【作者】 王恒；

【导师】 蔡超；

【作者基本信息】 宁夏大学 ， 化学工程（专业学位）， 2015， 硕士

【摘要】 5383铝合金因其优良的机械性能在海洋工程中得到了广泛的应用。但国内科研人员对5383铝合金在海洋环境中较为系统的腐蚀行为数据掌握较少,因此迫切需要开展相关的研究工作。本论文采用电化学极化曲线、电化学噪声(EN)、电化学阻抗谱(EIS)并采用扫描电镜(SEM)和能谱(EDS)等技术研究了5383铝合金在模拟海水中的腐蚀行为,得出以下主要结论：(1)5383铝合金无论在静态海水还是在流动海水,其耐蚀性能整体上都表现出随着腐蚀时间的延长逐渐下降,但不同阶段相对不同。(2)5383铝合金在流动海水中的耐蚀性能会随着腐蚀时间的延长优于相同阶段下的静态海水中的耐蚀性能,并且阴极过程为腐蚀过程的控制步骤。(3)5383铝合金在静态海水中的腐蚀行为可以分为四个明显的腐蚀阶段：a)腐蚀初期,EIS谱高频与低频出现了两个明显的容抗特征,随着腐蚀时间的延长反应电阻Rt、钝化膜电阻Rp逐渐减小,而双电层电容Cdl呈增大趋势,表明海水中大量的侵蚀性离子(Cl-)攻击电极表面使其活性点发生溶解产生点蚀；b)腐蚀中期,高频容抗弧逐渐大于低频容抗弧,Rt、Rp逐渐增大,Cdl呈减小趋势,表明腐蚀产物形成了一个不完整的保护膜对基体起到了一定的保护作用：c)腐蚀过渡期,低频容抗弧逐渐变得模糊,Rt、Cdl出现了波动变化,表明腐蚀产物膜处于动态变化的状态；d)腐蚀后期,EIS谱基本不变,Rt、Cdl基本趋于稳定。(4)5383铝合金在流动海水中的腐蚀行为同样可以分为四个明显的腐蚀阶段：a)腐蚀初期,具有静态海水中类似的腐蚀行为,但持续时间要短,说明流动海水对其腐蚀程度大；b)腐蚀中期,EIS谱高频容抗特征明显,低频感抗模糊,Rt、Rp出现波动变化,说明流动海水加速了腐蚀产物膜的生成与溶解；c)腐蚀过渡期,EIS谱高频容抗特征明显,低频容抗模糊,Rt波动变化,Rp逐渐增大,说明流动海水有助于致密腐蚀产物膜的形成；d)腐蚀后期,EIS谱高频与低频出现了两个明显的容抗特征,腐蚀电位基本稳定,Rt、Rp随着时间的延长逐渐增大,说明此阶段5383铝合金表面腐蚀产物逐渐累积,对基体起到了一定的保护作用,相较于静态海水此时的耐蚀性能增强。更多还原

【Abstract】 5383 aluminum alloy has been widely used in ocean engineering, because of its excellent mechanical properties.However domestic researchers mastered less systematic data of the material’s corrosion behavior in marine environment, so there is an urgent need to carry out the related research work. This paper adopts the electrochemical polarization curve and electrochemical noise (EN), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) to study the corrosion behavior of 5383 aluminum alloy in simulated seawater, drawn the following conclusions:(1) No matter where 5383 aluminum alloy is whether static seawater or flowing seawater, its corrosion resistant performance showed gradual decline with the prolonging of corrosion time, but the corrosion resistant performance relatively different at different stages.(2) The corrosion resistant performance in flowing seawater of 5383 aluminum alloy will be better than that of the same phase in static seawater with the extension of corrosion time, and the control step of corrosion process was cathodic process.(3) The corrosion behavior of 5383 aluminum alloy in the static seawater can be divided into four distinct stages:a) at the primal stage, there existed two obvious capacitive reactance characteristics in the high frequency and low frequency range of the EIS. Reaction resistance Rt, passivation membrane resistance Rp decreased gradually, and the electric double layer capacitance Cdl showed a trend of increasing with the prolong of corrosion time. These indicated a large number of aggressive ions (Cl-) in simulated seawater attacking on electrode surface and giving rise to active points dissolve and causing pitting corrosion; b) at the second stage, capacitive reactance arcs in the high frequency were greater than in low frequency. Rt, Rp, increased gradually, Cdl showed a trend of decreasing, these showed that the corrosion products forming a incomplete protective film and this protective film played a certain protective effect on the substrate; c) at the transition period, the low frequency capacitive reactance arc blurred gradually, Rt, Cdl varied, showed that corrosion product film in dynamic change; d) at the later stage, EIS, Rt, and Cdl kept stable.(4) The corrosion behavior of 5383 aluminum alloy in the flowing simulated seawater also can be divided into four distinct stages:a) at the primal stage, it has the similar corrosion behavior with static seawater, but shorter duration, showed the degree of corrosion on the 5383 aluminum alloy was more serious in flowing simulated seawater; b) at the second stage, there existed obvious capacitive reactance characteristics in the high frequency range of EIS and the inductive reactance characteristics blurred in the low frequency range of EIS, Rt, Rp varied, showed that flowing simulated seawater accelerating the formation and dissolution of corrosion product film; c) at the transition period, there existed obvious capacitive reactance characteristics in the high frequency range of EIS and the capacitive reactance characteristics blurred in the low frequency range of EIS, Rt varied and Rp increased gradually, showed that flowing simulated seawater contributing to the formation of corrosion product film; d) at the later stage, there existed two obvious capacitive reactance characteristics in the high frequency and low frequency range of the EIS, corrosion potential stable basically, Rt and Rp were increasing gradually with the time extension, showed that surface corrosion products of 5383 aluminum alloy accumulating gradually and played a protective effect on matrix, compared with static seawater the corrosion resistant performance of 5383 aluminum alloy was better at this stage.更多还原