The oxide film formed by anodizing is tightly bonded to the metal substrate, which significantly improves the material's resistance to corrosive media (e.g., moisture, acid and alkali environments).
Author: Anna
Advantages of anodizing
1. Enhanced corrosion resistance
The oxide film formed by anodizing is tightly bonded to the metal substrate, which significantly improves the material's resistance to corrosive media (e.g., moisture, acid and alkali environments). For example, sulfuric acid anodized film has excellent corrosion resistance, and chromic acid anodized film further enhances the corrosion resistance due to its dense and low porosity.
2. Enhanced wear resistance
The high hardness of the oxide film effectively reduces surface wear. Oxalic acid anodized film hardness can reach HV300 or more, suitable for high friction scenes; hard anodized film (e.g., 150μm thick) is more used for surface strengthening of mechanical parts.
3. Decorative and coloring flexibility
The porous structure of anodic oxide film can adsorb dyes to achieve a variety of color effects. For example:
Sulphuric acid anodized films are transparent, colorless and easy to dye, and are widely used for electronic product housings;
Natural coloring processes (e.g. oxalic acid oxidation) produce yellow or grey films directly without additional dyeing.
4. Process Flexibility and Adaptability
Variety of electrolytes: different solutions such as sulfuric acid (low cost), oxalic acid (high corrosion resistance), phosphoric acid (porous pretreatment), etc. can be selected according to demand;
Controllable film layer: by adjusting the voltage, temperature and other parameters, it can be customized from ordinary protective film (5-20μm) to hard thick film (150μm).
5. Environmental protection and cost-effectiveness
Sulfuric acid anodizing has become the mainstream process due to the easy disposal of waste acid and low cost;
Part of the process is gradually replacing toxic electrolytes such as chromic acid-containing electrolytes to reduce environmental pollution.
6. Expandability
The barrier layer formed by boric acid anodizing can be used in electronic components such as capacitors;
Micro-arc oxidation (plasma electrolytic oxidation) generates ceramic film, which meets the needs of extreme environments such as aerospace.
Anodic oxidation has become the core technology for surface treatment of aluminum, magnesium, titanium and other metals by improving corrosion resistance, abrasion resistance, decorative properties and functional diversity, which is both practical and economical.