The invention relates to a high-
boron content
silicon-
boron-carbon-
nitrogen precursor and a preparation method thereof. The preparation method comprises the following steps: uniformly mixing functional,
bifunctional and trifunctional
chlorosilane containing unsaturated groups and hexamethyl-disilazane at a low temperature according to a certain ratio, raising the temperature and completely reacting, dropping 1,3-diethyl cycloborazane under low temperature conditions according to a certain ratio, fully reacting the reactants, and finally performing reduced pressure
distillation to obtain the
solvent and by-products produced by the reaction, thereby obtaining faint yellow
viscous liquid or a
solid product, namely the SiBCN
ceramic precursor. According to the synthetic method disclosed by theinvention, a novel Polyborosilicate resin is prepared by adopting a 'double
boron source', the boron content of the prepared SiBCN
ceramic can reach 20%, and the problems that the boron content is low and improvement of high
temperature resistance and
oxidation resistance of the
ceramic is not obvious can be solved. The elementary composition regulation range of the precursor disclosed by the invention is wide, and resins which are suitable to serve as a high-temperature-resistant
coating, a
fiber reinforcement or a ceramic-based
composite material matrix and have different elementary compositions can be prepared.