表面技术2025，Vol.54Issue(24)：118-127,10.DOI:10.16490/j.cnki.issn.1001-3660.2025.24.009
3.5%NaCl溶液中紫脲酸对AZ31B镁合金的缓蚀作用
Corrosion Inhibition Effect of Purple Polyamide on AZ31B Magnesium Alloys in 3.5%NaCl Solution
摘要
Abstract
In order to improve the corrosion resistance of magnesium alloys and gain a deeper understanding of the corrosion inhibition mechanism of corrosion inhibitors,this work explores the application of purple polyamide(PPA)as an organic corrosion inhibitor for AZ31B magnesium alloys.Magnesium alloys such as AZ31B are widely utilized in structural and transportation applications due to their low density and excellent mechanical properties.However,their inherently poor corrosion resistance in chloride-rich environments,such as marine and physiological media,remains a major barrier to their broader application.So,the development of effective,environmentally benign corrosion inhibitors is of significant scientific and industrial interest.In this work,the corrosion inhibition behavior of PPA in 3.5%NaCl solution was systematically investigated through a combination of electrochemical testing,including potentiodynamic polarization and electrochemical impedance spectroscopy(EIS),hydrogen evolution measurements,and static weight loss experiments.At 25℃,the corrosion inhibition efficiency of PPA was determined to be 74.9%by weight loss measurement,59.6%by hydrogen evolution,73.5%by EIS,and 53.9%by potentiodynamic polarization.This discrepancy reflected the different sensitivities and evaluation principles of each technique.With the increase of temperature and immersion time,the inhibition efficiency of PPA improved significantly,indicating enhanced adsorption stability and protective film integrity under elevated conditions,reaching a maximum of 93.9%(as determined by the weight loss method)at 50℃and 72 h.To understand the underlying inhibition mechanism,detailed surface characterizations were carried out.Specifically,a scanning electron microscopy(SEM)was employed to visualize changes in surface morphology before and after PPA treatment,revealing a more compact and uniform film in the presence of the inhibitor.On the contrary,a loose magnesium hydroxide layer was formed on the surface of AZ31B alloy in 3.5%NaCl solution.Energy-dispersive X-ray spectroscopy(EDS),X-ray diffraction(XRD),and X-ray photoelectron spectroscopy(XPS)analyses further confirmed the presence of a dense protective layer composed of Mg-Al layered double hydroxides(LDHs)intercalated with PPA species.These layered structures were known to offer barrier properties that physically isolated the metallic substrate from the aggressive chloride-containing environment. Mechanistically,the inhibition effect of PPA was attributed to its ability to form a stable,compact,and adherent interfacial layer.Upon dissolution in 3.5%NaCl solution,PPA molecules ionized and released protons,thereby acidifying the environment.This proton release transformed PPA into negatively charged anionic species.During corrosion,the hydrogen evolution reaction at the cathodic sites of AZ31B alloy surface increased the local pH,which eventually stabilized at approximately pH=10.This alkaline environment promoted the in-situ formation of Mg-Al LDH on the surface of the alloy.Simultaneously,the PPA anions became intercalated within the interlayer galleries of the LDH structure,effectively becoming an integral part of the protective film.This synergistic interaction between the inhibitor molecules and the LDH host not only reinforced the integrity of the protective LDH layer,but also enhanced its stability against dissolution and mechanical degradation.Consequently,the resulting PPA-intercalated LDH film served as a robust barrier that blocked the diffusion of corrosive species such as Cl-ions to the AZ31B surface,significantly retarding the corrosion process.关键词
紫脲酸/AZ31B/镁合金缓蚀剂/MgAl-LDH/缓蚀机理Key words
purple polyamide/AZ31B/corrosion inhibitor for magnesium alloy/MgAl-LDH/inhibition mechanism分类
矿业与冶金引用本文复制引用
翟亚如,熊金平,赵景茂,樊保民..3.5%NaCl溶液中紫脲酸对AZ31B镁合金的缓蚀作用[J].表面技术,2025,54(24):118-127,10.基金项目
国家自然科学基金(52371046)The National Natural Science Foundation of China(52371046) （52371046）
