Effect Of AlCrON Diffusion Barrier On High Temperature Oxidation Properties Of NiCrAlYSi Coating

With the development of aviation industry,the requirement of thrust weight ratio of engine is higher and higher,the temperature of engine inlet is increasing,and the working environment of turbine blade is becoming worse and worse.In order to meet the working needs of blades,MCr Al Y high temperature protective coating is widely used in Aeroengine Blades.During the long-term service of the blade,it is found that there is a serious element diffusion phenomenon between the MCr Al Y coating and the superalloy matrix,which seriously affects the service life of the coating and the blade.Adding a diffusion barrier layer between the coating and the matrix can effectively solve the element diffusion problem.AlCrON diffusion barrier layer and MCr Al Y/AlCrON coating system were prepared by arc ion plating technology.The phase,morphology,composition and bonding strength of the diffusion barrier layer and the coating system before and after oxidation were tested and investigated by XRD,SEM,EDS and nano scratch instrument.The element barrier ability of the diffusion barrier layer and the oxidation resistance of the coating system were deeply discussed.Al(Cr)ON diffusion barrier layers with different composition ratios were deposited by using alcr alloy targets with different target ratios and Cr single substance targets.The deposition rate of the coating increases first and then decreases.The phase in the AlCrON layer is mainly(Al,Cr)₂O₃or(Cr,Al)N solid solution phase,and the phase in the Cr ON layer is mainly Cr N and Cr₂O₃phase;With the increase of Cr content in the coating,the large particles on the surface of the coating decrease,but the density also decreases;The bonding ability of Al₇₀Cr₃₀ON coating is the best,which is 66.75 N.When the oxygen content in the reaction gas is increased,the oxide content in the coating increases,and the solid solution phase of(Al,Cr)ON gradually changes to(Al,Cr)₂O₃phase.Due to the increase of oxide,the coating is more dense,accompanied by the generation of large particles;The critical load increases first and then decreases.When the O₂flow is 40 sccm,the maximum critical load is 66.75 N.The coating system with or without diffusion barrier was oxidized at 1000?for 300 h at the same time.The oxidation weight gain curve showed that the weight gain of the coating with AlCrON diffusion barrier was significantly less than that without diffusion barrier;Through the analysis of the micro morphology of each system after oxidation,it is concluded that NiCrAlYSi/AlCr O40N system has the best high-temperature oxidation resistance and the lightest failure after oxidation for 300 h;It can be seen from EDS surface scan data that the element diffusion movement in NiCrAlYSi/AlCrON/DSM11 coating system is weaker than that of the samples deposited only with NiCrAlYSi protective coating,and the AlCrON diffusion barrier layer has excellent element barrier effect;The phase of the diffusion barrier layer gradually changes to dense in the oxidation process?-Al₂O₃layer,so as to realize the barrier effect on element diffusion,and the oxidation resistance of the coating system is greatly improved.