Research On Mechanical Properties And Fatigue Performances Of NiCrAlY And Magnisum Alloy Coatings

Aviation aircraft engine blades often work at high temperature,high pressure,vibration and other harsh environments and the conditions associated with corrosion and wear greatly reduce the service life of the aircraft engine blades.Fatigue damage caused by vibration is one of the main failure modes of the aircraft engine blades.From the point of view of surface engineering,surface failure is in the form of wear,corrosion,and high temperature oxidation and other failure modes. Generally, it is inevitable to avoid the surface failure, which will cause the variations of blade shape sizes and reduce the engine performace and efficiency. The development of surface failure will ultimately lead to overall failure.Therefore,the study on the thin-walled structures by using reasonable passive vibration ruppression method has an important practical significance, which will reduce the damage caused by the vibration stress and improve the surface quality has an important practical significance. In this study, the effect of mechanical properties fatigue performaces of coating caused by preparation, surface features and process parameters of the alloy damping coating on the thin-walled components will be discussed.Firstly, multiple sets of different process parameters of NiCrAlY and magnesium alloy coatings were prepared on the stainless steelsubstrates by using arc ion plating machine. Based on the material characteristics respectively, coatings with different surface characteristic were prepared by altering the current and substrate negative bias. Surface morphology and chemical composition were obtained by using measurement methods such as SEM(Scanning Electron Microscope) and EDS(EnergyDispersive Spectrometer). Through the discussion of SEM and XRD image, surface morphology and chemical composition under different perparing parameters were obtained. Based on the discussion and analysis of the test results, the influence rules of surface morphology, mechanical preperties on the coating with different parameters were obtained.Secondly, the metal coating contact fatigue properties were investigated by finite element analysis software (ANSYS14.5). Three-dimensional model of substrate coating and contact body was established and then was imported into finite element analysis software. The mesh, boundary conditions setting and loading of the three-dimensional model were conducted by using contact model of finite element analysis software. The contact fatigue preperties of the coating would be obtained after the simulation through finite element analysis software,and the influence regulations of the maximum contact stress of coating surface would be obtained by altering the elastic modulus and poisson’s ratio of coating. In the same working conditions, the maximum contact stress of coating surface increases with increase of elastic modulus,and decreases with increase of poisson’s ratio.The conclusion can be validated by relevant experiments,which provides the basis for prediction of contact fatigue life of coating.