A silicoboron carbonitride ceramic stable to 2,000°C

• Published in: Nature (London) 1996-08, Vol.382 (6594), p.796-798
• Main Authors: Riedel, Ralf, Kienzle, Andreas, Dressler, Wolfgang, Ruwisch, Lutz, Bill, Joachim, Aldinger, Fritz
• Format: Article
• Language: English
• Subjects: Applied sciences; Building materials. Ceramics. Glasses; Ceramic industries; Chemical industry and chemicals; Exact sciences and technology; Humanities and Social Sciences; letter; multidisciplinary; Science; Science (multidisciplinary); Structural ceramics; Technical ceramics
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/382796a0

CERAMICS based on silicon nitride and carbide are strong and stable at high temperatures, and are therefore under investigation for the fabrication of motor and turbine parts 1–3 . But silicon nitride decomposes at about 1,400 °C in vacuum and 1,775 °C in 0.1 MPa nitrogen 4,5 , limiting the high-temperature range of its technological uses. Here we describe a boron-containing silicon nitride/carbide ceramic that does not degrade at temperatures up to 2,000 °C even in nitrogen-free environments. We synthesize the material in a polymer-to-ceramic transformation 6 from a single polymeric polyborosilazane precursor. On heating at 1,000 °C in argon we obtain a ceramic with the composition Si 3.0 B 1.0 C 4.3 N 2.0 . The ceramic begins to convert to a polycrystalline composite of silicon nitride and carbide (with some non-crystalline boron nitride) at 1,700 °C, a process that is completed (without substantial change in elemental composition) at 2,000 °C.