Reliability Evaluation Of CMAS Corrosion Thermal Barrier Coatings Based On Nessus

As one of the three major thermal insulation protection technologies of aeroengine,thermal barrier coating has the characteristics of high temperature resistance,corrosion resistance and lightness.It plays the role of high temperature thermal protection in the process of engine service.It has good thermal insulation effect,can reduce the surface temperature of turbine blade and improve the working life of turbine blade to a certain extent.Due to a large number of particles dominated by element oxides such as Ca Mg Al Si in the air,During the flight of the aircraft,the particles will enter the engine,soften and stick to the surface of the thermal barrier coating under the action of high temperature,and then immerse into it through the pores in the coating,resulting in thermochemical coupling reaction with the coating.With the influence of time,temperature and other factors,the coating will gradually corrode and crack,and finally fail.CMAS corrosion is recognized as one of the most harmful failure behaviors,The improvement of corrosion resistance and other performance parameters of thermal barrier coating needs to be targeted and directional.Therefore,it is necessary to evaluate the reliability of CMAS corrosion thermal barrier coating to obtain the failure probability and sensitivity factor.The reliability evaluation results provide a guiding basis for improving the performance parameters of coating.The main research contents are as follows:Firstly,the models of CMAS deposited turbine blade thermal barrier coating and CMAS corrosion thermal barrier coating are established to simulate the deposition and corrosion process,and the failure critical state is determined.The CMAS deposition model is based on the influence of Young’s modulus,temperature and impact velocity.The temperature distribution of turbine blade and the deposition distribution of CMAS particles are obtained by ANSYS combined with programming simulation;The CMAS corrosion model selects the thermochemical coupling model based on the thermodynamic law.The control equations include CMAS concentration control equation,coating dissolution control equation,stress-strain control equation,etc.after obtaining the weak form of response,it is simulated in COMSOL to obtain the cloud diagram of CMAS penetration concentration and strain energy in the coating.Secondly,the failure behavior is analyzed according to numerical simulation,and the appropriate failure criteria and influencing factors to be studied are selected to obtain the limit state equation.In this paper,the energy release rate is considered,that is,when the strain energy accumulation at the interface of thermal barrier coating reaches the critical condition,it is judged as failure.At the same time,the statistical characteristics of each random variable,including mean value,standard deviation and distribution function type,are obtained,and the reliability evaluation method is selected,All the conditions and parameters obtained are input into Nessus reliability software and set according to the navigation items in the software.Finally,the failure probability and the sensitivity of each parameter under a certain working condition are obtained,and the results are analyzed.Thirdly,the CMAS parameters in the complex system,reduce the physical analysis workload and difficulty,select coating volume modulus,coating thickness,corrosion temperature and corrosion time as the dimension of basic quantity,fracture toughness,coating shear modulus,coating density and CMAS density in the above four basic dimensions,optimization parameters to reduce the calculation complexity.