Reactive hot pressing and sintering characterization of ZrB2-SiC-ZrC composites

The reactive synthesis route, microstructure and properties of ZrB2-SiC-ZrC composites prepared from a mixture of Zr/B4C/Si powders via reactive hot pressing were investigated. The reactions of the Zr/B4C/Si system commenced at 800 degrees C and completed after a 60 min hold at 1700 degrees C in argon atmosphere. The reacted products at 1700 degrees C were composed of fine particles and the size was smaller than 1 mu m, which provided a large driving force for densification. The powders were sintered at 1750 degrees C, 1800 degrees C, 1850 degrees C and 1900 degrees C, respectively. The results showed that the relative density and average grain size of the composites increased with the increase of sintering temperature. The relationships between the microstructural features and mechanical properties of the composites were discussed. (C) 2008 Elsevier B.V. All rights reserved.