海洋环境腐蚀与生物污损重点实验室知识库

随着海洋开发的不断深入，人们对海洋用钢的需求量也不断增加，随之而来的是钢铁的防污防腐蚀问题。在海洋环境五个区带中海水潮差区中的钢铁受到污损生物的影响及面临的金属腐蚀问题尤为严重，所以海洋用钢在海水潮差区的防污和防腐蚀尤为重要。对于生物污损问题目前一般采用人工去除的方法，对于钢铁的腐蚀问题有表面涂镀层、阴极保护等方法。目前的防污和防腐蚀方法都比较耗时耗力并需要定期维护，极为不便。

基于此背景，本文改进了耐候钢表面锈层稳定化处理技术，对比了三种常用钢材在海洋中的腐蚀速率，在干湿循环、盐雾、现场、等环境下，利用表面扫描电位、极化曲线、电化学阻抗谱、重量变化等方法研究了处理前后耐候钢的腐蚀行为和腐蚀机理。以掺硼金刚石（Boron-doped diamond, 简称BDD）电极作为阳极，通过探究羟基自由基生成的最优条件，研究电化学高级氧化生成羟基自由基的防污潜力。本文的主要结论如下：

（1）通过正交试验优化了耐候钢表面锈层稳定处理技术，具体配方(质量分数)是0.3%CuSO₄、0.15%FeSO₄、0.02%NaHSO₃、0.02%NaCl 和 0.005%Na₂HPO₄，余量为水。经过处理的耐候钢表面形成了一层主要由Fe₃O₄组成的致密氧化层，在干湿循环试验和盐雾试验中均表现出良好的耐腐蚀性。通过表面电位扫描可知，未处理的耐候钢表面上的锈层首先在局部分布，然后在干湿循环中逐渐形成不间断的锈层，并且平均表面电位随测试和稳定在大约-200mV，但是在盐雾试验中平均表面电位几乎保持不变。经改进的配方处理的耐候钢在加速腐蚀试验的初期具有稳定的电位，并具有良好的耐腐蚀性。

（2）根据重量变化试验的结果，在腐蚀加速试验中，用改进的处理液配方处理的耐候钢的重量变化率逐渐稳定，具有良好的耐腐蚀性。从腐蚀电流曲线可以看出，在腐蚀初期未处理的耐候钢的腐蚀电流要比处理过的耐候钢的腐蚀电流低，但随着腐蚀的进行，经处理的耐候钢的腐蚀电流逐渐降低，并且试验后期比未处理的耐候钢的腐蚀电流低。经处理的耐候钢在加速腐蚀环境中显示出良好的耐腐蚀性。

（3）根据XRD锈层分析未处理的耐候钢的表面锈层和深锈层的主要成分均为γ-FeOOH和α-FeOOH。处理的耐候钢表面锈层的主要成分为γ-FeOOH和α-FeOOH，而深锈层的主要成分为Fe₃O₄。从短期腐蚀加速试验结果可知，我们改进后的配方处理的耐候钢的锈层比文献中研发的配方处理的耐候钢的锈层稳定性好。

（4）用电化学高级氧化法在海水中电解并探究不同电解条件下氧化性物质的生成规律，在以钌铱钛电极作为阳极时，在含氯溶液中电解可生成次氯酸；而使用BDD电极作为阳极时，则可在含氯溶液中生成羟基自由基。

（5）以BDD电极作为阳极电解海水生成羟基自由基的量与时间成线性关系，而羟基自由基生成量在电压为2.8V时最大，阴极阳极的间距越小，电解生成羟基自由基的量越大。用试验结果的最优条件进行以BDD电极作为阳极的电化学高级氧化技术杀灭硅藻和三角褐指藻的试验，结果表明该方法对硅藻和三角褐指藻的杀灭效果良好。

With the continuous deepening of marine development, people's demand for marine steel is also increasing, and the problem of anti-fouling and anti-corrosion of steel also are inevitable. In the five zones of the marine environment, the steel in the tidal zone is affected by fouling organisms and the metal corrosion problems are particularly serious. Therefore, the antifouling and corrosion prevention of marine steel in the tidal zone is particularly important. For the problem of biofouling, artificial removal methods are generally used. For the problem of steel corrosion, there are methods such as surface coating and cathodic protection. The current anti-fouling and anti-corrosion methods are both time-consuming, labor-intensive and require regular maintenance, which is inconvenient.

