TY - JOUR
T1 - Corrosion Protection in Chloride Environments of Nanosilica Containing Epoxy Powder Coatings with Defects
AU - Fernández-Álvarez, María
AU - Velasco, Francisco
AU - Bautista, Asunción
AU - Gonzalez-Garcia, Yaiza
AU - Galiana, Beatriz
N1 - Accepted Author Manuscript
PY - 2020
Y1 - 2020
N2 - This paper describes the use of innovative, nanosilica containing epoxy powder coatings for the corrosion protection of steel. Two types of nanosilica particles (hydrophilic -HL- and hydrophobic -HB-) were mixed by ball milling with the powders (0.75 wt.%). The adequate homogeneity and embedding of nanoparticles were verified by transmission electron microscopy. The corrosion performance of the coatings as-received, and with HL and HB additions, were analyzed in 3.5 wt.% NaCl solutions. The mechanism and rate of delamination of defective coatings under drops simulating atmospheric conditions were analyzed by Scanning Kelvin Probe measurements for 30 d. The results show that the corrosion attack progresses through a cathodic delamination mechanism. Besides, fully-immersed samples, with and without defects, were monitored by electrochemical impedance spectroscopy. In defective coatings under these conditions, the occurrence of anodic undermining is proved. The results obtained reveal that the corrosion driven coating failure is delayed in the case of the epoxy coatings containing nanosilica. This delay is larger in the case of HB additions than HL additions in both atmospheric and immersion conditions. The corrosion mechanism observed is dependent upon exposure conditions. It is proposed that the nanoparticles delay water absorption, thus delaying corrosion attack.
AB - This paper describes the use of innovative, nanosilica containing epoxy powder coatings for the corrosion protection of steel. Two types of nanosilica particles (hydrophilic -HL- and hydrophobic -HB-) were mixed by ball milling with the powders (0.75 wt.%). The adequate homogeneity and embedding of nanoparticles were verified by transmission electron microscopy. The corrosion performance of the coatings as-received, and with HL and HB additions, were analyzed in 3.5 wt.% NaCl solutions. The mechanism and rate of delamination of defective coatings under drops simulating atmospheric conditions were analyzed by Scanning Kelvin Probe measurements for 30 d. The results show that the corrosion attack progresses through a cathodic delamination mechanism. Besides, fully-immersed samples, with and without defects, were monitored by electrochemical impedance spectroscopy. In defective coatings under these conditions, the occurrence of anodic undermining is proved. The results obtained reveal that the corrosion driven coating failure is delayed in the case of the epoxy coatings containing nanosilica. This delay is larger in the case of HB additions than HL additions in both atmospheric and immersion conditions. The corrosion mechanism observed is dependent upon exposure conditions. It is proposed that the nanoparticles delay water absorption, thus delaying corrosion attack.
UR - http://www.scopus.com/inward/record.url?scp=85097926257&partnerID=8YFLogxK
U2 - 10.1149/1945-7111/abd003
DO - 10.1149/1945-7111/abd003
M3 - Article
AN - SCOPUS:85097926257
SN - 0013-4651
VL - 167
JO - Journal of the Electrochemical Society
JF - Journal of the Electrochemical Society
IS - 16
M1 - 161507
ER -