SiO2和Al2O3在TiO2表面的成核包覆与成膜包覆

从理论和实验上研究了ＴｉＯ２表面包覆的机理和工艺条件，分析了ＴｉＯ２成膜包覆与成核包覆的动力学控制因素，并提出了 ＴｉＯ２与包覆物之间的微观结构模型．实验研究了对 ＴｉＯ２进行硅、铝二元包膜的过程，测得二氧化钛在浆液中的等电点为 ３．６． ｐＨ＝１０左右有最大的Ｚｅｔａ电位，有利于颗粒分散．硅酸聚合速度研究表明，ＰＨ＝９～１０时硅酸聚合速度降低，有利于形成均匀致密的膜，因而最佳包覆ｐＨ值为９～１０．从ＸＰＳ 谱中钛的 ２ｐ轨道电子结合能推测，包覆层的硅和铝是以化学键结合于 ＴｉＯ２表面．

TiO2 PARTICLE COATING AND STRUCTURE ANALYSIS OF SURFACE COATED WITH SiO2 AND Al2O3

Photochemical activity of TiO2 can be reduced through surface coating, which favors to increase dispersiveness, weather resistance and antipulverization. The binary coating process of Si and Al to TiO2 was studied experimentally. The isoelectic point of TiO2 in slurry was determined to be 3.6. Maximum Zeta potential occurred at pH equaling 10, which favors dispersion of particles. Measurement on the aggregation rate of Si and Al indicate that when pH is between 9 and 10, the aggregation rate of silicon acid is small, which favors to form homogeneous and compact membrane. Thus, the optimal condition for coating is pH between 9 and 10. According to the difference of 2p orbital electron binding energy of Ti obtained from XPS before and after coating, it can be inferred that Si and Al in the coating layer are combined to TiO2 surface through chemical bond.