Synthesis and pyrolysis of novel polysilazane to SiBCN ceramic

A novel synthesis route was developed to produce exceptionally thermal stable SiBCN-based ceramics. This route turns out to be cheaper, simpler and faster than the conventional route. The SiBCN-based preceramic polymer was synthesized by using three monomers, trichlorosilane (HSiCl3), boron trichloride (BCl3), and hexamethydisilazane (HMDZ), at a molar ratio of about 1:1:4. The product becomes an amorphous structure with crosslinked bonds during the elimination of (CH3)3SiCl. An intermolecular condensation with the loss of HMDZ occurs in a second stage without the addition of crosslinking agents. In the final pyrolysis stage, hydrogen-rich species such as CH4 are lost. The chemical structure and composition of the obtained polymer were investigated using IR, MAS-NMR, TGA, DSC, XRD, EA, AA, ICP, and EDS. Through the pyrolysis of preceramic polymers, the mechanisms of the structural and compositional changes at a high temperature were also examined. A preceramic polymer useful for nuclear application can be formed, which provides hydrothermal stability under autoclave test.