The invention relates to novel chlorine-containing silazane polymers, to their preparation, their further processing to ceramic material containing silicon nitride, and this material itself. In order to prepare the chlorine-containing silazane polymers, oligosilazanes of the formula (I) ##STR1## in which a >0, b.gtoreq.0 and n is about 2 to about 12, are reacted with at least one of the chlorosilanes Cl.sub.2 R.sup.4 Si--CH.sub.2 --CH.sub.2 --SiR.sup.4 Cl.sub.2, Cl.sub.3 Si--CH.sub.2 --CH.sub.2 --SiR.sup.5 Cl.sub.2, R.sup.6 SiCl.sub.3 or R.sup.7 SiHCl.sub.2 at 30.degree. C. to 300.degree. C., where, independently of one another, R.sup.1 and R.sup.2 =H, C.sub.1 -C.sub.6 -alkyl or C.sub.2 -C.sub.6 -alkenyl, R.sup.3, R.sup.4, R.sup.5, R.sup.6 and R.sup.7 =C.sub.1 -C.sub.6 -alkyl or C.sub.2 -C.sub.6 -alkenyl and where if b=0 the reaction with R.sup.7 SiHCl.sub.2, if R.sup.7 =C.sub.1 -C.sub.6 -alkyl and none of the other chlorosilanes is present, is to be excluded. The chlorine-containing silazane polymers according to the invention can be converted by reaction with ammonia into polysilazanes, which in their turn can be pyrolysed to form ceramic materials containing silicon nitride.

The invention relates to novel chlorine-containing silazane polymers, to their preparation, their further processing to ceramic material containing silicon nitride, and this material itself. In order to prepare the chlorine-containing silazane polymers, oligosilazanes of the formula (I) ##STR1## in which a>0, b.gtoreq.0 and n is about 2 to about 12, are reacted with at least one of the chlorosilanes Cl.sub.2 R.sup.4 Si--CH.sub.2 --CH.sub.2 --SiR.sup.4 Cl.sub.2, Cl.sub.3 Si--CH.sub.2 --CH.sub.2 --Sir.sup.5 Cl.sub.2, R.sup.6 SiCl.sub.3 or R.sup.7 SiHCl.sub.2 at 30.degree. C. to 300.degree. C., where, independently of one another, R.sup.1 and R.sup.2 =H, C.sub.1 -C.sub.6 -alkyl or C.sub.2 -C.sub.6 -alkenyl, R.sup.3, R.sup.4, R.sup.5, R.sup.6 and R.sup.7 =C.sub.1 -C.sub.6 -alkyl or C.sub.2 -C.sub.6 -alkenyl and where if b=0 the reaction with R.sup.7 SiHCl.sub.2, if R.sup.7 =C.sub.1 -C.sub.6 -alkyl and none of the other chlorosilanes is present, is to be excluded. The chlorine-containing silazane polymers according to the invention can be converted by reaction with ammonia into polysilazanes, which in their turn can be pyrolyzed to form ceramic materials containing silicon nitride.

The invention relates to novel polymeric chlorosilazanes, to their preparation, to their processing to form ceramic material containing silicon nitride, and to said material itself. The polymeric chlorosilazanes are prepared by reacting a mixture of oligosilazanes of formula (I) ##STR1## in which n is about 2 to about 12, and oligosilazanes of formula (II), (RSiHNH).sub.m, in which m is about 3 to about 12, with at least one of the chlorosilanes Cl.sub.2 R.sup.2 Si--CH.sup.2 --CH.sub.2 --SiR.sup.2 Cl.sub.2, Cl.sub.3 Si--CH.sub.2 --CH.sub.2 --SiR.sup.3 Cl.sub.2, R.sup.4 SiCl.sup.3 or R.sup.5 SiHCl.sub.2 at 30.degree. C. to 300.degree. C., where R and R.sup.1 to R.sup.5 are C.sub.1 -C.sub.6 alkyl or C.sub.2 -C.sub.6 alkenyl groups which can be identical or different. The polymeric chlorosilazanes according to the invention can be converted into polysilazanes by reaction with ammonia, and these in turn can be pyrolyzed to form ceramic materials containing silicon nitride.

The invention relates to novel polymeric hydridochlorosilazanes, to their preparation, to their processing to form ceramic materials containing silicon nitride, and to said materials themselves. The polymeric hydridochlorosilazanes are prepared by reacting oligohydridoorganosilazanes of the general formula (R.sup.1 SiHNH).sub.n, in which n is about 3 to about 12, with at least one of the chlorosilanes R.sup.2 SiHCl.sub.2, R.sup.3 SiCl.sub.3, Cl.sub.2 R.sup.4 Si--CH.sub.2 CH.sub.2 --SiR.sup.4 Cl.sub.2 or Cl.sub.3 Si--CH.sub.2 CH.sub.2 --SiR.sup.5 Cl.sub.2 at 30.degree. C. to 300.degree. C., where the radicals independently of one another have the following meanings: R.sup.1 =a C.sub.1 -C.sub.6 alkyl or C.sub.2 -C.sub.6 alkenyl group, R.sup.2 =a C.sub.2 -C.sub.6 alkenyl group if R.sup.2 SiHCl.sub.2 is reacted with the oligosilazanes by itself, or R.sup.2 =a C.sub.1 -C.sub.6 alkyl or C.sub.2 -C.sub.6 alkenyl group if R.sup.2 SiHCl.sub.2 is reacted with the oligosilazanes as a mixture with other chlorosilanes, and R.sup.3, R.sup.4, R.sup.5 =a C.sub.1 -C.sub.6 alkyl or C.sub.C.sub.2 -C.sub.6 alkenyl group, and where R.sup.3 SiCl.sub.3 is used only as a mixture with at least one of the other chlorosilanes (containing R.sup.2, R.sup.4 or R.sup.5). The polymeric hydridochlorosilazanes according to the invention can be converted into polysilazanes by reaction with ammonia, and these in turn can be pyrolyzed to form ceramic materials containing silicon nitride.

The invention relates to a process for the production of a ceramic/fiber composite. The process comprises impregnating fibers with a molten polysilazane in a first step, converting the polysilazane in the fibers into the infusible state in a second step and, in a third step, heating the impregnated fibers to 800.degree. to 2000.degree. C. in an atmosphere of nitrogen, noble gas, or ammonia.