Corrosion Behavior of Cold Sprayed Zn15Al Alloy Coating on Q235 Carbon Steel in NaCl Aqueous Solution
Cold-sprayed coatings Zn(CS-Zn)and Zn15Al alloy(CS-Zn15Al)were prepared on Q235 carbon steel plates via low-pressure cold spraying technique.The corrosion behavior of the coatings in 3.5％NaCl aqueous solution was assessed by means of electrochemical measurement of open circuit po-tential,electrochemical impedance and potentiodynamic polarization curves,as well as SEM with EDS,XRD.The results indicate that the CS-Zn coating undergoes severe corrosion during immersion,while the CS-Zn15Al coating corrodes at a slower rate and exhibits superior corrosion resistance.XRD results reveal that the dominant corrosion product of CS-Zn is ZnO,which possesses porous structural character-istics that disrupt the compactness of the corrosion product layer.Furthermore,its semiconductor proper-ties decrease the charge transfer resistance,thereby accelerating the process of corrosion.In the con-trast,as for CS-Zn15Al,the incorporation of Al facilitates the formation of protective corrosion products,namely Zn5(OH)8Cl2·H2O and layered double hydroxides Zn6Al2(OH)16CO3·4H2O.The shielding effect of CS-Zn15Al coating was significantly enhanced by this layer of corrosion products.Furthermore,electro-chemical measurements demonstrate that the addition of Al reduces the corrosion potential of the coat-ing,thereby enhancing its cathodic protection ability,and decreases the corrosion current density due to the generation of protective corrosion products.In conclusion,the addition of Al can synergistically en-hance the anticorrosion performance and durability of the coating.
material failure and protectionzinc alloy coatingselectrochemical impedance spectros-copycold spraying
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