硝酸对AlOOH溶胶流变特性的影响

为控制氧化铝陶瓷膜制备中的涂膜工艺,以异丙醇铝为原料,硝酸为胶溶剂,制备了AlOOH溶胶。通过旋转流变仪、Zeta电位分析仪等表征手段,研究了硝酸用量对AlOOH溶胶流变特性的影响。结果表明,硝酸与异丙醇铝摩尔比R(n(HNO₃):n(Al(C₃H₇O₃)₃))为0.3~0.6时,AlOOH溶胶表现出假塑性流体特征。通过Herschel-Bulkley模型拟合流变测试数据得到的流动指数随着R的增大而减小,稠度系数随之增大;振幅扫描中储能模量(G′)与损耗模量(G″)均随着R增大而上升;频率扫描中G′与G″的交点随着R的增大而逐渐靠近低频。随着R的增大,AlOOH溶胶假塑性增强,稠度增大,弹性与黏性均上升,更易转变为凝胶。当R≥0.7时已经转化为凝胶,不再符合流体规律。Zeta电位的高低影响AlOOH溶胶的分散性,进而影响上述现象。

Influence of HNO3 on Rheological Properties of AlOOH Sol

In order to control the coating process in the preparation of alumina ceramic membrane, AlOOH sol was prepared by using aluminum isopropoxide as the raw material and HNO₃ as the peptizer. The influence of the amount of HNO₃ on the rheological properties of AlOOH sol was studied through rotational rheometer and Zeta potential measurement. The results show that when the molar ratio of HNO₃ to aluminum isopropoxide R(n(HNO₃):n(Al(C₃H₇O₃)₃)) is in the range of 0.3 to 0.6, AlOOH sol exhibits pseudoplastic fluid characteristics. The Herschel-Bulkley model was used to fit the rheological test data. As R increases, the fluid index (n) decreases, while the consistency coefficient (k_HB) increases. The storage modulus (G′) and loss modulus (G″) increase with the increase of R. The intersection of G′ and G″ in the frequency sweep gradually approaches the low frequency with the increase of R. With the increase of R, the pseudoplasticity of AlOOH sol increases, the consistency increases, the elasticity and viscosity both increase, and it is easier to gelation. While R is above 0.7, it has been transformed into a gel, which does not conform to the fluid law. The level of the Zeta potential affects the dispersibility of the AlOOH sol, thereby affects the above phenomenon.