镁合金表面锆钛硅烷复合膜层的制备及耐蚀性研究

Preparation and Corrosion Resistance of Zirconium-Titanium/Silane Composite Film on Magnesium Alloy Surface

目的在镁合金表面制备耐蚀环保锆钛硅烷复合膜层,并研究其腐蚀性能。方法将锆盐、钛盐转化技术与绿色有机硅烷技术进行复合联用,通过先浸入含有锆盐、钛盐、单宁酸的无机溶液,再浸入5%(体积分数)的双-[γ-(三乙氧基硅)丙基]四硫化物有机硅烷溶液,在镁合金AZ31表面制备出了耐蚀环保锆钛硅烷复合膜层,通过扫描电子显微镜和能谱仪观察分析了复合膜层的微观形貌以及元素组成,利用极化曲线和交流阻抗谱电化学测试手段评价了膜层的耐腐蚀性能。结果经过不同锆钛硅烷复合处理后,镁合金表面形成一层均匀、平整且有干枯河床状纳米尺度微裂纹的锆钛硅烷复合膜,膜层普遍表现出良好的耐蚀性能。与空白镁合金试样相比,复合膜层试样出现最小腐蚀电流密度,为1.51μA/cm2,腐蚀速度约为空白样的1/50,交流阻抗值最大提高约20倍,腐蚀电位出现的最大正移接近100 mV。结论锆钛硅烷复合膜层对腐蚀性介质有显著的物理阻隔作用,显著抑制了镁溶解,阻滞了镁合金表面的电化学反应过程,降低了镁合金的腐蚀速度。

The work aims to prepare an anti-corrosion and environment-friendly Zirconium-Titanium/Silane composite film on magnesium alloy and investigate its corrosion properties.A conversion technology based on zirconium salt and titanium salt was combined with green organosilane technology to prepare the anti-corrosion and environment-friendly Zirconium-Titanium/Silane composite film on the AZ31 magnesium alloy by immersing into the inorganic solution containing zirconium salt,titanium salt and tannic acid and then into the organosilane solution containing 5%volume concentration of bis-(γ-triethoxysilylpropyl)-tetrasulfide.The microstructure and element composition of the composite film were observed and analyzed by scanning electron microscope(SEM)and energy dispersive spectrometer(EDS).The corrosion resistance of the film was evaluated by polarization curves and electrochemical impedance spectroscopy.After the complex treatment by different Zirconium-Titanium/Silane,the Zirconium-Titanium/Silane composite film formed on the surface of the magnesium alloy showed homogeneous,flat,and some dry-riverbed-like nanoscale microcracks and had good corrosion resistance.Compared with the blank magnesium alloy,the minimum corrosion current density of the treated samples reached 1.51μA/cm2,the corrosion rate was about 1/50 that of the blank sample,the electrochemical impedance spectroscopy was increased by 20 times at most and the maximum positive shift of the corrosion potential was close to 100 mV.The Zirconium-Titanium/Silane composite film has a significant physical barrier effect on the corrosive medium and obviously inhibits the dissolution of magnesium,blocks the electrochemical reaction process on the surface of the magnesium alloy,and reduces the corrosion rate of the magnesium alloy.