Static Characteristic Calibration Of Thin-film Thermocouple Based On Temperature Extrapolation Method

Due to the fast response and small size,the thin-film thermocouples(TFTCs)show promise for use in high spatial and temporal resolution surface temperature measurements.The accurate static characteristics calibration of TFTC is the precondition of high precision transient surface temperature measurements.But standardized thermocouple static calibration method is unsuitable for TFTC,because of the huge different temperature profiles in calibration and application,the research of TFTC static characteristics calibration has the scientific research value and the engineering value.To solve this problem,a static characteristics calibration of TFTC based on temperature extrapolation and laser heating is proposed in this article,the main contents are as follows:First,design a self-calibration thin-film temperature sensor integrated a gold platinum TFTC and two thin-film platinum resistance thermometers;simulate the processing of TFTC static calibration,and analyze the temperature profiles of TFTC under calibrating;get the extrapolation method,research the influence from convection intensity,lay a theoretical foundation for using temperature extrapolation method to calibrate the static characteristics of TFTC.Second,manufacture the self-calibration thin-film temperature sensor using screen-printing technology,and choose gold\platinum slurry and aluminum oxide as materials of thermo electrode and substrate respectively,the thickness of thermo electrode is 25?m,the thickness and the diameter of substrate is 0.36 mm and 22 mm respectively.Third,design the static calibration systems of thin-film platinum resistance thermometers and TFTC respectively.Design the signal processing circuit and the host computer procedure,which could record the resistances of platinum resistors and EMFs of TFTC simultaneously with ac exciting and quadratic demodulation.Fourth,heat the hot junction of TFTC by laser,and extrapolate the temperature of hot junction based on extrapolation model and two calibrated thin-film platinum resistance thermometers,calculate the Seebeck coefficients according to the EMFs of TFTC;Research the influence of calibration method from convection and the repeatability of this method.The results show that the static calibration method based on temperature extrapolation and laser heating technology can calibrate the static characteristic of TFTC from room-temperature to 200?,when the temperature gradient is concentrated in the legs mainly.Then,the result of TFTC's static characteristic is close to the standard bulk thermocouples',but the EMFs of TFTC are a bit lower then standard thermocouples' when the temperature is same,because the materials and the preparation technology of both are different.The static characteristics calibration of TFTC based on extrapolation method is suitable in different convection,which shows good environmental suitability,and the method also has good repetition.This signifies that the proposed calibration method is reliable and effective.