| Zirconia materials (ZrO2) have excellent performance, such as high melting point, good chemical stability, high resistance to acid-base slag, but poor performance in thermal shock resistance. The melting point of aluminium titanate (Al2TiO5) is 1860℃, and thermal expansion coefficient is 5×10-6/℃. It can resist the erosion of the molten steel at 1650℃. In this project ZrO2 with Al2TiO5 was combined by namo-technology, and a composite with excellent characters may be obtained.The raw materials are aluminum sulfate, titanous sulfate, and zirconium oxychloride. The nano-powders of alumina, titania and zirconia were prepared by co-precipitation, and sintered at 1350℃, 1400℃, 1450℃, 1500℃, then zirconia-alunminium titanate composite was synthesized. In the end, the sintered characters, phase composition, microstructure and thermal shock resistance were studied.The result shows the bending strength of composite with alunminium titanate as the essential component. The bending strength of samples containing 5% zirconia sintered at 1500℃can reach to 103.2MPa. However, its thermal expansion rises linearly, and its performance of thermal shock resistance is poor. The sintered samples are cracked and then re-sintered at the same temperature. The bending strength is lowered to 25MPa, and thermal expansion is very low. The samples sintered at 1500℃show low and negative thermal expansion, the performance of thermal shock resistance is better, and the samples can resist 30 times thermal shock without damage.The bending strength of the composite with zirconia as the essential component and sintered at 1350～1400℃is low, and the strength of most of the samples is about 25MPa.The performance of thermal shock resistance of the samples is better, and can resist more than 20 times thermal shock. When sintering temperature form 1450 to 1500℃, the thermal expansions decrease with sintering temperature, and the temperature that tetragonal zirconia changes to monoclinic zirconia decreases.
|
PDF Full Text Request