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| Corrosion Behavior of Thermal Sprayed Zinc-Aluminum Alloy Coating with High Aluminum Content in Tropical Island-reef Atmospheric Environment |
| Received:October 31, 2023 Revised:February 18, 2024 |
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| DOI：10.7643/issn.1672-9242.2024.03.017 |
| KeyWord:arc thermal spraying high Al-Zn based alloy coating tropical island-reef atmospheric corrosion corrosion rule |
| Author | Institution |
| GUO Qiang |
Beijing Institute of Machinery and Equipment, Beijing , China |
| ZHAO Wei |
First Military Representative Office of Air Force Equipment Department in Beijing, Beijing , China |
| ZHANG Chong |
Beijing Institute of Machinery and Equipment, Beijing , China |
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| Abstract: |
| 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 coatings 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 morphology, 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 hydroxy 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. |
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