Development And Performance Study Of High Temperature Film Thermocouple Sensors

At present,many engineering applications require equipment to work in more than 1000℃high-temperature environment,such as the development testing of space vehicles,air missiles,gun weapons.However,due to the limitation of material properties and electromechanical behavior,most modern electronic temperature measuring devices can not work in the place which is beyond 600℃,so it is impossible to optimize the thermal protection of military equipment.Therefore,how to measure the instantaneous temperature change of more than 1000℃in real time and accurately is still a difficult problem restricting the development of military equipment.For that reason,the thin film thermocouple sensor has been developed,and its upper limit for temperature measurement is 1800℃.The following are specific research processes:Based on the working principle of the thermocouple.It is deduced that the Thomson coefficient is the most important factor affecting the thermocouple Seebeck coefficient;Through comparison and analysis,the Pt Rh30/Pt Rh6 is selected as the sensor thermal electrode material and the 99 alumina ceramic is selected as the base material;The whole structure of the needle thin film thermocouple sensor is designed,and the diameter size is determined to be 2 mm by using the COMSOL simulation analysis software;The ceramic matrix of lead matrix was prepared by ceramic sintering.In order to select sensor functional film and protective film material,the Zr O₂、Al₂O₃ protective film and Pt Rh30、Pt Rh6 functional film after annealing were measured by SEM、EDS、AFM,and finally identified Pt Rh6 film as sensor functional film and Al₂O₃film as sensor protective film.After the preparation of the sensor,the static test of the developed sensor is carried out by using the combined heat source method.The average sensitivity of the sensor is 8.422μV/℃,which is similar to the standard B thermocouple,and the change of the thickness of the functional film has little effect on the sensitivity.The repeatability of the sensor is only1.81%,and the measurement error is not more than 4/1000 of measured value in the range of 0-1500℃.And it can continuously and accurately measure temperature more than 6 h at1200℃.Subsequently,the dynamic response time of high temperature thin film thermocouple sensor is microsecond by theoretical calculation,simulation analysis and experimental test;and a dynamic measurement error correction method is designed by using Origin nonlinear surface fitting method.The dynamic compensation error of thin film thermocouple sensor is better than that 4/1000 of measured value.Furthermore,the upper limit of dynamic temperature measurement is measured by acetylene flame,and the maximum temperature measurement limit is 1803.1℃.The development of high temperature film thermocouple sensor provides a practical basis for the optimization of weapons and equipment in military industry.