镁合金在水溶液中的快速腐蚀是其广泛应用的主要障碍之一,和涂层在其腐蚀保护中起着至关重要的作用。最近,保护和功能集成涂层在镁合金研究领域备受关注。在这项工作中,提出了一种简单的化学转化方法,通过浸入由Ca(OH)2和NaHCO3制成的水溶液中,在镁-钕合金上制备复合涂层。浸泡过程后,获得由两个自发形成的层组成的涂层。顶部的花状层由Mg5(OH)2(CO3)4·4H2O组成,Mg(OH)2和CaCO3,并猜测其内部致密层为Mg(OH)2。电化学阻抗谱,极化测试,和析氢相结合来评估模拟体液中的耐腐蚀性,模拟海水溶液,和模拟混凝土孔隙溶液,这表明涂层样品比未涂层样品具有更好的耐腐蚀性。用氟化硅烷对涂层样品进行改性后,可以实现具有151.74°的平均水接触角和约4°的滑动角的防水表面。因此,我们的结果表明,有效的腐蚀防护和潜在的自清洁能力已经集成在镁合金的表面在这项研究。此外,从基体与其外液相互作用的角度讨论了自层涂层的形成机理。
Rapid
corrosion in aqueous solutions of magnesium alloys is one of the major obstacles to their wide application, and coating plays a crucial role in their
corrosion protection. Recently, protection- and function-integrated coatings have attracted much attention in the research field of magnesium alloys. In this work, a simple chemical conversion process is proposed to fabricate a composite coating on a magnesium-neodymium alloy through immersion in an aqueous solution made of Ca(OH)2 and NaHCO3. After the immersion process, a coating consisting of two spontaneously formed layers is acquired. The top flower-like layer is composed of Mg5(OH)2(CO3)4∙4H2O, Mg(OH)2 and CaCO3, and the inner dense layer is speculated to be Mg(OH)2. Electrochemical impedance spectroscopy, polarization tests, and hydrogen evolution are combined to evaluate the
corrosion resistance in simulated body fluid, simulated seawater solution, and simulated concrete pore solution, which reveals that the coated sample has better
corrosion resistance than the uncoated one. After the coated sample is modified with fluorinated silane, a water-repellent surface can be achieved with an average water contact angle of 151.74° and a sliding angle of about 4°. Therefore, our results indicate that effective
corrosion protection and potential self-cleaning ability have been integrated on the surface of the magnesium alloy in this study. In addition, the formation mechanism of the self-layered coating is discussed from the viewpoint of the interaction between the substrate and its external solution.