无机及有机材料复合膜对碳钢腐蚀行为的影响

【作者】 林志峰；

【导师】 张盾；

【作者基本信息】 中国科学院研究生院（海洋研究所） ， 海洋化学， 2011， 博士

【摘要】 随着人类对海洋开发利用的逐步深入和规模不断扩大,海洋腐蚀给国民经济造成的重大损失日益增加。海洋腐蚀不仅缩短了海洋工程结构的使用寿命,大大增加维护维修的费用,而且还直接影响这些设施或设备的使用安全,甚至会造成灾难性事故,从而带来巨大的经济损失。因此,研究海水中金属的腐蚀与防护具有重要的应用意义和经济价值。本文主要应用恒电位电解方法制备了两种无机粒子/聚电解质复合膜（氧化锌（ZnO）/聚二烯丙基二甲基氯化铵（PDDA）复合膜和ZnO/壳聚糖（CS）复合膜）及一种无机粒子/金属复合膜（锌（Zn）/二氧化硅（SiO₂）复合膜）。应用X射线衍射（XRD）、扫描电子显微镜（SEM）、傅里叶转换红外光谱（FT-IR）等方法对复合膜的相关性质进行了研究,并应用极化曲线、交流阻抗等方法对复合膜耐蚀性进行研究。主要结论如下:1、采用吸附方法在碳钢表面制备了PDDA薄膜,极化曲线结果表明在2 g L^-1的PDDA溶液中吸附1 h制得的膜层具有较好的耐蚀效果。SEM结果表明与空白样品相比,表面吸附PDDA膜的碳钢样品在氯化钠（NaCl）溶液中浸泡2 h后未有腐蚀产物生成。这表明PDDA在碳钢防腐领域有一定应用价值。2、采用恒电位电解法在碳钢表面制备了ZnO薄膜,系统研究了硝酸锌（Zn（NO₃）₂）溶液的温度、浓度、沉积电位、搅速等因素对所成膜耐蚀性的影响。结果表明,与其它条件相比,当Zn（NO₃）₂溶液温度为50 oC、浓度为5 mM、沉积电位为-1.2 V、搅速为200 r min^-1时,在碳钢表面制得的膜层具有最佳耐蚀性。3、采用恒电位电解法在碳钢表面制备了ZnO/PDDA复合膜。极化曲线结果表明与所选用其他条件相比当溶液中PDDA浓度为2 g L^-1时制得的复合膜最有最佳耐蚀性。XRD结果表面产物中有ZnO存在;FT-IR结果表明复合膜中有PDDA存在。SEM结果表明与ZnO膜相比,ZnO/PDDA复合膜表面变得更加致密。4、采用恒电位电解法在碳钢表面制备制备了ZnO/CS复合膜。极化曲线结果表明与所选用其他条件相比当溶液中CS浓度为0.6 g L^-1时制得的复合膜最有最佳耐蚀性。XRD结果表面产物中有ZnO的存在;FT-IR结果表明复合膜中有CS存在。SEM结果表明与ZnO膜相比,ZnO/CS复合膜表面更加平滑,这是由CS良好成膜性决定的。5、通过电解Zn（NO₃）₂和正硅酸乙酯（TEOS）混合溶液的方法在碳钢表面制备了Zn/SiO₂复合膜。极化曲线结果与所选用其他条件相比表明当溶液中TEOS浓度为0.012 M时制得的复合膜最有最佳耐蚀性。SEM结果表明随着TEOS加入,制得的膜层逐渐变平滑,当TEOS为0.012 M时复合膜表面最致密。XRD结果表明未加TEOS时,产物为ZnO;当TEOS浓度为0.012 M时,产物为Zn和SiO₂。电化学交流阻抗结果表明随着浸泡时间延长,阻抗先逐渐减小,这是由于电解质不断进入,且未在膜层表面形成腐蚀产物层造成的;当浸泡时间超过120 h后,阻抗值逐渐增大,说明膜层表面有腐蚀产物聚集。通过对阻抗谱进行电路拟合发现,膜层在NaCl溶液中浸泡时间超过120 h后膜电阻和电荷转移电阻均增大。更多还原

