High-Temperature-Sensing Smart Bolt Based on Indium Tin Oxide/In2O3 Thin-Film Thermocouples with Nickel-Based Single-Crystal Superalloy via Screen Printing

Abstract

In this study, thin-film thermocouples (TFTCs) were combined with a smart bolt to design a smart bolt that can directly test high temperature in service monitoring and parameter calculation for gas turbine structure design. The first-principles calculation was used to analyze the design of the surface properties of nickel-based alloys and insulating layers, and finite element analysis was used to optimize dimension parameters by controlling the thermal stress matching of insulating layers and sensitive layers. The effect of the glass powder with different particle sizes on the microstructure of the ITO and In2O3 films was studied via SEM. The preferred particle size of the additive glass powder is 400 nm. The XRD pattern shows the (222) peak has the highest intensity. The intensities of the (222) and (622) peaks increase after the heat treatment. The calibration results show that the average Seebeck coefficient of the TFTCs can reach 64.9 μV/°C at 1100 °C with a maximum voltage of 71.4 mV. The repeatability error of the cycles of the sensor after heat treatment is ±1.05%. The repeatability of the sensor is up to 98.95%. The smart bolts were tested for application in small aero engines. It can be seen that under the impact of 1000 °C, the thermal response of the prepared smart bolt is better than that of the K-type armored thermocouple, and the thermal balance is achieved faster. The intelligent bolt sensor proposed in this work has better engineering application prospects owing to its convenience of installation in harsh environments.

Flexible thin film thermocouples: From structure, material, fabrication to application

“…Then, the temperature of the object in contact with the hot end of the thermocouple is measured. 34 , 35 , 37 , 38 , 74 , 75 , 76 , 77 , 78

Figure 3 Principle of temperature measurement in flexible TFTCs

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“…Typically, the response speed of TFTCs is in the millimeter range. 34 , 35 , 37 , 38 , 39 , 40 , 43 , 44 , 45 , 48 , 65 , 73 , 111 , 112 , 113 , 114 …”

“…Accurate measurement of temperature is necessary in many physical and chemical processes and plays an important role in many important practical applications such as industrial production, medical diagnosis, and weather forecasting, among others. 34 , 35 , 36 , 37 , 38 Thermocouples are temperature sensing devices that consist of two wires made of different metal alloys connected together at one end. These metal alloys have different electrical properties that vary with temperature, and the voltage they produce is proportional to the difference in temperature between the two wires.…”

Research on a dedicated thin-film thermocouple testing system for transient temperature measurement

“…Thin-film thermocouple (TFTC) utilizes the Seebeck effect for temperature measuring, with the thickness of thermal junction on the order of microns [7]. TFTC are characterized by small size, small heat capacity, short thermal response time, high accuracy, high sensitivity, low interference and damage to the measured target and test environment, and are suitable for occasions with narrow space and difficult installation [8][9][10].…”