【作者】 王双红；

【导师】 刘常升； 王林山；

【作者基本信息】 东北大学 ， 材料学， 2009， 博士

【摘要】 在现代经济的各个领域中,铝及其合金被广泛使用,成为了其使用量仅次于钢铁的第二大类金属材料。为了防止铝及其合金的腐蚀,通常采用铬酸盐钝化技术在铝及其合金表面形成铬酸盐钝化膜,但铬酸盐钝化膜含有六价铬,对环境污染严重,对人体危害大,世界各国纷纷出台政策法规限制或禁止铬酸盐钝化技术的使用,并要求使用环保的无铬钝化技术用于铝及其合金的腐蚀防护。在无铬钝化技术的实践选择中,钛锆基的无铬钝化体系逐渐显示出良好的工业应用前景,但是钛锆基钝化膜的耐蚀性和油漆附着力远不及铬酸盐钝化膜,不能满足许多使用条件下对制备技术和性能的要求。为了研发出环保型、高性能、低成本的无铬钝化新技术。本论文基于钛锆基钝化技术进行了优化和改进,提出了钛锆盐-有机膦酸盐的复合处理技术。利用有机膦酸分子的化学特性与钛锆钝化膜相杂化,获得一层疏水性的有机膦酸盐膜层,强化钛锆钝化膜与油漆间的附着力,同时使得整个涂层体系具有更好的腐蚀防护性能。本论文以AA6061铝合金为试验基材,主要采用一步成膜法,即有机膦酸作为添加剂添加到钛锆基处理液中处理铝合金以获得钛锆钝化膜与有机膦酸盐膜相杂化的复合膜。为了验证一步成膜法获得的钛锆-有机膦酸盐复合膜的性能与结构,本论文又采用了两步成膜法与一步成膜法进行对比研究,即有机膦酸作为后处理剂,对钛锆钝化膜进行二次有机膦酸封闭处理获得钛锆-有机膦酸盐复合膜。同时,本论文也研究了A356合金表面的钛锆-有机膦酸盐复合膜以及AA6061合金表面的自组装有机膦酸盐膜的涂漆性能。利用扫描电子显微镜(SEM)及附带的能谱分析(EDAX)、原子力显微镜(AFM)、激光共聚焦显微镜(LSCM)、傅里叶红外光谱(FTIR)和X射线光电子能谱(XPS)等分析手段系统深入地研究了所成膜的表面形貌、元素构成、化学结合状态和相关机理。利用点滴试验、中性盐雾试验(SST)和电化学测试等腐蚀试验手段考察了所成膜的耐蚀性能和涂漆性能。利用单因素实验和正交实验,对处理液的配方进行了设计和优化,确定了处理液的基本组成及用量；确定了有机膦酸的种类及用量；优化了一步成膜法所成膜的制备工艺。利用电化学测试和盐雾试验研究了复合膜的耐蚀性能,电化学结果表明,一步法优于两步法,一步法所成膜的耐腐蚀性能与铬酸盐膜相当。盐雾试验结果表明,未涂漆的一步法所成膜的耐盐雾性能与两步法所成膜相当。利用SEM和AFM分析了复合膜的表面形貌,结果表明,一步法和两步法所成膜都为连续膜。利用FTIR和XPS分析了复合膜的结构,结果表明,一步法和两步法所成膜的结构都为钛锆钝化膜和有机膦酸盐膜相互杂化构成的复合结构。利用浸泡试验和盐雾试验研究了复合膜的涂漆性能,结果表明,钛锆-有机膦酸盐复合膜与油漆间的附着力明显提高,涂漆后的钛锆-有机膦酸盐复合膜能有效抑制涂层的起泡和脱漆,提高涂层的耐蚀性能,与涂漆后的六价铬酸盐膜性能相当。利用浸泡试验和盐雾试验研究了钛锆-有机膦酸盐复合膜/油漆体系对A356合金的防护性能,结果表明,涂漆后的钛锆-有机膦酸盐复合膜能提高A356合金的附着力性能和耐蚀性能。对有机膦酸自组装分子技术在AA6061合金上的应用进行了探讨,结果表明,氨基三甲叉膦酸能在铝合金表面自组装形成氨基三甲叉膦酸盐膜,涂漆后的氨基三甲叉膦酸盐膜的耐盐雾性能和附着力性能与涂漆后的六价铬酸盐膜相当。总之,一步法所成的钛锆-有机膦酸盐复合膜的结构与二步法所成膜相同,具有独特结构和优异性能。结构都为钛锆钝化膜和有机膦酸盐膜相互杂化构成的复合结构。涂漆后的钛锆-有机膦酸盐复合膜的附着力明显提高,有效抑制涂层的起泡和脱漆,提高了整个涂层的耐蚀性能,与涂漆后的六价铬酸盐膜性能相当。钛锆-有机膦酸盐复合膜具有优异性能的机理在于不同结构的膜层间的协同作用,使复合膜具有更优异的机械阻碍作用及其电绝缘,有效地抑制了氧和电子的自由扩散和迁移,阻碍Cl-的渗入,提高了铝合金的耐蚀性能。涂漆后,复合膜结构中的有机膦酸盐膜层能够与油漆中的有机树脂通过共价键连接,增加了整个涂层体系的附着力,阻止了水、氧、Cl-的侵入,抑制腐蚀引起的电渗透作用,避免了起泡和脱漆等现象的发生。更多还原

