Preparation and Properties of Waterborne Epoxy Anti‐Corrosion Coatings Modified by Nano‐SiO2 and Flaky Al

ABSTRACT The issue of corrosion prevention for steel has long been a subject that draws widespread concern in the relevant fields. This study focused on the preparation of anti‐corrosion coatings on Q235 steel surfaces. Waterborne epoxy resin (WEP) served as the film‐forming matrix, with SiO 2 and Al utilized as fillers. Three groups of samples, namely WEP, WEP/SiO 2 , and WEP/SiO 2 /Al, were prepared. The innovation was introduced in the coating preparation process, where silica sol was substituted for silica powder, effectively augmenting the dispersion of the silica filler within the WEP matrix. The coating morphologies were characterized using a metallographic microscope and scanning electron microscope (SEM). Results showed that compared to the WEP coating, the WEP/SiO 2 /Al coating had fewer surface defects. For mechanical property evaluation, pencil hardness and adhesion tests were carried out. It was found that SiO 2 and Al synergistically boosted the pencil hardness of the WEP coating to a maximum of 4H while maintaining a similar adhesion grade to that of the WEP coating. Static water contact angle (WCA) tests indicated that the WCA values of WEP/SiO 2 and WEP/SiO 2 /Al coatings were 79° and 81°, higher than that of the WEP coating (76°), and retained good hydrophobicity after 20 wear cycles. Electrochemical impedance spectroscopy tests revealed that the impedance value of the WEP/SiO 2 /Al coating reached 2.17 × 10 8 Ω cm 2 , which is higher than that of the WEP/SiO 2 coating and the WEP coating. Moreover, its corrosion potential shifted positively by 248.8 mV compared to the WEP coating, signifying a significant enhancement in anti‐corrosion performance. The excellent comprehensive performance of the WEP/SiO 2 /Al coating can be attributed to the fact that SiO 2 and Al synergistically enhance the mechanical and anti‐corrosion properties of the WEP coating.