Conversion mechanism of polyborosilazane into silicon nitride-based ceramics

✍ Scribed by O. Funayama; H. Nakahara; M. Okoda; M. Okumura; T. Isoda

• Publisher: Springer
• Year: 1995
• Tongue: English
• Weight: 690 KB
• Volume: 30
• Category: Article
• ISSN: 0022-2461
• DOI: 10.1007/bf00354405

✦ Synopsis

The pyrolysis of polyborosilazane in anhydrous ammonia has been studied up to 1200~ through the analysis of the gas phase and the characterization of the solid residue by elemental analyses, thermogravimetric analysis, Fourier transform-infrared analysis, X-ray photoelectron spectroscopy, X-ray diffraction and 29Si cross-polarization/magic angle spinning-nuclear magnetic resonance. The pyrolysis mechanism involves four main steps:

(1) below 400 ~ an evaporation of residual solvent and reaction with ammonia leading to an increase of nitrogen content; (2) from 400 600~ reaction with ammonia leading to an increase of nitrogen content and formation of preceramic polymer-ceramics intermediate solid with a three-dimensional network along with evolution of gaseous species; (3) from 600-800 ~ completion of loss of C-H functionalities and progress of formation of an amorphous ceramic, accompanied by evolution of CH4 and H2; (4) from 800-1200~ completion of formation of an amorphous hydrogenated Si-B-O-N solid composed of SiN4_xOx(x=O,1,2,3) and BN3_FOy (y=0, 1), along with evolution of H2