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Analysis on the development direction of metal anti-corrosion self repairing coatings

analysis on the development direction of metal anti-corrosion self repairing coatings

the main reports of this forum are as follows: January 18, 2021

Abstract: coating anti-corrosion coatings on metal surfaces is an effective measure commonly taken to protect the corrosion of metal products. Due to various environmental factors or the performance characteristics of the coating itself, it is inevitable that some small invisible micro cracks will appear on the coating surface during the construction process. These micro cracks will continue to spread and expand when exposed to the air, causing the coating to peel off from the substrate and reducing the protection life of the coating. Therefore, intelligent coatings with certain self-healing ability have been widely concerned by academia and industry. In this paper, the importance, development status, coating types and future development direction of metal anti-corrosion self-healing coatings are described. The self-healing mechanism of microcapsule self-healing coatings, polymer self-healing coatings and loaded corrosion inhibitor self-healing anti-corrosion coatings were discussed. It is pointed out that the key points for the development of intelligent anticorrosive coatings to be repaired should be: 1) simplifying the process and improving the operability; 2) Research on polymer intelligent coating with self repairing at room temperature; 3) Expand the application of natural materials in protective coatings

development status of self-healing anti-corrosion coatings

according to alicja et al., 542 literature reports on self-healing protective coatings were published from the 1980s to 2015. The specific distribution is shown in Figure 1. The figure shows that the number of literature on self-healing coatings showed a rapid growth trend from 2010 to 2015. At the same time, the global distribution and European distribution of the research on the re processing and forming of self-healing coatings are counted. The statistical results are shown in Figure 2 and figure 3. The results shown in Figure 2 and figure 3 show that there are more studies on self-healing coatings in Asia and Europe in terms of global distribution, and there are more studies in Germany in terms of European distribution

types of metal anti-corrosion self-healing coating

microencapsulated self-healing coating

white et al. Designed a typical microencapsulated self-healing composite material system. The specific design idea is shown in Figure 4. The system wraps the repair agent in microcapsules, and then loads the microcapsules into a composite structure containing a catalyst capable of polymerizing the repair agent. The specific self repair process is as follows: a) cracks are generated when the coating is damaged; b) The crack causes the microcapsule to crack and release the repair agent; c) The crack will be repaired by polymerization reaction after the repair agent contacts with the catalyst

Figure 4 Schematic diagram of automatic repair concept

the theoretical research of microencapsulated self-healing coating is relatively mature, but there are some difficulties in the process of industrial use. The content of microencapsulation containing repair agent is small, which can not achieve the repair effect, and the content is too large, which will affect the mechanical properties of the coating. Moreover, strict control is required not only in the production of microcapsule coating, but also in the construction process

polymer self-healing anticorrosive coating

polymer self-healing coating is not as difficult to control as microcapsule self-healing coating in the production and construction process. However, the mechanical properties, film hardness and wear resistance of polymer self-healing coatings are low, and the self-healing process needs heating

loading corrosion inhibitor type self-healing coating

adding metal corrosion inhibitor is a common method in metal corrosion protection. Although hexavalent chromium can effectively inhibit the corrosion of metal substrates, its toxicity does not meet the requirements of environmental protection. In recent years, some environmentally friendly corrosion inhibitors have been developed, such as cerium, molybdic acid, phosphoric acid and organic corrosion inhibitors, which can effectively replace hexavalent chromium. Although the corrosion inhibitor can effectively form a protective passive film on the metal surface to inhibit the further corrosion of the metal, due to the poor compatibility between the corrosion inhibitor and the coating, it will affect the anti-corrosion effect if directly added to the coating. Moreover, it is very difficult to disperse the inhibitor evenly into the coating due to the interaction of chemical bonds. In order to solve this problem, many scholars have designed a series of solutions

the self-healing coating prepared by loading corrosion inhibitor into porous materials and then adding resin solves the problems of complex production and construction of microencapsulated self-healing coating and weak mechanical properties of polymer self-healing coating. However, the corrosion inhibitor needs to be released from the porous structure in the process of self repair to achieve the purpose of repair. In this way, the release capacity of the corrosion inhibitor will be limited. It needs to be released quickly in the process of repair to achieve satisfactory results

development direction of self-healing metal anticorrosive coatings

the use of self-healing properties to prolong the service life of anticorrosive coatings has attracted extensive interest in academia and industry. However, there is still a certain gap from the ideal self-healing anti-corrosion coating like biology. In the future, the development of self repairing anti-corrosion coatings will focus on the following:

the most comprehensive results of output

1) simplifying the process and improving the operability. From the perspective of practical application, the simpler the production formula and production and construction process, the higher the practical application value and the more widely used. For example, the microcapsule self-healing system that is widely studied now has the problem that the microcapsule breaks early in the production or use process and cannot achieve the purpose of self-healing

2) study the polymer intelligent coating with self repair at room temperature. For composite coatings that use some properties of polymers to achieve self-healing, the self-healing process generally requires a heating process. Generally, the self-healing can be achieved at a temperature of about 80 ℃ ~ 160 ℃. Such self repair did not achieve the goal of spontaneous. Therefore, it is a future development trend with industrial practical value to study the anti-corrosion coating that can achieve the purpose of self repair at room temperature

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