Silicon nitride-containing ceramics
AssigneeDow Corning Corporation
InventorJohn P. Cannady
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Abstract
What is disclosed is a process for preparing a silicon nitride-containing ceramic material from a R.sub.3 SiNH-containing silazane polymer, which has been rendered infusible by treatment with certain reactive metal halides, by heating the infusible silazane polymer to an elevated temperature under an inert atmosphere. Suitable reactive metal halides are of the general formula MX.sub.n or R.sub.b SiX.sub.(4-b) where M is a metal atom of valence n, X is chlorine or bromine, R is selected from the group consisting of vinyl, hydrogen, phenyl, and alkyl radicals containing 1 to 3 carbon atoms, and b has a value of 0, 1, or 2. Preferred reactive metal halides are SiCl.sub.4 and HSiCl.sub.3.
Claims52
A method of preparing a silicon nitride-containing ceramic material, which method comprises (1) treating a R.sub.3 SiNH-containing silazane polymer with a reactive metal halide of general formula MX.sub.n or R.sub.b SiX.sub.(4-b) at a temperature below the softening point of the R.sub.3 SiNH-containing silazane polymer for a time sufficient to render the silazane polymer infusible where R is selected from the group consisting of vinyl, hydrogen, phenyl, and alkyl radicals containing 1 to 3 carbon atoms;
- M is a metal atom of valence n;
- X is a halide atom selected from the group consisting of chlorine and bromine;
- and b has a value of 0, 1, or 2;
- where said reactive metal halide has fewer carbon atoms than the R.sub.3 SiNH-endblocking group;
- and where said reactive metal halide has at least two halide atoms;
- and (2) heating the infusible silazane polymer of step (1) in an inert atmosphere or vacuum to a temperature of at least 750.degree. C. until said infusible silazane polymer is converted to a silicon nitride-containing ceramic material.
A method of preparing an infusible silazane polymer, which method comprises treating a R.sub.3 SiNH-containing silazane polymer with a reactive metal halide of general formula MX.sub.n or R.sub.b SiX.sub.(4-b) at a temperature below the softening point of the R.sub.3 SiNH-containing silazane polymer for a time sufficient to render the silazane polymer infusible when R is selected from the group consisting of vinyl, hydrogen, phenyl, and alkyl radicals containing 1 to 3 carbon atoms, M is a metal atom of valence n, X is a halide atom selected from the group consisting of chlorine and bromine, and b has a value of 0, 1, or 2, where said reactive metal halide has fewer carbon atoms than the R.sub.3 SiNH-endblocking group, and where said reactive metal halide has at least two halide atoms.
Dependencies are inferred from the claim text.