Introduction to Corrosion Products of Copper: Corrosive Substances in Air

When copper slowly oxidizes in the air, it forms copper green, which is mainly composed of basic copper carbonate (Cu ? (OH) ? CO3) and has a green color. This is the most common corrosion product of copper, and in humid air, this green substance gradually appears on the surface of copper. Corrosive substances in sulfur-containing environments

If copper is in a sulfur-containing environment, it may produce black copper sulfide (CuS). Copper sulfide is usually produced when copper comes into contact with sulfur-containing substances such as hydrogen sulfide. In a chlorine containing environment, copper is corroded to produce green copper chloride (CuCl ?). Copper chloride sometimes appears blue-green, depending on its concentration and form of existence. In addition, under different corrosion conditions, copper corrosion products may have other colors and compositions, such as brown, blue, and other different colored corrosion products that may appear in certain complex environments.

How to improve the corrosion resistance of copper?

Adopting surface treatment methods

Passivation treatment: A dense passivation film is formed on the surface of copper using chemical methods. This film can prevent corrosive media such as oxygen and moisture from coming into contact with the copper surface, thereby improving its corrosion resistance. For example, using passivators such as chromate and benzotriazole for treatment can effectively enhance the corrosion resistance of copper in atmospheric environments. Electroplating or chemical plating: A corrosion-resistant metal or alloy, such as nickel, chromium, zinc, etc., can be plated on the surface of copper. These coatings can act as a physical barrier to prevent corrosive media from corroding copper. Electroplated nickel can improve the corrosion resistance of copper in humid environments, while chrome plating can endow copper with better wear resistance and corrosion resistance. Chemical nickel phosphorus alloy plating can also provide good corrosion resistance protection for copper. Organic coating: Apply a layer of organic coating, such as epoxy resin, polyurethane, etc., on the surface of copper. Organic coatings can isolate corrosive media while also serving a decorative purpose. For some copper products used indoors or in mildly corrosive environments, such as decorations, electrical enclosures, etc., using organic coatings is a simple and effective anti-corrosion method.

Adopting alloying or microalloying

Adding alloying elements: Adding some alloying elements such as tin, aluminum, nickel, etc. to copper can change its microstructure and improve its corrosion resistance. For example, tin bronze is an alloy formed by adding tin element to purple copper, which has good corrosion resistance and mechanical properties, and is widely used in fields such as ships and chemicals. Aluminum bronze adds aluminum element to purple copper, which has higher strength and corrosion resistance. Microaloying is achieved by adding trace amounts of alloying elements such as boron, zirconium, titanium, etc., which can refine the grain size of copper and improve its corrosion resistance. These trace elements can form stable compounds at the grain boundaries of copper, preventing the diffusion of corrosive media. For example, trace amounts of boron can significantly improve the corrosion resistance of copper in seawater.

environmental control

Lowering humidity can effectively reduce the occurrence of corrosion in environments where copper products are stored or used. Dehumidification equipment, desiccants, and other methods can be used to control environmental humidity. For some humidity sensitive occasions, such as electronic devices, precision instruments, etc., maintaining a low humidity environment is crucial for improving the corrosion resistance of copper. Avoid contact with corrosive media. When using copper products, try to avoid contact with corrosive media such as acids, alkalis, salt solutions, etc. If contact cannot be avoided, protective measures can be taken, such as using corrosion-resistant packaging materials, coatings, etc. For example, when transporting red copper products, plastic film, foam and other packaging materials can be used for protection to avoid contact with external corrosive media.

Pay attention to maintenance

Cleaning the surface and regularly cleaning copper products to remove dirt, dust, and other impurities can reduce the occurrence of corrosion. Gentle cleaning agents and soft cloths can be used for cleaning, avoiding the use of highly corrosive cleaning agents. Also, it is important to regularly inspect the surface condition of copper products and promptly identify and repair corroded areas. For minor corrosion, methods such as sanding and polishing can be used for repair; For severe corrosion, professional repair or replacement may be necessary. For example, regular inspection and repair of copper pipes used in chemical equipment can ensure the safe operation of the equipment and prevent accidents such as leaks caused by corrosion.

Article source: Internet

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