How to prevent aluminum plate from corrosion and oxidation?

Commonly used aluminum plates

• Pure aluminum plate

1050/1060/1070/1100/1200; thickness 0.1-20mm; width 800-2200mm.

• Alloy aluminum plate

2A21/3003/3105/5052/5083/5086/5754/6061/6063/6082/8011; thickness 0.5-260mm; width 800-2800mm.

• Curtain wall aluminum plate

1060/1100/3003; thickness 0.95-2.85mm; width 0.8-1.5m. Used for roofs, art ceilings, balconies, beverage cans, cable protective layers, etc.

Characteristics and advantages of aluminum plates

◆ Easy to process

After adding certain alloy elements, aluminum alloys with good properties or deformed aluminum alloys with good processing plasticity can be obtained.

◆ Good electrical and thermal conductivity

The electrical and thermal conductivity of aluminum is second only to silver, copper and gold.

◆ Low density

The density of aluminum and aluminum alloys is close to 2.7g/cm³, which is about 1/3 of iron or copper.

◆ High strength

Aluminum and aluminum alloys have high strength. After a certain degree of cold working, the matrix strength can be strengthened. Some grades of aluminum alloys can also be strengthened by heat treatment.

◆ Good corrosion resistance

The surface of aluminum is easy to naturally produce a dense and firm AL₂O₃ protective film, which can well protect the matrix from corrosion.

What are the main reasons for corrosion and oxidation of aluminum plates?

Aluminum and aluminum alloys show excellent corrosion resistance in the atmosphere and freshwater environments. However, in actual use, black oxidation and surface corrosion will occur. In some environmental media, local corrosion such as pitting, intergranular corrosion and stress corrosion will also occur.

◎Aluminum will form a passive protective film in oxidizing acid solution, which is not easy to corrode. However, in non-acidic acid (such as hydrochloric acid) solution, the passive oxide film is dissolved, accelerating corrosion. In alkaline solutions with a PH value of more than 8.5, the corrosion of aluminum will also accelerate.

◎In water containing Cl-, the passivation protective film will produce defects and pitting corrosion will occur, especially when Cu₂+ and Fe₃+ coexist, which is more harmful. Therefore, it cannot be used in environments such as water containing trace heavy metal ions and industrial water.

◎The reason for the black change of aluminum surface: the precipitation of fine heterogeneous metal elements attached to the aluminum surface and the exposure of aluminum itself reduce the reflectivity of the aluminum surface; the precipitated metal primary color attached to the aluminum surface and the exposed metal elements change into colored oxides and hydroxides. The aluminum surface is easily blackened in a humid and oily environment.

◎Aluminum and aluminum alloys are very likely to cause contact corrosion when they are in long-term contact with dissimilar metal materials: compared with high-potential copper (-0.20V) and iron (-0.58), low-potential aluminum (-0.85V) and high-potential metal materials are placed in an electrolytic solution in an electrically bonded manner, which will cause battery corrosion.

How to prevent aluminum plate from corrosion and oxidation?

▶1. Use environment: Aluminum parts should be stored and used in a dry environment without metal ion pollution as much as possible

▶2. Processing medium: Aluminum parts should be processed with special cutting fluid to avoid contact with acidic and alkaline liquids

▶3. Daily contact: Avoid long-term contact with metal materials such as copper and steel in oily and humid environments

▶4. Surface treatment: Such as painting, sandblasting, anodizing, etc., to form a protective layer on the surface

▶5. Choose aluminum alloy grades with strong corrosion and oxidation resistance (3003 aluminum plate/aluminum coil, 5052 aluminum plate/aluminum coil, etc.). This type of aluminum alloy will have an oxide film on the surface. If it needs to be used outdoors for a long time, you only need to control this oxide film to more than 8μ to meet the needs of outdoor production and use.

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