水溶液法制备NaNO_3-LiNO_3/石墨复合高温相变材料研究  

Study on high-temperature phase change composites of NaNO_3-LiNO_3/expanded graphite by saturated water solution method

作　　者：李月锋[1,2] 张东[1] 

机构地区：[1]同济大学材料科学与工程学院,上海201804 [2]上海应用技术学院理学院,上海201418

出　　处：《功能材料》2013年第10期1451-1456,共6页Journal of Functional Materials

基　　金：国家高技术研究发展计划(863计划)资助项目(2009AA05Z419);上海应用技术学院科学技术发展基金资助项目(KJ2011-05)

摘　　要：利用饱和水溶液法,在NaNO3和LiNO3混和溶液中添加膨胀石墨(EG),在温度90℃的水浴箱内用强力电动搅拌机搅拌,随后放入120℃电热恒温鼓风干燥箱内24h烘干,得到NaNO3-LiNO3/EG高温复合相变材料,并分别制备了EG含量为10%、20%、30%的相变材料。利用SEM、DSC、Hot-disk和自行设计的自动循环设备分别对复合相变材料的微观形貌、相变温度、潜热、导热系数以及热循环过程中储放热行为进行了测试。研究表明,NaNO3-LiNO3共晶盐能够被吸附到石墨片层之间,形成稳定、均一的复合相变材料。随EG含量的增加,复合相变材料的有效潜热不断降低,但是相变温度变化微小,相变材料本身的储热性能也没有显著的变化,因此EG没有改变相变材料的储热性能。EG含量的增加,会显著提高复合相变材料的导热系数,并且随EG含量的增加而不断增大。EG含量低的复合材料在多次蓄放热的热循环过程中,热稳定性较好。饱和水溶液法制备NaNO3-LiNO3/EG复合相变材料是一种非常有效的强化复合材料导热功能的制备方法。在实际应用中,要综合考虑储热量、导热性能和热稳定性等各方面因素进行优化选择,以便使储热系统能够高效率、快频率、长寿命地运行。The NaNOa-LiNO3/expanded graphite high-temperature phase change composite were prepared by saturated water solution method, with agitating the suspension in a water bath at a temperature of 90℃ and then drying it in an electric heating drying oven at a temperature of 120℃ over 24 hour. The composites with EG amount of 10%, 20% and 30% were prepared in the similar method. The morphology, phase change temperature and latent heat, thermal conductivity and endothermic and exothermic behavior during thermal cycling of EG composites were characterized by scanning electron microscopy （SEM）, differential scanning calorimetry （DSC）, Hot Disk thermal constants analyzer and self-designed automatic cycle equipment. The results show that the composites are uniform and well dispersed with the NaNOa-LiNOa eutectic adsorbed during the graph- ite laminar, and the thermal storage performance of the eutectic does not weaken with added EG. At increasing graphite amount, the thermal conductivity of the composite is found to progressively increase with intensifications up to 10 but the effective latent heat is found to reduce. The composite with lower graphite amount displays better thermal stability behavior. It is proven that saturated water solution method is a simple and effi- cient technique for improving the salt thermal conductivity. It is necessary to optimal selection and design between heat storage and thermal conductivity in practical applications.

关 键 词：NaNO3-LiNO3 膨胀石墨 饱和水溶液法 高温相变材料 

分 类 号：TB332[一般工业技术—材料科学与工程]