【摘要】 采用SEM和EDS等手段考察在微观尺度下Al-Zn-Si-RE涂层的结构和成分均匀性,采用动电位极化曲线和电化学阻抗谱研究了Al-Zn-Si-RE涂层在3.5%NaCl溶液中的腐蚀行为。结果表明,Al-Zn-Si-RE涂层具有典型的片层结构,显著增加了腐蚀介质到达基体的路径,涂层在微观尺度下成分分布均匀,可充分发挥高铝涂层耐蚀性;Al-Zn-Si-RE涂层的腐蚀过程分为4个阶段:浸泡初期涂层表面金属粉的活化腐蚀;第二阶段腐蚀产物在金属粉表面覆盖,显著降低金属粉的溶解速度;第三阶段腐蚀介质渗透到涂层与基体界面,锌铝粉短暂的牺牲阳极保护作用;腐蚀后期,涂层的耐蚀机理主要为腐蚀产物的物理屏蔽作用。腐蚀过程中,涂层的防护机制表现为牺牲阳极的阴极保护和腐蚀产物的屏蔽效应综合作用。更多还原

【Abstract】 The microstructure and corrosion performance in 3.5%Na Cl solution of an Al-Zn-Si-RE containing water-borne coating were investigated by means of SEM with EDS as well as potentiodynamic polarization curves and electrochemical EIS. The results indicate that Al-Zn-Si-RE coating shows a typical lamellar structure, which significantly increases the length of diffusion path for corrosive species; and an excellent coating uniformity in micro scale, which may be beneficial to its protectiveness. The corrosion process of Al- Zn- Si- RE coating can be divided into four stages during immersion in 3.5%Na Cl solution: I) the active corrosion of Al-Zn-Si-RE flakes on the surface layer; II) the coverage of Al-Zn-Si-RE flakes by the corrosion product layer thereby decreasing their dissolution; III) the temporary sacrificial anode protection of the coating for the steel substrate when the electrolyte reached the interface coating/substrate; IV) the barrier protection caused by corrosion products. Therefore, the protection mechanism of the coating is physical barrier combined with a weak sacrificial anode protection.更多还原