Aluminum Surface Treatment Additives Processing method
What are the aluminum surface treatment methods?
Aluminum surface treatment of the surface there are anodizing, electrophoresis coating and powder coating three kinds of treatment, each way has its own advantages, occupy a considerable market share. Review of the history of the development of aluminum, there are two branches, on the one hand is the development of surface treatment, on the other hand is the development of profiles, powder coating treatment appears slightly later with other treatment.
Aluminum and its alloy chemical oxidation of the oxide film is thin, usually the thickness of 0.5 ~ 4um, and the film is soft, not wear, corrosion resistance of regional electrochemical oxide film, but the chemical oxide film adsorption is strong, It is a good substrate for coating.
Chemical oxidation methods are alkaline solution oxidation (thickness 0.5 ~ 1μm), phosphoric acid - chromate method (thickness 3 ~ 4μm), chromate oxidation (about 0.5μm), low concentration fluoride treatment (thin) The
Aluminum and its alloy electrochemical oxidation, is in the electrolyte, aluminum products as the anode, in the role of external current, the formation of oxide film, commonly known as anodic oxidation. The main methods are: sulfuric acid anodizing (5 ~ 20μm, simple process, good oxidant properties), chromic acid anodized (2 ~ 5μm, not suitable for copper content of more than 4% of the aluminum alloy oxidation), oxalic acid anode Oxidation (8 ~ 20μm), and other methods are hard and porcelain anodic oxidation. In order to improve the corrosion resistance, wear resistance and other properties of the oxide film, after oxidation should be closed treatment, commonly used methods are hot water closed, water vapor closed, potassium dichromate solution closed, organic matter closed and other methods.
After treatment of aluminum and its alloys dicast, because of its surface oxide film on the general variety of coatings have good adhesion, so according to the actual situation to choose oily or water-based paint, such as paint or self-induced paint, if the decorative requirements are not High, you can not paint the primer.
Sometimes from the economic point of view, the general aluminum parts in the painting before the only grinding, degreasing, washing and other processes, the surface is only a layer of natural oxide film. At this point in the choice of paint and coating process on the need to change. In order to increase the adhesion of the coating to the substrate, it is necessary to add additives in the oil-based paint to enhance the adhesion of the aluminum alloy, or to increase the coating process in the coating process, the primer should choose to have adhesion to the aluminum Of the painting. For the water-based nano-paint, because of its resin emulsion particles in the nano-scale, it has a good wetting effect on the substrate, do not need to join other additives can be well attached to the alloy matrix, because of its own fullness And anti-sagging limit, so when the decorative requirements are not particularly high, you can not paint the primer, and to achieve the purpose of decoration and protection.