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A composite material with anisotropic microstructure was fabricated by DC electric field. Alumina was used as filler for thermal conductivity and polysiloxane resin was used as matrix. According to the alumina morphology and loading amount, various anisotropic microstructures were assembled. The thermal properties of the composite material were investigated parallel to the direction of the applied electric field accordingly. For plate-like alumina with 20 vol% loading, a thermal conductivity of 0.44 W/mK was achieved. With spherically shaped alumina, with an equal loading of 20 vol%, a higher thermal conductivity of 0.46 W/mK was achieved. The increase in the thermal conductivity of the fabricated alumina composites with anisotropic microstructure was attributed to increased filler-to-filler connectivity. [ABSTRACT FROM AUTHOR]

The effect of starting phase of raw material on the microstructure and the fracture toughness of silicon carbide was investigated. The starting phase was adjusted by varying the mixed ratio of α-SiC and β-SiC powders, and they were hot pressed with sintering aids. From the microstructure, some elongated grains were found among equiaxial grains. The anisotropic grain growth was resulted from phase transformation of the β-SiC to the α-SiC with 4H polytype during sintering or heat treatment. Volume fraction, maximum length, and aspect ratio of elongated grains were the highest at 50 vol.% β-SiC in the starting SiC powder, which showed the highest fracture toughness about 6.0 MPa m 1/2. [Copyright &y& Elsevier]