热喷涂高铝含量Zn-Al合金涂层热带岛礁大气环境腐蚀行为研究

目的 研究Zn-Al合金涂层在热带海洋大气环境中的腐蚀行为，为低合金钢长效防护涂层的选用提供依据。方法 采用电弧热喷涂和高铝合金丝制备高铝含量Zn-Al合金涂层，通过户外暴露试验，采用目视、扫描电镜及能谱仪、金相显微镜、XRD、电化学交流阻抗谱和动电位极化曲线等方法，对不同暴露周期的涂层宏观、微观表面形貌、成分组成、截面形貌、腐蚀产物组成、电化学性能和腐蚀速率等进行观察、测试。结果Zn-Al合金涂层是以质量比为50%:50%的Zn/Al合金组成。在0～540 d周期内，涂层腐蚀产物主要由碱式锌铝碳酸盐化合物Zn₆Al₂(OH)₁₆CO₃·H₂O和羟基锌铝碳酸盐化合物Zn_0.70Al_0.30(OH)₂(CO₃)_0.15·x H₂O、Zn_0.71Al_0.29(OH)₂(CO_3<...

Corrosion Behavior of Thermal Sprayed Zinc-Aluminum Alloy Coating with High Aluminum Content in Tropical Island-reef Atmospheric Environment

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.