Preparation of Directionally Solidified B<SUB>4</SUB>C&ndash;TiB<SUB>2</SUB>&ndash;SiC Ternary Eutectic Composites by a Floating Zone Method and Their Properties

Abstract

Directionally solidified B 4 C-TiB 2 -SiC composites were prepared by a floating zone method using B 4 C, TiB 2 and SiC as starting materials. The B 4 C-TiB 2 -SiC system was ternary eutectic whose eutectic composition was 51.2B 4 C-8.1TiB 2 -40.7SiC (mol%). The ternary eutectic composite showed a lamellar microstructure where B 4 C(104), TiB 2 (100) and SiC(111) planes were perpendicular to the growth direction. The Vickers hardness of the B 4 C-TiB 2 -SiC ternary eutectic composite was 28 to 32 GPa. The electrical conductivity was 6 to 9 Â 10 4 Sm À1 , and the thermal conductivity was 35 to 45 WK À1 m À1 in the temperature range from 298 to 1100 K.

Preparation of TiC-TiB<SUB>2</SUB>-SiC Ternary Eutectic Composites by Arc-Melting and Their Characterizations

“…Some promising results have been reported for the B 4 C-SiC, B 4 C-TiB 2 and B 4 CTiB 2 -SiC eutectic composites. [18][19][20] However, the study on the TiC-TiB 2 -SiC eutectic composite has not been reported. In this study, the TiC-TiB 2 -SiC ternary composites were prepared by arc-melting, and the microstructure, hardness, thermal conductivity and electrical conductivity were investigated.…”

Preparation of ZrB2-SiC composites by arc melting and their properties

“…A melt-solidification process is another route to synthesize fully dense composites. We have preciously prepared several carbide-boride composites by arc melting and floating zone melting, and investigated the microstructure and some characters of B 4 C-SiC, 15) TiB 2 -SiC, 16) B 4 CTiB 2 -SiC 17) and TiC-TiB 2 -SiC 18), 19) eutectic composites. Since the eutectic composites have a self-assembled lamellar or rod-like microstructure with a highly coherent interface, they would have a highly thermally stable microstructure and high mechanical properties.…”

Directionally Solidified Boride and Carbide Eutectic Ceramics

“…Both SiC [110 WÁ(KÁm) À1 ] and TiB 2 [80 WÁ(KÁm) À1 ] have relatively large thermal conductivities at room temperature. 114,115 The thermal conductivity generally follows rules of mixing; however, in Fig. As shown in Fig.…”

“…39,114-116 Therefore, thermal conductivity at various temperatures has been investigated in B 4 C-TiB 2 , B 4 C-SiC, and B 4 C-TiB 2 -SiC ternary DSEs produced via FZ method by Gunjishima et al 39,114 and Li et al, 115 respectively. Both SiC [110 WÁ(KÁm) À1 ] and TiB 2 [80 WÁ(KÁm) À1 ] have relatively large thermal conductivities at room temperature.…”

“…114 Thermal conductivity in DSEs are also found to be orientation dependent, as found in electrical properties. 39,114,115 Although understanding of the interrelationship between microstructure scale, thermal properties, and electrical properties in boride and carbide DSEs is limited, some compositions, that is, B 4 C-TiB 2, B 4 C-SiC , and B 4 C-TiB 2 -SiC DSEs, have been evaluated. 19(a), the measured thermal conductivities of B 4 C-TiB 2 DSEs are slightly lower than calculated thermal conductivities and may be influenced by either microstructure connectivity and/or phonon scattering at B 4 C/TiB 2 interfaces.…”