Abstract
The thermal conductivity and the thermal expansion of Si3N4-SiC whisker composites were investigated. Specimens were prepared by hot-pressing at 1800°C-39.2MPa-60min using Y2O3-La2O3 or MgO as a sintering aid. The thermal conductivity of composites increased with an increase in SiC whisker content. Moreover, the thermal conductivity normal to the hot-pressing direction was higher than that parallel to the hot-pressing direction due to orientation of whisker. In the system Y2O3-La2O3, an Si3N4 matrix showed abnormal thermal expansion above 1000°C caused by the glass phase composed of Si3N4, Y2O3 and La2O3, but the composites showed nearly linear thermal expansion up to 1400°C. In MgO system, linear thermal expansion curves were obtained regardless of whisker content.
