Study on the effect of surface modification of aluminum powder used in epoxy coating systems for corrosion protection of steel substrates
DOI:
https://doi.org/10.54939/1859-1043.j.mst.IMBE.2025.56-62Keywords:
Epoxy coating; Aluminum pigment; APTES; KH-792; Corrosion resistance; PDP.Abstract
This study investigates the corrosion resistance of epoxy coatings containing aluminum (Al) powder surface-modified with silane coupling agents, namely 3-aminopropyltriethoxysilane (APTES), N-[3-(trimethoxysilyl)propyl]ethylenediamine, and 3-(2-aminoethylamino)propyl-dimethoxymethylsilane (KH-792). The modification process was carried out in isopropanol with sodium metasilicate to enhance the dispersion and compatibility of aluminum flakes with the waterborne epoxy matrix. The coatings were applied onto mild steel (CT3) substrates by spraying. Silane treatment improved filler distribution, increased adhesion, and reduced micro-defects, with the epoxy–Al–APTES system showing the best protective performance, as indicated by a positive shift of the corrosion potential (Ecorr) and a significant decrease in corrosion current density (icorr). The protection mechanism was attributed to the combination of physical barrier effects, sacrificial anodic protection of aluminum, and enhanced cross-linking through chemical interactions between silane and epoxy. The modified aluminum powders were characterized using SEM, EDX, FTIR, and XRD, while the corrosion resistance was evaluated by potentiodynamic polarization (PD) and electrochemical impedance spectroscopy (EIS) in 3.5 wt.% NaCl solution.
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