Abstract: A method for producing a silicon nitride filter, which comprises subjecting a molded product comprising from 35 to 58 mass % of metal silicon particles, from 30 to 62.5 mass % of organic polymer particles, from 0.3 to 10 mass % based on the content of the organic polymer particles of the following inorganic particles A and from 1 to 15 mass % based on the content of the metal silicon particles of the following inorganic particles B, to a heat treatment in nitrogen to substantially convert metal silicon into silicon nitride: inorganic particles A: inorganic particles of at least one member selected from the group consisting of an oxide, a hydroxide and a salt of an element selected from the group consisting of Si, Ti and Ce; inorganic particles B: inorganic particles of at least one member selected from the group consisting of an oxide, a hydroxide and a salt of an element selected from the group consisting of Mg, Y, La, Nd, Yb, Ca and Fe.

Abstract: A method for producing a silicon nitride honeycomb filter, which comprises heat-treating in a nitrogen atmosphere a green body comprising from 50 to 85 mass % of metal silicon particles having an average particle diameter of from 5 to 50 ?m, from 5 to 30 mass % of glass hollow particles having a softening temperature of from 400 to 1000° C. and from 10 to 20 mass % of an organic binder to convert metal silicon substantially to silicon nitride.

Abstract: A method for producing a silicon nitride filter, which comprises heat-treating in nitrogen a green body comprising from 60 to 95 mass % of metal silicon particles having an average particle diameter of from 10 to 75 ?m, wherein particles having particle diameters of from 5 to 100 ?m are at least 70 mass % in the entire metal silicon particles, and from 5 to 40 mass % of a pore-forming agent, to convert metal silicon substantially to silicon nitride. More preferably, the green body contains at least one member selected from the group consisting of an inorganic acid salt, an organic acid salt and a hydroxide containing at least one metal element selected from the group consisting of Mg, Ca, Fe and Cu.

Abstract: A method for producing a silicon nitride filter including heat-treating in nitrogen a green body containing from 40 to 90% of metal silicon particles having an average particle diameter of from 1 to 200 ?m and from 10 to 60% of a pore-forming agent, where the total amount of the metal silicon particles and the pore-forming agent is at least 90%, forms a porous product made substantially of silicon nitride.

Abstract: A silicon nitride porous body which is a body having a generally columnar outer shape and at least two through-holes mutually parallel to one another and which has generally perpendicularly oriented columnar crystals on the surface of the through-holes.

Abstract: A method for the production of a silicon nitride filter includes heat treating in nitrogen a green body containing from 40 to 90% of metal silicon particles having an average particle size of from 1 to 200 &mgr;m and from 10 to 60% of a pore forming agent. The green body contains at least 90% of the metal silicon particles and the pore forming agent and forms a porous product. The filter is excellent in heat resistance, corrosion resistance, acid resistance and mechanical strength and suitable for dust arresting or dust removing and is particularly suitable as a filter for particulates. The porosity of the silicon nitride filter is from 40 to 70% and the cumulative pore volume of pores with diameters of at most 1 &mgr;m is from 1 to 15 vol % of the total pore volume.

Abstract: The present invention provides a silicon nitride filter which is a filter excellent in heat resistance, thermal shock resistance, corrosion resistance, acid resistance and mechanical strength and suitable for dust arresting or dust removing, and which is particularly useful as a filer for particulates, and a method for its production.

Abstract: The present invention provides a silicon nitride filter which is a filter excellent in heat resistance, thermal shock resistance, corrosion resistance, acid resistance and mechanical strength and suitable for dust arresting or dust removing, and which is particularly useful as a filer for particulates, and a method for its production.

Abstract: A silicon nitride porous body which is a body having a generally columnar outer shape and at least two through-holes mutually parallel to one another and which has generally perpendicularly oriented columnar crystals on the surface of the through-holes.

Abstract: An electrification removing component comprising:a ceramics for removing electrification of which surface resistivity is in a range of 2.times.10.sup.6 through 10.sup.10 .OMEGA./cm.sup.2 ; and an electric conductive material connected to the ground; said ceramics for removing electrification being electrically connected to the electric conductive material with an area by contact or bonding on surfaces of the ceramics for removing electrification and the electric conductive material.

Abstract: An ornament has a jewelry holding member which is provided jewelry mounts both on the upper and lower sides thereof, and a plurality of rings which are rotatably secured to the jewelry holding member in such a manner as to cross one another. According to the present invention, since a plurality of rings are rotatable secured to a jewelry holding member at positional offset from one another, a single jewelry ring can have two designs which are entirely different from each other, and either one of these designs can be selectively displayed without requiring any change in the construction of the ring.

Abstract: A dense sintered silicon carbide ceramic has high strength and a flexural strength of at least 25 kg/mm.sup.2 at room temperature and 1400.degree. C. which is obtained by molding a mixture of an aluminum oxide source at a ratio of 0.5 to 35 wt. % as Al.sub.2 O.sub.3 and silicon carbide at a substantial residual portion followed by a pressureless sintering.