Anodizing process of black anodized aluminum sheet metal

The black anodized aluminum sheet metal is among the most popular type of andozied aluminium sheets. Aluminum itself is a kind of material with strong corrosion resistance. However, it will form aluminum oxide on the surface of aluminum after encountering oxygen in the air. After a long time, its anti-corrosion and stagnation resistance will be slowly relieved in this way. In addition, aluminum is very sensitive to acidic substances that will destroy the surface layer of aluminum. In order to overcome the defects in corrosion resistance, hardness and wear resistance of aluminum alloy surface, expand the application range and prolong the service life, surface treatment technology has become an indispensable part of the use of aluminum alloy. Metal oxide films of the black anodized aluminum sheet alter the sheet’s surface conditions and properties, improve its corrosion resistance, enhanced its wear resistance and hardness, and protect the metal surface.

In manufacturing a black anodized aluminum sheet metal, the anodizing process entails applying an aluminum sheet as the anode, and a lead plate as the cathode. The aluminum and the lead plate are placed together in an aqueous solution containing sulfuric acid, oxalic acid, chromic acid etc. During the prcoess an oxide film comes into being on the aluminum sheet metal’s surface. Anodization, if not specifically indicated, generally refers to anodization of sulfuric acid. The anodized film of aluminum is porous in the outer layer, and it is easy to adsorb dyes and colored substances, so that it can be dyed and improved in decorativeness. After the oxide film is sealed by hot water, high-temperature steam or nickel salt, the corrosion resistance and wear resistance can be further improved.

At the same time, the anodized alu sheet has a very high melting point, which makes it very resistant to heat. And the anodized aluminum plate not only has many excellent properties, but also is relatively easy to be colored and has a high aesthetic appearance. That’s how colored anodized aluminum sheets, including black ones, are manufactured.