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氯化镁介质中氧化铝表面的相互作用力

孙静; 高濂   

  1. 中国科学院上海硅酸盐研究所高性能陶瓷与超微结构国家重点实验室 上海 200050
  • 收稿日期:2001-03-20 修回日期:2001-05-10 出版日期:2002-03-20 网络出版日期:2002-03-20

Interaction Forces Between Alumina Surfaces in Magnesium Chloride Solutions

SUN Jing; GAO Lian   

  1. State Key Lab of High Performance Ceramics and Superfine Microstructure; Shanghai Institute of Ceramics; Chinese Academy of Sciences; Shanghai 200050; China
  • Received:2001-03-20 Revised:2001-05-10 Published:2002-03-20 Online:2002-03-20

摘要: 利用原子力显微镜研究了氯化镁介质中氧化铝表面的相互作用力随盐浓度、pH的变化规律.在中性条件下;当MgCl盐浓度由10-5mol/L增加到10-2mol/L时,长程排斥作用由于双电层压缩,作用范围从一百多纳米减弱到十几纳米,实验测得的双电层厚度的实际值与理论值较好的吻合.保持MgCl介质浓度不变;pH由3.64变化到9.09;氧化铝表面的相互作用始终表现为排斥力,与测得的Zeta电位值始终为正值相一致.当pH=9.5时,由于镁离子的水合氢氧化物在氧化铝表面的特性吸附,产生了短程非静电徘斥力,首次用原子力显微镜证实了Mg2+特性吸附层的存在,厚度约为5nm。

关键词: 原子力显微镜, 氧化铝, 氯化镁, 相互作用力

Abstract: The surface forces between alumina colloidal sphere and alumina flat surface in magnesium chloride
solutions were measured by an atomic force microscope. The forces between alumina surfaces were measured as a function of surface separation, salt
concentration, and pH. Experimental decay lengths for the repulsive electric double layer interaction were in good agreement with the theoretical Debye
lengths in the range of 0.0001mol/L to 0.01mol/L. The Debye length decreased with the increasing of the salt concentrations due to the compression of the
electric double layer. No attractive force could be detected in the pH range between 3.64 and 9.09, and the zeta potential was always positive, which
strongly verified the existence of the specific adsorption. The short-ranged non-DLVO forces were observed in the magnesium chloride solutions at pH 9.52.
Magnesium ions took the form of Mg(OH)+ and Mg2(OH)3+ to form the adsorption layer, which changed into precipitation layer with the rise of pH,
the thickness was estimated as 5nm.

Key words: atomic force microscope, α-Al2O3, magnesium chloride, interaction force

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