In industrial production and infrastructure construction, metal corrosion is a core issue affecting structural safety and equipment service life. Direct economic losses caused by corrosion worldwide each year account for 2%~4% of GDP, covering numerous sectors such as chemicals, marine engineering, transportation, and energy. As the development of heavy equipment, marine engineering, and municipal infrastructure continues to advance domestically, demand for long-lasting and reliable protection solutions is increasing year by year. The appropriate application of anti-corrosion technology has become crucial for controlling operation and maintenance costs and ensuring engineering safety.

Anti-corrosion technology is a general term for engineering technologies that delay the corrosion process of materials and extend the service life of components through physical isolation, chemical regulation, or electrochemical intervention. Corrosion essentially involves oxidation-reduction reactions occurring between metals and environmental media. The core principle of protection is therefore to disrupt the necessary conditions for these reactions, isolate water, oxygen, and corrosive media from contact with the substrate, or alter the electrochemical properties of the metal itself.

Current mainstream protection solutions fall into four major categories to suit different operating conditions and cost requirements. The first is coating protection, which is also the most widely used solution. Its principle is to form a dense barrier layer on the metal surface to isolate corrosive media. Common anti-corrosion coatings use epoxy resin, polyurethane, or fluorocarbon resin as film-forming materials, combined with rust-inhibiting fillers and functional additives. They are applied through multiple processes, including surface derusting and the application of primer, intermediate, and top coats. Some functional coatings can also release corrosion-inhibiting ions through passivating fillers, forming secondary protection at locally damaged areas. The second is electrochemical protection, which is divided into the sacrificial anode method and the impressed current method. The former connects low-potential metals such as zinc and aluminum so that they corrode preferentially to protect the substrate, while the latter uses an external power supply to make the substrate the cathode and suppress oxidation reactions. These methods are mainly used in long-term immersion environments such as soil and seawater. The third is corrosion-resistant material modification, which improves the corrosion potential of steel by adding alloying elements such as chromium and nickel, thereby reducing its corrosion tendency at the source. Typical examples include stainless steel and weathering steel. The fourth is corrosion inhibitor protection, which involves adding a small amount of chemical substances to the medium to form a molecular film and inhibit the rate of electrode reactions. It is mainly used in closed circulating systems.

Protection performance is affected by multiple factors. The quality of surface pretreatment is a key prerequisite. Failure to meet the required derusting grade and residual oil contamination can directly reduce coating adhesion, resulting in premature peeling. Uniformity of coating thickness is equally important. When thickness is insufficient at weak areas such as edges, corners, and welds, these areas can easily become points of corrosion breakthrough. In addition, the concentrations of acids and alkalis, humidity, and chloride ion content in the environment also directly determine the service life of the protection system.

For users purchasing anti-corrosion coatings, supplier selection should not be guided solely by price. Particular attention should be paid to checking third-party salt spray resistance and weathering test reports for the products and confirming their suitability for the user’s operating conditions. The supplier’s application capabilities and experience in similar scenarios should also be assessed. Experienced service providers can offer comprehensive support throughout the process, including operating-condition surveys, solution design, and subsequent maintenance.

The industry still faces several common challenges: in complex and highly corrosive environments, the service life of a single protection system often fails to meet expectations, resulting in high subsequent maintenance costs; the quality of on-site application is heavily influenced by manual operations, making consistency difficult to control; and increasingly stringent environmental policies have also imposed higher requirements on replacing traditional solvent-based coatings.

In practical applications, solutions must be customized according to specific needs. Chemical storage tanks commonly use a combination of acid- and alkali-resistant coatings and cathodic protection. Cross-sea bridges often use a multilayer system consisting of a fluorocarbon topcoat and an epoxy primer. Municipal pipeline networks commonly use a combination of sacrificial anodes and polyethylene anti-corrosion layers. In the future, anti-corrosion technology will develop toward greater environmental sustainability and functionality. Water-based coatings, self-healing coatings, and combined protection systems integrating multiple technologies will become mainstream.