Preparation and properties of functionalized nano-TiO2/epoxy resin superhydrophobic anticorrosive composite coating
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摘要: 超疏水材料在金属防腐领域具备巨大的潜在应用前景。为得到疏水性能及防腐性能俱优的纳米TiO2/环氧树脂复合涂层材料,首先以三甲氧基十七氟癸基硅烷和γ-氨丙基三乙氧基硅烷(KH550)对纳米TiO2表面功能化;以全氟辛基甲基丙烯酸酯对固化剂二乙烯三氨(DETA)进行氟化;最后通过一步共混法和两步喷涂法分别制备出两种复合涂层。利用FTIR、XPS、1HNMR分析氟化固化剂(F-DETA)和氟化纳米TiO2(f-TiO2)的物相组成和组织结构。接触角测试仪和静置实验表明,当三甲氧基十七氟癸基硅烷和γ-氨丙基三乙氧基硅烷的摩尔比为1∶15时f-TiO2的性能最佳,所制备的复合涂层接触角达到164.9°。SEM表征结果显示通过两步法制备的f-TiO2/环氧树脂复合涂层具备更均匀的粗糙表面、涂层内部孔隙率较低且环氧树脂层与f-TiO2层具备梯度结构。摩擦实验证明两步法制备的f-TiO2/环氧树脂复合涂层的超疏水性具备较好的机械稳定性。Tafel极化曲线和电化学阻抗谱(EIS)研究表明,通过两步法制备的f-TiO2/环氧树脂复合涂层具有优异的防腐性能,其腐蚀抑制效率高达99.99%。Abstract: Superhydrophobic materials have great potential application prospects in the field of metal anticorrosion. In order to obtain TiO2/epoxy resin composite coating material with excellent corrosion resistance, firstly, the surface of nano-TiO2 was modified with trimethoxy heptafluorodecyl silane and γ-aminopropyltriethoxysilane (KH550), and then the diethylenetriamine (DETA) as curing agent was fluorinated with perfluorooctyl methacrylate. Finally, two kinds of composite coatings were prepared by blending method and two-step method respectively. The phase composition and microstructure of fluorinated curing agent (F-DETA) and fluorinated nano TiO2 (f-TiO2) were analyzed by FTIR, XPS and 1HNMR. The contact angle tester and static test show that when the molar ratio of trimethoxyheptafluorodecyl silane to γ-aminopropyltriethoxysilane is 1∶15, the performance of f-TiO2 is the best. The contact angle of the composite coating reaches 164.9°. SEM was used to characterize the micro-morphology of the coating surface and cross-section. The results show that the f-TiO2/epoxy resin composite coating prepared by two-step method has uniform rough surface, low porosity inside the coating, and gradient structure between epoxy resin layer and f-TiO2 layer. The friction experiment proves that the super hydrophobicity of f-TiO2/epoxy resin composite coating prepared by two-step method has certain mechanical stability. Tafel polarization curve and electrochemical impedance spectroscopy (EIS) show that the f-TiO2/epoxy resin composite coating prepared by two-step method has excellent corrosion resistance, and its corrosion inhibition efficiency is as high as 99.99%.
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Key words:
- nano TiO2 /
- epoxy resin /
- superhydrophobicity /
- anticorrosion /
- composite coating
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图 11 p-DETA/epoxy CYD-127表面 ((a)~(b))、F-DETA/epoxy CYD-127表面 ((c)~(d))、f-TiO2-15-F-DETA/epoxy CYD-127 (B)表面 ((e)~(f))、f-TiO2-15-F-DETA/epoxy CYD-127 (T)表面 ((g)~(h)) 和断面 ((i)~(j)) 的SEM图像
Figure 11. SEM images of p-DETA/epoxy CYD-127 surface ((a)-(b)), F-DETA/epoxy CYD-127 surface ((c)-(d)), f-TiO2-15-F-DETA/epoxy CYD-127 (B) surface ((e)-(f)), f-TiO2-15-F-DETA/epoxy CYD-127 (T) surface ((g)-(h)) and cross section ((i)-(j))
