Feature
Definition of Anodizing
Anodizing is the successful development and control of a natural oxidation process that occurs when alumlinum is exposed to the atmosphere. Electricity and chemicals are used jointly to produce a hard . transparent surface that is integral base Aluminum.
Characteristics
- Hard. Comparable to a sapphire
- Transparent, similar to glass
- Insulative and static-resistant
- Wide variety of colors and finishes
- Integral with Aluminum surfaces,non-flaking
Physical property of Aluminum anodizing
| Porosity of thermal conductivity | 6x1010/cm2 |
|---|---|
| Coefficient ofthemal conductivity | 0.16cal/cm.sec.°C |
| Electrical resistance | 12-13mΩ-cm |
| Potential resistance | 400V |
| Film thickness | 5〜20μm(normal) 30〜100μm(hard anodizing) |
| Porosity ratio | 20〜30% |
| Hardness | 200〜250Hv(normal), 400〜450Hv(hard anodizing) |
| Density | 3.18g/cm3(20°C) |
| Heat resistance | 300°C |
| Coefficitent of thermal expansion | 4.5x10-6M/°C |
Applications for anodizing
- Increased corrosion resistance
- Increased wear abrasion resistance
- Improved base for paint adhesion
- Provides an electrically non-conductive surface
- Provides thermal insulation
- Protects polished and other mechanically finished surfaces
- Improves appearance of the substrate
Anodizing process
Pretreatment：The Aluminum surface is first cleaned chemically treated. Etching results in a satin matte appearance.
Anodizing：Once the surface is prepared, the anodic film is built.
Post Treatment：The porous anodic film can be colored in this stage.
Sealing：Many of the colors are fade-resistant. Sealing the anodic film normally consists of a hot water bath basically swells the pores shut.
Surface Preparatiion
- Mechanical Polish
- Scrubbing
- Sandblasting
- Chemical Polish
- Etching
Various of Anodizing
- Sulfuric Acid
- Chromic Acid
- Oxalic Acid
