Research On Preparation And Characteristic Of Cold-sprayed Coating Zink/aluminum Based On Corrosion Resistance Of Ship Ballast Ta

Due to seawater wet-dry cycling is a common corrosion condition in the ocean industry for water ballast tanks of ships,the actual working environment is very abominable,and the cleaning and maintenance become difficult in the operation of the ship.So the corrosion protection of the ballast tank is very important to ensure the safety of the ship At present common used anti-corrosion means for ballast water tank are anti-corrosion coating and metal coating,such as Al and Al-Zn coatings.This kind of coating can be used to achieve the same as the organic coating separating the corrosive medium and substrate,and cathodic protection for substrate by sacrificing anode.The cold sprayed coating has the advantages of high compactness and low porosity for the surface engineering technology.It is foreseen a bright future applying the cold sprayed coating in solving corrosion prevention for water ballast tanks of ships.In this paper,pure Al coating,Al-50%Zn composite coating and Zn-15 Al alloy coating were prepared by cold spraying.The characteristics of these three kinds of coatings were studied by means of analytical methods and electrochemical tests.The corrosion resistance of the three coatings were compared.The micro morphology of the coating was observed by SEM.The results showed that the surface of the three kinds of coating had no obvious defects,which was formed by the stacking of particles with large plastic deformation.Zn-15 Al alloy coating is more compact.The Q235 steel,Cold Sprayed Al coating,Cold Sprayed Al-50%Zn coating and Cold Sprayed Zn-15 Al coating in different soaking time were tested separated by corrosion potential,linear polarization test,electrochemical impedance spectroscopy and potentiodynamic polarization curves test.Then the variation of corrosion current density was obtained by fitting software..Through the analysis of the change of the self corrosion potential,it can be found that the potential change of the Zn-15 Al and Al-50%Zn coating is smaller,the final stability is-0.95 V,and the Cold Sprayed Al coating tends to be stable around-0.85 V.The three kinds of coatings can provide good cathodic protection to the substrate.From the linear polarization curve and potentiodynamic polarization curve analysis,the corrosion current density of the coating decreased gradually after 336 h and remained stable.From the observation of electrochemical impedance spectroscopy,capacitance arc diameter Zn-15 Al alloy coating and Al-50%Zn composite coating increased gradually with the passage of time.It showed that the polarization resistance of coating was an increasing trend,there appeared rapid corrosion when the coating Zn acted as sacrificial anode,corrosion products were covered the coating surface,which slowed down the corrosion.In the later stage of immersion,the Zn-15 Al coating can maintain stable corrosion current density.According to the corrosion potential and electrochemical test results,the Zn-15 Al alloy coating has better corrosion effect.