| 轻质合金纳米自组装颗粒涂层和纳米底漆腐蚀行为的研究 | |
| 史洪微 | |
| 关键词 | 材料学 纳米自组装颗粒相涂层 纳米 涂层 腐蚀 铝合金 抑制剂 底漆 桥联结构 Coatings suppressor Primer 涂层 Coating Surface coatings Coating materials Protective coatings electroless deposited coatings liquid phase deposited coatings BESCHICHTUNG ENDUIRE REVETEMENT COUCHES DEPOTS REVETEMENTS UEBERZUEGE 涂料 Blakodizing 抑制剂 底漆 |
| 其他题名 | Study on Corrosion Behavior of Self-assembled Nano-phase Particles Coating and Nano-composite Primer on Light Alloys |
| 中文摘要 | 铬酸盐转化涂层和含有铬酸盐的底漆应用于飞机蒙皮漆体系中有悠久的历史。但由于铬酸盐的致癌效应，这种转化涂层已经逐渐被各国限制和禁止使用，无铬的转化层和低铬底漆开发和性能研究成为近年来研究的热点。目前，国外针对此方面的研究日益增多，而我国对此方面的研究所见甚少。我国正在加紧制定和实施大飞机研发计划，对飞机涂层体系的相关研究也迫在眉睫，所以，本文针对飞机蒙皮的铝合金上的无铬转化涂层和纳米环氧底漆的研究具有重要的现实意义。 本文采用不同的实验方法研究了无铬的纳米自组装硅烷转化涂层在涂覆LY12铝合金上的制备方法和性能表征；研究了添加典型无机和有机缓蚀剂对硅烷转化涂层耐腐蚀性能的影响；同时，本文也探讨了硅烷转化涂层涂覆AZ91D镁合金的耐腐蚀性能，以及对镁合金磷酸盐转化膜的封孔能力；研究了环氧底漆中添加纳米粒子对底漆耐腐蚀性能的影响。 首先，研究了自组装纳米颗粒相涂层的成膜机制。研究结果表明，以GPTMS(γ-缩水甘油醚基丙基三甲氧基硅烷)和TMOS(正硅酸甲酯)为前驱体制备的溶胶以纳米级的颗粒状态存在，且粒径随稀释水的增加而下降，固化剂二乙烯三胺加入后，颗粒彼此交联而成自组装涂层。涂层常温固化易产生孔洞或缺陷，需加入消泡剂消泡；高温固化可制备均一、平整的涂层。固化成膜前后红外光谱的变化证明了Si-O-Si单元的形成和胺固化导致的GPTMS上的环氧基团的消失。 其次，用EIS(电化学阻抗谱)研究了典型有机和无机抑制剂对不同固化剂固化的涂层耐腐蚀性能的影响，提出了适合于此种涂层体系的等效电路,考察了等效电路中各参数的变化。拟合结果表明，涂层在浸泡初期即体现了两个时间常数的特征，随着浸泡的进行，无抑制剂涂层和添加MBT(巯基苯并噻唑)的涂层在浸泡中期出现代表铝合金点蚀的第三个时间常数，表明MBT对涂层的耐蚀作用影响不大。添加CeCl3和MPD(2-甲基哌啶)的涂层在浸泡后期出现第三个时间常数的特征或在浸泡后期并不出现第三个时间常数，涂层Rox值较高，说明无机抑制剂CeCl3和有机抑制剂MPD能有效地抑制铝合金的腐蚀。对比CeCl3,电化学阻抗谱的结果表明，添加Ce(NO3)3的涂层在浸泡过程中对铝合金具有良好的自愈合作用。拟合结果也表明，二乙烯三胺固化的涂层具有最好的耐腐蚀性，长链胺反而使涂层耐腐蚀性下降。 再次，对自组装硅烷转化涂层在AZ91D镁合金表面的防护进行了探索。用自组装硅烷涂层对镁合金磷酸盐转化膜进行封孔，极化曲线显示封孔后的涂层比封孔前的腐蚀电流密度降低两个数量级。添加MPD的溶胶-凝胶涂层封孔后的涂层在Harrison溶液中浸泡的电化学阻抗谱也体现了一个时间常数的特征,浸泡96h涂层未出现开裂。结果表明，封孔后的涂层已经具有较好的耐腐蚀能力。 最后，研究了纳米粒子对飞机用环氧底漆耐腐蚀性能的影响。在环氧清漆和色漆中加入1%(wt.%)的纳米TiO2或纳米SiO2，可以增强环氧清漆和色漆的耐腐蚀性能。对于硅烷偶联剂GPTMS(γ-缩水甘油醚基丙基三甲氧基硅烷)处理的纳米SiO2对底漆体系的改善作用，提出了桥联结构的模型。由于纳米SiO2上的多羟基特性，促进了其能够与硅烷偶联剂的交联，形成一种网状结构。这种结构可以增加涂层的稳定性，使涂层难于被破坏，同时延长了水和Cl-的传输路径，抑制环氧涂层的起泡和缺陷的形成。; The application of chromate conversion coating and primer containing chromate has a long history. However, due to the carcinogenic effect of chromate, the above conversion coating and primer are being restricted in use or will be inhibited in the future. The research on the substitute of chromate has been focused in recent years. At present, the increasing effort is being put of the research and development on the conversion coating without chromate and low-content chromate primer, but little work was done in domestic universities or institutions. China is now carrying out the plan of Large Airplane, so the need of study on coating system on plane is urgent. It is undoubtedly of practical significance to research on the non-chromate silane-based conversion coating and nano-composite epoxy primer on aluminum alloy in this paper. The preparation and performance of the non-chromate silane-based Self-assembled Nano-phase Particles Coating was studied using different experimental methods. The effect of typical inorganic and organic corrosion inhibitors on the anti-corrosion performance of self-assembled coatings was studied. Moreover, the protective ability of silane-based coating on AZ91D magnesium alloy and sealing effect of silane-based coating on AZ91D phosphated conversion coating were discussed. The effect of nano-particles on corrosion resistance of epoxy primer was studied as well. First, the mechanism of film forming of Self-assembled Nano-phase Particles Coating was studied. Experimental results showed that nano-sized siloxane particles were formed through the hydrolysis and condensation of the precursors, GPTMS(3-glycidoxypropyltrimethoxysilane) and