Preparation And Anti-corrosion Properties Study Of Self-healing Coatings On Metal Surface

Metal corrosion is a very common phenomenon in the production and life, which not only leads to economic losses directly but also brings a large amount of energy dissipation and potential safety hazard. So corrosion problem must be taken seriously. Surface coating and corrosion inhibitor are the most common corrosion protection measures. However, Surface coating can not be healed when damaged and corrosion inhibior is easy to lost, which limit their application. In this paper, I designed new types of self-healing coatings for corrosion protection of metal based on corrosion inhibitor encapsulation.Firstly, nanorod-like Cu(OH)2was fabricated on copper surface in site via chemical oxidation and then the Cu(8HQ)2network film (CNF) composed of needle-like fibers was transformed through controlling immersion time of8-hydroxyquinoline (8HQ) conversion solvent. The CNF was characterized by SEM, XRD and so on. The EIS was use to analyze and compare corrosion resistant properties of the fabricated CNF. The CNF was embedded with inhibitor BTA by solvent evaporation method and coated by epoxy as the top layer through dip-coating method. EIS and polarization curve were applied to evaluate self-healing properties of the scratched coatings. Results show that the stable CNF is synthesized by chemical conversion for15min and provided large specific surface for corrosion inhibitor encapsulation. BTA embedded in CNF and adsorbed8HQ are released to inhibit the corrosion process under the synergistic effect.Secondly, the spherical micro-pits (SMPs) as reservoirs used for inhibitor encapsulation were fabricated in copper substrate via HNO3etching technique with the assistance of CTAB and ultrasonication. The morphology of the SMP was controlled by changing the etching time and observed by SEM. BTA was embedded into SMPs and the qualitative and quantitative analyses of inhibitor encapsulation were carried out by FT-IR and TGA. After coated with epoxy and scratched, the self-healing system was evaluated by EIS and UV spectrophotometer. Results show that15min is selected as the optimum etching time to obtain well distribution of SMPs for corrosion inhibitor encapsulation.The local BTA concentration can remain stable over a period of time by released BTA.Finally, the3D porous micro-structure (PMS) prepared by electrodeposition using hydrogen bubbles as template is used as reservoir for encapsulation of corrosion inhibitor. The morphology of the PMS was modified by adding HC1and Na2SO4into the base plating solution and observed by SEM. The PMS was characterized by XRD and embedded with BTA, then coated with epoxy. The qualitative and quantitative analyses of inhibitor encapsulation were carried out by FT-IR and TGA. EIS, polarization curve and UV spectrophotometer were applied to evaluate self-healing properties of the scratched coatings. Results show that the PMS is improved by introducing both0.5M Na2SO4and0.2mL/L HC1into base plating solution. The achieved structure of the pore wall becomes more compact and no obvious dendrites are observed. Meanwhile, the pores of the PMS exhibit a uniform distribution. BTA embedded in PMS continued to be released and provided corrosion protection for exposed substrate through its internal3D interconnected structure.