磁场驱动的双核水基纳米流体的自组装凝固

To achieve stable water-based nanofluids with high concentrations and their high-quality crystals containing evenly distributed nanoparticle. In the proposal, ZrP nanodisks with strong ion-exchange capacity are chosen to adsorb small Al nanoparticles to form dikaryon and their surface properties are further modified during the preparation of nanofluids. The preparation method of Al/ZrP particles as well as the effects of Al/ZrP mass ratio and surfactant concentration on the particle size and the limiting concentration of stable nanofluids is studied. Magnetic field and temperature field are introduced to process the self-assembling solidification of nanofluids during which the Al/ZrP particles are engulfed by the solidification front methodically and uniformly. Modern testing means such as PIV、light scattering、light microscope and high-speed imaging technologies are adopted to investigate the movement characteristics of Al/ZrP particles and solidification front driven by the magnetic field and temperature field. Explore the mass and energy transfer mechanisms during the engulfment process to characterize the communication among the Al/ZrP particles and solidification front during the self-assembling solidification of nanofluids. Some quantitative relationships will be created between the self-assembling solidification rate and the magnetic field intensity and temperature gradient. The self-assembling solidification technology would be developed by controlling magnetic field for nanofluids. This research will enhance the thermal conductivity of nanofluids, and resolve the failure problems of nanofluids due to the rejection of nanoparticles by the advancing solidification front, which definitely is of significant academic value and has bright application prospects.

本项目以提高水基纳米流体的浓度，及其在固液相变中纳米颗粒的分散稳定性为目标，选取有强吸附作用的纳米碟片ZrP装载纳米粒子Al设计制备双核纳米基元，辅以分散剂的表面修饰与改性作用，提升纳米流体的稳定分散浓度。揭示纳米颗粒的浓度配比和分散剂浓度对基元尺度、纳米流体极限浓度的控制作用，探索尺度均匀的双核纳米基元制备方法；利用外磁场与温度场的协同作用来驱动固液界面有序"吞噬"基元的自组装凝固过程。通过PIV、光散射、光显微和高速成像等测试手段，观察在磁场与温度场作用下固液界面与双核粒子的运动特征，探索二者碰撞时的质量与能量传递机制以刻画其协同行为对自组装过程的调控作用，揭示"自组装"凝固速率与磁场强度和温度梯度之间的内在定量关系，建立一套磁场驱动控制的纳米流体"自组装"结晶技术。该研究有利于提高纳米流体的导热能力，避免了纳米颗粒被固液界面"排泄"而沉降带来的工质失效，具有重要的学术和应用价值。

本项目以提高水基纳米流体的浓度，及其在固液相变中纳米颗粒的分散稳定性为目标，选取有强吸附作用的纳米碟片ZrP装载纳米粒子TiO2设计制备双核纳米基元，辅以分散剂的表面修饰与改性作用，提升纳米流体的稳定分散浓度。揭示纳米颗粒的浓度配比和分散剂浓度对基元尺度、纳米流体极限浓度的控制作用，探索尺度均匀的双核纳米基元制备方法；利用外磁场与温度场的协同作用来驱动固液界面有序"吞噬"基元的自组装凝固过程。通过光显微和高速成像等测试手段，观察在磁场与温度场作用下固液界面与双核粒子的运动特征，探索二者碰撞时的质量与能量传递机制以刻画其协同行为对自组装过程的调控作用，揭示"自组装"凝固速率与磁场强度和温度梯度之间的内在定量关系，建立一套磁场驱动控制的纳米流体"自组装"结晶技术。该研究有利于提高纳米流体的导热能力，避免了纳米颗粒被固液界面"排泄"而沉降带来的工质失效，具有重要的学术和应用价值。