采用SEM和EDS等手段对比研究了热浸镀和热喷涂两种方法制备的AI-Zn-Si-RE合金涂层的微观组织,采用电化学测试技术研究了两种涂层在3.5%NaCl溶液中的腐蚀行为,并讨论了涂层腐蚀机制及不同制备工艺对涂层性能的影响。结果表明:1)热喷涂和热浸镀两种合金涂层都拥有牺牲阳极的保护作用,但热喷涂合金涂层的保护效果更显著。2)当热浸镀及热喷涂涂层表面出现致密的腐蚀生成物时,可以很大程度地提高涂层屏蔽作用。3)阻抗谱演化分析发现,热喷涂涂层存在氧化膜点蚀阶段而热浸镀涂层没有此阶段。随着腐蚀进行,热喷涂涂层表面不断生成腐蚀产物,涂层耐腐蚀性能提高,在试验结束时仍然处于前中期,而热浸镀涂层的低频容抗出现Wurburg扩散阻抗特征,随后涂层基本失去防腐蚀能力。

The microstructures of Al-Zn-Si-RE alloy coatings prepared by hot dipping and hot spraying were studied by SEM and EDS,the corrosion behavior of the coating in sodium chloride solution were studied by means of electrochemical testing technology.The corrosion mechanism of the coating was discussed,and the influence mechanism of different processes on the performance of the coating was clarified.The results showed that:1)Both hot spraying and hot dipping alloy coatings had the protective effect of sacrificial anode,and the protective effect of hot spraying alloy coatings was more remarkable.2)The shielding effect of the coating could be greatly improved when there was a dense corrosion product film on the surface of the hot-dipped and hot-sprayed coatings.3)Impedance spectroscopy analysis showed that there was a pitting corrosion stage in the thermal spraying coatings,but there was no pitting stage in the hot dipping coatings.With the corrosion proceeding,corrosion products were continuously generated on the surface of thermal spraying coatings,and the corrosion resistance of the coatings was improved.At the end of the experiment,it was still in the early and middle stages.The low frequency capacitance resistance of the hot-dip coatings presents Wurburg diffusion impedance characteristics,and then the coatings lose the anti-corrosion ability basically.