Sintering of in-Situ Synthesized Sic–TiB2 Composites with Improved Fracture Toughness |
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Authors: | Yutaka Ohya Michael J Hoffmann Günter Petzow |
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Affiliation: | Max-Planck-Institut für Metallforschung, Institut für Werkstoffwissenschaft, Pulvermetallurgisches Laboratorium, W-7000 Stuttgart 80, Germany |
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Abstract: | TiB2-particle reinforcement is one of the most successful methods for improving the fracture toughness of SiC ceramics.1–3 Commercially available TiB2 powders, however, have a large particle size and/or are highly reactive so that they are not favorable as a starting powder. In the present work, TiB2 particles are formed by an in situ reaction between TiC and boron. The reaction takes place during sintering between 1000° and 1600°C and is accompanied by a large volume expansion. Under optimum conditions, dense composites (> 98% of theoretical) can be obtained by pressureless sintering using B and C as sintering additives. The in situ reaction method enables, for the first time, a complete densification of SiC-particulate composites by pressureless sintering. The fracture toughness of the composites was approximately 30% higher than that of the monolithic SiC ceramic. |
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