柠檬酸催化稀土-硅烷复合转化膜的制备及性能研究

Preparation and Properties of Rare Earth-Silane Composite Conversion Coatings Catalyzed with Citric Acid

以柠檬酸为催化剂,硝酸铈[Ce(NO_3)_3]为稀土盐,乙烯基三甲氧基硅烷(VTMS)和正硅酸乙酯(TEOS)为硅烷单体,在Mg-Li合金表面制备了稀土掺杂硅烷复合转化膜,并与单一的稀土转化膜、硅烷转化膜和先稀土转化后硅烷转化得到的复合转化膜进行了比较。通过接触角、吸水率、电化学阻抗谱、极化曲线等测试研究了转化膜的疏水性、耐水性和耐腐蚀性。结果表明:在柠檬酸的催化下,制备的稀土掺杂硅烷复合转化膜更加致密,表面具有一定的粗糙度,可以有效提高涂层的耐水性和耐腐蚀性。转化膜的接触角为110. 26°,吸水率仅为1. 1%,腐蚀电流密度为1. 30×10^(-6)A·cm^(-2),电化学阻抗可达到2. 5×10~4Ω。

A rare earth doped silane composite conversion coating was prepared on Mg-Li alloy with citric acid as catalyst,cerium nitrate [Ce (NO3)3]as rare earth salt,vinyl trimethoxysilane (VTMS)and tetraethoxysilane (TEOS)as silane monomers.The properties of the prepared conversion coating was compared with the rare earth conversion coating,silane conversion coating and silane conversion coating after rare earth converted,respectively.The water resistance and anticorrosive properties of the conversion coatings were tested via the analysis of contact angle,water absorption,electrochemical impedance spectroscopy (EIS)and potentiodynamic polarization curves.The results indicated that the prepared rare earth doped silane composite conversion coating was denser and its surface had certainly roughness,which could improve the water resistance and anticorrosive properties of the composite coatings.The contact angle of the conversion coating was 110.26°.The water absorption was only 1.1%.The corrosion current density was 1.30×10^-6A·cm^-2 and the electrochemical impedance was up to 2.5×10^4Ω.