The effect of zinc pigment modification on protective properties of waterborne primers with reduced content of Zn
摘要
By using currently common solvent-based anticorrosive coating systems with zinc-rich primers, the market requirements for the protection of steel structures can be met. Nevertheless, there is an urgent need for new concepts for anticorrosion coatings from an environmental, volatile organic compound (VOC), and sustainability perspective. In order to be able to adapt flexibly to market requirements, to minimize the VOC content of the new coating products, and to meet environmental regulations, considerable efforts are made to develop environmentally friendly anticorrosion coatings. A water-based, zinc-rich primer would offer an environmentally friendly option for this. In the case of water base zinc pigmented primer formulations, there is a need to stabilize them in order to avoid gas formation during application. Furthermore, the zinc primer itself should be used and optimized with the aim of finding the optimal combination of pigments, fillers, and additives. Chemically treated and untreated zinc pigments of various shapes (dust, flakes) and a mixture of zinc dust with polyaniline and graphene were used in the study. The anticorrosive properties of coatings, containing different combinations of zinc pigments, were tested in corrosion chambers as well as by electrochemical impedance spectroscopy (EIS), thermocyclic electrolytic loading (TEL), detection of water uptake reversibility (WUR), and scanning Kelvin probe (SKP). To confirm the chemical composition of corrosion products, the analyses by X-ray diffraction (XRD) and energy-dispersive spectroscopy (EDS) were performed. The microstructure of coatings was tested by scanning electron microscopy (SEM). Based on the results of this study, it was found that the correct selection of binder and additives, as well as proper modification of zinc pigments, effectively prevents the release of hydrogen and produces waterborne coatings with very good anticorrosive properties despite the reduced content of zinc.
Graphical abstract