Khashayar Tabi, Mansour Farzam and Davood Zaarei
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…
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.
Details
Keywords
Mohammad Naser Kakaei, Iman Danaee and Davood Zaarei
The aim of this paper is to study the corrosion protection behavior of water‐borne inorganic zinc‐rich coatings based on potassium silicate/nanosilica developed with various zinc…
Abstract
Purpose
The aim of this paper is to study the corrosion protection behavior of water‐borne inorganic zinc‐rich coatings based on potassium silicate/nanosilica developed with various zinc and micaceous iron oxide (MIO) contents during cathodic protection stage.
Design/methodology/approach
The formulated coatings were applied on carbon steel panels and were subjected to electrochemical impedance spectroscopy (EIS) and free corrosion potential measurements for characterization of corrosion protection behavior. Also atomic force microscopy (AFM) and optical microscopy were used to investigate the surface topography of coatings.
Findings
All of the coatings preserved the cathodic protection ability throughout 75 days of exposure to 3.5% NaCl solution. Supporting results of electrochemical tests and microscopic observations revealed that replacement of zinc by MIO particles reduced both the rate of reactivity and the duration of cathodic protection of inorganic zinc‐rich coatings. It was observed that the coatings demonstrated a reactivation step after a dry‐wet cycle implying that cyclic immersion can change the overall duration of cathodic protection stage.
Originality/value
The paper describes formulation and investigation of corrosion protection behavior of an environmentally friendly zero‐VOC coating as well as providing an insight into EIS of zinc‐rich coatings.