Based on this background, this article improves the technology of stabilizing the surface rust layer of weathering steel, and compares the corrosion rates of three commonly used steels in the ocean. The corrosion behavior and corrosion mechanism of weathering steel before and after treatment were studied by using surface scanning potential, polarization curve, electrochemical impedance spectroscopy, weight change and other methods under dry and wet cycles, salt spray, on-site, and other environments. The Boron-doped diamond (BDD) electrode is used as the anode, and the optimal conditions for the generation of hydroxyl radicals are explored to study the antifouling potential of the formation of hydroxyl radicals by electrochemical advanced oxidation. The main conclusions of this article are as follows:

(1) The technology of stabilizing the rust layer on the weathering steel surface was optimized through orthogonal experiments. The specific formulation (mass fraction) is 0.3%CuSO₄、0.15%FeSO₄、0.02%NaHSO₃、0.02%NaCl and 0.005% Na₂HPO₄, the margin is water. A dense oxide layer mainly composed of Fe₃O₄ is formed on the surface of the treated weathering steel, which shows good corrosion resistance in both dry-wet cycle test and salt spray test. The surface scanning potential shows that the rust layer on the surface of the bare weathering steel is first distributed locally, and then gradually forms an uninterrupted rust layer during the dry-wet cycle. The average surface potential is stabilized at about -200mV along with the dry-wet cycle test, but the average surface potential remained almost unchanged during the salt spray test. The weathering steel treated with our improved formula has a stable potential in the initial stage of the corrosion acceleration test and has good corrosion resistance.

(2) According to the results of the weight change test, the weight change rate of the weathering steel treated with the improved treatment liquid formulation is gradually stable and has good corrosion resistance in the corrosion acceleration test. It can be seen from the corrosion current curve that the corrosion current of the bare weathering steel at the initial stage of corrosion is lower than that of the treated weathering steel, but as the corrosion progresses, the corrosion current of the treated weathering steel is gradually smaller than bare weathering steel. The treated weathering steel shows good corrosion resistance in corrosion acceleration test.

(3) According to XRD analysis of rust layer, the main components of surface rust and deep rust of bare weathering steel are γ-FeOOH and α-FeOOH. The main components of the surface rust of the treated weathering steel are γ-FeOOH and α-FeOOH, while the main component of deep corrosion is Fe₃O₄. It can be seen from the results of the short-term corrosion acceleration test that the rust layer of weathering steel treated with our improved formula is more stable than the rust layer of weathering steel treated with the formula developed by Gao.

(4) Electrolyze in seawater and explore the generation rules of oxidizing substances under different electrolysis conditions. When ruthenium-iridium-titanium electrode is used as anodes, hypochlorous acid can be generated by electrolysis in chlorine-containing solutions, and when BDD electrode is used as the anode, hydroxyl radicals can be generated in the chlorine-containing solution.

(5) The amount of hydroxyl radicals generated by electrolysis of seawater with BDD electrode as the anode has a linear relationship with time, and the amount of hydroxyl radical’s generation is the largest when the voltage is 2.8V. The smaller the distance between the cathode and the anode, the more the electrolysis generates hydroxyl radicals. We used the optimal conditions of the test results to carry out the experiment of killing diatom and phaeodactylum tricornutum with the BDD electrode as the anode by the electrochemical advanced oxidation technology, and the results show that the method has a good killing effect on the diatom and phaeodactylum tricornutum.