Magnesium alloy surface treatment technology

Because magnesium alloy is extremely active, there is often a layer of oxide on the surface, so the surface treatment of magnesium alloy is difficult. Special treatment methods must be adopted. The existing surface treatment technology is not mature, often making the alloy surface rough and using a large number of non -environmental chemicals. In recent years, the advanced surface treatment technology of magnesium alloy has developed new development.

The technology developed includes three parts: electroplating, conversion layer and anode oxidation. The surface treatment of magnesium alloys is mainly to improve the appearance of the product and improve wear resistance and anti -corrosion performance. The function has the following points:

(A) Decorative surface;

(B) Form a protective layer to prevent magnesium alloy being exposed to the air;

(C) Fill and modify the surface small holes of the die castings;

(D) Increase the adhesion between the magnesium alloy substrate and the organic coating;

(E) Improve wear resistance;

(F) I isolation of magnesium alloys and other metals to prevent electrochemical corrosion.

When choosing an appropriate surface treatment process, you must first consider the needs of the product, such as surface conductivity, abrasion resistance, product application environment, and other ingredients of the selected magnesium alloy material. The surface treatment technology of magnesium alloy is for the above points.

    1. Plating

    Magnesium alloy plating is mainly divided into two categories. One is to perform directly without electrical nickel after the alloy is activated; on the other hand, it can also be placed after sinking zinc. The relevant process is as follows:

     Directly without electrical nickel method

     Removing oil → pickling → activation 1 → activation 2 → non -electric nickel → heat treatment → electroplating copper → other electroplating

     Zinc method

     Removing oil → pickling → activation 1 → activation 2 → sinking zinc → electroplating copper → other electroplating

      After the preliminary treatment, the magnesium alloy can be plated on the metal according to the product requirements, and it can also obtain more diverse and better plating layers through vacuum ion electroplating. The surface of the magnesium alloy after electroplating can ultimately achieve light, good conductivity, good adhesion, and can pass the> 100 -hour salt mist test.

     2. anode oxidation

     The biggest advantage of magnesium alloy anode oxide is hard, abrasion resistance and corrosion resistance, and insulation. The process is as follows:

     Skin -free → pickling → anode oxidation → dyeing

     Through special equipment and electrolytes, choose the appropriate voltage, generate plasma (Plasma) and microarc during the oxidation process, so that the surface of the magnesium alloys will generate a dense and hard ceramic oxidation layer, and can pass> 100 100 Salt and fog test. The surface of the magnesium alloy after treatment can be dyed with general aluminum anode oxidation, and can also directly cover organic coatings or other types of coatings.

     3. Converter layer

The conversion layer of magnesium alloy can bring short protection and corrosion resistance to the surface of the magnesium alloy. At the same time, it can also become a solid underlying layer between the alloy and the organic coating, making the organic coating more adhesive. In terms of conversion layers, chromiumization is the most commonly used method, and the effect is the best; however, due to environmental protection problems, the use of Six -Valing chromium (CR6+) technology is a must -have. Therefore, it has replaced the inherent chromium with phosphorification and has achieved certain results. After phosphorurative magnesium alloys can pass a 24 -hour neutral salt mist test, and after the surface is added with organic coating, the salt fog test can even exceed 300 hours.