Application of novel sol-gel composites on magnesium alloy

• 作者: D.Seifzadeh S.Nezamdoust Z.Rajabalizadeh
• 来源期刊: 镁合金学报(英文)
• 学科: 工学
• 关键词: SOL-GEL COMPOSITE Magnesium alloy CORROSION
• 年，卷（期）: 2019,（3）
• 页码范围: 419-432
• 页数: 14页
• 分类号: TG1

摘要

Application o f defect-free,adherent,and corrosion protective sol-gel film on the magnesium alloys is generally difficult.In this study,two novel sol-gel/conversion coating composites were successfully deposited on AM60B magnesium alloy in order to provide sufficient protection against the corrosion.The first composite(Ti-Zr/hybrid)was obtained via combination o f a hybrid sol-gel film(synthesized by mixing tetraethoxysilane(TEOS),and 3-glycidyloxypropyl-trimethoxysilane(GPTMS))as outer layer and Ti-Zr conversion coating as primer.Also,the second composite(Ti-Zr/PTMS)was applied in a similar manner by combination o f phenyl-trimethoxysilane(PTMS)so lgel film with the Ti-Zr conversion coating.The morphology and elemental composition of the Ti-Zr conversion film were assessed by the Scanning Electron Microscopy(SEM)and Energy Dispersive X-ray Spectroscopy(EDS),respectively.A cracky conversion film was applied on the alloy surface after immersion in the Ti-Zr conversion coating bath which was mainly composed of MgO,T i02,Zr02,and MgF2 compounds.Uniform,but not-adherent PTMS and hybrid sol-gel films(pure sol-gel films)with obvious defects were directly deposited onto the magnesium alloy without the Ti-Zr pretreatment which were morphologically characterized by the SEM.However,formation o f relatively uniform and completely defect-free Ti-Zr/hybrid and Ti-Zr/PTMS composites after using the Ti-Zr conversion coating as pretreatment was revealed by the SEM observations.In addition,the defects of the Ti-Zr conversion coating were completely filled by the sol-gel layers.The Ti-Zr/PTMS and Ti-Zr/hybrid composite coatings were provided much better corrosion protection capacity than the pure PTMS and hybrid sol-gel films,respectively which was confirmed by the Electrochemical Impedance Spectroscopy(EIS)and Potentiodynamic Polarization(PDP)examinations in 0.05 M NaCl solution.