Several Classifications for Hard Anodic Oxidation Treatment of Aluminium Profiles

Anodizing is the most basic and common method of aluminum alloy surface treatment all over the countries. Anodic oxidation can be divided into general oxidation and hard anodic oxidation. The film obtained from the electrolytic coloring of aluminum and aluminum alloy is of good wear-resisting, sun resistance, heat resistance and corrosion resistance. It is widely used in the decoration of modern architectural aluminum profile. However, aluminium anodic oxide film with high porosity and adsorption capacity, is vulnerable to pollution and erosion-corrosion medium, it must seal hole processing, in order to improve the corrosion resistance, contamination resistance, and fixed chromatophore.

After hard anodic oxidation treatment, aluminum and its alloy can be generated on the surface of tens to hundreds of microns in thickness anodic oxidation film, due to the layer of oxide film with high hardness (on aluminium alloy can reach 400-6000 kg/mm², up to 1500 kg/mm²) on the pure aluminum, through for research and development of aluminum alloy hard anodic oxidation process can get excellent abrasion resistance, heat resistance, (oxidation film melting point is 2050 ℃) and insulation, greatly improving the material itself physical properties, chemical properties and mechanical performance, won the widely used in defence and machinery manufacturing.

Alloys containing more silicon (over 7%) is hard to anodic oxidation in the sulfuric acid system, and ZL102 alloy silicon content as high as 10%-13%, the existence of high silicon, easy to cause to segregation of silicon wafers, lead to a difficult film, film uniformity is poor.

Mixed acid temperature hard anode oxidation is given priority to with sulfuric acid, add a small amount of oxalic acid and dibasic acid, to gain a thicker film, and to expand the upper limit of temperature, can be allowed to increase the anodic oxidation temperature to between 10-20 ℃, hard oxide film obtained the characteristics of similar to sulfuric acid oxidation film. The electrolysis under 10-20 ℃, can obtain good oxidation film abrasion resistance and high tinctorial yield;A high current density of mixed acid electrolytic, can prevent oxidation membrane dissolved, can implement under high temperature, reduce the production cost, make the film more smooth, bright and clean, fine, thickness, hardness higher.