Wang Xiao-Xin,Cao Yun-Qing,Fu Hong-Li,Jiang Mei-Yan,Hu Ji-Ming
This work aimed at understanding the role of silane pretreatment layer in an organic coating system. The study consists of two parts. In the first part, the anticorrosion performance and interfacial property of silane-pretreated epoxy coatings were studied. The results showed that pretreatment with functional 3-glycidoxypropyl-trimethoxysilane (GPTMS) strongly improves the adhesion of epoxy-coated AA2024-T3 aluminum alloy due to the high interfacial compatibility between silane and epoxy coatings and that pretreatment with nonfunctional bis-1,2-[triethoxysilyl]ethane (BTSE) remarkably reduces the adhesion to the alloy because of low compatibility. Nevertheless, the BTSE film provides higher resistance to corrosion than the GPTMS-pretreated coating system, because the former is more hydrophobic and thicker.
Liangliang Xiong,Mei Yu,Yingquan Li,Xiangxin Kong,Songmei Li,Jianhua Liu
Salicylaldehyde@ZIF-8/graphene oxide (SZG) nanosheets were fabricated by anchoring salicylaldehyde@ZIF-8 nanoparticles on graphene oxide. SZG nanosheets were modified by amino silane 3-aminopropyltriethoxysilane (f-SZG) to improve the compatibility with epoxy coating. Sedimentation test showed the excellent dispersion stability of f-SZG in resin epoxy even after standing for 480 h. The cross-sectional microstructure of coatings implied the strong f-SZG/coating matrix interface by transforming the cleavage fracture to the ductile. Additionally, the stimuli-responsive release to H + and Al 3+ ions of f-SZG is maintained after the silanization. Compared with other samples, f-SZG0.5 epoxy coatings show the optimal long-term corrosion protection property with the lowest reduction rate of |Z| 0.01Hz (13.6%) after 480 h immersion and the intact surface after 27d salt spray test due to the stronger interfaces of f-SZG/epoxy matrix and coating/substrate, the proper content (0.5 wt.%) and the enhanced cross-linked density of coating.
Inhibitory effects of sodium abietate (SA) and sodium lignin sulfonate (SLS) were discussed using a series of tests and theoretical calculations. Experimental outcomes obtained via weight loss and electrochemistry data showed that SA and SLS significantly inhibited the corrosion of AA2024-T3 Aluminum alloys in NaOH media. The inhibition efficiency ( η %) for SA and SLS was up to 96.02% and 98.82% at 5 × 10 −3 mol·L −1 , respectively. SA and SLS acted as anode-dominated mixed-type inhibitors in aggressive solutions as recorded by electrochemical methods. In addition, the surface analyses further corroborated the protection of the metal surface from corrosion as added with SA and SLS that can form an adsorbed film on the metal surface. The adsorption obeyed Langmuir isotherm which illustrated the adsorptions of the SA and SLS were a mix of physical and chemical adsorptions. Moreover, the inhibition performance of both inhibitors with the molecular structure shown in quantum chemical calculations and molecular dynamics simulation found that be suitable for explaining the inhibitive action of the two. The study suggests SA and SLS as green sources appropriate for anticorrosive applications.
Graphene oxide (GO) was introduced into sol-gel systems to enhance the corrosion protective properties of the obtained film on AA2024-T3 aluminum alloy . The characterization of morphology, microstructure and component of the films indicated that GO covalently reacted with silanol groups from hydrolyzed 3-glycidoxypropyl-trimethoxysilane (GPTMS) monomer , forming silane functionalized GO (SGO) by C O Si covalent bonds . Corrosion protective properties of the films were evaluated through electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and immersion tests studies. The results showed that the addition of GO improved the corrosion protective properties of sol-gel film distinctly by providing the good barrier property of layered GO and enhancing the cross-linking density of the film. The significant improvement of GO on sol-gel film mainly focused on the resistance and capacitance of film itself. The optimal concentration of GO addition was 0.5 mg mL −1 , at which the film was uniform and showed good corrosion protective properties in 0.05 M NaCl aqueous solution. The corrosion current density of the sol-gel film with 0.5 mg mL −1 GO was one order magnitude smaller than that of sol-gel film without GO. The protection efficiency of the film was up to 99.45%.
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