氧化铝粉体在硅溶胶中分散行为的研究

STUDY OF DISPERSION BEHAVIOR OF ALUMINA POWDERS IN SILICA SOL

利用 ζ电位、沉降实验、流变学测试研究了氧化铝粉体在硅溶胶中的分散行为 .研究发现 ,硅溶胶分散的氧化铝浆料在pH =10附近沉降最低和粘度最小 ,表明氧化铝在硅溶胶中分散的最佳 pH条件为 pH =10左右 .还发现氧化铝在硅溶胶中分散受硅溶胶浓度的影响较大 ,其浆料粘度随硅溶胶浓度的增加而减小 ,在其质量分数为 10 %～ 15 %之间达到最低 ;当浓度进一步增加时 ,其粘度呈现微小的增加 .为此 ,本研究指出 ,氧化铝在硅溶胶中分散机理为静电位阻稳定 ,这是由于带负电荷的氧化硅胶粒在氧化铝颗粒表面形成一包覆层 。

The dispersion behavior of alumina powders in silica sol was investigated by zeta potential, sedimentation and rheological measurements. It is found that the zeta potential of alumina in silica sol changes significantly in comparison with that of alumina in the deionized water, which can be attributed to the absorption of silica colloidal particles with negative charge on the surface of alumina particles. It is shown that sol-dispersed alumina slurry shows a minimum value in sedimentation volume and viscosity at the pH value of 10, which is indicative of the best dispersion of alumina in silica sol. The dispersion and stabilization of alumina particles in silica sol are therefore attributed to the electrostatic and steric effects resulting from the absorption of negatively charged colloidal silica particles.