The work aims to investigate the corrosion behavior of thermal sprayed Zn-Al alloy coatings with high aluminum content in the tropical marine atmospheric environment,so as to provide selection evidence of long-term protective metal coat-ings on low alloy steel.An outdoor exposure test in a tropical island-reef atmospheric environment was conducted to research the corrosion behavior of Zn-Al alloy coatings with high content of Al on low alloy steel.By the means of visual observation,scanning electron microscope(SEM),energy diffraction spectrum(EDS),optical microscope,X-ray diffraction,electrochemical impedance spectroscopy(EIS)and potential-dynamic polarization curve,et al,the macroscopic and microscopical surface mor-phology,chemical composition,section morphology,corrosion product composition,electrochemical properties and corrosion rate were observed and tested.The weight ratio of Zn and Al in Zn-Al alloy coatings was 50%:50wt%.The corrosion product layer on the Zn-Al alloy coating mainly consisted of basic zinc aluminum carbonate compound Zn6Al2(OH)16CO3.H2O,and hy-droxy zinc aluminum carbonate compounds such as Zn0.70Al0.30(OH)2(CO3)0.15·xH2O and Zn0.71Al0.29(OH)2(CO3)0.145·xH2O,which sealed the pores in the Zn-Al alloy coating.Compared with the uncorroded coating,the coating after 180 d,360 d and 540 d exposure increased by an order of magnitude,and the free corrosion potential increased about 200 mV,and the self-corrosion current density decreased to about one-third of the uncorroded coating.After corrosion,the Zn-Al alloy coating shows low and stable corrosion rate,which shows excellent anti-corrosion properties.Dense and viscous corrosion products seal the pores of the coating,improving the corrosion resistance of the Zn-Al alloy coating.
关键词
电弧热喷涂/高铝锌基合金/涂层/热带岛礁/大气腐蚀/腐蚀规律
Key words
arc thermal spraying/high Al-Zn based alloy/coating/tropical island-reef/atmospheric corrosion/corrosion rule
维普
万方数据