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通过设计模拟腐蚀环境电解池,利用电化学阻抗谱、扫描电镜和傅立叶红外光谱分析,研究处于3%(质量分数)Na Cl电解质膜下环氧涂层/碳钢体系的干湿循环腐蚀行为。结果表明,涂层破损区域的表面裸露碳钢在第4次干湿循环的腐蚀速率达到最大,然后腐蚀速率随干湿循环呈降低趋势。而涂层下碳钢的腐蚀速率在第6个干湿循环达到最大,之后逐渐降低并趋于稳定。涂层下碳钢和裸露碳钢表面由于氧扩散差异,导致形成氧浓差电池,使处于敞开液膜下的裸露碳钢成为阳极,其腐蚀速率总是高于涂层下碳钢。由于离子定向迁移或扩散的作用,导致裸露碳钢的中心区域至其边缘腐蚀产物为多层阶梯状分布,而涂层下基体金属腐蚀形貌呈波纹状。
The corrosion and corrosion behavior of epoxy / carbon steel under 3% (mass fraction) NaCl electrolyte membrane was studied by means of simulating the corrosion environment of the electrolytic cell. The electrochemical corrosion resistance (ECDC), electrochemical scanning electron microscopy and Fourier transform infrared spectroscopy (FTIR) The results show that the corrosion rate of bare carbon steel on the surface of the damaged area of the coating reaches the maximum at the 4th dry-wet cycle, and then the corrosion rate tends to decrease with the wet-dry cycle. While the corrosion rate of carbon steel under the coating reaches the maximum at the 6th cycle of wetting and drying, then gradually decreases and tends to be stable. Due to the difference of oxygen diffusion, the oxygen-poor cells are formed on the surface of the bare carbon steel and the bare carbon steel. The bare carbon steel under the open liquid film becomes the anode, and the corrosion rate is always higher than that of the coated lower carbon steel. Due to the ion migration or diffusion, the corrosion products in the center of the bare carbon steel to the edge are multi-stepped and distributed, while the corrosion morphology of the metal under the coating is corrugated.