高热导率和机械稳定性的La(Fe,Si)₁₃/Cu制备及热、磁、机械性能研究

Synthesis of La(Fe,Si)₁₃/Cu Magnetocaloric Composite with High Thermal Conductivity and Mechanical Stability

摘要: La(Fe,Si)₁₃磁热材料居里温度仅有210 K左右，远低于室温，需要对其进行吸氢处理，使得材料的居里温度升至室温附近。然而La(Fe,Si)₁₃块体在吸氢过程中材料的体积会发生膨胀，导致其破碎成粉末。本研究采用化学镀和热压的方法制备出了La(Fe,Si)₁₃/Cu复合材料，并借助显微镜、X射线衍射仪、能谱仪、综合物性测量系统等研究了其显微形貌、磁相变行为、导热性能及机械强度。本研究获得的具有网格状导热通道的La(Fe,Si)₁₃/Cu磁热复合材料的热导率和抗压强度显著提高。由此可见，本研究所提出的新结构和制备方法也适用于其他磁热材料，并且将显著提高其磁热性能中的热性能和力学性能，从而为磁制冷机和热磁发电机的商业化铺平道路。

Abstract: The Curie temperature (T_C) of the La(Fe,Si)₁₃ magnetocaloric material is about 210 K, far below room temperature. Hydrogenation is needed to raise the T_C to room temperature. However, the La(Fe,Si)₁₃ bulk materials will break into powders after hydrogenation due to the volume expansion during hydrogenation. In the present work, La(Fe,Si)₁₃/Cu magnetocaloric composite have been successful synthesized by electroless plating and hot pressing. The microscopic morphology, magnetic phase transition behavior, thermal conductivity and mechanical strength have been studied using microscope, X-ray diffractometer, energy dispersive spectroscope and physical property measurement system, etc. The La(Fe,Si)₁₃/Cu magnetocaloric composite with continuous Cu network significantly improve the thermal conductivity and compressive strength. The proposed novel microstructure and synthesis methods are also applicable to other magnetocaloric materials, which will significantly improve the thermal and mechanical properties of magnetocaloric properties and hence pave the way for the commercialization of magnetic refrigerators and thermomagnetic generators.