Overview of aluminium alloy passivation treatment Aluminium alloy passivation is a process that uses aluminium metal to react with an oxidising agent to form a dense, protective oxide film covering the surface of aluminium. The composition of this oxide film is a composite of aluminium oxide and other metal oxides, and its appearance changes in colour as the spectrum changes.
Common colours for aluminium passivation
Author: Robby
I. Overview of aluminium alloy passivation treatment
Aluminium alloy passivation is a process that uses aluminium metal to react with an oxidising agent to form a dense, protective oxide film covering the surface of aluminium. The composition of this oxide film is a composite of aluminium oxide and other metal oxides, and its appearance changes in colour as the spectrum changes. The thickness of the passivation layer is generally between 1-10 microns, this oxide film has good corrosion resistance, and at the same time has good friction resistance.
II. The common passivation colour
1. Silver-white passivation. Corrosion resistance is the same as natural aluminium oxide corrosion resistance. 2.
2. Black passivation. Reacts at low temperatures and a deep black aluminium oxide film appears on the surface. The surface hardness is high, but the corrosion resistance is reduced.
3. Golden yellow passivation. After strong oxidation treatment to form a rich colour layer, the surface hardness is high, while the corrosion resistance is also very good.
4. Red or purple passivation. Formed under high temperature and strong acid environment, the surface colour is bright, but relative to the general passivation treatment, the corrosion resistance is low.
III. The advantages and disadvantages of aluminium alloy passivation treatment
1. The surface of aluminium alloy after passivation treatment has good corrosion resistance and wear resistance.
2. Passivation treatment for processing higher precision aluminium alloy materials will cause a certain degree of influence, processing before the need to consider this factor.
3. Passivation does not increase the hardness of aluminium alloys.
4. The corrosion resistance and other properties of aluminium alloys of different colours after passivation treatment are different, and it is more important to choose the passivation layer that suits your needs.
To sum up, aluminium alloys will show different colours after passivation treatment, the common ones are silver-white, black, golden yellow, red or purple. The passivation treatment will have a certain degree of impact on aluminium alloys with high machining precision, so this factor needs to be considered before machining. It is even more important to choose a passivation layer that suits your needs.