Ceramic composition and method for producing the same

Claim 1

A method for producing a ceramic composition, characterised by sintering a molded product comprising at least one component selected from silicon nitride powder, silicon carbide powder, and polysilazane represented by the following formula (A), (B), or (C) is formed by sintering in a state without sintering aid, under pressurized component at least one selected from nitrogen, ammonia in sintering atmosphere at 800 to 2200°C wherein, the formula (A) represents a polysilazane which have a skeleton structure having the repeating units of the formula: and in which polysilazane, a plurality of precursor residues having the units represented by the formula: forming structural unit represented by the formula: and a part being connected to each other by the structural unit represented by the formula: Further, in respective formulae, R₁, R₂, R₃, and R₄ denote such ones as hydrogen (except for R₄), a lower alkyl group having from 1 to 6 carbon atoms consisting of methyl, ethyl, n-propyl, isopropyl, etc.; a substituted or unsubstituted vinyl group; a substituted or unsubstituted allyl group; a substituted or unsubstituted lower aryl group having from 6 to 10 carbon atoms such as phenyl, tolyl, xylic, etc.; a tri(lower)-alkyl, or di(lower) alkylsilyl group such as trimethyl, dimethyl, triethylsilyl, etc.; or a di-(lower) alkylamino group (except for R₄) such as dimethyl, diethyl, methylethyl, diisopropylamino, etc., and moreover, R₁, R₂, R₃ and R₄ may be the same or different. The formula (B) denotes polysilazane which have the skeleton structure having a repeating unit represented by the formula: and the residues in the precursor having the repeating units represented by the formula: being connected to each other with the structure units represented by the formula: and the above-described precursor being constituted of the units represented by the formula: and the formula: Further, in the formulae, definiting of R₁ is the same as that in the case of the formula (A), and R₅ and R₆ are lower alkyl group having from 1 to 6 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, etc.; substituted or unsubstituted vinyl group; substituted or unsubstituted lower aryl group such as phenyl tolyl, xylic, etc.; tri(lower) alkyl or di(lower) alkyl group such as trimethyl, dimethyl, triethylsilyl, etc.; or a di(lower) alkylamino group, and R₁, R₅, and R₆ may be the same or different. The formula (C) is polysilazane which have skeleton structure having the repeating unit of the formula: and a plurality of precursor residues having the unit represented by the formula: become partly the structure unit having the formula: and are partly connected to each other by the structural unit having the formula: and further, a part of the precursor is constituted of the unit having the formula: and the formula: Further, each definitions of R₁, R₂, R₃, R₄, R₅, and R₆ are the same ones as in the above-described formula, (A) and (B), and R₁, R₂, R₃, R₄, R₅, and R₆ may be the same or different.

Claim 2

A method for producing a ceramic composition, characterised by sintering a molded product comprising at least one component selected from silicon nitride powder, silicon carbide powder, and polysilazane represented by the following formula (A), (B), or (C) is formed by sintering in a state without sintering aid, under pressurized component at least one selected from nitrogen, ammonia in sintering atmosphere at 800 to 2200°C wherein, the formula (A) represents a polysilazane which have a skeleton structure having the repeating units of the formula: and in which polysilazane, a plurality of precursor residues having the units represented by the formula: forming structural unit represented by the formula: and a part being connected to each other by the structural unit represented by the formula: Further, in respective formulae, R₁, R₂, R₃, and R₄ denote such ones as hydrogen (except for R₄), a lower alkyl group having from 1 to 6 carbon atoms consisting of methyl, ethyl, n-propyl, isopropyl, etc.; a substituted or unsubstituted vinyl group; a substituted or unsubstituted allyl group; a substituted or unsubstituted lower aryl group having from 6 to 10 carbon atoms such as phenyl, tolyl, xylic, etc.; a tri(lower)-alkyl, or di(lower) alkylsilyl group such as trimethyl, dimethyl, triethylsilyl, etc.; or a di-(lower) alkylamino group (except for R₄) such as dimethyl, diethyl, methylethyl, diisopropylamino, etc., and moreover, R₁, R₂, R₃ and R₄ may be the same or different. The formula (B) denotes polysilazane which have the skeleton structure having a repeating unit represented by the formula: and the residues in the precursor having the repeating units represented by the formula: being connected to each other with the structure units represented by the formula: and the above-described precursor being constituted of the units represented by the formula: and the formula: Further, in the formulae, definiting of R₁ is the same as that in the case of the formula (A), and R₅ and R₆ are lower alkyl group having from 1 to 6 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, etc.; substituted or unsubstituted vinyl group; substituted or unsubstituted lower aryl group such as phenyl tolyl, xylic, etc.; tri(lower) alkyl or di(lower) alkyl group such as trimethyl, dimethyl, triethylsilyl, etc.; or a di(lower) alkylamino group, and R₁, R₅, and R₆ may be the same or different. The formula (C) is polysilazane which have skeleton structure having the repeating unit of the formula: and a plurality of precursor residues having the unit represented by the formula: become partly the structure unit having the formula: and are partly connected to each other by the structural unit having the formula: and further, a part of the precursor is constituted of the unit having the formula: and the formula: Further, each definitions of R₁, R₂, R₃, R₄, R₅, and R₆ are the same ones as in the above-described formula, (A) and (B), and R₁, R₂, R₃, R₄, R₅, and R₆ may be the same or different.

Claim 6

A method for producing a ceramic composition as claimed in Claim I, wherein polysilzane is the one represented by the formula (A), and in the formula, polysilazan has a methyl group for all of R₁, R₂, R₃ and R₄.