碳钢表面防腐超疏水TiO_2/PDMS涂层的制备及性能

针对碳钢腐蚀电位相对更负、更容易发生腐蚀的特点,在Q235钢表面制备超疏水TiO_2/PDMS涂层以提高其耐蚀性能。采用表面活性剂分散纳米TiO_2并进行改性,然后与PDMS混合,用溶胶凝胶法在Q235钢表面制备有聚二甲基硅氧烷(PDMS)过渡层的TiO_2/PDMS超疏水涂层。借助扫描电镜(SEM)、接触角测量仪、红外光谱(FT-IR)及X射线衍射仪(XRD)表征其表面涂层的表面形貌、化学成分及疏水性能,用电化学试验和浸泡试验测试其防腐性。结果表明:TiO_2/PDMS涂层表面具有独特的微纳结构,与水的接触角达到154.3°;其腐蚀电位由碳钢的-0.77 mV正移至超疏水涂层的-0.24 mV,腐蚀电流密度则下降两个数量级,即从5.02×10~(-6)A·cm~(-2)下降至3.95×10~(-8)A·cm~(-2);超疏水涂层的交流阻抗值高于碳钢基底3个数量级。经过7 d的3.5wt.%NaCl溶液浸泡,超疏水涂层并未发生失重。制备的TiO_2/PDMS超疏水涂层具有超疏水效果和良好的长期耐腐蚀性。

Preparation and Properties of TiO2 / PDMS Anticorrosion Superhydrophobic Coating on Carbon Steel

In order to improve the corrosion resistance of Q235 steel, superhydrophobic TiO₂ / PDMS coating was prepared on Q235 steel to improve its corrosion resistance. The nano-TiO₂ was modified by surfactant to avoid the agglomeration problem caused by its small surface energy. After the polydimethylsiloxane (PDMS) transition layer was prepared on the surface of Q235 steel, the TiO₂ / PDMS superhydrophobic coating was prepared on the surface of Q235 steel by sol-gel method after mixing the modified TiO₂ with PDMS. Scanning electron microscope ( SEM), contact angle meter, infrared spectrum (FT-IR) and X-ray diffraction(XRD) were used for characterization. Corrosion resistance was tested by electrochemical experiment and immersion test. The results indicate that: the surface of TiO₂ / PDMS coating has a unique micro / nano structure with the water contact angle of 154. 3°, which proves the coating with excellent superhydrophobic property was prepared. The electrochemistry results showed that compared to the bare Q235, the coating prepared has good corrosion resistance with a positive shifted corrosion potential(from -0. 77 mV to -0. 24 mV), a decline in the corrosion current density(from 5. 02×10^-6 A·cm^-2 to 3. 95×10^-8 A·cm^-2 , up to two orders of magnitude) and a increased alternating current impedance(three orders of magnitude). The base material protected by the coating is identified for a fine long-term corrosion resistance due to the no weight loss after the 7 days immersion in 3. 5wt. % NaCl solution. TiO₂ / PDMS superhydrophobic coating successfully prepared on Q235 steel surface by sol-gel method has superhydrophobic effect and good long-term corrosion resistance.