Abstract
In this study, calcium carbonate (CaCO3) microparticles having pH-sensitive properties were loaded with sodium lignosulfonate (SLS), a corrosion inhibitor. Scanning electron microscope (SEM), UV–VIS spectrophotometer (UV-vis), X-ray diffraction (XRD), and attenuated total reflection-Fourier-transform infrared spectroscopy (ATR-FTIR) were applied to evaluate the properties of the synthetic microparticles. This material could lead to the release of corrosion inhibitor under different pH conditions of the aqueous media. However, the extent of release of the corrosion inhibitor in the acidic media was higher, leading to enhanced shielding effect of the Q235 steel. These microparticles can serve as anti-corrosion additive for epoxy resin-coated Q235 steel. Electrochemical experiments were used to assess the anti-corrosive ability of the epoxy coatings in simulated concrete pore (SCP) solution, confirming the superior corrosion inhibition of the epoxy coating via incorporation of 5 wt % calcium carbonate microparticles loaded with SLS (SLS/CaCO3). The physical properties of coating specimens were characterized by water absorption, contact angle, adhesion, and pencil hardness mechanical tests.
Highlights
Among the various building materials used in civil engineering, concrete is considered as one of the most critical materials
This study explores the anti-corrosion properties of a novel composite prepared by the combination of sodium lignosulfonate (SLS) and pH-sensitive CaCO3 particles in the epoxy coatings applied on Q235 steel
Calcium carbonate was used as pH-sensitive micro-containers for the loading of SLS as corrosion inhibitor, which were confirmed with FTIR, X-ray diffraction (XRD), and Scanning electron microscope (SEM)
Summary
Among the various building materials used in civil engineering, concrete is considered as one of the most critical materials. Earlier reports in the literature have shown the application of epoxy coatings modified by CaCO3 microspheres with a variety of inhibitors over aluminum alloy as anti-corrosive coating [19]. These coatings were found to enhance the impact resistance, thermal stability, and corrosion resistance. Recent work demonstrated that CaCO3 microbeads have been modified with various inhibitors: cerium nitrate, salicylaldoxime, and 2,5-dimercapto-1,3,4-thiadiazolate to extend the corrosion inhibition ability of coating and impart pH sensitivity. This study explores the anti-corrosion properties of a novel composite prepared by the combination of SLS and pH-sensitive CaCO3 particles in the epoxy coatings applied on Q235 steel. After immersion in the SCP solutions containing 3.5 wt % sodium chloride, the inhibition protection of the coated Q235 coupons was evaluated by electrochemical measurements and physical properties tests
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