Let’s talk about metal surface treatment
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Before being exposed to the operating environment, metals are treated with passivators or film-forming agents (such as mixtures of chromates, phosphates, alkalis, nitrates, and nitrites), which result in the formation of a stable and dense passivation layer on the surface, thereby greatly enhancing its corrosion resistance. Its difference from the corrosion inhibitor protection method is that no additional corrosion inhibitors are required in the subsequent operating environment (such as the atmosphere or water); through anodic treatment, a denser film can be formed on the surface of aluminum than that formed in the atmosphere. These types of membranes exhibit excellent corrosion resistance in mild corrosive environments (atmosphere and water). The bluing of steel parts’ surfaces is another widely used example. Overall alloying is relatively expensive; the surface alloying method can be used, in which easily passivized alloying elements such as chromium, molybdenum, and silicon are diffused into the surface of steel. Typically, the steel components are placed in a mixture of powdered chromium, aluminum, and silicon, or in metal vapor, and heated for diffusion coating. The surface deposit forms a passivation film in oxidizing environments, and its resistance to high-temperature oxidation as well as certain corrosion resistances are superior to those of the base steel. Due to its thin protective layer and low wear resistance, its lifespan is shorter than that of the overall alloy, making it unsuitable for long-term exposure to highly corrosive media. A more modern surface treatment technique is ion implantation, in which elements such as boron, carbon, phosphorus, silicon, nitrogen, molybdenum, palladium, platinum, or other precious metals are ionized and accelerated using an ion implanter. These high-energy ions then collide with the base metal, penetrating into its surface to form an amorphous alloy layer of certain depth and concentration. It possesses much higher corrosion resistance than the base metal, and has now been applied to small components.
Metal surface treatment is intended to improve the corrosion resistance and durability of metals. By treating the metal with specific chemicals such as passivators or film-forming agents (e.g., chromates, phosphates, etc.), a stable and dense protective layer can be formed on the metal surface. This treatment method allows the metal to function without the need for additional corrosion inhibitors, and is particularly suitable for mild corrosive environments such as those found in air and water. In addition, techniques such as surface alloying or ion implantation are employed to further enhance the surface properties of metals. Although these methods are more expensive or have limited durability in certain environments, they provide a higher level of corrosion resistance, making them suitable for specific application requirements. .