纳米流体的制备及稳定性分析

Preparation and Stability of Nanofluids

采用"两步法"制备了Al__2O_3-水和SiO_2-水纳米流体,并分别采用十二烷基硫酸钠(sodium dodecyl sulfonate,SDS)和阿拉伯树胶(Arabic gum,AG)作为分散剂。通过圆环法测定了25℃时SDS水溶液的临界胶束浓度(critical micelle concentration,CMC)。利用悬浮物测试仪分析了纳米流体的稳定性,并着重分析比较了超声分散时间、分散剂浓度、分散剂种类对纳米流体稳定性的影响。分析结果表明:Al_2O_3纳米颗粒在超声分散3 h时具有最佳的稳定性,SiO_2纳米颗粒在超声分散5 h时获得最佳稳定性。添加阴离子表面活性剂SDS的质量分数在CMC附近时,对两种纳米流体均具有最好的稳定性,而高分子表面活性剂AG的质量分数与纳米粒子的质量分数相仿时,具有最好的稳定性。

Sodium dodecyl sulfate( SDS) and Arabic gum( AG) were adopted as the dispersant to prepare the Al_2O_3-water and SiO_2-water nanofluids via two steps method. The critical micelle concentration( CMC) of SDS solution at 25 ℃ was determined by ring method. By intelligent suspended matter,the effects of ultrasonic dispersion time,dispersant concentration and dispersant type on the suspension stability of nanofluids were analyzed. The results show that Al_2O_3-water nanofluids has the best stability in ultrasonic dispersion for 3 hours while the SiO 2-water nanofluids has the best stability in ultrasonic dispersion for 5 hours. Two types of nanofluids have the best stability when the the mass concentration of anionic surface active agent SDS is around CMC. When the high molecular surfactant AG is added in the same as the nanoparticle's mass concentration,two types of nanofluids also have the best stability.