【作者】 王春丽；

【导师】 吴建华；

【作者基本信息】 哈尔滨工程大学 ， 材料学， 2013， 博士

【摘要】 船舶与海洋工程结构等海洋结构物均由多种金属合金材料构成，极易形成电偶腐蚀，因此海洋结构物的耐久性除了与金属材料本身耐蚀性（腐蚀行为）有关外，还与金属合金材料之间的电偶腐蚀作用密切相关，电偶腐蚀给海洋结构物的安全性造成了巨大危害，研究海洋结构物金属材料的电偶腐蚀可为设计选材和腐蚀防护提供基础数据和技术基础，具有重要的理论意义和经济价值。本文选取典型海洋环境工程材料：工业纯钛（TA2）、低合金高强钢（1#钢，921A，2#钢）、铜镍合金（B10），系统地研究并获得了单一金属材料的腐蚀变化规律、双金属偶合TA2/921A，B10/921A，1#钢/921A，1#钢/2#钢，2#钢/921A电偶腐蚀变化规律和典型三金属偶合TA2/B10/921A与1#钢/2#钢/921A电偶腐蚀变化规律，同时探讨了涂层和牺牲阳极阴极保护对电偶腐蚀的控制作用。对单一金属材料腐蚀规律的研究发现，TA2与B10（钝化金属）在低溶解氧含量（0~6mg/L）时，氧分子浓度的升高利于钝化膜的形成与修复，其腐蚀速率随溶解氧增加而线性减小；在高溶解氧含量（≥6mg/L）时基本形成致密稳定的钝化膜，耐腐蚀性能随之稳定；对于低合金高强钢（非钝化金属），氧含量的升高加快了氧分子的扩散速度，致使阴极氧去极化的速度增大，腐蚀速率与溶解氧含量呈线性增大关系。温度升高对氧扩散速度的促进作用大于其对溶解氧含量降低作用，金属材料的耐蚀性随温度升高而下降。通过对双金属偶合体系腐蚀行为的研究发现，高电位差（≥500mV）偶对TA2/921A，B10/921A阳极发生溶解反应，腐蚀加剧，腐蚀过程与自腐蚀相同；电偶腐蚀的保护作用使阴极几乎不发生腐蚀，低电位差（≤75mV）偶对1#钢/921A，1#钢/2#钢，2#钢/921A阴极虽因电偶作用较小，未达到完全保护而依然发生自腐蚀，但腐蚀明显减缓。高电位差偶对的电偶腐蚀速率随阴阳极面积比（Sc/Sa）呈线性增长，但因电偶电位正移，驱动电压逐渐减小而存在极限值；低电位差偶对电偶腐蚀速率因电位差低，驱动电压随面积比增加下降很快，在较小的Sc/Sa情况下即达到极限值，且不与Sc/Sa呈线性关系。偶对电偶电流密度与氧含量呈线性函数增大关系；温度对电偶腐蚀速度的影响规律符合阿累尼乌兹定律。三金属偶合体系中阳极与自腐蚀同样发生溶解反应，不同之处在于电偶作用加速了腐蚀反应产生FeOOH的过渡步骤。高电位差偶系TA2/B10/921A发生强极化作用，阳极921A发生强烈腐蚀，阴极TA2与B10受到电偶作用的完全保护，几乎无腐蚀；低电位差偶系1#钢/2#钢/921A发生弱极化作用，阳极921A腐蚀加速，阴极1#钢与2#钢腐蚀明显减缓。高电位差偶系电偶腐蚀速率随阴阳极面积比（Sc/Sc/Sa）呈线性增长，但因面积比增大使阳极极化加大，电偶电位正移，驱动电压逐渐减小而存在极限值；低电位差偶系1#钢/2#钢/921A电偶电位随阴阳极面积增大而正移，在Sc/Sc/Sa为3:3:1时，2#钢腐蚀电位因低于电偶电位而发生极性逆转，由阴极转为阳极。偶系阳极的腐蚀电流密度与溶解氧浓度呈线性函数增大关系；与温度之间呈指数函数增大关系，其规律符合阿累尼乌兹定律。双金属和三金属偶合体系均符合混合电位理论，对电偶腐蚀行为采用极化曲线分析与实际测试结果具有很好的一致性，可利用极化曲线较快速准确预测多种材料构成的电偶腐蚀行为。涂层与牺牲阳极联合保护较单独采用涂层保护更好地对电偶腐蚀起到防护作用。在联合保护情况下，铝阳极提供完全保护电流及稳定的保护电位，有效地延缓了做为阴极的涂层体系失效过程，在120天的实验周期内，涂层电阻一直保持在7.3×10~7·cm~2以上。海水中溶解氧含量增加或温度升高对涂层劣化及电偶腐蚀有促进作用，但在联合保护情况下，增大的电偶作用有效地减缓了阴极涂层体系的劣化程度，在65℃条件下，涂层电阻仍达1.1×10~7·cm~2。更多还原

