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In normal environments, steel structures must be protected, and the most common method is to use coating protection. Generally, anti-corrosion and rust-proof coatings are used. This type of coating provides protection through two mechanisms: 1. A barrier effect: On the surface of the steel structure, the coating forms a complete organic film layer that separates the environmental agents (oxygen, water, acids, alkalis, salts, etc.) from the steel, thereby eliminating the conditions necessary for the formation of \"corrosion cells\" and thus protecting the steel from corrosion. This is a physical effect, and its reliability has certain limits. Primarily, organic film layers cannot completely isolate the environment; there are always media such as oxygen and water that can penetrate the steel surface. The ability of penetration depends on the material of the film and the construction methods used. On the other hand, over time, the effect of the membrane layer in isolating the environment weakens; therefore, physical isolation alone often cannot effectively protect the steel structure. 2. Addition of corrosion-resistant components (corrosion inhibitors): This is a unique feature of coatings designed for corrosion and rust prevention. When a certain amount of a substance known as a \"corrosion inhibitor\" is added to the film-forming material, even if the organic film layer cannot completely isolate the environment and a \"corrosion cell\" has already formed, the corrosion inhibitor can effectively prevent or slow down the occurrence and progression of corrosion in the steel structure, thereby achieving better protective effects. Anodic metal layers (zinc, magnesium, aluminum, etc.) provide sacrificial protection (cathodic protection), while cathodic metal layers (nickel, chromium, etc.) mainly serve to isolate the structure from its environment; once such protective layers are damaged or incomplete, it accelerates the corrosion of the steel.