| Metal corrosion causes great economic loss to our production and life. Coating protection have become one of the most economical, effective and widely used method for the metal protection.There is no VOC or only little VOC in Water-based coatings, which completely use water as solvent or dispersant, suitable not only indoor but also outdoor occasions. Furthermore water-based coatings are going to replace of solventbased coatings which are widely used in furniture, construction, marine and other fields. Water-based coatings contain hydrophilic groups, such as hydroxy groups, amino group and so on, which is necessary for forming the stable emulsion. However there is still hydrophilic component in the coatings after curing and the hydrophilic component can form polar channels so that water and other moleculers will permeate the coating which will make the coting invalidly. Therefore, how to reduce the hydrophilic groups in coating and obtain high performance of anti-corrosion coating becomes the focus in water-based coating research.In this paper, the phosphate group was introduced into the epoxy resin molecular framework, and the chemical structure was characterized by infrared spectroscopy and nuclear magnetic resonance spectroscopy respectively. Specific processes include the following three parts:1. The corrosion inhibition of HEP on Q235 C-steel was studied in 3.5% NaCl solution. The results showed that HEP had good inhibition performance on carbon steel. It can significantly reduce the corrosion rate of carbon steel in 3.5% NaCl solution and it is a good waterborne anti-rust agent and HEP emulsion P4 showed the best inhibition effect.2. The HEP emulsion P4 was added to the water-based acrylic polyurethanes (APU) according to different quality grades and the corrosion inhibition effect of HEP on metal was studied. The electrochemical test results show that the charge transfer resistance Rct of the coating containing HEP is much higher than that of pure APU and its Rct value was 30 times higher than that of pure APU. The surface and cross section morphology of the coating are observed by SEM. The results show that the coating and Q235 steel substrate are firmly combined, the coating section was compact and the surface of the coating is very smooth. Adhesion test results show that coating adhesion levels containing HEP have been improved compared to the pure APU coating.3. HEP emulsion were also added to the two component epoxy coatings, the corrosion mechanism of Q235 steel and coating failure process were studied. Electrochemical test results show that the protective effect of the epoxy coating containing HEP on Q235 steel is much higher than that of pure epoxy coating, the anti-corrosion performance of the coating with 0.2% P4 is the best. Coatings surface scanning electron microscope shows that the surface of the coatings contain HEP is smooth without any holes and defects, however, the pure epoxy coating surface appears obvious rough.4. Self-emulsified epoxy polyurethaness were prepared using HEP emulsion and water dispersible isocyanate curing agent. Polarization curves and electrochemical impedance spectroscopy were used to analyze the corrosion protective properties of coatings on Q235 carbon steel. The results show that the epoxy phosphate/polyurethane coating has good corrosion protection for Q235 steel, the P4 prepared by the HEP 3:2.5 has the best corrosion protection effect of the coating on carbon steel. The surface of the coating is smooth without any hole or defect. |
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