硅烷膜及若干其它预处理层在涂装防护体系中的作用：实验研究和分子动力学模拟

发布时间：2018-11-12 18:34

【摘要】：新型预处理层涂装体系是目前应用最为广泛的金属腐蚀防护手段,其中结合力和防护效果是我们最为关注的问题。在实验研究中可以很容易的宏观评价涂层与基体结合力的大小和体系防护性能的优劣,但对于探讨发生在涂层／基体界面上的涂层失效的机制问题往往难以实现。分子动力学模拟是一种原子尺度的计算机模拟手段,在复合材料和表界面研究中应用颇多。本论文将实验与分子动力学模拟相结合,分别在宏观和原子层面上评价了两种硅烷预处理层对环氧涂层体系的结合力和耐腐蚀性能的影响；还利用分子动力学模拟技术研究了其他几种预处理层与不同聚合物涂层间的相互作用。本论文的具体研究内容包括：(1)研究了两种硅烷膜为预处理层的涂层体系的界面结合力和防护性能。采用了拉伸试验和EIS, SVET等腐蚀性能测试,发现具有有机官能团的GPTMS硅烷能明显增强涂层与基体间的结合力,BTSE却有着相反的作用；两种硅烷预处理层都能显著改善涂层体系的耐腐蚀性能,GPTMS在短期防护方面比较有优势,而BTSE有利于长期防护。分子动力学模拟结果显示,GPTMS硅烷膜体系在干态和湿态时都具有最大的界面相互作用能,而且从界面处的各组分浓度分布来看,GPTMS与环氧具有更宽的交融界面,说明与涂层的相容性更好,有利于增大结合力：当体系遭受水分子的入侵后,两者都能影响环氧涂层的吸水过程和聚合物链的流动性,但GPTMS膜层自身会略微膨胀,变得不致密,BTSE膜层会略微收缩变得更为致密,以抵挡水分子对体系防护性能的破坏,说明BTSE膜层更有利于保护金属。(2)采用分子动力学模拟计算了其他几种无机氧化物预处理膜层与后续涂层间的相互作用。结果表明未经预处理的金属基体与涂层之间的相互作用都比较薄弱,而预处理层能显著增强涂层体系的结合力,而且与后续涂层基本上不存在选择性问题。通过分析聚合物链在界面处的形态和浓度分布,发现相互作用的强弱主要受两个因素的共同影响：一是聚合物涂层与表面的接触情况；二是界面处聚合物中官能团分布的密集程度。
[Abstract]:The new pretreatment coating system is the most widely used method of metal corrosion protection at present, among which the bonding force and the protective effect are the most concerned problems. In the experimental study, it is easy to evaluate the strength of adhesion between coating and substrate and the protection performance of the system, but it is difficult to discuss the mechanism of coating failure on the interface between coating and substrate. Molecular dynamics simulation is a kind of computer simulation method on atomic scale, which is widely used in the study of composite materials and surface interfaces. In this paper, the effects of two kinds of silane pretreatment layers on the adhesion and corrosion resistance of epoxy coating system were evaluated at the macro and atomic levels by combining the experiments with molecular dynamics simulation. Molecular dynamics simulation was also used to study the interaction between other pretreatment layers and different polymer coatings. The main contents of this thesis are as follows: (1) the interfacial adhesion and protective properties of two kinds of silane coatings were studied. The tensile test and EIS, SVET corrosion test showed that GPTMS silane with organic functional group could obviously enhance the adhesion between the coating and the substrate, but BTSE had the opposite effect. Both kinds of silane pretreatment layer can significantly improve the corrosion resistance of the coating system. GPTMS has advantages in short term protection, while BTSE is favorable for long term protection. The results of molecular dynamics simulation show that the GPTMS silane membrane system has the largest interfacial interaction energy in dry and wet state, and from the concentration distribution of each component at the interface, GPTMS and epoxy have a wider interface. It shows that the compatibility with the coating is better, which is beneficial to increase the adhesion: when the system is invaded by water molecules, both of them can affect the water absorption process of the epoxy coating and the fluidity of the polymer chain, but the GPTMS film itself will expand slightly and become not compact. The BTSE film shrinks slightly more tightly to withstand the destruction of the protective properties of the system by water molecules. The results show that the BTSE film is more favorable for metal protection. (2) the interaction between the other inorganic oxide pretreated coatings and the subsequent coatings is calculated by molecular dynamics simulation. The results show that the interaction between the unpretreated metal substrate and the coating is relatively weak, while the pretreated layer can significantly enhance the adhesion of the coating system, and there is basically no problem of selectivity between the pre-treated metal substrate and the subsequent coating. By analyzing the morphology and concentration distribution of the polymer chain at the interface, it is found that the interaction is mainly affected by two factors: first, the contact between the polymer coating and the surface; The second is the density of the functional groups in the polymer at the interface.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG174.4

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