The process of uniformly coating the anti-corrosion coating on the surface of the object to form a continuous and dense protective covering layer (or coating) is called anti-corrosion coating. Generally speaking, there are three functions of the protective anti-corrosion coating:
One: the role of shielding and insulation, that is, through the anti-corrosion coating (film) on the surface of the structure, the protected structure is isolated from the external corrosive environment, and plays the role of shielding the corrosive environment. For example: The outer anti-corrosion coating of buried steel structures or steel pipelines or gold structures not in corrosive media (water), strictly speaking, the absolute sense of insulation and shielding coating does not exist, Because most of the anti-corrosion coatings on the outside of the steel structure are made of organic polymer materials, at least the outer structure is made of these materials, and it is impossible for these materials to be absolutely impermeable to water and oxygen.
There is also a view that the anti-corrosion effect of the coating described above is realized by shielding the corrosive environment and preventing water in the corrosive environment from penetrating to the steel surface. Turtle anti-corrosion coating is proven against water and hungry consumption stings. The test shows that: Any steel surface with anti-corrosion coating is used to test the consumption of water and oxygen. Sometimes it is greater than the water and oxygen consumption of the steel surface without anti-corrosion coating. This shows that the protective mechanism of the coating is not to prevent the penetration of water and hydrogen, but the adhesion of the coating to the steel surface makes the polymer groups in the coating prevent the substitution of water and oxygen, making them difficult to penetrate. Reach the surface of the steel, and not prone to corrosion reactions.
Second: Cathodic protection function, that is, in a corrosive environment, the coating on the surface of the protected structure can play an electrochemical protection role. Provide cathodic protection current to the protected metal structure. like. Hot-dip galvanized, heat-unlocked aluminum coatings and alloys of thermal sprayed galvanized and aluminum, etc., which belong to the metal coating
Third: Other special protection and protective functions, such as mechanical protection (wear resistance), UV aging resistance, corrosion protection coating under high temperature environment, etc.
Different types of coatings are applied on different surfaces to be coated, and have different process characteristics. In the coating process. Coating quality and performance are the basis for obtaining a good coating; while coating technology and coating process are the key to a protective coating with good quality. In other words, the quality of the anti-corrosion layer or protective coating depends largely on the construction process and construction technology of the coating. Before anti-corrosion coating is carried out on any protective interface, surface pretreatment before coating or pre-treatment of coating is required. Statistics show. The surface pretreatment before painting has a very important effect and significance on the quality and tortoise of the anti-corrosion coating.