【Abstract】 Aluminum and aluminum alloy are widely applied on every field of modern economy; its usage quantity is the second only next to steel material. As it well known, the chromate passivation technique is proverbially used for the corrosion resistance of aluminum and aluminum alloy. However, the chromate passivation films contains hexavalent chrome which is a kind of extremely poisonous to environment and carcinogenic to the body, many countries in the world have released some policies or laws to restrict or forbid the usage of chromate passivation technique and appealed to use chrome-free passivation technique. In the practice choice of chrome-free passivation technique, the titanate and/or zirconate passivation system showed gradually nicer foreground of industrial application, but its corrosion resistance and adhesion to paint are so far from chromate passivation films that it can not meet needs of preparation technique and performance in many usage condition. For the sake of researching and developing environmental-friendly and high-performance and low-cost chrome-free passivation technique, the titanate-zirconate and organophosphonate composite treatment technique was put forward on the base of optimizing and improving the titanate-zirconate passivation technique in this paper. A hydrophobic layers hybridized with the titanate-zirconate films was obtained using chemistry characteristic of an organophosphonic acid to intensify the adhesion to paint and improve the corrosion resistance of the whole coatings system.AA6061 aluminum alloy in this paper was mainly investigated by one-step method, namely, an organophosphonic acid was added to the titanate-zirconate treatment solution as addition reagent and the titanate-zirconate organophosphonate hybrid films was obtained on AA6061 aluminum alloy. The two-step method was studied to contrast the performance and structure of the titanate-zirconate organophosphonate hybrid films obtained by one-step method, namely, the organophosphonic acid as post-treatment reagent was used to block off the titanate-zirconate films on AA6061 aluminum alloy. The paint performance of the titanate-zirconate organophosphonate hybrid films with paint on A356 aluminum alloy and a self-assemble organophosphonate layers with paint on AA6061 aluminum alloy was investigated, too.The morphology, element composition, chemistry state and corresponding mechanism were systematically investigated by scanning electron microscopy with energy dispersive spectroscopy (SEM/EDAX), atomic force microscopy (AFM), laser scanning confocal microscope (LSCM), fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The corrosion resistance and paint performance were explored by the methods of dropping test, neutral salt spray test and electrochemical test.The composition of the treatment solution was designed and optimized by single factor test and orthogonal test; The basic composition and concentration of the treatment solution were confirmed; The kind and concentration of organophosphonic acid were determined; The preparation technique parameters of the hybrid films obtained by one-step method was researched. The corrosion resistance performance of the hybrid films was evaluated by electrochemical test and salt spray test. The electrochemical results show that one-step method is better than two-step method, the hybrid films obtained by one-step method is good as the chromate passivation films. The salt spray test results show that the hybrid films by one-step method without paint is similar to the hybrid films by two-step method without paint. The morphology of the hybrid films was observed by SEM and AFM, the test results show that the hybrid films by one-step method and two-step method are both continuous films. The characterization and structure of the hybrid films were analyzed by FTIR and XPS, the test results show that the structure of the hybrid films by one-step method and two-step method are both hybrid composite structure of the titanate-zirconate films and organophosphonate films. The paint performance of the hybrid films was evaluated by adhesion test, dipping test and neutral salt spray test, the results show the adhesion of the hybrid films to paint is obviously increased compared with the titanate-zirconate films, the blistering and de-painting are effectively restrained, the corrosion performance of the hybrid films is advanced and similar to the chromate passivation films with paint.The performance of the titanate-zirconate organophosphonate hybrid films/paint system on A356 alloy was investigated by dipping test and neutral salt spray test. The results show that the titanate-zirconate organophosphonate hybrid films can improve the adhesion and the corrosion resistance on A356 aluminum alloy.The application of the organophosphonic acid as a self-assemble molecular technique (SAM) on AA6061 aluminum alloy was explored. The aminotrimethylene phosphonate films were formed by aminotrimethylene phosphonic acid adsorption on the surface of AA6061 aluminum alloy. The results show that the corrosion resistance and the adhesion of the aminotrimethylene phosphonate films with paint have a similar performance comparing with the chromate passivation films with paint.To sum up, the structure of the titanate-zirconate organophosphonate hybrid films obtained by one-step method is similar to two-step method, which have particular structure and superior performance. The structure is hybrid composite structure of the titanate-zirconate films and the organophosphonate films. The adhesion to paint of the titanate-zirconate organophosphonate hybrid films is obviously advanced, the blistering and de-painting are effectively restrained, and the corrosion resistance performance is similar to the chromate passivation films with paint. The mechanism of the the hybrid films having superior performance rests with synergy effects between different structure films. This structure make the hybrid films have more superior barrier and insulation, block off infiltration of Cl- ion and improve the corrosion resistance. After coated paint, the organophosphonate films in the structure of the hybrid films can link with the resin in the paint by covalence bond, improve the corrosion resistance of the whole coatings system, block off infiltration of H2O, O2 and Cl" ion, restrain electroosmosis and avoid blistering and de-painting.更多还原