Metal silicide-based thermocouples were fabricated by screen printing thick films of the powder compositions onto alumina tapes followed by lamination and sintering processes. The legs of the embedded thermocouples were composed of composite compositions consisting of MoSi2, WSi2, ZrSi2, or TaSi2 with an additional 10 vol % Al2O3 to form a silicide–oxide composite. The structural and high-temperature thermoelectric properties of the composite thermocouples were examined using X-ray diffraction, scanning electron microscopy and a typical hot–cold junction measurement technique. MoSi2-Al2O3 and WSi2-Al2O3 composites exhibited higher intrinsic Seebeck coefficients (22.2–30.0 µV/K) at high-temperature gradients, which were calculated from the thermoelectric data of composite//Pt thermocouples. The composite thermocouples generated a thermoelectric voltage up to 16.0 mV at high-temperature gradients. The MoSi2-Al2O3//TaSi2-Al2O3 thermocouple displayed a better performance at high temperatures. The Seebeck coefficients of composite thermocouples were found to range between 20.9 and 73.0 µV/K at a temperature gradient of 1000 °C. There was a significant difference between the calculated and measured Seebeck coefficients of these thermocouples, which indicated the significant influence of secondary silicide phases (e.g., Mo5Si3, Ta5Si3) and possible local compositional changes on the overall thermoelectric response. The thermoelectric performance, high sensitivity, and cost efficiency of metal silicide–alumina ceramic composite thermocouples showed promise for high-temperature and harsh-environment sensing applications.
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机译:通过将粉末组合物的厚膜丝网印刷到氧化铝带上,然后进行层压和烧结工艺来制造基于金属硅化物的热电偶。嵌入式热电偶的分支由复合成分组成,这些成分由MoSi2,WSi2,ZrSi2或TaSi2与另外的10 vol%Al2O3组成,形成硅化物-氧化物复合物。使用X射线衍射,扫描电子显微镜和典型的冷热结测量技术检查了复合热电偶的结构和高温热电性能。 MoSi2-Al2O3和WSi2-Al2O3复合材料在高温梯度下表现出较高的塞贝克系数(22.2–30.0 µV / K),这是根据复合材料// Pt热电偶的热电数据计算得出的。复合热电偶在高温梯度下产生高达16.0 mV的热电电压。 MoSi2-Al2O3 // TaSi2-Al 2 sub> O 3 sub>热电偶在高温下表现出更好的性能。发现在温度梯度为1000°C时,复合热电偶的塞贝克系数在20.9和73.0 µV / K之间。这些热电偶的计算塞贝克系数和测量塞贝克系数之间存在显着差异,这表明次级硅化物相(例如Mo 5 sub> Si 3 sub>,Ta 5 sub> Si 3 sub>)和整个热电响应的可能局部组成变化。金属硅化物-氧化铝陶瓷复合热电偶的热电性能,高灵敏度和成本效益显示出对高温和恶劣环境传感应用的希望。
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