This paper explains sintering properties of Al2O3-70(referred to as the 70 green sample) natural mullite that was prepared by the process of homogenization, wet grinding, vacuum extrusion and high-temperature tunnel kiln sintering. The results show that 70 green sample's dehydroxylation temperature started in 528 °C; 70 green sample's sintering densification started in 1500 °C; 70 green sample had not completed sintering in the 1600 °C, and at this temperature, to prolong the holding time also won't realize densification. After sintering at 1600 °C, the sample's bulk density is 2.82. In this sample, the mullite phase was uniform distribution, density, low porosity and most are closed porosity.
The present explains sintering characters of the Al2O3-86 homogenized bauxite under wet processes homogenization, which includes classified bauxite mine, wet grinding, vacuum extrusion, sintering in tunnel kiln,etc. DSC and TG reveal an evident peak of absorption heat at 531°C, resulting from the dehydroxylation of bauxite. Green samples held at 550°C*6hrs were heated up to different temperatures, and the properties of weight loss, linear change, bulk density and apparent porosity were measured. The data show that liquid-phase emerge and sintering process goes slowly above 1100°C. At 1500°C, large amounts of liquid-phase form, making liquid-phase sintering have a positive effect. The analysis of XRD and SEM indicate that, corundum grains develop more inadequate and most of the corundums interlace in a compact way, which can separate the widespread liquid phase and improve the sintering capability of homogenized bauxite.
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