Chemical Vapor Infiltration of TiB2-Matrix Composites

• Published in: Journal of the American Ceramic Society 1994-09, Vol.77 (9), p.2395-2400
• Main Authors: Besmann, Theodore M., Miller, James H., Cooley, Kevin M., Lowden, Richard A., Starr, Thomas L.
• Format: Article
• Language: English
• Subjects: Applied sciences; Building materials. Ceramics. Glasses; Ceramic industries; Chemical industry and chemicals; Exact sciences and technology; Miscellaneous; Technical ceramics
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/j.1151-2916.1994.tb04610.x

The efficiency of the Hall–Heroult electrolytic reduction of aluminum can be substantially improved by the use of a TiB2 cathode. The use of TiB2 components, however, has been hampered by the brittle nature of the material and the grain boundary attack of sintering‐aid phases by molten aluminum. In the current work, TiB2 is toughened through the use of reinforcing fibers, with chemical vapor infiltration used to produce the TiB2 matrix. In early efforts it was observed that the formation of TiB2 from chloride precursors at fabrication temperatures below 900–1000°C may have allowed the retention of destructive levels of chlorine. At higher fabrication temperatures (>1000°C), using appropriate infiltration conditions as determined from the use of a process model, TiB2/THORNEL P‐25 fiber composites have been fabricated in 20 h. The improved composite material has been demonstrated to be stable in molten aluminum in short‐duration (24 h) tests.