Treatment of anodized film for aluminum profiles

The surface problems encountered in the machining process of aluminum profiles will also be anodized after forming films, which will always be affected by some impurities. To solve these problems is a headache for many enterprises. The measures to solve the surface treatment of aluminum profile will be mentioned below. Of course, enterprises can develop better film forming technology to fight against anodic oxidation if they have the conditions. First of all, the film forming speed of aluminum profiles is different from that of different types of aluminum profiles. After electrochemical conversion treatment, the difference in the appearance color is more obvious than that of anodic oxide films obtained by different formulations of other processes. High purity aluminum, slow film forming speed; Low purity aluminum, the opposite. Therefore, the anodizing needs to be mastered differently according to different aluminum materials. To do this, different types of aluminum components are not allowed to be tied together in the same string, so as not to control the appropriate anodic oxidation time for each. Chemical and mechanical treatment, or direct chemical treatment. For the severely anodized metal surface, the anodized layer is thick, the aluminum profile can not be cleaned directly with solvent and chemical treatment, and it is best to mechanical treatment first. Some methods can be used as reference:

First, degreasing treatment, with absorbent cotton wet solvent to wipe, remove oil, and then clean cotton cloth to wipe several times. The thickness of hard oxidation is generally required to be 25-150um, the thickness of most hard anodized film is 50-80um, the thickness of the film is less than 25um, the hard anodized film is used for parts such as tooth bonds and spiral and other occasions, and the anodized film thickness for wear resistance or insulation is about 50um. Under some special technological conditions, It is required to produce hard anodized film with a thickness of more than 125um. However, it must be noted that the thicker the anodized film is, the lower the microhardness of the outer layer and the higher the roughness of the film surface. Sandblasting oxidation to strengthen the cleaning before dyeing, the product should be fully cleaned after being removed from the oxidation tank, especially the cracks of the workpiece and the blind holes, otherwise the residual acid will slowly flow out in the dyeing, so that the PH of the dyeing liquid deviates from the normal range, and the color of its parts and other places have obvious differences, and even corrosion of the oxide film. Common solvents include trichloroethylene, ethyl acetate, acetone, butanone and gasoline.

Two, after degreasing, chemical treatment in the following solution: ammonium hydrogen fluoride 3-3.5, chromium oxide 20-26, sodium phosphate 2-2.5, concentrated sulfuric acid 50-60, boric acid 0.4-0.6, water 1000 impregnated at 25-40°C 4.5-6min, that is, washing, drying. This method has high bonding strength and is suitable for bonding epoxy adhesive and epoxy-butadiene adhesive within 4h after treatment.

After degreasing, the anodized treatment was carried out in the following solution: impregnated with 22g/l concentrated sulfuric acid at 1-1.5A/dm2 DC strength for 10-15min, then impregnated with saturated potassium dichromated solution at 95-100°C for 5-20min, then washed and dried. The treated metal surface is highly active, and it is more likely to be contaminated by dust and moisture again. So the treated metal surface should be bonded as quickly as possible.

After the film on the surface of aluminum profile is polluted, the quality of the subsequent coating is affected. Aluminum profiles can also be self-assembled into a film using a new aluminum surface without using the above method. Through this new film forming technology, the anodization resistance is more advanced than the previous traditional technology.