Effects of potassium silicate on corrosion behavior of dacromet coating

Abstract

Purpose

Potassium silicate sealer was applied on solvent-cleaned, acid-pickled, dacromet-coated steel to improve its corrosion resistance. The purpose of this paper is to study the corrosion behavior of dacromet-coated steel.

Design/methodology/approach

Potassium silicate sealer was applied on solvent-cleaned, acid-pickled, dacromet-coated steel to improve its corrosion resistance. Electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and salt spray were carried out. SEM was used to study the morphological appearance of the surface.

Findings

The EIS behavior indicated that solvent-cleaned dacromet-coated steel sealed with potassium silicate showed that the corrosion current density was 2.664E − 5 A.cm² which was reduced to 8.752E − 6 A.cm² and the corrosion rate, which was 2.264E − 2 mm.year⁻¹, was reduced to 7.438E − 3 mm.year⁻¹ in NaCl 3.5 wt.per cent. EIS was used in NaCl 3.5 wt.%, and the Bode plot characteristics showed that the corrosion protection of solvent-cleaned, dacromet-coated steel was enhanced when sealed with potassium silicate. The EDS results of salt-sprayed, solvent-cleaned samples after 10 days indicated that the main corrosion products are composed of SiO₂, ZnO and Al₂O₃.

Research limitations/implications

The detection of Li element in EDS was not possible because of the device limitation.

Originality/value

The current paper provides new information about the sealing properties of potassium silicate and its effects on the corrosion resistance of dacromet coating, which is widely used in many industries such as the automobile industry.

Citation

Tabi, K., Farzam, M. and Zaarei, D. (2019), "Effects of potassium silicate on corrosion behavior of dacromet coating", Anti-Corrosion Methods and Materials, Vol. 66 No. 6, pp. 819-826. https://doi.org/10.1108/ACMM-11-2018-2026