Anodized aluminum material requirements

         For decorative anodizing, the requirements for aluminum and aluminum alloy materials are higher. Generally only pure aluminum, aluminum, magnesium, aluminum manganese alloy can be dyed more vivid colors. For alloys containing higher silicon and iron, the dark color of the resulting oxide film can only be dyed darker. When decorating anodized aluminum and aluminum alloy parts, the following points should be noted in the material selection:

         For parts that require a mirrored surface, the aluminum content must be higher than 99 . 99 % of high purity aluminum or 5A 66 aluminum magnesium alloy. After the parts are chemically or electrochemically polished, anodizing with sulfuric acid results in a colorless, transparent, bright film that can be dyed with various bright colors.

         For parts that require surface lightness lower than the above, the aluminum content can be selected to be higher than 99 . 9 % of industrial high purity aluminum and LT65 , LT67 aluminum magnesium alloys.

         For the general decorative parts, there is a maximum allowable content of other components and impurities in the aluminum. The values ​​are shown in Table 1 . Among them, aluminum magnesium alloy is the best choice.

Table 1 General Decorative Requirements Requirements for Other Components and Impurities in Aluminum Materials for Anodizing

When choosing aluminum, you should also pay attention to:

1) The surface of the selected aluminum should not have serious scratches, tissue defects and inclusions. They affect the appearance and corrosion resistance of the oxide film.

2) Some aluminum alloys should be heat treated using reasonable specifications. The grain size has a certain influence on the structure and properties of the oxide film. The coarse grains react non-uniformly during the oxidation process and often have an orange-like appearance. Therefore, it is generally desirable for the aluminum material to have a fine grain structure.