Preparation and performance of different aluminum filmson titanium dioxide surface

Using sodium metaaluminate, aluminum sulfate and phosphoric acid as raw materials, different aluminum films were prepared at various pH values. Crystal structure, thermal stability, microstructure and physical properties of the films were analyzed by XRD, infrared spectroscopy, thermogravimetry, SEM, BET, ZETA potential. The results show that the ZETA potentials of the hydrated alumina obtained at different pH are all positive with poor hydrophilic properties, while the ZETA potential of aluminum phosphate is negative with good hydrophilic properties. The hydrated alumina obtained at pH = 4～5 has a nearly spherical amorphous structure, and it loses the bound water at 200 ℃ and 930 ℃. AlO(OH) obtained at pH = 8～9 has a flocculent boehmite structure with a large specific surface area and it loses the bound water at 402 ℃. The granular bayerite block with clear interface and uneven size distribution can be obtained at pH = 10～10.5, which loses the bound water at 297.5 ℃ and 513 ℃, respectively. Amorphous aluminum phosphate is prepared by adding phosphoric acid into sodium metaaluminate, whose morphology is an aggregate of spherical small particles. The order of absorption in the ultraviolet region from strong to weak is amorphous hydrated alumina> aluminum phosphate> gibbsite> boehmite hydrated alumina. The pigment performance of titanium dioxide can be improved by coating of these aluminum compounds on the surface of titanium dioxide, but hydrated alumina will reduce the water dispersibility of titanium dioxide.