Do you know the difference between hard anodizing and ordinary anodizing?
Author: Marisa
Hard oxidation is the full name of hard anodizing. The main purpose of hard anodizing of aluminum alloy is to improve the various properties of aluminum and aluminum alloys, including corrosion resistance, wear resistance, weather resistance, insulation and adsorption. It is suitable for both deformed aluminum alloys and die-cast aluminum alloy parts.
I. Advantages of hard oxidation of aluminum alloy:
1. The surface hardness of aluminum alloy after hard oxidation can reach up to HV500
2. The thickness of oxide film is 25-250um.
3. Strong adhesion. According to the oxidation characteristics generated by hard oxidation: 50% of the generated oxide film penetrates into the aluminum alloy, and 50% adheres to the surface of the aluminum alloy (bidirectional growth)
4. Good insulation: The breakdown voltage can reach 2000V (perfect sealing)
5. Good wear resistance: For aluminum alloys with a copper content of no more than 2%, the maximum wear index is 1000 revolutions. The wear index of all other alloys should not exceed 1000 revolutions.
6. Non-toxic: The oxide film and the electrochemical process used to produce the anodized film should be harmless to the human body. Therefore, in order to reduce the weight of products, facilitate mechanical processing, and meet environmental protection and low toxicity requirements, some parts of some products are currently replaced by stainless steel, electroplating hard chrome and other processes by aluminum alloy hard oxidation.
II. Differences between hard anodizing and common anodizing:
50% of the oxide film of hard anodizing penetrates into the aluminum alloy, and 50% adheres to the surface of the aluminum alloy. Therefore, the external size of the product becomes larger and the inner hole becomes smaller after hard anodizing.
A Differences in operating conditions:
1. Different temperatures: Ordinary anodizing is about 18-22℃, and those with additives can reach 30℃. Too high temperature is prone to powder or cracks: Hard anodizing is generally below 5℃℃. Relatively speaking, the lower the temperature, the higher the hardness.
2. Concentration difference: Ordinary anodizing is generally about 20%; hard anodizing is generally 15% or lower.
3. Current/voltage difference: Ordinary anodizing current density is generally: dm2; while hard anodizing: dm2; Ordinary anodizing voltage ≤18V, and hard anodizing is sometimes as high as 120V.
B Differences in film performance:
1. Film thickness: Ordinary anodizing film thickness is relatively thin; hard anodizing generally has a film thickness of >15um, which is too low to meet the requirement of hardness >300HV.
2. Surface condition of the hand: the surface of ordinary oxidation is smoother, while the surface of hard oxidation is rougher (microscopically, it is related to the surface roughness of the substrate).
3. Different porosity: ordinary oxidation has high porosity; while hard oxidation has low porosity.
4. Ordinary oxidation is basically a transparent film; hard oxidation is an opaque film due to its thick film.
5. Different applicable occasions: ordinary oxidation is mainly suitable for decoration; while hard oxidation is mainly functional, generally used in wear-resistant and electrical-resistant occasions.