Thermoelectricity and antivibration properties of screen-printed nanodoped In1.35ZnO2.11/In2O3 thin-film thermocouples on alumina substrates

Abstract

Owing to the low flow field disturbances and fast response, thin-film thermocouples (TFTCs) are used to measure the service temperature of aero-engines. Indium tin oxide (ITO) and In2O3 are widely used in high–temperature measurements. However, ITO undergoes phase transition and consequent thermoelectric failure at above 1300 °C. In this study, In1.35ZnO2.11/In2O3 TFTCs were prepared on alumina substrates via screen printing method through introduction of ZnO nanopowder followed by annealing treatment. Results show that prepared TFTCs exhibited good thermoelectric properties at 1500 °C. The morphology, structure, and electrical coefficients of TFTCs were investigated. The average Seebeck coefficient was 39.8 μV/°C at 1500 °C with a drift rate (DT) of 0.84 °C/h, which was significantly improved with respect to that of ITO/In2O3, corresponding to 44.5 μV/°C at 1270 °C with a DT of 5.44 °C/h and failed at higher temperature. The result of lumped capacity method test show that the response time was 4.8 ms at 100 °C. Preliminary engine gas temperature measurements with a heat load of 1000 °C at 1 Mach show that these TFTCs are promising candidates for engineering applications. Finally, the structural reliability under high-magnitude vibration and impact tests (10–2000 Hz/20 g and 100 g/11 ms) was also investigated. As a result of the excellent bonding strengths of 47.36 and 59.83 N between the film and the substrate for both In1.35ZnO2.11 and In2O3, respectively, destructive cracking and peeling of the film were not observed, and no change in the Seebeck coefficient of the sample occurred after impact and vibration tests. These results provide an important basis for the potential application of In1.35ZnO2.11/In2O3 TFTCs in aero-engine high-temperature measurements of flow channel components.