Optimal fabrication of a thin-film thermocouple (TFTC) using Alumel/chromel junctions.

ABSTRACT

Thin-film thermocouple (TFTC) technology is a novel measurement method that produces a thermocouple sensor during the deposition process, even though it is a complex surface, to obtain the surface temperature. TFTC is a thin film sensor for measuring temperature by contact methods, consisting of two different metals which can generate thermoelectric forces named "Seebeck effects". In the past decade there have been many attempts to measure the cutting temperature during machining processes using TFTF sensors. However, research has not yet progressed to optimize the sensor performance or fabrication process. This paper studies a preliminary technique for the fabrication of a TFTC sensor on a cutting tool surface and optimizes the deposition conditions, TFTC design, and sensor performance. Chromel and Alumel, which are materials commonly used in K-type thermocouples, were used for the thermal evaporation process. When the Chromel has a nickel to chrome ratio of 91, low resistivity and minimal variation with increasing temperature were observed. When the contact area of the deposited electrode (+) and (-) poles increased, the resistivity decreased and the TFTC sensitivity improved. Data acquisition tests using a DAQ system connected to the TFTC sensor show the lowest resistivity in TFTC B and C types are able to measure temperature data. It is expected that the heat generated during the cutting process can be detected using the TFTC sensor with B-type shape and Chromel with a 91 nickel to chrome ratio.