【作者】 付东兴；

【导师】 李庆芬； 徐滨士；

【作者基本信息】 哈尔滨工程大学 ， 材料学， 2008， 博士

【摘要】 涉海装备在服役过程中极易受到海水和海洋大气环境的影响而发生严重的腐蚀。传统的有机涂层需要经常进行维护,不能满足人们对涉海装备在服役过程中长时间不维修或少维修的需求。因此,开展针对钢结构表面长效防腐涂层的技术和理论研究,对于解决涉海装备在苛刻海洋环境下的防腐问题具有重要意义。本文采用再制造关键技术——高速电弧喷涂技术在Q235钢表面制备Zn-Al-Mg-RE金属涂层,再在涂层表面涂装有机涂层,构建了复合防腐涂层。利用热盐水浸泡试验、铜离子醋酸盐雾加速腐蚀试验、电极电位试验和电化学交流阻抗试验检测了金属涂层和有机涂层之间的协同性;通过SEM、EDAX、XRD、人工缺陷试样常温浸泡试验、电化学交流阻抗试验以及自主研发的装置结合离子色谱仪研究了该复合防腐涂层的耐蚀机理;通过理论计算和试验研究了不同物化性能的腐蚀产物对复合涂层表面有机涂层失效形式的影响;在分析某型舰船和水陆装备典型零部件腐蚀失效形式的基础上,采取该复合防腐涂层对其进行防腐处理,并进行了应用考核。主要得到了以下结论:在溶液介质腐蚀环境和盐雾腐蚀环境中,与Al涂层相比,Zn-Al-Mg-RE涂层与有机涂层在腐蚀环境中均具有更好的协同性。在喷涂Al涂层复合防腐涂层界面处,碱性腐蚀产物破坏了有机涂层的结合键,渗透压促使有机涂层剥离,导致鼓泡发生;而在Zn-Al-Mg-RE涂层表面形成的腐蚀产物寿命较长,不易分解,起到了钝化膜的作用。电化学交流阻抗试验结果表明:有机涂层中存在微观孔隙或宏观孔隙时有机涂层与Zn-Al-Mg-RE涂层仍然具有较好的协同性。在测试过程,该复合防腐涂层体系的涂层孔隙电阻一直保持在10~7Ωcm~2以上,说明有机涂层对金属涂层一直起到有效的保护作用;在浸泡后期,涂层电容长时间保持恒定,说明Zn-Al-Mg-RE涂层腐蚀产物的存在有效地弥补了有机涂层自身的微观孔隙。当有机涂层中存在宏观孔隙时,腐蚀产物先封闭宏观孔隙附近的微观孔隙,然后封闭新形成的微观孔隙、腐蚀产物与有机涂层之间的微观孔隙以及腐蚀产物之间的微观孔隙。通过这种方式,腐蚀产物在宏观孔隙中形成致密的微观结构,阻止腐蚀介质对界面的破坏。本文提出了喷涂Zn-Al-Mg-RE涂层的复合防腐涂层的耐蚀机理——双重自封闭机理。将制备了人工缺陷的试样在5%NaCl溶液中浸泡430小时,发现有机涂层中的人工孔隙被Zn-Al-Mg-RE涂层的腐蚀产物堵塞,通过SEM进一步检测发现人工孔隙中腐蚀产物的微观结构非常致密,由此说明该复合防腐涂层具有向上封闭有机涂层中微观缺陷的作用。自由膜渗透试验结果表明:随着时间的延长,氯离子在Zn-Al-Mg-RE涂层自由膜中的渗透速率逐渐减慢,最后溶液中的氯离子浓度保持恒定不变,说明Zn-Al-Mg-RE涂层的腐蚀产物能够堵塞自身的微观孔隙,阻止腐蚀介质的继续渗透。本研究发现了Zn-Al-Mg-RE涂层表面的腐蚀产物中含有纳米晶,并提出了纳米腐蚀产物形成机理。将喷涂了Zn-Al-Mg-RE涂层的试样浸泡于5%的NaCl溶液中30天、120天和210天,通过XRD检测涂层表面腐蚀产物的晶粒度,发现腐蚀产物中存在纳米级的腐蚀产物,纳米级的腐蚀产物能够使腐蚀产物的微观结构变得非常致密,从而说明该复合防腐涂层具有双重自封闭特性的原因是Zn-Al-Mg-RE涂层能够生成纳米级的腐蚀产物。本文还得出了渗透压型鼓泡边缘的扩展速率和腐蚀产物体积膨胀型鼓泡的临界弯曲力矩。并通过实验验证了喷涂Al涂层的复合防腐涂层表面有机涂层鼓泡的主要影响因素为渗透压力;而喷涂Zn-Al-Mg-RE涂层的复合防腐涂层表面有机涂层鼓泡的主要影响因素为腐蚀产物生成时的体积膨胀力。在某型舰船和水陆装备上的应用研究表明喷涂Zn-Al-Mg-RE涂层的复合防腐涂层具有良好的耐海水腐蚀性能。可在不改变装备原有防护体系的前提下,解决原有体系防护寿命短、效果差、成本高的问题。更多还原