【Abstract】 The structures of ship and ocean engineering are part of marine structures composed bymany kinds of metal alloy materials that is easy to form galvanic corrosion. Therefore, exceptthe relevance to corrosion resistance (corrosion) of metal materials, the durability of marinestructures is closely related to galvanic corrosion between metal alloy materials. As galvaniccorrosion is great dangerous to safety of marine structures, the galvanic corrosion research onmetal materials adopted by marine structures can provide data base and technical foundationfor the design of material selection and corrosion protection, that has important theoreticalsignificance and economic value. This paper selected the typical marine environmentalengineering material: commercially pure titanium (TA2), high strength low alloy steel (1#,2#,921A), copper nickel alloy (B10). The systematic study was conducted to obtain the changerule of single metal corrosion, and galvanic corrosion of bimetal coupling of TA2/921A,B10/921A,1#/921A,1#/2#and2#/921A and typical multi-material system of TA2/B10/921Aand1#/2#/921A. The control effect on galvanic corrosion of coating and sacrificial anodesprotection were also studied.For TA2and B10(the passive metal), increasing oxygen concentration is beneficial toformation and repair of passivation film with dissolved oxygen content at0~6mg/L, and thecorrosion rate decreases linearly with dissolved oxygen; the compact and stable passive filmwas formed with oxygen content≥6mg/L, and then the corrosion resistance trended tostability. For high strength low alloy steel (the non passivation metal), the oxygen contentincrease promotes the diffusion rate of oxygen molecules, resulting in the acceleration ofcathode oxygen depolarization, and the corrosion rate increases linearly with dissolvedoxygen. The effect of temperature raises on the diffusion rate of oxygen is greater than on thedecreases of dissolved oxygen content, and the corrosion resistance of metal materialsdecreased with the increase of temperature.The anode in bimetal coupling system had dissolution reaction, corrosion was aggravated,the corrosion process was the same as self-corrosion; cathodic reduction of dissolved oxygenoccurred, the protective effect of galvanic corrosion made the cathode of high potentialdifference (≥500mV) pair TA2/921A, B10/921A was almost no corrosion, and the cathode oflow potential difference (≤75mV) pair1#/921A,1#/2#,2#/921A was still self-corrosion due to small galvanic effect without complete protection, but the corrosion obviously slowed down.galvanic corrosion rate of high potential difference pair showed linear growth with the arearatio of cathode to anode (Sc/Sa), but had extreme because the galvanic potential shift anddriving voltage decreases; galvanic corrosion rate of low potential difference pair reachedextreme under small Sc/Sa without linear relationship, due to low potential difference andrapid decrease of driving voltage with area ratio increase. Density of pair galvanic currentincreased linearly with oxygen content. Galvanic current density increased with thetemperature accord with Arrhenius equation.The anode in multi-material system had dissolution reaction, corrosion process wasdifferent from corrosion in that the galvanic effect accelerates the transition step of corrosionreaction; reduction of dissolved oxygen occurred on catholic surface, high potential differencemulti-material system of TA2/B10/921A had strong polarization, anodic921A strongly wascorroded strongly, catholic TA2and B10were almost no corrosion due to completelyprotected by galvanic effect; low potential difference multi-material system of1#/2#/921A hadweak polarization, accelerated corrosion on anode921A and slowed down corrosionobviously on cathodic1#and2#. Galvanic corrosion rate of high potential differencemulti-material system showed linear growth with Sc/Sc/Sa, but had extreme because that theincreased area ratio enhanced anodic polarization, galvanic potential shifted positively anddriving voltage decreased gradually; galvanic potential of low potential differencemulti-material system of1#/2#/921A shifted positively with Sc/Sc/Sa increase, the2#corrosion potential reversed polarity as it was lower than galvanic potential under condition ofSc/Sc/Sa was3:3:1, from cathode to anode. The corrosion current density of anode couplingsystem increased linearly with oxygen content. Galvanic current density increased with thetemperature accord with Arrhenius equation.Bimetal and multi-material system are both accord with the mixed potential theory, andresults of polarization curve analysis with the galvanic corrosion behavior performed greatconsistence with the actual test. It can be applied to predict the galvanic corrosion behavior ofvarious materials by using polarization curve rapidly and accurately.Compared to the coating protection, the united protection of coating and sacrificial anodeshowed better resistance to the galvanic corrosion. Under united protection, the case ofaluminum anode provided complete protection current and stable protection potential, which effectively delayed the failure process of coating system as cathode. During120-daysexperimental period, the coating resistance has been maintained above7.3×10~7·cm~2. Theincrease of dissolved oxygen content and temperature in seawater promoted the coatingdegradation and galvanic corrosion, and galvanic corrosion further promote the failureprocess of anodic coating system with single coating. In united protection of coating andsacrificial anode, the enhanced galvanic effect slowed degradation speed of cathode coatingsystem, the coating resistance was maintained at1.1×10~7·cm~2under the worst condition of65℃.更多还原