Views: 33 Author: Site Editor Publish Time: 2024-10-12 Origin: Site
For aluminium alloys that have not been given a special surface treatment, a natural uniform silvery-white colour is usually a better indication. A good quality aluminium alloy should have a smooth and uniformly coloured surface if the process is properly controlled during casting and machining. If the silver-white surface has visible black spots, yellow spots or uneven colour, it may mean that the aluminium alloy has been contaminated during processing or that the raw material is of poor quality. For example, aluminium that has been mixed with too many impurity elements during the melting process may result in an abnormal surface colour.
In addition, the lustre of natural silver-white aluminium alloys can also reflect quality. Aluminium alloy with good luster indicates that its surface is relatively flat and its microstructure is uniform, which may be due to the use of advanced processing technology, such as precision rolling or forging technology, which makes the internal tissue of the aluminium alloy dense, thus forming a good reflective effect on the surface. The aluminium alloy with dull luster may be damaged on the surface during processing, or there are more defects such as pores inside, which affects the reflection of light.
The colour of anodized aluminium alloy should be even and have a certain depth. If the colour is not of the same depth, it may be caused by uneven current distribution or inconsistent oxidation time during the oxidation process. For example, in mass production of aluminium alloy doors and windows, if the anodizing equipment fails, resulting in too little current in some areas, the growth of the oxide film in these areas will be slower, and the colour will be lighter than other normal areas.
The colour stability of aluminium alloy after high quality anodic oxidation is better. The colour of the products produced through the qualified process is not easy to fade during long-term use (e.g. in the outdoor environment subjected to sunshine and rain). This is because a high-quality anodising process results in a dense oxide film structure that effectively locks in the injected dye. Whereas, if the anodized aluminium alloy is of poor quality, obvious fading may occur within a short period of time (a few months or even a few weeks), which indicates that the quality of the oxide film is poor, and it may be that the thickness of the oxide film is insufficient or the pore structure is unreasonable, resulting in the dyes not being able to be well attached and preserved.
For spraying colour aluminium alloy, the first thing to look at is the adhesion of the coating. You can use a sharp object in the inconspicuous parts of the light scratch, if the coating is easy to fall off, indicating that the spraying quality is poor. For high-quality sprayed aluminium alloy, the coating should be firmly attached to the surface of the aluminium alloy, with uniform colour and no defects such as flow marks and bubbles. For example, in the spraying of aluminium alloy wheels for automobiles, a good product has a flat and smooth coating with full colour.
From the point of view of the durability of the colour, high-quality sprayed aluminium alloy has less colour change after a long period of use, friction or environmental erosion. If the sprayed colour of aluminium alloy quickly flakes and discolours during use, such as from the original bright white to dark yellow, it is likely to be caused by the poor quality of the sprayed material or the spraying process, such as the inappropriate baking temperature, improper primer treatment and other factors.
