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氧化铝表面短程、非双电层斥力研究

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:2001-09-21 修回日期:2001-11-06 出版日期:2002-11-20 网络出版日期:2002-11-20

Short-ranged Non-DLVO Forces between Alumina Surfaces

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:2001-09-21 Revised:2001-11-06 Published:2002-11-20 Online:2002-11-20

摘要: 利用原子力显微镜研究了MgCl2介质中氧化铝表面相互作用力随距离的变化.发现当MgCl2介质浓度为10-4mol/L,pH分别为3.96和7.92时,在两表面距离<10nm处存在一 短程非双电层排斥力.pH进一步提高到9.5,MgCl2介质浓度在10-4~10-2mol/L时,也存在短程排斥作用.它阻止了两表面由于范德华力产生的吸引.在较低和中等pH条件下,短程斥力来源于水合镁离子在氧化铝表面的特性吸附;在较高pH条件下,镁离子以各种氢氧化物形式吸附在氧化铝表面产生短程排斥力.随pH的升高,这种吸附层变得致密而失去弹性.

关键词: 氧化铝, 氯化镁, 短程斥力, 原子力显微镜

Abstract: The surface forces between alumina colloidal sphere and alumina flat surface in sodium chloride and magnesium chloride solutions were measured by atomic force
microscope. A short-ranged, non- DLVO force was observed in 10-4 mol/L MgCl2 solutions keeping the pH as 3.96 and 7.92 respectively. When pH was raised to 9.5,
the short-ranged repulsive force was also observed, it hindered the two surfaces close to each other due to the attractive Wan der Walls force. We proved that
in the first condition, the short-ranged non DLVO force was originated from the specific adsorption of magnesium ions, which could be verified from Zeta potential
measurements. In another case, this short -ranged repulsive force was from the specific adsorption of several kinds of magnesium hydroxides. With the rising of
pH, the adsorbed layer became dense and lost its elasticity.

Key words: α-Al2O3, magnesium chloride, short-ranged repulsive force, atomic force microscope

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