復(fù)合表面改性及功能特性
(華南理工大學(xué) 機(jī)械與汽車工程學(xué)院 國家金屬材料近凈成形工程技術(shù)研究中心，廣州 510640)
摘 要: 采用微弧氧化與有機(jī)鍍膜技術(shù)對AZ31鎂合金進(jìn)行復(fù)合表面改性，分別對微弧氧化膜的形成過程及表面特征、微弧氧化膜表面有機(jī)鍍膜過程、微弧氧化膜與復(fù)合膜的潤濕性及耐腐蝕性進(jìn)行研究。結(jié)果表明：鎂合金經(jīng)微弧氧化改性后，由于表面具有微納多孔粗糙結(jié)構(gòu)，同時(shí)具有較高的表面自由能和極性分量，與蒸餾水接觸時(shí)存在較強(qiáng)的范德華力和毛細(xì)管吸附力，且對強(qiáng)極性水分子具有很強(qiáng)的相溶性，使其蒸餾水的靜態(tài)接觸角接近0°，表現(xiàn)為超親水特性；而微弧氧化膜表面再經(jīng)有機(jī)鍍膜復(fù)合改性后，具有較低的表面自由能，對強(qiáng)極性水分子具有一定的排斥作用，使其靜態(tài)接觸角達(dá)到113.7°，表現(xiàn)為疏水特性；微弧氧化膜經(jīng)有機(jī)鍍膜表面改性后，耐腐蝕性能明顯改善，疏水復(fù)合膜層在0.1 mol/L NaCl溶液中，與基體相比，其動電位極化腐蝕電流密度減小3個(gè)數(shù)量級，而電化學(xué)阻抗提高3個(gè)數(shù)量級，表現(xiàn)為類似純電容行為。
關(guān)鍵字: 鎂合金；微弧氧化；有機(jī)鍍膜；復(fù)合表面改性；超親水；疏水；耐腐蝕性
（National Engineering Research Center of Near-net-shape Forming for Metallic Materials,
School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640, China）
Abstract:A duplex surface modification method combined with micro-arc oxidation (MAO) and developed polymer plating was applied to AZ31 magnesium alloy. The growth and surface morphology of MAO-modified film, electrochemical reaction process during polymer plating on MAO-modified film surface, wettability and corrosion behaviors of MAO-modified film and duplex-modified film were researched. The results show that a superhydrophilic surface is fabricated after MAO modification and its contact angle (CA) of distilled water is almost 0, because Van der Waals force and capillary suction effect are relatively strong contacted with the distilled water when MAO-modified surface formed with micro- and nano-porous rough structures, moreover, MAO-modified film with high surface free energy and high polar component have very strong intermiscibility to strong-polar water molecules. However, the alteration from superhydrophilic to hydrophobic surface with contact angle of 113.7° is realized by duplex modification of polymer plating on MAO-modified film surface due to repelling interaction between the strong-polar water molecules and duplex-modified surface with low surface free energy. The corrosion resistance has been greatly improved by duplex modification of polymer plating on the MAO-modified film surface. Compared with bare magnesium alloy, the corrosion current density of hydrophobic duplex-modified film from potentiodynamic polarization decreases by three orders of magnitude, while the electrochemical impedance from electrochemical impedance spectroscopy increases by three orders of magnitude as the duplex-modified film presents similar to pure capacitance behavior in 0.1 mol/L NaCl solution.
Key words: magnesium alloy; micro-arc oxidation; polymer plating; duplex surface modification; superhydrophilic; hydrophobic; corrosion resistance
