【作者】 刘浩；

【导师】 李晶莹；

【作者基本信息】 青岛科技大学 ， 环境工程（专业学位）， 2025， 硕士

【摘要】 镁合金是重要的轻量化工程材料,具有密度小,强度高,导电、导热性能好,生物相容性好等优良特性。其在航空航天精密零部件加工、汽车骨架材料、电子3C产品和医疗器械等领域有广泛的应用前景。然而,其耐腐蚀性能差,尤其是在高盐高湿热带海洋大气环境中严重的腐蚀严重制约了镁合金的工程化应用。本文通过对镁合金腐蚀性行为及防护技术的研究,在镁合金腐蚀行为、南海大气环境中AZ91镁合金腐蚀性研究等方面开展了大量工作,系统研究了AZ系列镁合金腐蚀行为,AZ91镁合金在南海大气恶劣环境中的腐蚀行为,通过镁合金腐蚀防护技术,开发镁合金表面基于化学镀的多元复合涂层,旨在解决镁合金的耐蚀性差的问题。（1）通过电化学测试、析氢实验和失重测量,研究了铝和锌对AZ系列镁合金腐蚀行为的影响。结果表明,铝的添加促进了β-Mg₁₇Al₁₂相的析出,增加了局部腐蚀倾向,而锌的添加则通过形成共晶相缓解了微电偶腐蚀,但加速了腐蚀产物的解吸,导致腐蚀加剧。镁合金的腐蚀主要受电偶腐蚀、点蚀和晶间腐蚀的影响,腐蚀产物的形成与解吸过程对腐蚀速率有显著影响。（2）通过户外大气暴露实验和电化学测试,研究了AZ91镁合金在三亚热带海洋大气暴露两年期的腐蚀行为。结果表明,南海地区的高温、高湿度和高氯离子沉积速率显著加速了镁合金的腐蚀,暴露初期腐蚀速率急剧增加,在暴露6个月后达到峰值,随后呈现逐渐减缓的趋势。镁合金在热带海洋大气中的腐蚀类型主要表现为点蚀和丝状腐蚀,腐蚀产物层的修复过程在一定程度上延缓了腐蚀的进一步发展。（3）开发了基于化学镀镍的复合涂层体系,包括化学镀镍底层、LDHs中间层和超疏水表层。通过优化化学镀镍工艺参数,成功制备了致密的镍磷镀层,显著降低了腐蚀电流密度,提高了极化电阻。LDHs中间层通过其二维层状结构和离子交换能力,进一步增强了涂层的耐蚀性。超疏水表层通过“气垫效应”阻隔了腐蚀介质的渗透,显著提升了涂层的耐蚀性和自清洁性能。本研究通过系统实验和理论研究,探究了Al和Zn元素对镁合金腐蚀行为的影响,揭示了镁合金在海洋大气环境中的腐蚀行为,并成功制备了基于化学镀镍的多级复合涂层体系,为镁合金的高效防腐及功能化表面改性提供了新的思路。研究结果对延长镁合金制品的使用寿命和实现推动绿色制造促进循环经济具有重要意义。更多还原

【Abstract】 Magnesium alloys,as a light engineering material,are characterized with typical superiority in terms of low specific density,mechanical strength to weight ratio,good thermal conductivity,and good biocompatibility.Due to the superior properties,they have found their wide application possibility in various industrial applications,especially for aerospace high-precision component forming,automotive structural material preparation,consumer electronic equipment and biomedical products.The main drawback of magnesium alloys is that the corrosion is very poor,especially in high humidity and high saline marine atmosphere ambient.The above susceptibility is also seriously impeding their practical engineering applications in such service conditions.In this paper focused on the corrosion behavior of magnesium alloys and their protective technologies,systematically investigating the corrosion mechanisms of AZ series magnesium alloys,the corrosion behavior of AZ91 magnesium alloy in the harsh marine atmospheric environment of the South China Sea,and the development of a multi-level composite coating system based on electroless nickel plating,aiming to enhance the corrosion resistance and functionality of magnesium alloys.（1）The effects of aluminum and zinc on the corrosion behavior of AZ series magnesium alloys were studied through electrochemical tests,hydrogen evolution experiments,and weight loss measurements.The results indicated that the addition of aluminum promoted the precipitation of theβ-Mg₁₇Al₁₂ phase,increasing the tendency for localized corrosion,The addition of zinc alleviated micro galvanic corrosion through the formation of eutectic phase,but accelerates the desorption of corrosion products,leading to intensified corrosion.The corrosion of magnesium alloys is primarily influenced by galvanic corrosion,pitting,and intergranular corrosion,with the formation and desorption of corrosion products significantly affecting the corrosion rate.（2）The corrosion behavior of AZ91 magnesium alloy in the tropical marine atmospheric environment of the South China Sea was investigated through field tests and electrochemical measurements.The results indicated that the high temperature,high humidity and high chloride deposition rate in the South China Sea significantly accelerated the corrosion of magnesium alloys.The corrosion rate reached its peak after six months of exposure and gradually decreased thereafter.The corrosion types were mainly pitting and filiform corrosion.The repair of the corrosion product layer to some extent slowed down the further development of corrosion.（3）A multi-level composite coating system based on electroless nickel plating was developed,including an electroless nickel plating underlayer,an LDHs intermediate layer,and a superhydrophobic top layer.By optimizing the electroless nickel plating process parameters,a dense nickel-phosphorus coating was successfully prepared,significantly reducing the corrosion current density and increasing the polarization resistance.The intermediate layer of LDHs further enhanced the corrosion resistance and self-healing functionality of the coating through its two-dimensional layered structure and ion exchange capability.The superhydrophobic top layer blocked the penetration of corrosive media through the"air cushion effect,"significantly improving the corrosion resistance.Through systematic experiments and theoretical analysis,this paper explored the effects of Al and Zn on the corrosion behavior of magnesium alloys and analyzed the corrosion behavior of magnesium alloys in marine atmospheric environments.We developed a multi-level composite coating system using electroless nickel plating.This method offered new solutions and technical support for effective corrosion protection and functional surface modification of magnesium alloys.The research results were of great significance for extending the service life of magnesium alloy products,promoting green manufacturing,and advancing the circular economy.更多还原