图 13 分别涂有不同复合涂层的Q235钢板在3.5 wt% NaCl溶液中浸泡2天的Nyquist图 ((a)~(b)),Bode-阻抗图(c),Bode-相位图 (d) 和等效电路图 ((e)~(f))
Figure 13. Nyquist plot ((a)-(b)), Bode-impedance plot (c), Bode- phase plot (d) and equivalent circuit diagram ((e)-(f)) of different composite coatings respectively immersed in 3.5 wt% NaCl solution for 2 days
Rs—Solution resistance; Qa—Constant phase of air layer; Ra—Air layer resistance; Qc—Constant phase of coating; Rc—Coating resistance, Qdl—Constant phase of double-layer; Rct—Charge transfer resistance
图 14 涂有f-TiO2-15-F-DETA/epoxy CYD-127 (T)的Q235钢板在3.5 wt% NaCl溶液中浸泡2、7、14、28天的Nyquist图 (a)、Bode-阻抗图 (b) 和Bode-相位图 (c)
Figure 14. Nyquist plot (a), Bode- impedance plot (b) and Bode- phase plot (c) of Q235 steel plates coated with f-TiO2-15-F-DETA/epoxy CYD-127 (T) immersed in 3.5 wt% NaCl solution for 2, 7, 14 and 28 days
表 1 四种氟化纳米TiO2(f-TiO2)的制备条件
Table 1. Preparation conditions of four fluorinated nano TiO2 (f-TiO2) samples
Sample TiO2/g KH550/g (A) Trimethoxy (1H,1H,2H,2H-
heptadecafluorodecyl) silane/g (B)Ethanol-water
solution/mLMole ratio
of A to Bf-TiO2-1 4 0.44 1.14 100 1∶1 f-TiO2-3 4 0.66 0.57 100 3∶1 f-TiO2-7 4 0.77 0.28 100 7∶1 f-TiO2-15 4 0.83 0.14 100 15∶1 表 2 四种f-TiO2的XPS测试数据
Table 2. Data of XPS for four f-TiO2 samples
Sample Atomic fraction/at% F N C f-TiO2-1 84.06 1.42 14.52 f-TiO2-3 75.93 3.29 20.78 f-TiO2-7 75.71 4.29 19.99 f-TiO2-15 51.63 9.48 38.89 表 3 Q235钢板及分别涂有不同复合涂层的Q235钢板极化曲线数据
Table 3. Polarization curve data of Q235 steel plate and Q235 steel plate coated with different composite coatings respectively
Sample Ecorr/mV icorr/(A·cm−2) ba/(mV·dec−1) bc/(mV·dec−1) vcorr/(mm·y−1) Rp/(kΩ·cm2) IE /% Bare −1 010 5.55×10−4 230.89 −145.49 6.45 69.83 — p-DETA/epoxy CYD-127 −766 7.48×10−6 575.28 −641.14 8.70×10−2 1.76×104 98.65 F-DETA/epoxy CYD-127 −667 3.54×10−6 550.15 −644.71 4.12×10−2 3.64×104 99.36 f-TiO2−15-F-DETA/epoxy CYD-127 (B) −629 8.24×10−8 306.25 −435.23 9.58×10−4 9.47×105 99.98 f-TiO2−15-F-DETA/epoxy CYD-127 (T) −321 1.53×10−8 366.54 −527.98 1.78×10−4 6.14×106 99.99 Notes: Ecorr—Corrosion potential; icorr—Corrosion current density; ba—Anode slope; bc—Cathode slope; vcorr—Corrosion rate; Rp—Polarization resistance; IE —Inhibition efficiency. 表 4 分别涂有不同复合涂层的Q235钢板在3.5 wt% NaCl溶液中浸泡2天的电化学阻抗参数
Table 4. Electrochemical impedance parameters of Q235 steel plate coated with different composite coatings respectively immersed in 3.5 wt% NaCl solution for 2 days
Sample Rs/Ω Qa Ra/Ω Qc Rc/Ω Qdl Rct/Ω Ya/(S·sn cm−2) na Yc/(S·sn cm−2) nc Ydl/(S·sn cm−2) ndl p-DETA/epoxy
CYD-127884.1 6.018×10−10 0.998 3.049×105 3.686×10−6 0.267 1.514×105 F-DETA/epoxy
CYD-1271301 6.646×10−10 0.999 1.216×106 1.763×10−7 0.766 2.033×105 ef-TiO2−15-F-DETA/epoxy
CYD-127 (B)2614 9.854×10−10 1 1.654×106 3.259×10−8 0.573 1.571×107 4.737×10−7 0.697 60.38 f-TiO2−15-F-DETA/epoxy
CYD-127 (T)6159 2.129×10−10 1 5.347×106 1.131×10−8 0.579 9.582×107 2.089×10−9 0.799 4.669×107 Notes: Y—Proportional factor; n—Adjustable parameter. -
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