Magnesium metal non-spark anodizing treatment

Similarities between non-spark treatment and spark treatment

The process of non-spark surface treatment for magnesium metal and its alloys is exactly the same as that of spark treatment: alkali degreasing → water washing → acid etching → water washing → direct/ac anodizing → water washing → pure water washing - hot water washing → hole sealing → decorative coating → transparent coating → top coat.

The difference between non-spark treatment and spark treatment

The difference is that the solution composition, the use of special solution, can make the material surface by no spark, micro arc Yang plate oxidation treatment to obtain a more uniform and complete anodic film, not only has a strong corrosion resistance, but also a satisfactory bright decorative effect.

Advantages of low energy consumption and no spark process:

1. Alkaline process is very stable, environmental protection and green;

2. No spark, the film layer is uniform and smooth;

3. Low voltage, more energy saving;

4. Strong corrosion resistance, ASTM B117 salt spray test for more than 200 h, still intact;

5. Coating hardness of 300 HV ~ 400 HV;

6. The film layer is porous structure, which is the best structure of the coating;

7. Meet a variety of standards, such as ASTM B893-98, ASTM D2651-01, MIL-M3171, MIL-45 2002.

Process flow after anodizing

After anodizing, the first step is to seal the hole, and then the coating. Powder coating, liquid coating and electrophoretic coating can be obtained. Different properties can be assigned to the coating according to the use of the workpiece, but it is important to ensure that the coating has the following basic characteristics:

1. Good corrosion resistance, corrosion penetration depth is (0 ~ 2) mm after 240 CASS test;

2. Good exhaust performance;

3. Quite high mechanical properties, including impact resistance;

4. If one or more additional coatings are needed, it is suitable for liquid coating;

5. According to the relevant technical standards, fully meet the requirements of use.

The anodized magnesium alloy die castings that have been sealed with transparent paint are gray after anodization, and the sealing coating is transparent. After sealing the hole, painting, can also be used "pigment" or metal sealing hole.

The second decorative coating can be water-soluble coating or solvent-based, but should meet the following requirements: strong outdoor weather resistance;Good adhesion with the inner coating;The transparent second coating may be a water-based or solvent-based coating, but must have the following properties:

1. Excellent ductility and flatness;

2. Good transparency;

3. Strong corrosion resistance and corrosion resistance of chemical products;

4. Quite high mechanical properties;

5. Excellent anti-wear performance;

6. Good solvent resistance;

7. Strong anti-ULTRAVIOLET (UV) radiation ability.

In order to maintain the beautiful decorative effect and excellent corrosion resistance of magnesium alloy materials and workpiece, surface treatment must be carried out. According to the different uses, it can be coated with chromium or chromium free conversion coating or anodized treatment.Compared with the conversion coating, anodic oxidation film has better performance, and there are many choices according to the final use of the workpiece and the economic benefit. However, the author thinks that the low-energy micro-arc non-spark anodic oxidation process is the first choice, which has good treatment effect, reliable and simple, and low cost.