Synthesis, sintering and characterization of Al2O3-13 wt.% TiO2 composite powder prepared by polymer assisted co-precipitation route

Abstract

Composites of alumina (Al2O3) and titania (TiO2) are known for their high toughness, low thermal expansion, and low thermal conductivity. Alumina-Titania coatings are excellent candidates for providing protection against abrasive wear, resistant to high temperature erosion with cryogenic compatibility, high adhesion strength, and are resistant to high thermal shock. High temperature formation of Al2TiO5 (AT) is reason for the excellent property. It is reported in literature that nano-composite of Al2O3-TiO2 or Al2O3-AT has 2-3 times better thermo-mechanical property. In most of the cases Al2O3-TiO2 composite powder prepared by mechanical mixing of nano alumina and titania powder which are costly. There are very few reports on in-situ synthesis of Al2O3-TiO2 composite by simple wet chemical method. In our present work, an alumina-titania composite powder containing 13 wt.% titania was prepared by polymer assisted co-precipitation technique. Co-polymer Pluronic P-123 was used in the precipitation process. The influence and effect of concentration of the surfactant on the morphology and size of the obtained materials were investigated. The particle size for polymer assisted composite powder is found to be less than the sample prepared by the simple co-precipitation process. The phase evolution and reaction mechanism was studied by XRD and DSC-TG. The Fourier transformation infrared spectroscopy (FTIR) measurement was carried out in order to investigate the presence of polymer. The particle size and morphology was analyzed for with and without polymer synthesized powder. Densification behavior of nano-composite powder was studied by dilatometry. 95% of sintered density can be achieved at 1650oC. Our derived process is able to achieve homogeneous distribution of Al2O3-Al2TiO5 phase in sintered samples.