Characterization of Directionally Solidified B<SUB>4</SUB>C-SiC Composites Prepared by a Floating Zone Method

Abstract

Directionally solidified B 4 C-TiB 2 composites were prepared by a Floating Zone method. TiB 2 phases in a rod shape were continuously connected in the B 4 C matrix. The c-axes of TiB 2 and B 4 C phases were perpendicular and tilted 22° to the growth direction, respectively, The (101) and (120) planes of the B 4 C were in parallel to the (001) and (100) planes of TiB 2 , respectively. The electrical conductivity of the composite parallel to the growth direction (σ || ) was greater than monolithic B 4 C by a factor of 100 to 1000. The thermal conductivity of the composite parallel to the growth direction (κ || ) was about one and a half times as high as that of B 4 C. The anisotropy of electrical and thermal conductivity were basically explained by a mixing law using the values of B 4 C and TiB 2 . The microhardness of the composite was almost the same as that of B 4 C. The electric discharge machining of the composite was possible owing to the enhancement of electrical conductivity.