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开展了ZrNiSn热电块体材料的微波快速合成-烧结研究,并对样品的物相组成、电性能、热性能、微观结构和综合热电性能进行了测试和表征分析。相组成分析表明,采用微波固相合成在4~5 min内即获得了单一相纯度很高的ZrNiSn合金,但存在少量杂质Sn;合成样品经30 min微波烧结后,部分Sn因二次反应而消除。电性能分析表明,电阻率较高为13.7~16.9μ?·m,从而对功率因子产生较大影响,功率因子最高为1683μW·m~(-1)·K~(-2)。热性能分析表明,ZrNiSn样品的热导率随着温度升高而降低,热导率最大为4.288 W·m~(-1)·K~(-1),晶格热导率仅为2.86~3.96 W·m~(-1)·K~(-1),热性能良好。微观结构分析表明,微波烧结抑制了ZrNiSn晶粒长大,ZrNiSn基体晶内和晶界分布有大量纳米晶粒,绝大部分属于晶内析出,且分布较均匀,少部分分布在晶界。综合热电性能ZT值随测试温度的增加显著上升,在573~673 K获得最大值0.25。
The microwave rapid synthesis - sintering of ZrNiSn thermoelectric bulk materials was carried out. The phase composition, electrical properties, thermal properties, microstructure and thermoelectric properties of the samples were tested and characterized. The phase composition analysis showed that ZrNiSn alloy with high single phase purity was obtained in 4 ~ 5 min by microwave solid phase synthesis, but there was a small amount of impurities Sn. After 30 min microwave sintering, part of Sn due to secondary reaction eliminate. The analysis of electrical properties shows that the higher the resistivity is from 13.7 to 16.9 μΩ · m, which has a great influence on the power factor, with the highest power factor of 1683 μW · m -1 · K -2. Thermal analysis shows that the thermal conductivity of ZrNiSn samples decreases with the increase of temperature, the maximum thermal conductivity is 4.288 W · m -1 K -1, the lattice thermal conductivity is only 2.86 ~ 3.96 W · m -1 K -1, the thermal performance is good. The results of microstructure analysis show that microwave sintering restrains the growth of ZrNiSn grains, and a large number of nanocrystalline grains are distributed in the grain boundaries and grain boundaries of ZrNiSn. Most of the grains are precipitated in the grains and distributed more uniformly and less in the grain boundaries. The ZT value of the comprehensive thermoelectric properties increased significantly with the increase of the test temperature and reached a maximum value of 0.25 at 573-673 K.