【Abstract】 The corrosion problems of oceanic equipments serving in marine water and marine atmosphere environment are serious. Conventional organic coatings always need maintenance and don’t meet the demand of un-maintenance or less-maintenance at a long time. Therefore, technology and theory studies on long-term anticorrosion coatings against the equipments are of great importance.In the paper, high velocity arc spraying technology (HVAS) which is one of the key remanufacturing technologies was used to produce Zn-Al-Mg-RE coating, and then organic coatings were applied on the coating. The synergy effect between the coatings was investigated by immersion testing, chloride copper acetic acid spraying testing (CASS), electrode potential testing and EIS testing. The anticorrosion mechanism of the composite coatings was studied with SEM, EDAX, XRD, immersing samples with artificial defects in 5%NaCl solution, EIS testing and testing combining device which was designed by the author and ion chromatograph. The influence of physicochemical property of corrosion products on failure behavior of the organic coatings was studied on the basis of theory compute and testing. After surveying typical components failure process of some ship and some amphibious equipment, the composite coatings were applied, and anticorrosion property of the composite coatings in real oceanic environment was examined at the same time. Main conclusions were drawn as following:Comparing with Al coating, the Zn-Al-Mg-RE coating had better synergy effect with organic coatings both in solution corrosive medium and salt spraying corrosive medium. In the organic coatings/Al coating interface, the adhesion was destroyed by the alkalinous corrosion products and the delamination of organic coatings was accelerated by osmotic pressure, which led to the appearance of blister. While, the life of stable corrosion products that acted as a passivating film on the surface of Zn-Al-Mg-RE coating was longer. EIS results indicated that organic coatings had better synergy effect with Zn-Al-Mg-RE coating when there were micro-pores or macro-pores in the organic coatings. The pore resistance of the composite anticorrosion coatings system kept higher than 10~7Ωcm~2 during all the testing, which indicated that the organic coatings protected the metallic coating effectively all the time. The coating capacitance kept constant at a long time at the later stage of testing, which indicated that micro-pores in the organic coatings were remedied by the Zn-Al-Mg-RE coating corrosion products. When there were macro-pores in the organic coatings, micro-pores around macro-pores were preferentially blocked by the corrosion products, then the new micro-pores, the micro-pores between the corrosion products and the organic coatings and in the corrosion products were blocked by the corrosion products. By this way, the microstructure of corrosion products in macro-pores became compact and the destruction of corrosion medium to interface was inhibited.The double self-sealing anticorrosion mechanism of the composite anticorrosion coatings was brought forward. After samples with artificial defects immersed in 5%NaCl solution for 430 hours, the artificial defects in the organic coatings were blocked by the Zn-Al-Mg-RE coating corrosion products. The compact microstructure of the corrosion products was observed by SEM. The results showed that the composite coatings had the function of blocking micro-pores in the organic coatings. Free-film permeation testing indicated that the diffusion of chloride ions into the Zn-Al-Mg-RE coating free-film slowed down with time and the chloride ions concentration in the solution kept constant at the later stage of testing, which indicated that the corrosion products of Zn-Al-Mg-RE coating had the function of blocking the micro-pores in the coating and the permeation of corrosion medium was held.The nanocrystals in the corrosion products were discovered and the formation mechanism of the corrosion products was brought forward. The samples with Zn-Al-Mg-RE coating were immersed in 5%NaCl solution for 30 days, 120 days and 210 days, and the grain sizes of the corrosion products was calculated from the XRD testing. Results indicated that there were nanometer corrosion products in the corrosion products and microstructure of the corrosion products became much compact, which made it clear that the reason of the composite anticorrosion coatings had double a self-sealing characteristic was ascribed to the formation of the nanometer corrosion products.Brim spreading velocity of osmotic pressure blister and critical bending moment of volume expansion blister were computed. The main factor influencing blister of organic coatings on Al coating was osmotic pressure, while, the main factor influencing blister of organic coatings on Zn-Al-Mg-RE coating was volume expansion force during corrosion products generating, which were identified by testing.The composite coatings were applied to ships and amphibious equipments. Results showed that the composite coatings protected the equipments effectively. The organic coatings system originally applied on the equipments was not changed and problems such as short life, badly protecting and high cost were settled.更多还原