In situ alumina/aluminum titanate bulk ceramic composites prepared by SPS from different structured composite powders

摘要

Nanostructured Al_2O_3/TiO_2 composite powders (spherical particles composed of nanosized alumina and titania grains) were successfully prepared by ball-milling, spray drying and heat treatment. As-received microstructured and the as-prepared nanostructured Al_2O_3/TiO_2 composite powders (M and N powders, respectively) were then used to consolidate in situ alumina/aluminum titanate bulk ceramic composites by spark plasma sintering. The sintering behavior of the starting powders and the effect of the starting powders with different microstructure on the microstructure and mechanical properties of Al_2O_3/Al_2TiO_5 bulk ceramic composites were investigated. N powder showed enhanced sintering behavior compared with M powders. The obtained N bulk composite possesses much finer and more homogenous microstructure than M bulk composite. The mechanical properties of N bulk composite are significantly higher than that of M bulk composite, e.g. the flexural strength, fracture toughness and Vickers hardness of N bulk composite are 91.6 percent, 37.2 percent and 145.6 percent higher than that of M bulk composite, respectively. The improved mechanical properties of N bulk composite compared with that of M bulk composite are attributed to the enhanced densification and the finer and more homogeneous microstructure through the use of the novel nanostructured composite powders.