Study On Interpretation Technology Of Crystal Temperature Measurement On High Temperature Hot End Parts

Accurate temperature measurement on the surface of the hot-end components of aero-engines,such as turbine blades,is essential for verifying the validity of the engine simulation model,evaluating the combustion efficiency of gas,evaluating the design effect of thermal barrier coating and cooling,and for the design,testing,troubleshooting and maintenance of the engine.The temperature measurement method based on SiC crystal has the advantages of small size,multi-point measurement,no need of complicated leads,suitable for temperature measurement in special places,such as high rotating speed and narrow semi-closed space.Based on the crystal temperature measurement interpretation technology,aiming at temperature interpretation of the hot-end components of aero-engines,this paper systematically studied the interpretation technologies including SiC micro-crystal calibration,interpretation algorithms and database establishment.At the same time,the preparation of AlN crystal thin film and its temperature measurement interpretation technology were studied innovatively based on the temperature measurement principle of SiC crystal.At last,A visual interpretation software for miniature temperature-measuring crystals is developed based on C#language.First,the temperature measurement and interpretation technology of SiC microcrystal was studied.The neutron-irradiated SiC crystal samples were calibrated at 500-1400℃ for 5-15 minutes.Raman spectroscopy and X-ray diffraction were used to analyze the structure of the samples before and after calibration.The results of Raman spectroscopy showed that the peaks at 790cm^-1 and 973cm^-1 shifted to the right with the increase of calibration temperature,and the peak intensity decreased.X-ray diffraction results showed that the diffraction angle 2θof SiC crystal increased approximately linearly with the decrease of heat treatment temperature and time,and the FWHM of diffraction peak increased approximately linearly with the increase of heat treatment temperature and time.These phenomena indicated that the lattice defects gradually decreased with the accumulation of annealing time and the increase of annealing temperature,which means that the lattice gradually recovered from disordered state to ordered structure.Based on the functional relationship among lattice parameter value of SiC calibration sample and calibration temperature and time,the temperature interpretation algorithm of 2θand FWHM was established by polynomial fitting of MATLAB.Then the calibration curves of 2θand FWHM were drawn,and the temperature interpretation database was established.Secondly,the research on the preparation and interpretation technology of AlN crystal film temperature measurement was processed.Weak C-axis preferred AlN thin films with（002）diffraction peak were prepared on Al₂O₃ ceramic wafers by medium frequency sputtering.XRC results showed that AlN thin films had a wide full width at half maxima,which demonstrated that the film has a weak preference.The film with weak（002）preference had more intrinsic defects than high（002）preferred film.The 2θvalue of（002）diffraction peak of AlN thin film crystals annealed in vacuum still increased gradually with the increase of annealing temperature and annealing time.The interstitial atoms in the crystals filled the gaps causing lattice shrinks,which could be used as the basis for temperature interpretation.In the same way,based on the functional relationship between lattice parameter value of AlN thin films and temperature and time,the temperature interpretation algorithm of 2θwas established by polynomial fitting of MATLAB.Then the calibration curves of 2θwas drawn,and the temperature interpretation database was established.Finally,according to the temperature measurement interpretation algorithm of SiC crystal and AlN crystal thin film,the micro-crystal temperature interpretation software was carried out on the WPF software based on C#language.The visual interface and three functional modules were designed,which contained processing module of normalized time history curve,temperature interpretation modules based on 2θand FWHM respectively.The three functional modules could be applied to process the normalized time history curve,with that the equivalent time and the highest temperature of the tested sample can be calculated by using built-in functions and algorithms.The developed micro-crystal temperature measurement interpretation software can be applied to the temperature interpretation of SiC micro-crystal and AlN crystal film,and the error range of the software interpretation is 0.16% to 9.7%.