Aluminum surface oxidation color and passivation color are different in the following aspects:
formation mode: natural oxidation is the oxidation film formed by the full reaction of aluminum with oxygen in nature, without any chemical treatment. Passivation is the process of forming a dense and compact A12O3 film layer on the surface of aluminum products to protect the surface of aluminum products from external corrosion damage.
Corrosion resistance: The oxide film after natural oxidation does not have the strong corrosion resistance and mechanical properties of passivation treatment. Appearance effect: Natural oxidation has different colors, such as natural silver, black, blue, purple, etc., so it is usually used for decorative aluminum products, such as jewelry, watches and some decorative building materials.
Since it is not possible to provide a direct comparison of images, it is recommended to find related images through search engines or related books for comparison.
The passivation and oxidation of aluminum alloy are the same, and the two are called only, according to custom.
As for the natural color, it is actually close to the natural color, which will be a little blue and yellow phase, whether it is with trivalent chromium or chromium-free passivation