**6. Conclusion**

This chapter provides brief information on metal corrosion and corrosion prevention methods. Some of the most common metal corrosion mechanisms, such as uniform, galvanic, crevice, pitting, and erosion-corrosion, as well as mechanically assisted corrosion, are introduced. In addition, various methods of preventing metal corrosion, such as cathodic protection, galvanizing, painting, and coatings, are discussed and their advantages and disadvantages are addressed. A summary of the information mentioned in this chapter is summarized here.

Investigations show that corrosion is an inevitable and costly phenomenon, and its prevention is of great importance. The Cathodic protection as a classic method is efficient, but it is expensive and requires skilled workers and manpower as well as periodic inspections. Galvanizing is also an effective method but has only limited applications for steel. Furthermore, the galvanized coating can easily chip off and create an uneven surface that leads to corrosion and possible loss of life. Painting is also mainly decorative and does not help to prevent corrosion effectively. Paints can easily deteriorate due to environmental factors or mechanical damage and expose the surface to corrosive factors. It can be said that coatings are the most efficient method to prevent corrosion as they are cost-effective and provide a significant barrier to corrosive factors. Definitely, coatings prolong the service life of metals, but they face the problem of cracking defects and mechanical damage. However, a new generation of coatings called self-healing coatings has been introduced and developed in recent years, which has solved the mentioned problems.

Self-healing materials can heal (recover/repair) internal damages automatically and autonomously. Different design strategies such as the release of healing agents, reversible cross-links, and miscellaneous technologies including electrohydrodynamics, and shape memory effect are available for self-healing fabrication. Release of healing agents is probably the most convenient method to fabricate self-healing coatings in which healing agents are loaded in a container and added to a polymer matrix, and when damage occurs, it releases and repairs the damaged area. This method is widely used and effective because the healing agent can be released in a stable and controlled manner. Two main classifications can consider for self-healing coating,

*Self-Healing Coatings DOI: http://dx.doi.org/10.5772/intechopen.109500*

autonomous and non-autonomous. Autonomous self-healing coating can repair their bulk integrity or functional properties without any external physical intervention. But In non-autonomous systems, healing effects accomplish by external stimuli such as heat and light. Both mechanisms are very important and have their own applications despite their few limitations.

Considering the above mentioned properties, self-healing coating are a promising method for prevention of metal corrosion and they have revolutionized the coating systems. Although they are still in the early stages of their development, they have shown a great potential for wide applications and seems to completely replace traditional coatings in the future.
