Research On The Effect Of Surface Treatment On The Microstructure And Properties Of Al-Cu-Mg-Ag Alloy

Al-Cu-Mg-Ag alloy has the advantages of light weight,high specific strength and good heat resistance,which makes it have a broad application prospect in the aviation field.However,the application of Al-Cu-Mg-Ag alloy is limited by the complex service environment and the corrosion of materials in corrosive media.In this thesis,Al-Cu-Mg-Ag alloy was surface modified by magnetron sputtering coating technology and anodic oxidation+magnetron sputtering composite surface treatment technology.Salt spray corrosion,electrochemical corrosion and hardness testing were used to study the influence of surface treatment on the hardness and corrosion resistance of the alloy.The mechanism was discussed by scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS)and X-ray diffraction(XRD).The main conclusions are as follows:(1)The mechanical and corrosion resistance of Al-Cu-Mg-Ag alloy can be improved by TiCN coating on the surface of the alloy prepared by DC magnetron sputtering.The effects of the magnetron sputtering process parameters on the hardness of the film layer,the maximum corrosion depth after neutral salt spray,the corrosion current density and the bond strength of the film base were obtained in the following order respectively:N₂/Ar>C target power>Ti target power;C target power>N₂/Ar>Ti target power;C target power>N₂/Ar>Ti target power;Ti target power>C target power=N₂/Ar.When the power of C target is 200 W,the power of Ti target is 100 W and the ratio of nitrogen to argon is 1:40,the TiCN film with excellent corrosion resistance,hardness and adhesion force can be obtained.(2)The sequence of deposition film and heat treatment process has a significant effect on the properties of Al-Cu-Mg-Ag alloy.Compared with Al-Cu-Mg-Ag alloy,the corrosion current density and corrosion rate of the alloy deposited TiCN film before heat treatment decrease significantly,and the maximum corrosion depth of neutral salt spray decreases by 107.9?m.The corrosion resistance of the alloy under the salt spray environment is improved obviously.At the same time,the films deposited by magnetron sputtering have excellent adhesion,good compactness and no porosity can be observed,and the N and C elements diffuse into the aluminum alloy matrix,which improves the hardness of aluminum alloy and the adhesion of the film base.(3)The Al-Cu-Mg-Ag alloy treated by anodic oxidation+magnetron sputtering has better corrosion resistance and higher hardness than the alloy treated by magnetron sputtering alone.The porous layer is formed on the surface of the alloy after anodic oxidation,and most of the anodic oxidation holes are closed or partially filled by magnetron sputtering coating.With the increase of the anodic oxidation time,the corrosion resistance of Al-Cu-Mg-Ag alloy increases first and then decreases,and the hardness increases first and then decreases.The maximum corrosion depth of the alloy with anodic oxidation time of 10 min is 72.0?m,which is 116.4?m lower than that of single magnetron sputtering,the corrosion current density is 1.543?A/cm²,and the hardness is 189.4 HV.