Molecular Dynamics Of Influence Of Alumina Doping On Damping Properties Of YSZ Coatings

In order to ensure the stable performance of hot end components of aero engine and gas turbine at high temperature,thermal barrier coating is usually used to protect the body.The performance of yttria-stabilized zirconia(YSZ)thermal barrier coating,which is widely used at present,can no longer meet the needs of the high-speed development of aircraft engines.It was found that YSZ doped with other metal oxides to increase the phase transition temperature,so as to prepare thermal barrier coating ceramic materials with better high-temperature resistance,corrosion resistance and oxidation resistance.As one of the important factors affecting the mechanical properties of thermal barrier coatings,the study on the formation and expansion of micro-cracks has become one of the hot topics in improving the mechanical properties of thermal barrier coatings.However,the micro-crack scale of thermal barrier coating is nanoscale,and the relationship between it and the mechanical properties of coating is not clear,so it is difficult to observe it by experiment.In this paper,the formation of micro-crack and the effect of micro-crack propagation on the mechanical properties of coating were studied.In terms of experimental research,YSZ coating and alumina doped YSZ coating with different doping amounts were respectively prepared by electron beam evaporation coating machine,and the sample surface morphology was characterized by SEM.The crystal phase structures of the two coatings were obtained by XRD diffractometer.A dynamic mechanical analyzer(DMA)was used to analyze the damping properties of the coating.In the simulation study,the ideal YSZ and alumina doped YSZ models and microcrack models were established by molecular dynamics simulation.By applying cyclic stress to the model,parameters such as kinetic energy and position of molecules during mechanical loading were output to analyze the formation and propagation mechanism of microcracks.By simulating the stress-strain curve,strain energy,damping factor and other parameters under different conditions,the microscopic mechanism of the damping effect of microcracks on the mechanical properties of coating was obtained.The experimental results show that the incorporation of alumina has a certain degree of influence on the model.With the continuous incorporation of alumina,the damping property of the coating first increases and then decreases,indicating that the incorporation of a certain amount of alumina can greatly improve the mechanical property of the coating.Simulation results show that the doped alumina model consumes more energy under the same stress,which indicates that the doped alumina model has better damping performance.From the energy distribution and position distribution of the atoms at the microcrack obtained,it can be seen that the atom diffusion at the microcrack of the doping model is more uniform,which has a better effect on preventing the coating failure caused by crack growth.