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How to surface treatment and processing of zinc alloy die casting?

Published on:

2023-03-20

Zinc alloy die-casting is a precision casting method that uses high pressure to force molten metal into a complex shaped metal mold.
There are more post-processing processes for aluminum alloy products, mainly based on the following:
1、Sandblasting, the main role is surface cleaning, sandblasting before painting (painting or plastic spraying) can increase the surface roughness, which has a certain contribution to the improvement of adhesion, but the contribution is limited and not as good as chemical painting pretreatment.
2、Passivation is a method to transform the metal surface into a state that is not easily oxidized, and to slow down the corrosion rate of the metal.
3、Coloring: There are two main processes for coloring aluminum: one is aluminum oxidation coloring process, and the other is aluminum electrophoresis coloring process, which forms various colors on the oxide film to meet certain usage requirements, such as optical instrument parts commonly used with black, medallions with golden yellow, etc.
Conductive oxidation (chromate conversion film) - for both protection and conductive occasions.
4, chemical polishing chemical polishing is the use of aluminum and aluminum alloy production in acidic or alkaline electrolyte solution in the selective self-dissolving effect, to level the surface of polishing system year, in order to reduce its surface roughness, PH chemical processing method.
This polishing method has the advantages of simple equipment, no power supply, not subject to the size of the size of the parts, high polishing speed and low processing costs. The purity of aluminum and aluminum alloy has a great impact on the quality of chemical polishing, the higher its purity, the better the polishing quality, and vice versa, the worse.
5, chemical oxidation: oxide film is thin, the thickness is about 0.5 ~ 4 microns, and porous, soft, with good adsorption, can be used as a base layer of organic coatings, but its wear resistance and corrosion resistance are not as good as anodic oxide film;
Aluminum and aluminum alloy chemical oxidation process can be divided into two categories according to the nature of the solution: alkaline oxidation method and acid oxidation method.
According to the nature of the film layer can be divided into: oxide film, phosphate film, chromate film, chromic acid - phosphate film.
6、Painting: It is used for the external protection and decoration of the equipment, usually on the basis of oxidation. Aluminum parts should be pre-treated before painting in order to make the coating and the workpiece combined firmly, there are three general methods: phosphate (phosphate method), chromating (chromium chromate), chemical oxidation.
7, electrochemical oxidation, aluminum and aluminum alloy chemical oxidation treatment equipment is simple, easy to operate, high production efficiency, does not consume electricity, wide range of application, not subject to the size and shape of the parts. The thickness of the oxide film is about 5-20 microns (hard anodic oxide film thickness up to 60-200 microns) has high hardness, good heat resistance and insulation, higher corrosion resistance than chemical oxidation film, porous, and has good adsorption capacity.