Method for making polysilazanes and silicon nitride therefrom.

摘要

A method of preparing silazane polymers, with 3 or more repeating units, of the general formula
<Chemistry id="chema01" num="0001"><Image id="ia01" he="5" wi="55" file="IMGA0001.TIF" imgContent="chem" imgFormat="TIFF" inline="no" /></Chemistry><UnorderedLists id="ula01" listStyle="none"><ListItem>and a (CH<Sub>3</Sub>)<Sub>2</Sub>NH byproduct group where R is</ListItem><ListItem>hydrogen, an alkyl group having 1-6 carbon atoms or</ListItem><ListItem>an aryl group having 6-12 carbon atoms, a = 0, or 1,</ListItem><ListItem>b = <Sub>2</Sub>-<Sub>4</Sub>, c = <Sub>0</Sub>-<Sub>2</Sub>, d = 0 or 1, e = 0-2, f = 0-2, g =1-3 and</ListItem><ListItem>a+c+e+f+g=4 for the polymer units; and R' is hydrogen or methyl, whereby the silazane polymer is substantially free of halide impuriites by transaminating an aminosilane of the general formula (R)<Sub>a</Sub>((CH<Sub>3</Sub>)<Sub>2</Sub>N) <Sub>b</Sub>H<Sub>c</Sub>S with an amine of the general formula (CH<Sub>3</Sub>)<Sub>d</Sub>NH<Sub>3-d</Sub>; the amine has a molecular weight lower than 45; all in the presence of an acid catalyst or the ammonium salt of the acid and thereafter condensing to form the polymer. Silicon nitride or silicon nitride containing ceramics. are produced by pyrrolizing the silazane polymers.</ListItem></UnorderedLists>