Preparation And Properties Of Copper-based Superhydrophobic And Corrosion Resistant Ni-Co Film

Metal materials are widely used in aerospace,automotive manufacturing,machinery industry and petrochemical industries,but the corrosion of metal materials has always been a major problem in its use.Due to the unique characteristics of the superhydrophobic surface,it provides new ideas for corrosion and protection of materials.In this thesis,a hydrophobic Ni-Co coating was prepared on the surface of a copper substrate by electrodeposition,and the different influencing factors in one-step electrodeposition and two-step electrodeposition processes were investigated,including bath temperature,current density,electrodeposition time,etc.The surface morphology and chemical composition of different nickel-cobalt coatings were analyzed using SEM and EDS techniques.Tafel straight-line extrapolation and AC impedance techniques were used to test the corrosion resistance of different nickel-cobalt coatings.The following conclusions were obtained:(1)Using a one-step electrodeposition process,not modified by surface free energy,a Ni-Co film sample with excellent hydrophobicity can be prepared under the optimal electrodeposition process conditions,and its contact angle reaches 145.5°.The results of SEM show that the surface micro-roughened structure of this nickel-cobalt film sample consists of dense,spherical grains with an average grain diameter of 1-2 ?m,which is in agreement with the microscopic characteristics of the hydrophobic surface.(2)Using a two-step electrodeposition process,not modified by surface free energy,a superhydrophobic double Ni-Co film sample can be prepared with a contact angle of 155°.The results of SEM show that the microstructure of the sample prepared by the two-step electrodeposition process can still retain some features of the one-step electrodeposition process,but its microstructure is more compact and rounder,and the hydrophobic properties of the surface are enhanced.(3)Tafel and AC impedance techniques were used to test the corrosion resistance of different Ni-Co coatings.The results showed that the double Ni-Co film with superhydrophobic properties have the best corrosion resistance.Through soaking experiments,it was shown that the superhydrophobic double Ni-Co film has long-term corrosion resistance.