A study of the low temperature plasma polymerization on enhancing interface of painted cold rolled steel in salt bath

Enhanced corrosion protection of painted cold rolled steel (CRS) by low temperature plasma polymerization was investigated. It was found that the surface treatment on CRS prior to painting by plasma cleaning with hydrogen plasmas and then plasma coating by plasma polymerization with tetraethyl orthosilicate (TEOS) plasmas in room temperature (23 °C) can be used for improving the corrosion protection of painted CRS. Tape adhesion tests (ASTM 3359 Method) demonstrated this improvement, with a rating of “0” for untreated CRS for aging at 3.5% NaCl solution for 6 days and “5” for hydrogen plasma-cleaned and TEOS plasma-deposited CRS at certain plasma conditions even for aging at 3.5% NaCl solution for 10 days. The results of this study indicated the performance of corrosion protection on painted CRS was dependent on the surface characteristics of CRS, the wettability of CRS and the work of adhesion of paint to CRS. In this study, the work of adhesion of paint to CRS and the wettability of CRS were calculated from the surface free energy of paint and CRS. The surface free energy of paint and CRS were calculated by the contact angle measurement using sessile drop method, the surface characteristic such as surface morphology of CRS was monitored by atomic force microscopy (AFM) and the surface composition of CRS was characterized by using Electron Spectroscopy for Chemical Analysis (ESCA).