1. Passivation is a method to change the surface of metal into a state that is not easy to be oxidized and delay the corrosion rate of metal. An active metal or alloy in which chemical activity
Passivation refers to the appearance of greatly decreasing sex and becoming a precious metal state.
2. Anodic oxidation: refers to the process of plating a thin layer of other metals or alloys on the surface of some metals by using the principle of electrolysis. Brush plating is used for local plating or correction.
Barrel plating is used for small parts, such as fasteners, washers, pins, etc. After electroplating, it can obtain protective decoration and various functional appearance on the finished mechanical products
Layer, it can also correct worn and machined workpieces. Electroplating solutions include acidic, alkaline and acidic and neutral solutions with chromium agents, regardless of the choice
The three plating methods should be universal to a certain extent with the finished products to be plated and the plating bath, hanging tools, etc. 3. Spraying: used for external protection of equipment
Decoration is usually carried out on the basis of oxidation. Aluminum profiles should be pretreated before coating to make the coating firmly connected with the workpiece. There are usually three kinds
Method: (1) Phosphating (phosphate method), (2) Chrome (chrome free), (3) Chemical oxidation.
4. Sandblasting, the primary effect is appearance finishing. Sandblasting before painting (painting or plastic spraying) can add surface roughness, which has a certain contribution to the improvement of adhesion, but
Limited contribution, not as good as chemical coating pretreatment.
5. Chemical oxidation: the oxide film is thin, about 0.5 ~ 4 microns thick, porous, soft, and has excellent adsorption, which can be used as the bottom layer of organic coating,
However, its wear resistance and corrosion resistance are not as good as anodic oxide film
6. The chemical oxidation technology of aluminum and aluminum alloys can be divided into two categories: alkaline oxidation method and acid oxidation method according to the nature of its solution. According to the properties of the film, it can be divided into: oxidation
Material film, phosphate film, chromate film, chromic acid phosphate film. Conductive oxidation (chromate conversion film) - used for both protective and conductive occasions.
7. Coloring: there are two main technologies for coloring aluminum: one is aluminum oxidation coloring technology, and the other is aluminum electrophoresis coloring technology. On the oxide film
Various colors are formed to satisfy the application requirements. For example, optical instrument parts are often black, and commemorative medals are golden yellow.
8. Chemical polishing is the selective self dissolving effect of aluminum and aluminum alloy in acid or alkaline electrolyte solution to level and polish the surface of the year,
The following chemical processing methods are used to reduce the surface roughness and pH. This polishing method has simple equipment, no power supply, and is not constrained by the external dimensions of the workpiece
, high throwing speed and low processing cost. The purity of aluminum and aluminum alloy has a great influence on the quality of chemical polishing. The higher its purity is,
The better the polishing quality is, the worse it is.
9. Electrochemical oxidation. The chemical oxidation treatment equipment for aluminum and aluminum alloys is simple, easy to operate, high production efficiency, no power consumption, and wide application range,
It is not constrained by the size and shape of the part. The thickness of oxide film is about 5 ~ 20 microns (the thickness of hard anodic oxide film can reach 60 ~ 200 microns), with a high
Hardness, excellent heat resistance and insulation, corrosion resistance higher than chemical oxide film, porous, excellent adsorption ability.
