Corrosion inhibition of galvanized steel by LDH-inhibitor hybrids Mechanisms of Inhibitor Release and Corrosion Reactions

Authors: 
V. Shkirskiy
Journal: 
PhD thesis
Year: 
2016
Pages: 
247
Abstract: 

Protection mechanisms of layered double hydroxide (LDH) anticorrosion coatings on galvanized steel were investigated. On the first step, the mechanisms of the action of MoO42-, L-cysteine and L-phenylalanine as water soluble inhibitors were verified. MoO42- showed the best performance associated with the rapid (less than 2 s) formation of Mo(V)-rich films on Zn surface in alkaline solutions. On the second step, factors affecting the release of MoO42- from Zn2Al/-LDH were identified. Presence of only Cl- in the solution resulted in a less than 40 % release of MoO42- after 24 h of the immersion with the Fick’s diffusion inside LDH controlling the overall process. Addition of carbonates resulted in the complete release after 1 h with the change of the release kinetics attributed to the surface controlled reaction. The immersion tests of coated samples showed slight inhibiting effect of MoO42-/LDH anticorrosion coatings in Cl- and high in CO32- solutions coherent with higher level of MoO42- released.

Graphical abstract: 
action of LDH hybrid polymer coatings
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