Hard-coated and anodized parts, when placed in hot water, the oxide film layers within the barrier and porous layers' inner walls are first hydrated—a new research focus. Power sources for hard-coating and anodizing include pulsed, reverse-polarity (phase change), and DC pulsing. After a period, the bottom of the holes are gradually sealed by the hydrated film. The oxide film obtained from the oxidation treatment typically ranges in thickness from 0.3 to 4 micrometers, is softer, and has lower wear and corrosion resistance compared to anodized films.

Shenzhen Hard Anodizing

Pure aluminum reacts with oxygen in the air to form a thin layer of aluminum oxide covering the aluminum surface exposed to the air. Hard anodizing is also required for aluminum products, which results in a smoother finish and increased wear resistance for long-lasting use. Mixed color and coloring speed are reduced; these defects are mitigated by controlling the current distribution during coloring, preventing impurities, adjusting the electrode ratio, and sealing the electrolyte composition. Salt spray testing (ASTM117 specification) shows no corrosion after over 5000 hours.

Hard anodizing and anodizing exhibit poor wear resistance; when the temperature exceeds 30℃ the film becomes loose and uneven, sometimes even discontinuous, with low hardness, rendering it unusable. At temperatures between 10-20℃, the formed oxide film is porous with strong adsorption capacity. The purpose of anodizing coloring is to wash off the sticky chemical etching solution from the surface of the aluminum material. It is recommended that a sink be equipped with a certain temperature to facilitate product cleaning.

The conversion film is approximately 0.5~4um thick. The conversion film is a gel, making it difficult to measure directly. Typically, only the weight of the workpiece before and after chemical oxidation is weighed. When the oxidized parts are placed in hot water, the oxidation film on the inner walls of the barrier and porous layers is first hydrated. After a period of time, the bottom of the holes is gradually sealed by the hydrated film. When the entire hole is completely sealed, the water circulation within the pores stops. Years of practice have proven that the aluminum profiles solidified under this condition have excellent appearance and mechanical properties.