Synergistic effect of thiourea in epoxy functionalized silica sol–gel coating for copper protection

In this paper, we try to employ a method of a combination of epoxy functionalized silica sol (ESol) and thiourea (TUA) to obtain a coating of excellent anticorrosion effect on copper. In order to compare the anticorrosion ability of the ESol + TUA coating with other coatings, the samples of ESol and ESol with diethylenetriamine (ESol + DETA) coatings have also been prepared. We use a variety of corresponding methods to study the properties of ESol with and without adding DETA and TUA. Aqueous contact angle analysis is used to evaluate the wetting properties of these sol–gel coatings. Scanning electron microscopy (SEM) is used to observe the surface morphology of these coatings and their cross sections. The anticorrosion ability of these coatings is evaluated by electrochemical methods and salt spray tests. The results show that ESol + TUA coating has the best anticorrosion ability. This is because adding TUA improves the physical barrier effect due to the denser coating compared to the regular ESol coating; in addition, it improves the adhesion between the coating and copper surface.