浸渍工艺及烧成温度对SiO2纳滤膜微观结构的影响

以平均粒径为10 nm和80 nm的硅溶胶为主要原料,采用浸渍提拉法在50 nm超滤支撑体上制备了SiO2纳滤膜.研究了烧成温度对膜层密度和气孔率、物相组成、热膨胀及显微结构的影响,探讨了溶胶浓度与膜厚度的关系,确定了合适的烧结温度和镀膜工艺.结果表明:随烧结温度升高至800℃以上时,SiO2纳滤膜的密度显著提高,在850℃以上会析出方石英相,导致其在200℃左右因方石英相变而出现膨胀突变;600℃和700℃分别是10 nm和80 nm硅溶胶制备的SiO2纳滤膜的合适烧结温度;以浓度为16.9wt％的10 nm硅溶胶镀膜在600℃烧成后可以形成微结构均匀、厚度约1μm的SiO2纳滤膜.

Effect of Impregnation Process and Sintering Temperature on the Microstructure of SiO2 Nanofiltration Membrane

SiO2 nanofiltration membrane was prepared on 50 nm ultrafiltration support by impregnation method using silica sol with average diameter of 10 nm and 80 nm as raw material .The effects of sintering temperature on the membrane density and porosity , phase composition , thermal expansion and microstructure were investigated .The influence of sol concentration on film thickness was explored , and the suitable sintering temperature and coating process were determined .The results show that the density of SiO2 nanofiltration membrane is increased with the raising of temperature up to 800 ℃, and a cristobalite phase is formed when the temperature up to 850 ℃, which leads to the expansion of the membrane change greatly at about 200 ℃.600 ℃and 700 ℃are the appropriate sintering temperature for 10 nm and 80 nm silica sol respectively .A nanofiltration membrane with uniform microstructure and 1μm thickness was obtained coating with 10 nm silica sol in 16.9wt％concentration and sintering at 600℃.