Correlation of interfacial electrode potential and corrosion resistance of plasma polymer coated galvanized steel. Part 1: Ultra-thin plasma polymer films of varying thickness

Ultra-thin SiO2-like plasma polymer films were deposited on zinc coated steel. Such films led to a strong inhibition of cathodic and anodic electrochemical reactions and a negative shift in the electrode potential. When the SiO2-like films are additionally coated with a few micron thick organic film, the resulting interface electrode potential is further shifted cathodically down to −0.8 VSHE as measured by means of a scanning Kelvin probe. This interface potential is about the same as the free corrosion potential of zinc in a chloride containing electrolyte. Accordingly, the interface proved to be extremely resistant to cathodic de-adhesion processes.