Research Of SiBCN Ceramic Heat Flux Sensitive Film Element Based On Alumina Substrate

In aero turbine engine,the working environment of its components is high temperature and high pressure.In order to meet the requirements of optimization design and health management of engine components,it is necessary to obtain the state information of engine components and systems during the working process,and accurately measure the state parameters of engine components.Among them,heat flux is a particularly important parameter.High temperature heat flux produces intense thermal impact on the internal components of the engine,especially turbine blades,resulting in thermal fatigue failure and causing ablation,cracking and other damages.In order to obtain this parameter,many scholars at home and abroad began to study the high temperature heat flow sensor which can be applied to the aviation turbine engine.In this paper,the precursor ceramic thin film electric bridge heat flux sensor is fabricated by using SiBCN on alumina substrate using Wessenberg direct writing process.According to the working principle of Wheatstone electric bridge heat flux sensor,a thin film heat flux sensor based on electric bridge structure is designed.Studied SiBCN sensitive layer of film and determine its preparing process,was studied by SEM and EDS SiBCN ceramic thin film on the surface of the micro morphology and element content and distribution,and its microstructure was characterized,the study found that the quality of process parameters on the film forming and the influence of the microstructure,crystal morphology of XRD test observation and analysis.The thin film heat flux sensor was prepared on the alumina substrate,and according to the different heat flux response and the measurement requirements of different heat flux range,the experimental platform of three heat flux source testing was built.The steady state test and calibration repeatability test were carried out on the thin film heat flux sensor,and the maximum heat flux value was 67.24kW/m2.A laser test platform was built to test the dynamic response of the sensor,and the cut-off frequency of the dynamic response of the sensor was obtained as 3270Hz.The thickness of the thermal resistance layer of the thin film heat flow sensor is optimized,and the test system is improved,and the calibration is repeated again.The test results show that the performance of the heat flux sensor has been greatly improved,and the output signal repeatability and stability have been significantly improved.Among them,the heat flow sensor has the best performance in the heat source test,the heat flow sensor linear fitting comprehensive sensitivity coefficient is 60.1 mV/(W/cm2),the degree of nonlinearity is 3.5%,the hysteresis error is 3.1%,the comprehensive test accuracy is 3.5%.The comprehensive sensitivity coefficient of polynomial fitting is 70mV/(W/cm2),and the comprehensive test accuracy is 2.4%.