TMOS(tetramethoxysilane). The size of the particles decreased with the increase of distilled water. After diethylentriamine cured, the particles were crosslinked to form self-assembled coating. The coating was prone to form pinholes and defects if it was cured at room temperature, and the addition of anti-foam agent was required to reduce the bubbling, while the even coating can be prepared by high-temperature curing. FTIR of sol and cured film proved the formation of Si-O-Si unit and disappearing of epoxy group on GPTMS. Second, EIS (Electrochemical Impedance spectra) was used to investigate the effect of several corrosion inhibitors on the corrosion resistance of self-assembled coatings cured by different curing agent. The equivalent electrical circuits fitted with the corrosion process of the coatings were put forward and the change of the parameters of the equivalent electrical circuits was investigated. The fitted results showed that, two time constants appeared at the initial period of immersion, and three time constants that represent pitting corrosion of aluminum alloy appeared at the intermediated period of immersion of coatings without inhibitor and with MBT(mercaptobenzothiazole), indicating the addition of MBT did not improve the corrosion resistance of the coating. On the contrary, three time constants appeared at the end period of immersion or did not appear for the coatings with the addition of CeCl3 and MPD, also high Rox was obtained, indicating the excellent corrosion inhibition of the inhibitors. In contrast to CeCl3, addition of Ce(NO3)3 could play self-healing effect on aluminum alloy in the immersion process. Fitted results also showed that the coatings cured by diethylentriamine had the best corrosion resistance, the use of longer-chain amine weakened the corrosion resistance. Then, the protection of self-assembled coating on AZ91D magnesium alloy was explored. Polarization curves showed that the current density of crack-sealed coating by self-assembled coating was lower by two orders of magnitude than un-sealed phosphated conversion coating on AZ91D magnesium alloy. EIS results showed one time constant in the immersion of sealed coating. Also no crack was found on the sealed coating with the addition of MPD after immersed in Harrison solution for 96h. The above showed that the sealed coating had excellent corrosion resistance. At last, the effect of nano-particles on the corrosion resistance of epoxy primer on aircraft was investigated. The results of Electrochemical Impedance Spectrum (EIS) and salt spray test indicated that the 1%(wt.%) addition of nano-TiO2/SiO2 significantly improved the anticorrosion resistance of epoxy resin and primer. The enhancement of the anticorrosion resistance can be explained by the formation of layered ring structure of GPTMS treated nano-SiO2. The multi-hydroxyls on SiO2 promoted the formation of network structure combined with GPTMS. First, the coating is more compact due to the framework of layer nano-SiO2 particles. Second, due to the lengthened transport path, water and Cl- ion are more difficult to arrive at the coating/substrate interface. Accordingly, the bubble and delamination are difficult to occur to destroy the stable structure. |
| 语种 | 中文 |
| 出处 | 轻质合金纳米自组装颗粒涂层和纳米底漆腐蚀行为的研究.史洪微[d].中国科学院金属研究所,2005.20-25 |
| 其他责任者 | 韩恩厚 |
| 内容类型 | 其他 |
| 源URL | [http://210.72.142.130/handle/321006/17041]  |
| 专题 | 北京工业大学 |
| 推荐引用方式 GB/T 7714 | 史洪微. 轻质合金纳米自组装颗粒涂层和纳米底漆腐蚀行为的研究. |
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