氯化钠-硫酸钠/硅基相变材料的热物性研究

Thermal properties of sodium chloride⁃sodium sulfate/silicon⁃based phase change composites

采用高温熔融法制备NaCl-Na_(2)SO_(4)共晶熔盐,使用介孔MCM-41和微孔13X硅基材料为载体制备相变复合材料,研究相变复合材料的物相、结构、微观形貌及热物性的变化。结果表明,负载熔盐后硅基材料的孔结构保持完好,晶体结构维持不变,硅基材料作为骨架在高温下起到定型和提高稳定性的作用。NaCl-Na_(2)SO_(4)熔盐熔点为623℃,介孔MCM-41负载熔盐后其熔点为618℃,微孔13X负载熔盐后其熔点为607℃,负载熔盐后复合材料熔点略有降低。NaCl-Na_(2)SO_(4)熔盐在700℃的高温下质量损失率>3%,与其相比,负载MCM-41硅基材料后其分解温度提高,比热容为0.652 J/(g·℃),MCM-41硅基材料与共晶盐有良好的相容性。该研究能有效地改善熔盐在服役过程中的易泄漏和强腐蚀问题,具有重要的研究意义和应用价值。

NaCl-Na_(2)SO_(4) eutectic molten salts were prepared by the high temperature melting process.Composites phase change materials with silicon porous matrix were prepared by employing the mesoporous MCM-41 and microporous 13X as carriers for the problems of leakages and strong corrosion of molten salts.The changes in the structure,microtopography and thermophysical property of the composite phase change materials were investigated by the various methods.The results showed that the pore structure and crystalline structure of the silicon⁃based materials remained intact after the loading of molten salt.The silicon⁃based material as the skeleton played a role in setting and improving the stability at high temperature.The melting point of NaCl-Na_(2)SO_(4) molten salts was 623℃,the melting point of composites using the mesoporous MCM-41 was 618℃,and the melting point of composites using the microporous 13X was 607℃.The melting point of the composites was slightly reduced after loading with the molten salts.The weight loss of NaCl-Na_(2)SO_(4) molten salts was more than 3%at 700℃.The decomposition temperature of composites using MCM-41 was increased and the specific calorific value was 0.652 J/(g·℃).MCM-41 silicon⁃based material had good compatibility with eutectic salt.It could effectively improve the leakage and strong corrosion of molten salt in the service process and had important research implications and applications value.