As well known, at present, the application of the shell whether in life or industrial products is widely, in order to make the aluminum shell can adapt to a certain environment or achieve some functions, enterprises choose different processes to deal with the surface of the aluminum shell, for example: anodic oxidation. Anodic oxidation can make the surface of the product to form a layer of uniform, dense oxide layer, (Al2O3, 6H2O common name steel jade) this film can make the surface hardness of the product to reach (200-300HV). So what is the difference between anodic oxidation and hard anodized on aluminum shell?
1. Concentrations
Generally, concentrations of ordinary anodic oxidation is around 20% while hard anodized is around 15% or less.
2. Current
Generally, current density of ordinary anodic oxidation is 1-1.5dm2 while hard anodized is 1.5-3ADM /dm2.
3. Temperature
Temperature of ordinary anodic oxidation is around 18~22 degrees Celsius, if with additives can reach 30 degrees,but too high will be easy to appear powder or crack while hard anodized is generally below -5 degrees Celsius, relatively speaking, the lower the temperature, the higher the hardness.
4. Film Properties
film thickness: film thickness of hard anodized is greater than 15um, it is too low to meet the requirements of hardness while ordinary oxide thickness is relatively thin.
Surface state: the surface of ordinary anodic oxidation is flat while the surface of hard anodized is rough.
Porosity: ordinary anodic oxidation has high porosity while hard oxidation has low porosity.
Applications: ordinary anodizing is mainly used for decoration, which will use wire drawing, polishing, grinding and sand blasting in the early. The more various colors on oxidation, the adornment effect is better. However, hard anodized is given priority to with function with black or dark brown color, the thicker the film thickness, the deeper the color. Of course, the price also will be more expensive, generally used in the occasion of wear-resistant, resistant to electricity, such as: Cylinder class, meter class of products.
Above all, this is the difference between anodic oxidation and hard anodized on aluminum shell. Due to the anodic oxidation film in the natural environment chemical properties are very stable, the aluminum shell can be provided anti-corrosion protection when coated with a protective "coat" after anodizing.
