氧化铝-水纳米流体的分散性研究

Study on dispersion behavior of Al2O3-H2O nanofluids

通过在水介质中添加纳米氧化铝粒子，研制了一种新型传热冷却工质-氧化铝-水纳米流体，给出的纳米流体沉降照片和粒径分布显示了加入分散剂的悬浮液具有较高的分散性、稳定性．同时还测定了纳米Al2O3-水悬浮液的zeta电位和吸光度，探讨了不同pH值和SDBS分散剂加入量对纳米氧化铝粉体在水相体系分散稳定性的影响。结果表明：zeta电位的绝对值与吸光度有良好的对应关系，zeta电位绝对值越高，吸光度越大，粉体体系的分散性能越好；pH值约在8.0时，溶液的zeta电位绝对值较高，吸光度较大，说明此时有较好的分散效果．SDBS能显著提高水溶液中舢203表面zeta电位绝对值，增大了颗粒间静电排斥力，改善了悬浮液稳定性。在0．1％纳米Al2O3-水悬浮液中，SDBS分散剂最佳加入量（质量分数）为0．10％时，能得到分散稳定的悬浮液体系。

This paper presents a procedure for preparing a nanofluid which is solid-liquid composite material consisting of solid nanoparticles with sizes typically of 1-100rim suspended in liquid. By means of the procedure, Al2O3-H2O nanofluids with and without dispersant were prepared, whose sediment photographs and particle size distribution were given to illustrate the stability and evenness of suspension with dispersant. Aiming at the dispersion of nano-Al2O3 is regarded as the guide of heat transfer enhancement, the dispersion behavior of Al2O3 nanoparticles in water were studied under different pH values and different SDBS dispersant concentration by the method of zeta potential, absorbency and sedimentation photographs. The results show that zeta potential has good corresponding relation with absorbency, and the higher absolute value of zeta potential and the absorbency are, the better dispersion and stability in system is. The absolute value of zeta potential and the absorbency are higher at pH 8.0. Sodium dodecylbenzenesulfonate （SDBS） can significantly increase the absolute value of zeta potential of particle surfaces by electrostatic repulsions, which leads to the enhancement of the stability for Al2O3 nano-suspensions. In the 0.1% alumina nano-suspensions, the optimizing concentrations for SDBS is 0.10%, which has the best dispersion results.