Abstract
In this communication, a bis-silane prepolymer was used to modify epoxy resin, aiming to enhance the corrosion resistance of epoxy coatings on aluminum alloy substrates. The bis-silane prepolymer was prepared by tetraethoxysilane (TEOS) and γ-glycidoxypropyl trimethoxysilane (GPTMS). The corrosion behavior of silane-epoxy coatings was studied. Compared with silane monomer-modified epoxy coatings, bis-silane-modified epoxy coatings have lower coating capacitance (Cc), higher charge transfer resistances (Rdl), and lower double layer capacitance (Cdl) during long-time immersion. It indicates that bis-silane-modified epoxy coating has stronger waterproof permeability and substrate corrosion protection ability. In addition, due to the leaching of the silane component and cross-linking reaction between different silanes during the immersion process, the bis-silane-modified epoxy coatings exhibit much stronger “self-healing” ability.
Highlights
Studies have shown that the silane-modified epoxy coating system has better corrosion resistance, and the corrosion resistance of the coating increases with the increase of the amount of silane monomer
The TEOS prepolymer solution and glycidoxypropyl trimethoxysilane (GPTMS) prepolymer solution were prepared with the same method, in which, ethanol, TEOS, and deionized water were mixed in a volume ratio of 4:2:1
Bis-silane-modified epoxy coatings were prepared on Al-Zn-Mg-Cu alloy in the
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Will not completely polymerize through the hydrolysis polycondensation reaction, and there are some alkoxy groups that are not completely hydrolyzed. These incompletely hydrolyzed alkoxy groups will undergo a hydrolysis-polycondensation reaction during the subsequent immersion process, forming new Si-O-Si and Si-O-C structures, increasing the density of the coating [19,20]. Different silanes have different hydrolysis activities under the same hydrolysis conditions. In the mixed silane prepolymer formed by mixing different silanes, it is easy to synthesize a silane prepolymer that is partially hydrolyzed and polycondensed but still contains hydrolytically active alkoxy groups.
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