纳米TiO_2包覆Al_2O_3珠光颜料的制备及表征

Preparation and characterization of nano-TiO_2 coated Al_2O_3 pearlescent pigment

文章采用熔盐法制备了片状Al2O3粉体,以片状Al2O3粉体为基材,TiCl4为钛源,尿素为缓冲剂,用液相沉积法制备纳米TiO2/Al2O3珠光颜料。通过正交实验考察了反应温度、反应初始pH值、反应时间、钛盐质量分数和尿素加入量对包覆率的影响,得到了制备TiO2/Al2O3珠光颜料前驱体的最佳工艺条件,并确定了影响前驱体包覆率各因素的主次顺序。借助XRD、SEM以及EDS对制备的粉体进行表征,结果表明,熔盐法制备的Al2O3粉体层片结构非常明显,表面平坦光滑,平均粒度为6.18μm,厚度均匀且薄,径厚比大;在优化工艺条件下制得的纳米TiO2/Al2O3珠光颜料粉体表面包覆着一层致密光滑的TiO2薄膜,包覆层为金红石型TiO2,包覆率为27.65%。

The flaky Al2O3 powder was prepared by molten salt method. Nano-TiO2/Al2 O3 pearlescent pigment was prepared by liquid deposition method, using flaky AlcOa as substrate, TiCl4 as titanium source and urea as precipitant. The optimal technical parameters to make the precursor of TiO2/Al2 O3 pearlescent pigment were achieved with orthogonal experiments. The reaction temperature, initial pH value, reaction time, the concentration of TiCl4 and the amount of the urea additive in precursor were regarded as main factors influencing the coating rate of TiO2 on Al2O3 in the orthogonal experiment. The primary and secondary orders of those factors were also studied. The obtained TiO2/Al2o3 products were characterized by XRD, SEM and EDS, and the results showed that the flaky Al2O3 powder prepared with molten salt method was laminary in shape with a clear and smooth surface. The average particle size was 6.18μm and a thin and even thickness and a large aspect ratio were exhibited. Under the optimal technical conditions, the obtained nano-TiO2/Al2 O3 pearlescent pigment powder was coated by a layer of TiO2 thin film with a dense and smooth surface without rift. TiO2 was futile in structure and the coating rate of the pigment was 27.65%.