Study On Preparation Of Al₂O₃-SiO₂-ZrO₂ Composite Membrane By Sol-Gel Method

For the enhanced properties of the inorganic ceramic membrane such as thermal stability, chemical durability and high strength , more and more importance has been put on it in technological and industrial fields. It has been being used in environment protection engineering. Micro-porous Al₂O₃ membrane is a kind of inorganic membrane which is investigated widely in recent years. But with the applying in the high temperature field, its thermal stability become an important problem that needs urgent solution.In this paper, the effects of SiO₂ and ZrO₂ on Al₂O₃ membrane were mainly studied, also the preparation process of Al₂O₃-SiO₂-ZrO₂ composite membrane by sol-gel method was discissed in detail. Porous composite membrane was obtained through controlling various factors. After filtration process, the results showed that the filtration effect of sewage was satisfactory. DTA and XRD patterns showed that the membrane calcined at 1000℃was composed ofγ- Al₂O₃, t -ZrO₂ and amorphism SiO₂, the phase transformation wasn't occurred until 1200℃.During the preparation of AlOOH sol , Effects of peptizator, H2O/AL,hydrolysis time, hydrolysis temperature, aging time and composition were studied, it had been found that preparation period could be shortened by extending hydrolysis time. It was possibily because that , iso-propanol produced in the reaction could be volatilized when extending hydrolysis time, its harmful role to peptization process could be avoid in this condition.Impregnant and chemical constituents were studied as the main factors during the preparation of SiO₂-ZrO₂ sol. The influnce of chemical constituents and concentration on AlOOH-SiO₂-ZrO₂ sol were also studied. The results showed that composite sol was stable when AlOOH:SiO₂:ZrO₂ was 8:2.3:1～10:2.3:1, the particle size was minor in this ratio. Hence, sol grew according to RLCA model when AlOOH concent was little, DLCA model was available when AlOOH concent was big.SEM pictures of membrane showed that, the composite membrane was consist of flakes, Al₂O₃ concent was large, so it was similar to Al₂O₃'s. Al₂O₃ particles were attracted by SiO₂ paticles and ZrO₂ particles.