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Effect of nano‐silica on the corrosion behavior of silicate conversion coatings on hot‐dip galvanized steel
Author(s) -
Jamali F.,
Danaee I.,
Zaarei D.
Publication year - 2015
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.201407633
Subject(s) - potassium silicate , materials science , corrosion , dielectric spectroscopy , silicate , galvanization , coating , electrochemistry , polarization (electrochemistry) , metallurgy , nano , chemical engineering , composite material , sodium silicate , electrode , chemistry , layer (electronics) , engineering
Nano‐silica potassium silicate conversion coating was deposited in different silica ratio on the surface of hot‐dip galvanized (HDG) steel as an anti‐corrosion coating. The ratio of nano‐silica/potassium silicate has been optimized in order to obtain higher corrosion protection. The corrosion behavior of coatings was examined by means of electrochemical impedance spectroscopy, potentiodynamic polarization, and surface techniques. The corrosion resistance was increased with increasing silica ratio of silicate coatings. This can be related to the size of nano‐silica particles and the ability to fill the pores in potassium silicate coating. SEM images in agreement with the electrochemical results indicated that the coating obtained from silica ratio 3 was more homogeneous and without pores. Electrochemical impedance data shows that with increasing immersion time up to 60 s, the charge transfer resistance increased. Energy dispersive X‐ray analysis shows silica ratio increasing in silicate coatings.