SPS烧结工艺对填充方钴矿热电性能的影响

Effect of Spark Plasma Sintering on Sintering Process of Filled Skutterudites Thermoelectric Properties

采用熔融淬火和高温退火法合成填充方钴矿Yb0.3Co4Sb12块体,用高能球磨的方法将已经填充的方钴矿研磨为微纳米级粉末,然后采用等离子体快速烧结(SPS)技术将其烧结成块体材料。通过XRD分析材料的物相结构,使用SEM和TEM观察粉体和块体材料的微观形貌,发现高能球磨后的晶粒尺寸为50~500nm,分布较宽。重点研究讨论了烧结温度和烧结压力等烧结工艺对热电传输性能的影响:发现随着烧结温度的提高,材料的热电性能先升高后降低,这是由于烧结温度的升高使得样品致密度有效提高,引起材料热电性能提升,而过高的烧结温度造成材料晶粒异常长大导致材料的热导率提升,热电性能劣化;提高烧结压力可以略微提高样品的致密度与热电性能。研究发现,当烧结温度约为875K、烧结压力约为90MPa时,材料的热电性能最佳,热电优值(ZT值)在750K时达到1.19。

In this study,filled skutterudites Yb 0.3 Co 4 Sb 12 were synthesized by meltting quenching and annealing method. Then high-energy ball milling was employed to prepare micro/nano-structured powders. After that bulk materials were sintered by the technology of spark plasma sintering (SPS). The phase structure and morphology of the powder and the bulk materials were studied by XRD,SEM and TEM. The grain size after high-energy ball milling was 50~500 nm and the distribution is wide. The thermoelectric properties of the samples with different sintering processes like sintering temperature and sintering pressure were investigated in detail. The results show that with the increase of sintering temperature,the thermoelectric properties first increase and then decrease,which is caused by the increase of the sample density first and then the grain growth. And the densities and thermoelectric properties can be improved slightly by increasing sintering pressure. After sintered at about 875 K with 90 MPa,the thermoelectric properties of the material are the best,and the thermoelectric figure of merit (ZT value) reached 1.19 at 750 K.