摘 要

热镀锌钢板由于具有优异的加工和使用性能，并且在干燥的自然环境中具有优良的防腐蚀能力，因此在工业各个领域得到了广泛的应用。金属锌在湿度高于70%的大气中，表面易腐蚀，最常用的方法是在镀锌层表面制备一层化学稳定性较高的铬酸盐薄膜，来提高它的耐腐蚀性能。但铬酸盐钝化工艺中的Cr⁶ 具有剧毒性且污染环境。硅烷化处理由于其无毒、无污染、适用广泛、成本低、对金属有很好的耐蚀性及与有机涂层有优异的粘接性能等优点而引起国内外学者们的广泛关注，使得该工艺有望取代传统的铬酸盐钝化处理工艺。

本文用1,2-双(三乙氧基硅基)乙烷（BTSE）和-缩水甘油醚氧丙基三甲氧基硅烷（KH560）两种硅烷偶联剂对金属表面进行硅烷化处理。并添加氯化铈（CeCl₃）和硝酸镧（LaNO₃）两种稀土盐来改性硅烷转化膜。通过正交试验得到了制备改性稀土转化膜的工艺配方，并用硫酸铜点滴法和电化学测试法来表征其耐腐蚀性能，以此得到一种最优的稀土改性硅烷转化膜的配方。之后，又将最优稀土转化膜与改性前的普通转化膜进行对照实验，探究改性前后两种转化膜的性能和结构变化。对两种转化膜进行了耐腐蚀性能的测试（硫酸铜点滴实验和电化学工作站），结果表明改性后的转化膜耐腐蚀性能得到提升；对两种转化膜进行结构的探究即扫描电子显微镜（SEM）分析、傅里叶变换红外吸收光谱（FTIR）分析，结果表明稀土改性后的转化膜表面更加光滑且膜层更加致密厚实；对两种转化膜进行各项基础力学测试，结果表明改性后的硅烷转化膜的附着力和耐水性都无太大变化，附着力十分优秀，耐水性较差，并且稀土改性使得硅烷转化膜的硬度和单位面积膜重都有提升。

关键词：热镀锌；硅烷化处理；稀土改性；耐腐蚀性能

Abstract

Hot-dip galvanized steel sheet has excellent processing and use performance, and in the dry natural environment has excellent anti-corrosion ability, so in various fields of industry has been widely used. Metal zinc in the humidity of more than 70% of the atmosphere, the surface is easy to corrosion, the most commonly used method is in the galvanized layer surface preparation of a layer of chemical stability of the higher chromate film, to improve its corrosion resistance. However, Cr6 in the chromate passivation process is highly toxic and pollutes the environment. Silanization treatment has attracted much attention from domestic and foreign scholars because of its non-toxic, non-polluting, wide range of applications, low cost, good corrosion resistance to metals and excellent adhesion properties with organic coatings. The process is expected to replace the traditional chromate passivation process.

In this paper, the metal surface was silylated with 1,2-bis (triethoxysilyl) ethane (BTSE) and glycidyl etheroxypropyltrimethoxysilane (KH560) silane coupling agent. And the addition of cerium chloride (CeCl3) and lanthanum nitrate (LaNO3) two kinds of rare earth salt to modify the silane conversion film. The method of preparing modified rare earth conversion film was obtained by orthogonal test, and its corrosion resistance was characterized by copper sulfate dripping method and electrochemical test method, and an optimal formulation of rare earth modified silane conversion film was obtained. Then, the optimal conversion experiment of rare earth conversion film and modified general conversion film was carried out to study the performance and structure of the two conversion films before and after modification. The results show that the corrosion resistance of the modified film after modification is improved. The structure of the two kinds of conversion films is explored by scanning electron microscopy (TEM). The results show that the corrosion resistance of the modified film is improved by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The results show that the surface of the conversion film after the modification of rare earth is more smooth and the film is more dense and thick. The results show that the adhesion and water resistance of the modified silane conversion film are not changed greatly, the adhesion is very good, the water resistance is poor, and the rare earth modification makes the hardness and unit area of the silane conversion film Membrane weight has improved.

Key words: hot-dip galvanizing; silanization; rare earth modification; corrosion resistance.

目录

摘要 I

Abstract II

第1章 绪论 1

1.1前言 1

1.2硅烷偶联剂概述 1

1.2.1硅烷偶联剂的结构及分类 1

1.2.2硅烷偶联剂的作用机理 2

1.2.3金属表面硅烷钝化处理工艺 3

1.3稀土在金属防护方面的应用 3

1.3.1稀土钝化 3

1.3.2稀土金属盐掺杂改性制备硅烷膜 4

1.4本论文研究的目的意义、研究的主要内容及创新点 4

第2章 热镀锌表面硅烷转化膜的制备和研究 6

2.1引言 6

2.2实验部分 6

2.2.1实验基材 6

2.2.2实验仪器及设备 6

2.2.3实验药品 7

2.2.4基材的预处理 8

2.2.5转化膜制备工艺 8

2.2.6表征方法 9

2.2.7硅烷化处理工艺条件正交试验 10

2.3实验结果与分析 10

2.3.1硫酸铜点滴实验 10

2.3.2电化学实验 11

2.9本章结论 14

第3章 添加稀土改性对硅烷转化膜影响的研究 15

3.1引言 15

3.2实验部分 15

3.2.1实验设备 15

3.2.2实验药品 15

3.2.3硅烷转化膜的制备 16

3.2.4转化膜的性能测试 16

3.3实验结果与分析 17

3.3.1转化膜的表面形貌和微观结构 17

3.3.2转化膜的耐腐蚀性能 20

3.3.3转化膜的其它力学性能结果 23

3.4本章总结 24

第四章 全文总结 25

参考文献 26

致谢 28

第1章 绪论

1.1前言

钢板表面镀锌是目前国内外常采用的钢铁表面防护手段，热镀锌钢板因其价格便宜、耐腐蚀性强、具有优异的加工和使用性能而广泛的应用于家电、建筑、汽车制造和航空等领域^【1】。但是在潮湿的环境中镀锌层易被腐蚀，产生白色的腐蚀产物或表面变成灰暗色，影响镀锌层的外观和耐腐蚀性能力。为了减慢镀锌层的腐蚀速率，通常对镀锌层采取表面钝化处理，使其表面产生一层稳定的致密的薄膜，以增强其耐腐蚀性，提高表面光泽度和抗污染能力，延长使用寿命，这层薄膜被称为钝化膜或转化膜。

目前，国内外镀锌层表面的钝化处理大多采用铬酸盐钝化工艺技术，经过铬酸盐钝化处理后的镀锌层表面会生成一层铬酸盐薄膜，膜层中的铬主要以Cr³ 和Cr⁶ 存在，Cr³ 作为骨架，Cr⁶ 还具有自我修复功能，因此耐腐蚀性大大提高^【2】。传统的铬酸盐钝化工艺，操作简单，成本低廉，效果好，但六价铬是一种剧毒物质，具有致癌、致畸、有毒性和诱发基因突变的作用，美国环境保护局（EPA）将六价铬确定为17种高度危险的毒性物质之一，六价铬化合物口服致死量约1.5g左右，饮用水中六价铬含量超过0.1mg/L人体就会中毒^【3】。所以目前世界各国都开始限制Cr⁶ 的使用，开展环保的无铬的金属表面钝化工艺研究。