Synthesis and pyrolysis of novel polysilazane to SiBCN ceramic

• Published in: Journal of non-crystalline solids 2005-10, Vol.351 (37), p.2995-3005
• Main Authors: Lee, Jongsang, Butt, Darryl P., Baney, Ronald H., Bowers, Clifford R., Tulenko, James S.
• Format: Article
• Language: English
• Subjects: Applied sciences; Building materials. Ceramics. Glasses; Ceramic industries; Chemical industry and chemicals; Exact sciences and technology; Inorganic and organomineral polymers; Miscellaneous; Physicochemistry of polymers; Preparation; Technical ceramics
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/j.jnoncrysol.2005.06.038

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 (HSiCl 3), boron trichloride (BCl 3), 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 (CH 3) 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 CH 4 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.