ZnO改性Al_2O_3颗粒表面荷电性研究

Surface Charge Effect of Alumina Powders Modified by Zinc Oxide

以硝酸锌、尿素为主要原料,采用均相沉淀法在Al2O3粉体颗粒表面制备了纳米ZnO改性涂层,涂层由5～10nm的ZnO颗粒组成。宏观电泳测试和Zeta电位分析表明,经ZnO改性前后Al2O3颗粒在水溶液中的表面荷电性能发生了明显的改变,未改性Al2O3的Zeta电位等电点为pH=6.3,而ZnO涂层改性Al2O3颗粒在pH=2.2～12时均显示出荷负电性能。采用XRD、EDS能谱及拉曼光谱等分析测试并结合纳米ZnO的表面晶体结构特征,对ZnO改性Al2O3颗粒表面的负电荷来源进行了探讨。

For the modification of α-Al2O3 powders,the nano-crystalline ZnO coating was prepared by homogeneous precipitation method using zinc nitrate and urea as raw materials.The obtained coating composed of 5-10 nm grains is dense and uniform.Results show that the surface charge of Al2O3 powders changes obviously after modifying by nano-crystalline ZnO coating,through macroscopical electrophoresis testing and Zeta potential measurements.The isoelectric point is at pH=6.3 for unmodified Al2O3,but after modification with ZnO,its isoelectric point shifts towards a lower pH value,and modified Al2O3 particles is negatively charged at pH=2.2-12.The origins of surface net negative charge on modified Al2O3 particles were investigated by means of XRD,XPS,EDS energy spectrum and Raman spectrum,together with the surface characteristic of nanometer ZnO crystal structure.