The anodized aluminum sheet is as an anode in an electrolyte( such as sulfuric acid, chromic acid, oxalic acid, etc.), and electrolysis is carried out under specific conditions and the action of an applied current. Its surface will have a thin layer of alumina with a thickness of 5-200 microns. There are a lot of micropores in the thin oxide film layer, which can be colored into various bright colors.
The anodized aluminum plate has improved its hardness and wear resistance, up to 250 ~ 500 kg/mm2, good heat resistance, hard anodized film melting point up to 2320K, excellent insulation, high breakdown voltage 2000V, enhanced corrosion resistance, no corrosion after several thousand hours in ω=0.03NaCl salt spray.
Different trace elements have different effects on the anodizing effect. Pure aluminum sheet has the best oxidation effect. Due to the high content of zinc, the zinc element is the chemical component that has the greatest influence on the anodizing effect, so the anodizing effect of the 7 series is poor.
In general, the anodizing effect decreases in the following order: 1000 alloy>5 alloy >6 alloy >3 alloy >2 alloy >7alloy. The commonly used alloys are 1060, 5052, 6061, 6063, etc.
5052 aluminum alloy has exceptional anodizing quality and can meet any color needs. Its surface processing quality is outstanding and can be processed into a variety of different textures. It's ideal for larger electronics like laptops and TVs. In addition to excellent anodizing and color matching capabilities, this aluminum alloy has moderate strength and formability to meet the design requirements of many consumer electronics products.
There are common anodizing processes: sulfuric acid anodizing process, chromic acid anodizing process, oxalic acid anodizing process and phosphoric acid anodizing process. When using different electrolytes, the obtained oxide films have great differences in appearance and properties. In actual production, it is necessary to select a suitable anodizing process according to the purpose of use.
At present, the widely used anodic oxidation process at home and abroad is sulfuric acid anodic oxidation. Sulfuric acid anodization has low production cost, simple process, short time, easy production and operation, high film transparency, good candle resistance and wear resistance. Compared with other acid anodization, it has obvious advantages in various aspects.
1. Good workability: Anodized aluminum sheet has strong decorative properties, moderate hardness, and can be easily bent and formed for continuous high-speed stamping, which is convenient for direct processing into products without complex surface treatment, greatly saving production cost.
2. Good weather resistance: the anodized aluminum plate with standard thickness oxide film (3μm) will not change color, corrosion, oxidation and rust after long-term indoor use. The anodized aluminum plate with thick oxide film (10μm) can be used outdoors and can be exposed to sunlight for a long time without discoloration.