Study On The Corrosion Resistance Of Macroporous Alumina Support

Macroporous supports played an important role in preparation and application of ceramics membrane. In order to decrease the sintering temperature, macroporous supports always consist of alumina and a certain number of sintering aids such as kaolinite. The strength of macroporous supports immerged in NaOH solution decreased greatly with time prolonged because of the existence of kaolinite. In this paper, a series of research work has been done in order to improve the corrosion resistance of supports.The influence of morphology of starting alumina grain on the pore structure and corrosion resistance of supports was studied preliminarily, which suggested that alumina powder with mean particle size of 24μm was suited for the preparation of macroporous supports. In order to solve the low corrosion resistance of high purity alumina supports , the main work in this dissertation is as follows:1. The influence of the composition of intergrain phase on the properties of high purity alumina macroporous supports was studied extensively. Supports had good corrosion resistance when the R(Al₂O₃/( Al₂O₃+ SiO₂)) value was 71.8% in the intergrain phase which was composed of kaolinite and ultrafine alumina. When the Sintering temperature was 1600℃, the weight loss of such supports immerged in NaOH solution (80℃C,10wt%) for 168h was 1.37%.The presence of glass phase leads to the decrement of strength of high alumina supports.2. The influence of TiO₂ content on the properties of high alumina macroporous supports was studied. When the content of titania in the intergrain phase was 1wt%,disk supports had better corrosion resistance than that of supports consisting of Al₂O₃—SiO₂ system. When the Sintering temperature was 1600°C, the weight loss of such supports immerged in NaOH solution (80°C,10wt%) for 168h was 0.87%.3. Tubular macroporous supports with Al₂O₃ —SiO₂ system and with Al₂O₃ — SiO₂ —TiO₂ system which R value was 71.8% in intergrain phase were prepared, respectively. Effect of the sintering temperature on the properties of two kinds oftubular macroporous supports were investigated. Tubular macroporous supports with AI2O3—S1O2—T1O2 system had better corrosion resistance than that of supports with AI2O3 — S1O2 system. Although three point bending strength of those supports decreased greatly after corroded in NaOH solution (80°C,10wt%) for 24h, the bending strength of tubular macroporous supports with AI2O3 —SiO2^<sup>TiO2 system could keep at a applicable level 15 to 18MPa as time prolonged, which was suitable for industrial use. The bending strength of tubular'tnacroporous supports with AI2O3 — SiO2 system kept only 3 to 5MPa as corrosion time prolonged.4. Macroporous supports with 99% alumina content had better corrosion resistance than that of aforementioned high purity alumina macroporous supports. Three point bending strength of supports with 99% alumina content had almost no change after corroded in NaOH solution (80°C,10wt%) for 168h.