Manufacture And Corrosion Resistance Of Cr-based Alloy Coating Deposited By Magnetron Sputtering

Chrome plating is a kind of anti-corrosion coating with excellent comprehensive performance,it will not be corroded even in humid environment.In addition,the chromium coating has good gloss,appearance,hardness,wear resistance and heat resistance,which is very suitable for automobile wheels.Electroplating technology is considered to be one of the most common methods for coating mechanical parts,but it is very harmful to the environment and the human body.Magnetron sputtering technology is a very attractive green and environmentally friendly coating technology.The simple process controls the composition of the target and coating,and has good reproducibility,which is suitable for large-scale production of coatings.In this paper,magnetron sputtering technology is used to deposit CrNi and CrC coatings.X-ray diffractometer(XRD),atomic force microscope(AFM)and field emission scanning electron microscope(SEM)were used to characterize the coating structure and morphology.Finally,an electrochemical test was performed on the coating to analyze the corrosion resistance of the coating.XRD results show that the CrNi coating is mainly amorphous and contains a small amount of nanocrystalline structure,and some samples are completely amorphous.SEM and AFM results show that the coating surface is smooth and dense,with low roughness.The coating was electrochemically tested.The addition of nickel improves the corrosion resistance of the chromium coating.When the nickel content reaches 35 wt%,the corrosion resistance of the coating is the best.The corrosion potential is 571 m V,the corrosion current density is 2.238?A·cm^-2,and the impedance mode value is 90 K?.The EIS results show that the passivation film of the Cr₆₅Ni₃₅ sample is more stable and has stronger corrosion resistance without the diffusion process.XRD results show that the CrC coating is also a combination of amorphous and nanocrystalline structure,and some samples have a completely amorphous structure.SEM and AFM results show that the surface of the coating is smooth and dense,with low roughness.It can be seen from the cross-sectional mapping diagram of the coating that some elements have penetrated into the resin layer,thereby improving the adhesion of the coating and preventing it from falling off.Through orthogonal test analysis,the experimental parameters of the CrC coating with the best corrosion resistance are:argon flow rate 80 cc/min,acetylene flow rate 240 cc/min,target and substrate distance 100 mm,at this time the corrosion current density It is 0.1318?A·cm^-2,the corrosion potential is222 m V,and the impedance modulus value is 742.5 K?.In this paper,the silver-white CrNi coating and the black-bright CrC coating are obtained in a short time by magnetron sputtering,which has strong corrosion resistance.The thickness of the CrNi coating is about 140 nm,and the thickness of the CrC coating is about 180 nm.The preparation time is relatively short,which is suitable for the mass production of surface anticorrosive wheels.