【作者】 王珂；

【导师】 缪强；

【作者基本信息】 南京航空航天大学 ， 材料加工工程， 2015， 硕士

【摘要】 在海上大型钢结构的长效防腐蚀领域,热喷涂锌铝合金防腐涂层技术正逐步替代纯锌、纯铝涂层技术,因此,研究Al-Zn涂层的制备及其耐蚀性能对其应用具有重要的工程价值。本文利用正交试验的方法优化了电弧喷涂工艺参数,并采用优化后的工艺参数制备了Al-Zn-Si合金涂层与相同铝含量的Al-Zn伪合金涂层。采用光学显微镜、扫描电子显微镜、能谱分析仪、X射线衍射仪等分析了涂层腐蚀前后的组织。通过盐水全浸实验、中性盐雾实验、电化学测量技术,对比研究了相同铝含量的Al-Zn-Si合金涂层与Al-Zn伪合金涂层在不同模拟海洋环境下的耐蚀性能。为缩短实验时间,在涂层表面进行人工划叉破损处理,同时对部分涂层进行封孔后处理,研究封孔处理对涂层耐蚀性能的影响,并对Al-Zn-Si合金涂层的耐蚀机理进行了探讨。研究结果表明,优化后的最佳工艺参数为:喷涂电压28 V,喷涂电流180 A,喷涂距离150mm,空气压力0.6 MPa。Al-Zn-Si合金涂层与Al-Zn伪合金涂层厚度均约为200μm,且前者比后者组织成分更均匀,经过盐水全浸实验150 d、中性盐雾实验60 d,伪合金涂层比Al-Zn-Si合金涂层被腐蚀破坏更严重;涂层表面破损处均发生良好的自修复作用;封孔处理减轻了腐蚀破坏作用。Al-Zn-Si合金涂层与伪合金涂的腐蚀电流密度分别为2.482×10-5 A·cm-2、5.901×10-5A·cm-2,两涂层封孔处理后腐蚀电流密度分别为1.3×10-5 A·cm-2、1.35×10-5 A·cm-2。封孔处理后Al-Zn-Si合金涂层的电化学阻抗模值增加,Al-Zn-Si合金涂层的腐蚀产物主要为碱式氯化锌,锌铝羟基碳酸盐,碱式氯化铝。更多还原

【Abstract】 Zn-Al coatings are replacing the traditional pure Zn or Al coatings in the field of long life anti-corrosion for large steel constructions. Therefore, it is very important to study the preparation and corrosion resistance of Zn-Al coatings with high corrosion performance.In this paper, arc spraying technology was used to prepare Al-Zn-Si alloy coating and Al-Zn pseudo-alloy coating with the same Al content. The parameters were optimized through the Orthogonal test. The specimens with scratch route were used to accelerate the corrosion tests. Comparative studies on the corrosion products and electrochemical measurements were investigated to evaluate the corrosion resistance of the two coatings exposed in three kinds of simulated marine environments, including salt water immersion test and neutral salt spray test. X-ray diffraction technique(XRD), optical microscope(OM) and scanning electron microscope(SEM) were employed to study the microstructure and the composition of the corrosion products. Electrochemical measurement techniques were carried out by Tafel and EIS. Hole sealing treatment was also used to evaluate the change of the corrosion resistance. Furthermore, the corrosion mechanisms of Al-Zn-Si alloy coating in different environments were discussed.The results showed that the best arc spraying parameters on the performance of the Al-Zn-Si alloy coating is spraying voltage 28 V, spraying current 180 A, spraying distance 150 mm, spraying pressure 0.6 MPa. The components of Al-Zn-Si alloy coating were more uniform than that of Al-Zn pseudo-alloy coating. Al-Zn pseudo-alloy coating was corroded more seriously than Al-Zn-Si alloy coating after immersed in salt water for 150 d and exposed to neutral salt spray testing for 60 d.The scratches on the coatings were self-repairing well. Hole sealing treatment relieved the corrosion damage. The corrosion current densities of Al-Zn-Si alloy coating and Al-Zn pseudo-alloy coating were 2.482 ×10-5 A·cm-2 and 5.901×10-5 A·cm-2. The corrosion current densities of the two coatings after hole sealing treatment were 1.3×10-5 A·cm-2 and 1.35×10-5 A·cm-2 respectively. The impedance value of Al-Zn-Si alloy coating after hole sealing treatment increased. The corrosion products of Al-Zn-Si alloy coating were mainly Basic Zinc Chloride, Zinc aluminum carbonate hydroxide hydrates and Hydroxy aluminium chloride hydrate.更多还原