Zhang Jian, Zhang Cheng, Zhu Ting, Yan Yonggao, Su Xianli, Tang Xinfeng
State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China.
ACS Appl Mater Interfaces. 2021 Sep 29;13(38):45736-45743. doi: 10.1021/acsami.1c12533. Epub 2021 Sep 14.
The CuSe compound possesses extraordinary thermoelectric performance at high temperatures and shows great potential for the application of waste heat recycling. However, a thermoelectric device usually undergoes mechanical vibration, mechanical and/or thermal cycling, and thermal shock in service. Therefore, mechanical properties are of equal importance as thermoelectric performance. However, the mechanical performance and stability of the CuSe compound during long-term service at high temperatures have rarely been reported. In this study, we systematically investigated the mechanical properties of CuSe compounds synthesized by three varied methods (melting (M), self-propagating high-temperature synthesis (SHS), and a combination of SHS and ultrasonic treatment (UT)) and investigated the thermal stability of the SHS-UT compound under different annealing temperatures. The SHS-UT process effectively refines the grain size from 19 μm for the melting sample to 5 μm for the SHS-UT sample. The high density of grain boundaries in the SHS-UT sample effectively dissipates the energy of crack propagation; thus, the mechanical properties are greatly improved. The compressive strength, bending strength, and Vickers hardness of the SHS-UT sample are 147 MPa, 52.6 MPa, and 0.46 GPa, respectively, which are 21.5, 16.6, and 35.3% higher than those of the melting sample, respectively. Moreover, excellent thermal stability is achieved in the compound prepared by SHS and ultrasonication at a temperature below 873 K. After annealing at temperatures up to 873 K for 7 days, the excellent thermoelectric performance of the CuSe compound is well maintained with a value exceeding 1.80 at 873 K. However, with further increasing the annealing temperature to 973 K, the volatilization of Se and the precipitation of Cu result in the instability and significantly deteriorated thermoelectric performance of the material. This work provides an avenue for boosting the mechanical properties and commercial application of CuSe.
硒化铜化合物在高温下具有优异的热电性能，在废热回收应用中显示出巨大潜力。然而，热电装置在使用过程中通常会经历机械振动、机械和/或热循环以及热冲击。因此，机械性能与热电性能同等重要。然而，关于硒化铜化合物在高温长期服役期间的机械性能和稳定性鲜有报道。在本研究中，我们系统地研究了通过三种不同方法（熔炼（M）、自蔓延高温合成（SHS）以及SHS与超声处理（UT）相结合）合成的硒化铜化合物的机械性能，并研究了SHS-UT化合物在不同退火温度下的热稳定性。SHS-UT工艺有效地将晶粒尺寸从熔炼样品的19μm细化至SHS-UT样品的5μm。SHS-UT样品中高密度的晶界有效地耗散了裂纹扩展的能量；因此，机械性能得到了极大改善。SHS-UT样品的抗压强度、抗弯强度和维氏硬度分别为147MPa、52.6MPa和0.46GPa，分别比熔炼样品高21.5%、16.6%和35.3%。此外，通过SHS和超声处理制备的化合物在低于873K的温度下具有优异的热稳定性。在高达873K的温度下退火7天后，硒化铜化合物优异的热电性能得到很好的保持，在873K时的优值超过1.80。然而，随着退火温度进一步提高到973K，硒的挥发和铜的析出导致材料的不稳定性和热电性能显著恶化。这项工作为提高硒化铜的机械性能和商业应用提供了一条途径。
