Among the application products of magnesium alloy, pressure processing products, casting products and non-structural applications show a tripartite trend. Since the industrial application of magnesium, the application of magnesium in the metallurgical industry (preparation of aluminum alloy, steel desulphurization, nodular cast iron, etc.) accounted for 50%, 65%. The proportion of processing magnesium and magnesium alloy semi-finished products (plates, strips, tubes, rods, profiles) is very small, only 1% 1.6%. The proportion of extruded materials (tubes, bars, profiles) is even smaller, only 0.4% Mel 0.8%. Therefore, there is not much extruded magnesium that needs surface treatment every year. The surface treatment methods of extruded magnesium include oxidation coloring, anodizing, electroplating and so on.
Oxidation coloring of Extruded magnesium
The oxidation coloring process and parameters of extruded magnesium are shown in Table 1, and the pretreatment (degreasing, water washing, pickling, bright etching) and water washing after oxidation treatment are the same as those introduced above.
Preparation and management of trough liquid
Calculate the required chemical products according to the volume of the tank, add water to the volume of 1x2, add the chemical products to the tank one by one, heat, fan and stir the deoiling tank and oxidation tank, and fan and stir the pickling tank and light washing tank at room temperature. After mixing, add water to the specified volume, then stir evenly, sample analysis, test oxidation, qualified before formal production. The chemical analysis of the composition of the bath solution should be carried out regularly during the period of use.
Repair of oxide film defects
The oxide film on the surface of the extruded material should be uniform and firm. If it fails to pass the inspection, it can be repaired as follows:
Thoroughly remove the unqualified film and re-deal with it.
Local removal of defective oxide film, and then color with complementary color solution, the commonly used complementary color solution is shown in Table 2. After wiping off the oil with gasoline or industrial alcohol, gently polish with a glass sand cloth to expose clean magnesium, clean the dust with compressed air, wipe the surface with gauze soaked in alcohol, dry with a glass stick or stick wrapped with brocade yarn or cotton, dip it in oxidizing solution and wipe it repeatedly on the surface for about 35s and dry.
