between 5% by volume and 30% by volume, wherein the average pore diameter of the closed macropores is between 10 μm and 100 μm and their maximum pore diameter is in the range of approx. 120 μm.