摘要：为了提高TiO₂纳米流体的导热性能,将Ag纳米颗粒与TiO₂纳米颗粒混合,利用两步法制备出不同银钛物质的量比的Ag-TiO₂纳米悬浮液,并研究其导热性能与黏性。采用X射线衍射仪和扫描电子显微镜表征Ag-TiO₂纳米颗粒晶型和形貌;通过沉降法、激光粒度分析和吸光度测量法探究Ag-TiO₂纳米悬浮液的稳定性。结果表明:Ag纳米颗粒含量低有利于Ag-TiO₂纳米悬浮液稳定;质量分数为0. 3%的银钛物质的量的比为1∶6、1∶4、1∶2的Ag-TiO₂悬浮液,导热系数在常温下比TiO₂悬浮液导热系数分别增加了0. 83%、1. 66%、2. 33%,而黏度与基液水相比分别增加了37. 5%、27. 5%、22. 5%;银钛物质的量比为1∶2的Ag-TiO₂纳米悬浮液导热系数高于银钛物质的量比为1∶6和1∶4悬浮液的,而其黏度却低于银钛物质的量比为1∶6和1∶4悬浮液的。

关键词：Ag-TiO₂纳米颗粒；悬浮液；稳定性；导热性能；黏度

Abstract: In order to improve the thermal conductivity of TiO₂ nano-fluids，three kinds of silver － titanium dioxide ( Ag－ TiO₂ ) nano-particle suspension with 1∶6，1∶4 and1∶2 mole ratios of Ag∶Ti were prepared using two-step method．The characterization of Ag－TiO₂ nano-particle was confirmed by XＲD and SEM．The stability of nano-particle suspension was described by the gravity sedimentation，laser diffraction particle size analyzer and absorbance measurement．The result shows that the relatively lower mole contents of Ag nano-particles in Ag－TiO₂ nano-suspension have better stability．The thermal conductivity and viscosity of three kinds of Ag－TiO₂ nano-particle suspensions were experimentally investigated．It is found that the thermal conductivities with 1∶6，1∶4 and 1∶2 mole ratios of Ag∶Ti are increased by 0．83% ，1．66% and 2．33% respectively compared with that of TiO₂ suspension at room temperature for mass fraction of 0．3% ，while the viscosity increased by 37．5% ，27．5% and 22．5% respectively compared with that of water．The thermal conductivity of Ag－TiO₂ nanoparticle suspensions with 1∶2 molar ratio of silver－titanium dioxide is higher than that of the suspensions with 1 ∶ 6 and 1 ∶ 4 molar ratios．Inversely，the viscosity is lower than that of the suspensions with 1∶6 and 1∶4 molar ratios． 

Keywords: Ag－TiO₂ nano-particle; nano-particle suspension; stability; thermal conductivity; viscosity