Mechanism Of Microscopic Defects On Damping Performance Of YSZ Coatings:A Molecular Dynamic Study

The failure of mechanical component from mechanical vibration or abrasion is an important factor to affect the performance of aero-engines.Yttria-stabilized zirconia(YSZ)coating own the advantages of reducing the working temperature of the substrate metal,protecting them from erosion,oxidation of hot gas and abrasion resistance.Therefore,it has been widely used in aerospace,shipbuilding,automobile manufacturing and other areas.In recent years,many researchers notice a damping performance of YSZ coatings,which may be used for reducing the damage of vibration in high-temperature working circumstance of aero-engines.YSZ coatings own a rich micro-structure whereas the relationship between the micro-structure and damping performance is not clear.Figure out the effect of micro defect would offer a theory foundation of extending the life of terminal barrier coating and the stability of aero-engines.In this paper,vacancy,dislocation and crack models are established by the method of molecular dynamic.The effect of typical micro-defect on the damping properties of YSZ coating is analyzed with the result of experiment and simulation.For the experiment,beam intensity and substrate temperature of preparing process were changed to gain the samples with different micro-structure.The samples were tested by SEM,XRD and AFM to analyzed the surface and crystal structure.Taking advantage of DMA to evaluate the damping performance of samples for analyzing the mechanism with micro-structure.For the simulation,three micro-defects models were established and loading&unloading process were added on the models.Outputting stress-strain curves and micro-structure changing figures to analyze the reason for energy consumption caused by defect models.The effect of temperature on the defect models is investigated by calculating the damping factors(Q-1).Damping performance under the cycle strain is explained by stored energy in the model,which obtained by LAMMPS software.The experiment results illustrate damping performance can be improved by enhancing the beam intensity,which means interaction between the crystals and crystal layers is a reason for damping properties in the macro-scope level.Damping capacity is enhanced under the process of low substrate temperature,which indicate the micro-defect structure contribute to the damping performance of YSZ coating.As for the results from simulation,the damping properties of the dislocation model are derived from the internal friction between the dislocation structures when the strain direction changes.Under the cyclic stress,the dislocation model can provide continuous energy consumption for the YSZ coating.The damping mechanism of the micro-crack model is characterized by the rearrangement of atoms in the model under the action of strain.As for the vacancy model,on the one hand,the resource of damping properties of vacancy can be regarded as mass atom structure change.On the other hand,the new structure also lead to the damping properties.The temperature change model indicates that the change in atomic structure is the main reason of vacancy damping performance.Through the analysis of experimental research and simulation results,the damping mechanism of YSZ coating is obtained.