Aluminum profiles are alloy extrusion materials, and the normal surface color of aluminum profiles should be silver-white. The previous article introduced the reasons for the rough surface of industrial aluminum profiles. Here I will briefly talk about the reasons for the yellowing phenomenon that often occurs on the surface of the profile in addition to roughness and dullness.
There are two main reasons for the yellowing of the surface of the profile. One is the improper cooling method during the extrusion process of the profile, and the other is the improper surface treatment of the profile. The specific analysis is as follows:
- The profile needs to be cooled after being extruded by the die, in order to improve the mechanical and physical properties of the material. Coolant needs to be used in the cooling process, and different materials have different coolant effects. The most common ones are water or oil-based coolants. If water is used for cooling or the proportion of copper in the coolant is too large, it is easy to cause the surface of the profile to turn yellow. The reason is that aluminum is an active chemical metal element, and it is prone to chemical reactions when it comes into contact with materials in the air and water.
- The surface of industrial aluminum profiles is attached with an oxide film, which can increase the corrosion resistance and surface aesthetics of the profiles. Before the surface treatment of the profile, the extruded profile needs to be cleaned to remove the oil on the surface. If the surface of the profile is not cleaned properly, it is easy to cause the oxide film to be difficult to color in the subsequent oxidation process, or the coloring will be uneven, and yellowing will occur.
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