Electrochemical and Raman analysis of the corrosion products formed over hot dip galvanised steel wires exposed in different environmental sites

In this work, hot-dip galvanised steel wires were exposed in Belgium and Indonesia for 4.5 years and correlation of corrosion products formed on the exposed wires with their corrosion properties was studied. Corrosion products were identified with local Raman analysis and correlated with corrosion activity based on odd random phase electrochemical impedance spectroscopy and Tafel behaviour. Raman spectroscopy results confirmed that corrosion products formed in both atmospheric conditions differed either in quantity and/or in chemical nature, which indicated that ‘aged in Belgium’ and ‘aged in Indonesia’ wires did not have similar surface compositions. The comparison of the instantaneous corrosion behaviour of pristine and aged wires based on corrosion currents (polarisation curve) and impedance values in 0.1 M NaCl and 0.1 M Na2SO4 declared that aged in Belgium (AIB) and aged in Indonesia (AII) wires exhibited different corrosion behaviour, which confirmed that corrosion products formed in the environments of the exposed wires were dominating their corrosion behaviour.