UDCS'19 Fourth International Iron and Steel Syposium, Karabük, Türkiye, 4 - 06 April 2019, ss.178-181
In the automobile and steel industry, zinc-based electro-galvanized coatings have an increasing interest as they have excellent resistance to corrosion and mechanical properties.In the literature, however, there is insufficient research into the application of conversion coating to electrolytic zinc-coated steels and corrosion behavior.
In this study, the corrosion behaviour of free cutting (Ç-1113) steel in different thickness of electrolytic zinc plating was investigated using electrochemical methods. Corrosion potential (Ecor), corrosion current (icor) and other corrosion parameters were determined from current-potential curves.In these methods, potential ve time change, AC impedance and current – potential curves were taken into account respectively.
Steel samples coated in cyanide baths were obtained in thicknesses of 10 µ and 20 µ. Two different processing times were used for this.
The basic cyanide zinc coating bath was prepared by adding (1 gram per liter of zinc (Zn (CN)2) zinc cyanide, 85 grams (NaOH) sodium hydroxide, 40 grams (NaCN) sodium cyanide and 5 grams zinc brightener (patent)).
After this coating, samples were passivated by immersion in solution % 20 CrO3 +% 3 H2S04 +% 3 HNO3 for 60 seconds. After the current-potential curves of the coated steel samples were taken in aqueous medium, the change in the composition of the surface was investigated by SEM / EDS and XRD analyzes. The corrosion behaviour and corrosion rates of coated steel samples in aqueous medium were determined by three different methods. As a result, it was shown that the corrosion of 20 µ zinc coated steel samples in neutral environment decreased by 91% after the passivation process.