功能-结构一体化NiCr/NiSi薄膜热电偶的制备

Fabrication of NiCr/NiSi Thin Film Thermocouples With the Incorporating Function and Structure

采用多层薄膜结构制备了NiCr/NiSi薄膜热电偶,该薄膜热电偶依次由Ni基超合金基片、NiCrAlY过渡层、Al_O_3热氧化层、Al_O_3绝缘层、NiCr/NiSi薄膜热电偶层以及Al_O_3保护层构成。主要研究了热电偶层薄膜厚度和时效处理对热电偶性能的影响以及温度对Al_O_3绝缘层绝缘性的影响。静态标定结果表明,热电偶层厚度对NiCr/NiSi薄膜热电偶性能几乎没有影响。时效处理可显著提高NiCr/NiSi薄膜热电偶的热电性能和相对灵敏度。所制备的NiCr/NiSi薄膜热电偶的Seebeck系数达到37μV/K,最大相对灵敏度达到0.9左右。Al_O_3绝缘层在垂直方向的绝缘性随温度的升高而降低,在室温至300℃范围内,Al_O_3绝缘层在垂直方向的绝缘电阻大于100 MΩ,当温度升高到900℃时,Al_O_3绝缘层在垂直方向的绝缘电阻下降为16 kΩ。

NiCr/NiSi muhilayer thin film thermocouples are fabricated. The samples are multilayer structure which is composed of Ni-based superalloy substrates, NiCrA1Y buffer layer, thermal grown Al2O3layer, Al2O3 insulating layer, NiCr/NiSi thin film thermocouple layer and Al2O3 protecting layer. The influences of thickness of NiCr/NiSi thermocouple layer and the ageing treatment on the thermoelectrical properties are explored in detail The influences of temperature on the perpendicular resistance of Al2O3 insulating layer are also explored. The results of the static calibration of the samples show that the thickness of NiCr/NiSi thin film thermocouple layer does not influence the thermoelectrical properties of the samples. Ageing treatment can improve the thermoelectrical properties and the relative sensitivity of the samples obviously. The Seebeck coefficient and the maximal relative sensitivity of the samples are about 37μV/K and 0.9, respectively. With the increase of tem- perature, the perpendicular resistance ofAl2O3 insulating layer is decreased. The perpendieular resistance of Al2O3 insulating layer is bigger than 100 MΩ in the range of room temperature to 300℃. The perpendicular re- sistance of theAl2O3 insulating layer is 16 kΩ at 900 ℃.