Solving these problems is a headache for many aluminum extrusion profile manufacturers. The measures to solve the surface of aluminium extruded profiles will be mentioned below. Of course, aluminum extrusion profile manufacturers can develop better film-forming technology by themselves if they have the conditions. oxidation.
A very thin oxide film is formed on the surface of aluminium extruded profiles in the atmosphere, which makes it have a certain anti-corrosion ability; but because the film layer is loose, porous and uneven, it cannot be used as a reliable protective film layer, and the film layer is amorphous , so that aluminum and its alloys lose the luster of Dingyuan, and can not be used as a satisfactory decorative film for external use.
The oxide film obtained by chemical oxidation of aluminum extruded profiles, the thickness is generally 0.3-4p", soft, wear-resistant and anti-corrosion properties are lower than: anodic oxide film. Therefore, except for special purposes, rarely Used alone. Promote it to have better adsorption capacity, make its surface paint, and effectively improve the corrosion-resistant parts of aluminum profiles and the oxide film after anodizing treatment; the thickness is generally 5-20P" , the thickness of the modified anodic oxide film can reach 60-25p".
After electrochemical conversion treatment, the difference in appearance color is more obvious than the difference in oxide film obtained due to other process formulations. The purity of aluminum is high, and the film-forming speed is slow; the purity of aluminum is low, and the opposite is true.
Therefore, the oxidation needs to be mastered according to different aluminium extruded profiles. In order to do this, different types of aluminum extrusions are not allowed to be bundled in the same string, so as not to control the appropriate oxidation time.
Chemical treatment and mechanical treatment, or direct chemical treatment. For severely oxidized metal surfaces, the oxide layer is thick, and the aluminium extruded profiles cannot be directly cleaned with solvents and chemically treated, but it is better to perform mechanical treatment first.
① Degreasing treatment, wipe with absorbent cotton dampened with solvent, remove oil stains, and then wipe with clean cotton cloth several times. Common solvents include trichloroethylene, ethyl acetate, acetone, methyl ethyl ketone, and gasoline.
② After degreasing, chemically treated in the following solution: ammonium bifluoride 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 dipped at 25℃-40℃ for 4.5 min-6min, that is, washing and drying. This method has high bonding strength and can be bonded within 4 hours after treatment. It is suitable for epoxy glue and epoxy-nitrile glue.
③ After degreasing, carry out anodizing treatment in the following solution: immersion in concentrated sulfuric acid 22g/l under the DC intensity of 1-1.5A/dm2 for 10min-15min, and then in saturated potassium dichromate solution at 95℃-100℃ Immerse for 5min-20min, then wash with water and dry. The treated metal surface is highly reactive and is more likely to be contaminated by dust, moisture, etc., so the treated metal surface should be cemented as quickly as possible.
After the surface film of the aluminium extruded section is polluted, the quality of the subsequent coating will be affected. If the aluminum profile does not use the above method, the new aluminum surface can be self-assembled to form a film. Through this latest film forming technology, the anti-oxidation ability is better than the previous one. The traditional technology is advanced.