【作者】 王全全；

【导师】 柯昌美；

【作者基本信息】 武汉科技大学 ， 化学工艺， 2010， 硕士

【摘要】 随着全球环保意识的日益增强,含有高致癌性六价铬的达克罗涂层越来越受到限制。无铬达克罗涂层凭借其优异的耐蚀性、良好的结合力、无氢脆、无污染等特点,得到了极广泛的应用。本文的研究重点是无铬达克罗涂液的制备及涂层的耐蚀机理。研究了涂液的主要组分及含量对涂层性能的影响,确定了涂液的最佳配方;研究了操作条件对涂层性能的影响,确定了涂层制备的最佳工艺条件;通过扫描电镜、能谱分析、X衍射分析对涂层的成膜机理及耐蚀机理作了初步探讨。主要研究结果如下:(1)本研究采用的金属粉为鳞片状锌铝粉,确定锌铝粉比例为5:1时,涂层的外观较好、耐蚀性较强。(2)实验首次采用聚氨酯改性环氧树脂为粘结剂,聚酰胺树脂为固化剂。当聚氨酯改性环氧树脂与聚酰胺树脂间的比例为1.0:1.0时,涂层的结合力及耐蚀性得到显著提高。(3)考虑到树脂的溶解性及烘烤固化时溶剂的完全挥发,有机溶剂选用二甲苯与正丁醇,其比例为7:3。(4)考虑到金属粉在涂液中的润湿性及分散性,有机润湿剂选用醋酸丁酯。(5)以涂液中的主要组分为因素设计了正交试验,采用涂层外观、结合力及耐蚀性作为评价指标,通过综合考虑各方面性能确定涂液的最佳配方。(6)通过单因素实验确定了涂层的操作条件:烘干温度100～120℃,烘干时间为30min,固化温度230℃,固化时间25～30min。(7)实验制取的无铬达克罗涂层为银白色,表面均匀、光滑,耐硝酸铵时间达到230min,耐盐雾试验可达1200h无锈蚀,结合力好,完全无铬,符合环保要求。(8)通过扫描电镜、能谱分析及XRD对无铬达克罗涂层首次进行全面分析,初步探索膜层的成膜机理和耐蚀机理。推测出其防腐机理主要是屏蔽作用、电化学作用及钝化作用。更多还原

【Abstract】 With the whole environmental protection consciousness gradually enhancement, Dacromet coating will be forbidden in not further future because of the hexavalent chromium which can induce cancer. Non-chromium Dacromet coating has been widely applied due to its excellent corrosion resistance, good binding force, no hydrogen brittle and non-pollution.The preparation of non-chromium Dacromet coating solution and anti-corrosion mechanism of non-chromium Dacromet coating were the research focal point. The main components and content of coating solution to the coating performance influence were researched and the optimum formula of coating solution was determined. The operating condition to the coating performance influence was researched and the optimum conditions were determined. The mechanism of coating formation and corrosion resistance were discussed preliminary by using SEM, EDS and XRD. The main results were as follows:(1) The flake zinc powder and aluminum powder were used. For getting fairly good coating outward appearance and increasing the corrosion resistance, the ratio of zinc powder to aluminum powder is 5: 1.(2) The epoxy resin modified by polyurethane was first used as the cementing agent, and the curing agent was polyamide resin. When the mass ratio of epoxy resin modified by polyurethane to polyamide curing agents is 1: 1, the bonding force and corrosion resistance of coating were greatly enhanced.(3) Considered the resin’s dissolubility and the solvent complete volatility degree when roasting, xylene and normal butyl alcohol were used, and its radio is 7: 3.(4) Considered the metal powder’s wettability and dispersivity, the butyl acetate was used as wetting agent.(5) The orthogonal test was designed in which the results were evaluated by the appearance, bonding force and corrosion resistance. The influence of each component on coating’s performance was researched and then the optimum formula of coating solution was determined.(6) Through single factor experiment, the operating conditions were determined as follow: the preliminary baking temperature 100～120℃, the preliminary baking time 30min, the sintered solidification temperature 230℃, the sintered solidification time 25～30min.(7) The color of prepared coating is silvery white with a smooth surface. The experiment time of corrosion resistance for ammonium nitrate can reach 230 min and 1200 hours for salt fog without appearing rust. Meanwhile, the bond strength between coating and substrate is very well. The coating does not have the chromium completely. It conforms to the environmental protection requirement.(8) The non-chromium Dacromet coating was first analyzed by using SEM, EDS and XRD, and the mechanism of coating formation and corrosion resistance were deduced preliminary. Its anti-corrosion mechanism is conjectured as follows: shielding effect, electrochemical action and inactivation effect.更多还原