THERMOELECTRIC PROPERTIES OF CERAMIC THIN FILM THERMOCOUPLES

摘要

Thin film ceramic thermocouples are used to assess temperatures beyond 14000C in the hot sections of gas turbine engines. Several ceramic materials were systematically examined as thermoelements including indium tin oxide (ITO), zinc oxide (ZnO) and a NiCrCoAlY/alumina nanocomposite. These ceramic thermoelements were initially tested relative to a platinum reference electrode and the relationship between process parameters and thermoelectric properties, including Seebeck coefficient, sensitivity and voltage/temperature behavior was established. Bi-ceramic junctions comprised of ZnO and ITO generated a very large electromotive force at low temperatures but lacked high temperature stability. When ITO was combined with a NiCoCrAlY/alumina nanocomposite, a very large Seebeck coefficient with excellent emf/temperature behavior was realized. A ceramic thermocouple based on this combination was demonstrated at temperatures up to 1200°C.