Research On The Combustion Synthesis Of TiB₂/Al₂O₃ Composite Ceramic

Combustion synthesis technology is one of the most new attractive technologies to manufacture the materials. This paper discussed the application of Combustion synthesis technology in the field of composite ceramic fabrication. In this paper, TiB₂/Al₂O₃ composites are fabricated with Al, TiO₂and B₂O₃ powders by means of combustion synthesis combined dynamic mechanical pressing. The density of the product is up to 98.4%. On the basis of the fundamental research, (TiB₂+Al₂O₃)/M composite ceramic was prepared by adding Fe and Al as the metal bonding phase in the paper. And discussed the effect of metal addiction on the organization structure, formation processing and the density degree of product. Constitution phase, size of grain, grain appearance, fracture mechanism were investigated by X-ray diffraction, optics electron microscope, scanning electron microscope, energy spectrum analysis. By means of large number experiments, we studied the influence of grain size, pressing delay time, pressure and last time, the content of Fe on the product density. And found the optimal fabricating craft. By analyzing the result of X-ray diffraction, we could find the reactants with 10Al-3TiO₂ -3B₂O₃ system has mainly Al₂O₃ phase and TiB₂ phase. The result indicated that combustion synthesis reaction is complete and the constitution phase is in equilibrium generally. The result on the element surface scanning showed that the appearance of TiB₂ phase is regular massive, the average grain size is 3.5⁵um, and the TiB₂ phase is not homogeneously distributed in the Al₂O₃-matrix and mainly gathered in the Al₂O₃ grain boundary and corner angle. In addition, we could find that the appearance of Al₂O₃ phase is ir regular, and some bulky grains are found in some part area. Fe as the metal bonding phase is distributed between Al₂O₃ and TiB₂ phase boundary. From the appearance of fracture, we could find obvious grain extraction phenomenon with the increase of Fe content. This result indicated that the adding of Fe mend the brittleness of ceramic composite, and improve the fracture toughness. These basic researches were of guidance for optimizing processing techniques, by which ceramic materials with perfect properties might be obtained.