【Abstract】 The loss cost by marine corrosion has increased year by year because many marine engineering had built for marine development and utilization. Corrosion can reduce load carrying capacity either by generally reducing its size or by pitting, both of which can lead to huge economic losses or even catastrophic accident. Thus the research on metal corrosion and protection in seawater has important application significance and economic value.In this work, two kinds of inorganic/polyelectrolyte composite film （zinc oxide （ZnO）/poly （diallyldimethylammonium） （PDDA） composite film and ZnO/chitosan （CS） composite film） and a kind of inorganic particles/metal composite film （zinc （Zn）/silicon dioxide （SiO₂） composite film） have been fabricated by potentiostatic electrolysis method. The character of composite films was studied by X-ray diffraction （XRD）, scanning electron microscope （SEM） and fourier transform infrared spectrometer （FT-IR）. The corrosion resistance of composite film was studied by polarization curves method. The main conclusions are shown as follows:1、The PDDA thin film has been fabricated on carbon steel surface by self-adsorption method. Polarization curves indicated that compared with other conditions the film fabricated in 2 g L^-1 PDDA solution for 1 h had optimal corrosion resistance. SEM results indicated that compared with bare carbon steel, the sample with PDDA film had no corrosion products on surface after immersion in sodium chloride （NaCl） solution for 2 h. This result indicated PDDA has potential application in carbon steel corrosion protection field.2、ZnO film has been fabricated on the carbon steel surface by potentiostatic electrolysis method. The influence factors of corrosion resistance, such as temperature, concentration, potential and stir rate were studied. The results indicated that compared with other conditions the best condition for ZnO electrodeposition was zinc nitrate （Zn（NO₃）₂） concentration, 5 mM, potential, -1.2 V, stir rate, 200 r min^-1.3、A composite film consisting of ZnO and PDDA, has been fabricated on a carbon steel substrate by an potentiostatic electrolysis method. Polarization curves showed that compared with other conditions the composite film fabricated at the PDDA concentration of 2 g L^-1 had the best corrosion resistance. XRD results indicate that ZnO could be fabricated by electrodeposition in composite films. FT-IR results evidence the existence of PDDA in ZnO/PDDA composite film. SEM results show that compared with ZnO film, the composite film becomes more compact and smooth.4、ZnO/CS composite film was obtained on the carbon steel surface via potentiostatic electrolysis method. It is shown that compared with other conditions the ZnO/CS film obtained at the concentration of 0.6 g L^-1 has the best corrosion resistance. XRD results indicate that ZnO could be fabricated by electrodeposition in composite film. FT-IR results evidence the existence of CS in composite film. SEM results demonstrate that the composite film was much smoother and crack free. This was attributed to the good film-form property of CS.5、A Zn/SiO₂ composite film has been electrodeposited on the carbon steel surface via adding tetraethylorthosilicate （TEOS） in Zn（NO₃）₂ solution. Polarization curve results showed that compared with other conditions the composite film obtained at the TEOS concentration of 0.012 M had the best corrosion resistance. SEM results indicated that the film surface became compact with TEOS’s addition and the film showed best quality when the concentration was 0.012 M. XRD results showed that the product was ZnO when no TEOS was added. The products were Zn and SiO₂ when TEOS concentration was 0.012 M. Electrochemical impedance spectroscopy results indicated that the impedance of the film decreased with immersing time within 120 h, which could be attributed to the penetration process of electrolyte in solution. However, the impedance presented an increases trend with the immersion time after 120 h, which was a result of building-up of zinc corrosion products on coating surface. This trend was in accordance with the change of charge transfer resistance and film resistance.更多还原