纳米铜/石蜡相变驱动复合材料制备及热物理性能

采用高能球磨法制备了纳米铜/石蜡复合材料。通过TEM、 SEM、 XRD和DSC对复合材料的微观形貌、 物相及相变温度和潜热进行了表征和分析, 并研究了铜含量对复合材料的热敏性、 热膨胀性和热稳定性的影响。结果表明: 石蜡包覆在铜粒表面, 能显著提高其抗氧化性, 铜/石蜡复合颗粒近似球形, 粒径约为100 nm, 多个复合颗粒易团聚形成微米级颗粒; 铜含量对相变温度没有明显影响, 但相变潜热随铜含量的增加近似线性减少; 复合材料的热敏性随着铜含量的增加而提高, 但其热膨胀性则降低; 铜质量分数为60%的复合材料具有较短的升温时间, 体膨胀率降低较小, 且多次加热后稳定性较好, 可作为此类热敏微驱动器的理想材料。

Preparation and thermal performance of nano-copper/paraffin phase change composites for actuation

The nano-copper/paraffin composites were prepared by high energy ball milling. The microstructure, phase and thermophysical properties such as phase change temperature and latent heat enthalpy were characterized by means of TEM, SEM, XRD and DSC, and the impact of nano-copper particles on the thermal expansion, thermal sensitivity and thermal stability was also investigated. The results show that paraffin enwraps copper particles to form near-spherical composite particles with a mean size of 100 nm, which improves the antioxidant ability of nano-copper particles effectively. Those nano-composite particles tend to agglomerate to form micron-sized clumps of particles. Nano-copper particles do not exert noticeable effect on the phase change temperature, but the latent heat enthalpy of the nano-copper/paraffin composites decreases linearly with an increase of copper content. The thermal sensitivity of the composites improves effectively with the increasing of the copper content, while the thermal expansion decreases with the loading increasing. It is clear that the composites containing 60% mass fraction of copper is a desirable material for microactuator, with short heating time, a small decrease in volume expansibility and excellent thermal stability after being heated for many times.