Research On The Preparation And Properties Of CrAlN-based Coatings On The Surface Of Inconel 718 Alloy

At present,the country due to the consumption of industrial parts and other large economic losses,and with the rapid development of manufacturing,machining for bearings and other parts of the requirements of wear protection performance gradually increased,take the surface coating technology to enhance the performance of the workpiece in many solutions stand out,however,the early si ngle-layer coating gradually can not meet the needs of industry,so further development of more adaptable to industrial.Therefore,it is important to further develop high performance coatings that are more suitable for industrial development.In this study,CrAlN/Cr N bilayer,multilayer,and nano-multilayer hard coatings with different structures were deposited on the surface of Inconel 718 alloy,which is widely used as bearing components,by multi-arc ion plating technique,and the microstructure,mechanic al properties,mechanical properties from room temperature to high temperature,frictional wear properties and high temperature frictional wear properties of the three coatings under different loads and their wear mechanisms were investigated.and their wear mechanisms,the main conclusions are as follows:（1）The CrAlN/Cr N bilayer,multilayer,and nano-multilayer coatings prepared by multi-arc ion plating have a Na Cl-type face-centered cubic structure（fcc）with the main phase being the fcc-Cr N phase,selectively oriented in the（200）crystal plane.All coatings are structurally dense with columnar crystals g rowing perpendicularly upward to the substrate with thicknesses of 7.31,7.69,and 9.96μm,respectively.the hardness of all coatings exceeds 25 GPa,which is much hi gher than that of the Inconel 718 alloy substrate and facilitates improved wear resistance.With the refinement of the structure,the surface roughness of the coatings decreased to a minimum of 438 nm,and the bond strength between the coatings and the substrate gradually increased up to 23.2 N.（2）The mechanical properties of the three coatings were investigated after high temperature experiments.After the experiments at 350°C and 650°C,the CrAlN/Cr N multilayer coatings showed a nano-hardness closer to the original coating than the bilayer and nano-multilayer,and the bond strength with the substrate also performed well.For the tribological properties,the multilayer coatings were able to maintain low values of the average coefficient of friction at different temperatures,while the wear resistance was also the best performance among the thr ee coatings.In addition,the study analyzed the different wear mechanisms of the three coatings at different temperatures,and the oxidation products within the wear marks were mainly composed of Cr₂O₃ and Al₂O₃.（3）Tribological experiments were carried out with CrAlN/Cr N multilayer coatings at 650°C with loads of 2 N,4 N,and 6 N to investigate the effect of load on the high temperature tribological properties of the coatings.The friction coefficient of the coating decreased slightly with increasing l oad,which was mainly due to the formation of Cr₂O₃,Cr O₂,and Al₂O₃ in the wear marks to provide better lubrication.The wear rate of the coating increased significantly with increasing load,which was attributed to the increased fatigue wear of the coati ng at high loads and the larg e amount of flake flaking within the we ar marks.