Design and Fabrication of Thermocouple Sensors Based on a Ceramic Curved Alumina Substrate

Abstract

A platinum-platinum/rhodium thick-film thermocouple sensor based on an alumina curved-surface ceramic substrate was designed. The thermoelectric components were prepared by screen printing, which is simple, rapid, and low cost; additionally, screen-printed films have uniform thickness. We investigated the as-fabricated morphologies of Pt and Pt/Rh films using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that the thermocouple film prepared via this process was reasonably stable at high temperatures. We then repeated the test at 1300 °C and then at 1500 °C for 10 h to determine its thermal limits. After testing at 30-1300 °C thrice, the fabricated thermocouple showed excellent consistency and reusability, with a maximum output voltage of 11.733 mV and a Seebeck coefficient of 9.110 μV/ <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> C. Upon testing the thermocouple at 1500 °C for 10 hours, the peak voltage output was 12.821 mV. Therefore, we concluded that the sensor could be used for temperature monitoring in hostile environments such as measurement of turbine blade surface temperature for aeroengines.