镁合金表面自清洁、自修复防护膜研究

Self-cleaning and Self-healing Protective Coating on Magnesium Alloy

目的在镁合金表面制备具有自清洁、自修复功能的防护膜,实现镁合金的智能防护。方法采用提拉法在AZ61镁合金表面制备含有pH敏感型"核/壳"纳米结构缓蚀剂的无机-有机杂化硅膜,该膜层具有自清洁、自修复功能。利用扫描电子显微镜(SEM)表征膜层表面形貌,利用接触角测量仪(CA)表征膜层的润湿性和粘附性,利用粉笔灰模拟测试膜层的自清洁功能,利用电化学工作站测试膜层的防护性能,并结合分光光度计对缓蚀剂释放浓度的检测来评价膜层的自修复功能。结果制备的膜层中含有大量pH敏感型"核/壳"纳米结构缓蚀剂,且表面粗糙。水在膜层表面的静态接触角高达156.7°,而滚动角只有5°,表明膜层具有超疏水、低粘附特性,这样水滴滚落到膜层表面时,能够带走膜层表面的污染物,从而实现自清洁功能。开路电位及分光光度计测试表明,溶液pH的变化引起膜层中缓蚀剂释放,从而使膜层实现自修复。极化曲线测试结果表明,含有"核/壳"纳米结构缓蚀剂的膜层样品的腐蚀电流密度比镁合金基底样品小了接近2个数量级,其缓蚀效率可达99.36%。电化学阻抗谱(EIS)测试结果显示,含有"核/壳"纳米结构缓蚀剂的膜层阻值高达85105Ω·cm^2,且具有较持久的自修复防护能力。结论成功制备了含有pH敏感型"核/壳"纳米结构缓蚀剂的无机-有机杂化硅膜,该膜层具有自清洁、自修复功能以及优异的防护性能。

The work aims to realize the intelligent protection for magnesium alloy by preparing the coating with the self-cleaning and self-healing properties on the surface. The inorganic-organic hybrid silicon coating containing pH-sensitive 'core/shell' nanostructure inhibitors was prepared on the AZ61 magnesium alloy surface by dip-coating method. The obtained coating had self-cleaning and self-healing properties. The surface morphology of the coating was observed by scanning electron microscopy(SEM). The wettability and adhesion to water were evaluated by contact angle measuring instrument(CA). The chalk ashes were used to simulate the self-cleaning property of the coating. The corrosion protection performance of the coating was analyzed by the electrochemical workstation, and the spectrophotometer was used to evaluate the self-healing property of the coating by measuring the release concentration of the inhibitors. The as-prepared coating had the rough surface, which contained a large number of pH-sensitive 'core/shell' nanostructure corrosion inhibitors. The coating surface had a high static water contact angle of 156.7° and low roll-off angle of 5°, which indicated that the coating had superhydrophobic and low adhesive characteristics, so that water droplets could take away the pollutants when rolling down to the surface, thus realizing the self-cleaning property. Open-circuit potential tests and spectrophotometer measurements showed that the change of solution pH led to the release of corrosion inhibitors, thus the coating could heal. From the results of polarization curves, the corrosion current density of the coating containing 'core/shell' nanostructure inhibitors was nearly two orders of magnitude smaller than that of the substrate, and the corrosion inhibition efficiency could reach 99.36%. From the electrochemical impedance spectroscopy(EIS), the resistance of the coating containing 'core/shell' nanostructure inhibitors was as high as 85 105 Ω·cm^2, which had long-term self-healing protection ability. The inorganic-organic hybrid silicon coating containing p H-sensitive 'core/shell' nanostructure inhibitors has been successfully prepared and has self-cleaning, self-healing and excellent protective properties.