Study On High Speed Impact Damage Mechanism Of TiN/Ti Multilayer Coating

When a helicopter or transport plane is flying in harsh environments such as deserts and mountains,the sand particles in the air are sucked into the aero engine under the action of high-speed airflow,and the surface of the compressor blades will be severely eroded and worn,bringing huge safety hazards to the engine.The preparation of anti-erosion coatings on the surface of compressor blades is an efficient method to improve the performance of the blades.Ceramic/metal multilayer coatings have become a research focuses in erosionresistant coatings due to their high hardness and high toughness.In order to understand the toughening mechanism and impact deformation damage behavior of ceramic/metal multilayer coatings,this paper prepared TiN/Ti multilayer coatings and TiN monolayer coatings by physical vapor deposition(PVD)technology.The micro morphology and microstructure of the coating were analyzed by scanning electron microscopy(SEM)and Xray diffraction(XRD).The mechanical properties of the two coatings were analyzed by nanoindentation,scratch test and particle impact test.The toughening mechanism of TiN/Ti multilayer coatings is clarified.The effects of structural parameters on the micro-indentation mechanical properties and impact damage and deformation behavior of TiN/Ti multilayer coatings are studied by numerical simulation methods,which provide a good guide value for the design of erosion-resistant coatings.Main conclusions as follows:The TiN phases in TiN monolayer coatings and TiN/Ti multilayer coatings mainly grow in(111),(222)and(200)orientations.The TiN/Ti multilayer coating with a multilayer structure inhibits the growth of TiN columnar crystals and refines the grain size of TiN.TiN monolayer coating has higher Young's modulus and hardness than TiN/Ti multilayer coating,but its fracture toughness and coating bonding force are lower than TiN/Ti multilayer coating;Through the single particle impact test,it is found that due to the introduction of the ductile metal layer Ti layer,the impact resistance of the TiN/Ti multilayer coating is significantly improved compared to the TiN monolayer coating.The mechanism of action is that Ti in the multilayer coating consumes part of the impact energy and reduces the tensile stress in the coating.Secondly,the interface between the TiN layer and the Ti layer has an obvious hindrance to crack propagation.By simulating the indentation process of TiN/Ti multilayer coatings with different structures,it was found that the increase of the number of layers will reduce the hardness of the multilayer coating,and the increase of the layer thickness ratio will increase the hardness of the multilayer coating.The relationship between Young's modulus,hardness,structural parameters and indentation depth of TiN/Ti multilayer coating was established by fitting method;It was also found that the indentation stress of the TiN/Ti multilayer coating is mainly concentrated on the top TiN layer.Increasing the number of layers can reduce the stress of the coating,but it will increase the plastic deformation of the coating;The multilayer coating with the largest thickness ratio produces the largest stress during the indentation process,and the plastic deformation in the coating is the smallest.By simulating the process of particles impacting the TiN/Ti multilayer coating,it was found that increasing the number of layers can reduce the tensile stress in the coating and the plastic strain of the substrate;The increase of the thickness ratio of the coating will increase the tensile stress of the coating and the plastic deformation of the substrate.The simulation also found that TiN/Ti multilayer coating suffers from the combined effects of tensile failure and shear failure when subjected to particle impact.The TiN layer is mainly tensile failure,and the interlayer interface is mainly shear failure;The increase of the number of layers reduces the stress in the coating and alleviates the damage degree of the interface between the layers;As the layer thickness ratio increases,the interface damage of the coating becomes more and more serious,mainly due to the uncoordinated deformation of the TiN layer and the Ti layer.