Research On Vibration Damping Properties Of ZrO₂ Coating By Electron Beam Physical Vapor Deposition

ZrO2 coating(Yttrium oxide containing about 8%),because of its high melting point and low thermal conductivity,has been widely used in the field of thermal barrier coating to protect engine components from high temperature and corrosion.Recently,studying of YSZ coating found that it not only has the traditional good insulating properties,thermal shock,resistance to high temperature oxidation resistance,but also showed a remarkable damping performance.When subjected to dynamic stress and frequency,YSZ coating have the very strong strain and frequency correlation.Unfortunately,about the mechanism of damping characteristics,especially the microstructure on the damping performance influence mechanism is not fully clear.To study the damping mechanism of ZrO2 coating influenced by its internal microstructure,Multiple sets of different process parameters of ZrO2 coating were prepared on TC4 by the electron beam evaporation coating machine in laboratory.Surface morphology and structure properties of coating are determined through the SEM tests.Different coating texture,grain size,growth orientation and micro strain can be observed by X-ray diffract meter.The influence rules of different coating microstructure with substrate different process parameters can be obtained by analyzing and discussing the test results.The damping properties of coated samples are characterized by DMA(Dynamic Mechanical Analyzer)and Energy storage modulus and loss factor was obtained with strain changing in 0～0.08%range and frequency changing in 0～200 Hz.Comparing damping performance of samples under different process parameters,referring to the general theory of damping materials,combining with the DMA test of damping performance along with the change of strain and frequency,the damping mechanism of ZrO2 coatings energy storage modulus and loss factor of strain correlation and frequency correlation is affected by its microstructure structure can be probed.In conclusion,under the condition of high strain damping performance of the substrate can be obviously increased by ZrO2 coating.The loss factor of ZrO2 coating with mixed orientation is best in low frequency.Damping performance of ZrO2 coating impacted by its grain size,grain boundaries and vacancies.The composite structure model with of ZrO2 coating and TC4 substrate were established by ANSYS software.Modal damping analysis were obtained to study the natural frequency and loss factor of composite structure influenced by changing thickness of the coating,changing the elastic modulus ratio between the substrate and coating.In conclusion:with the increase of the elastic modulus ratio between the substrate and coating,because the initial stiffness increased,the natural frequency of model increases gradually,the structure of the damping ratio decreases;with the increase of coating thickness,the natural frequency of the structure decreases gradually,the damping ratio increases.