Abstract
Recent research by the authors has shown that plasma polymers can provide corrosion protection for metal substrates, and increase the corrosion protection performance of an E-coat system when used as a primer prior to application of the E-coat. It has also been determined that the adhesion of the plasma polymer to the substrate was the governing mechanism in providing corrosion protection, since the coatings are too thin to provide any significant barrier protection. Therefore, surface preparation of the metal prior to plasma-polymer deposition is of the utmost importance.
Plasma-polymerized coatings of hexamethyldisiloxane (PP-HMDS) were deposited on cold-rolled steel (CRS) panels, varying the plasma cleaning, and keeping the deposition conditions constant. Reflection Absorption Infrared Spectroscopy (RAIR) was used to verify similar coating characteristics for all samples. Electrochemical Impedance Spectroscopy (EIS) was used to qualitatively evaluate the corrosion protection effectiveness of the various plasma cleaning parameters used prior to the deposition of a plasma polymer. Humidity chamber tests (60°C and 85% RH) were also conducted to verify EIS results and to show that the deterioration of the coating adhesion can be determined using EIS.
