Aluminum alloy chromate-free passivation treatment method and aluminum alloy chromate-free passivation treatment fluid thereof

Abstract

The invention relates to the technical field of metal surface anti-corrosion treatment, and provides an aluminum alloy chromate-free passivation treatment method and aluminum alloy chromate-free passivation treatment fluid thereof. The treatment fluid is composed of 0.5 to 10.0 g/L of titaniferous compounds, 0.1 to 8.0 g/L of zirconium salt, 0.1 to 10 g/L of fluoride, 0.5 to 20 g/L of oxidizing agents and 0.2 to 15 g/L of complexing agents, wherein the pH ranges from 3.6 to 4.5. Aluminum alloy is treated for 1 to 5 minutes at the room temperature in the chromate-free passivation treatment fluid, and then is subjected to chromate-free passive membrane sealing treatment for 60 seconds to 120 seconds at the room temperature in sealing treatment fluid composed of 1% to 15% of organosilane, 2% to 40% of water-soluble fluorocarbon emulsion and 65% to 97% of deionized water, so that a compound chromate-free passive membrane is formed on the surface of the aluminum alloy, and after the compound chromate-free passive membrane is dried, the compound chromate-free passive membrane with high corrosion resistance is obtained on the surface of the aluminum alloy and can be directly used as the terminal protection layer of the aluminum alloy; and the chromate-free passivation treatment fluid does not contain heavy metal ions such as chromium ions, and is non-toxic, harmless to human bodies or the environment, clean and friendly to the environment.

Description

technical field [0001] The invention relates to the technical field of metal surface anticorrosion treatment, and in particular provides a chromium-free passivation treatment method for aluminum alloys and a chromium-free passivation treatment solution for aluminum alloys. Background technique [0002] Aluminum and its alloys are widely used in aerospace, vehicle manufacturing, home appliances, electronics, building materials and general hardware because of their advantages such as high specific strength, good thermal conductivity, non-magnetism, no low-temperature brittleness, corrosion resistance and excellent processing performance. . In order to improve the corrosion resistance of aluminum and aluminum alloys, the bonding force with organic coatings, and improve the appearance and decoration of aluminum alloy products, fine surface treatment must be carried out on aluminum alloy products. Anodizing and chemical passivation are the two most common and mature surface trea...

AI Technical Summary

Problems solved by technology

Sol-gel passivation technology has high requirements for aluminum alloy pretreatment technology, complex process, difficult maintenance, and high cost, and the market application is still in the stage of expansion; titanium / zirconium salt-organic polymer passivation treatment solution is titanium-containing / Zirconium compound and water-based polymer (water-based epoxy, water-based acrylic acid, water-based polyurethane or water-based polyester) or silicone are the basic film-forming substances, and the prepared passivation film has the characteristics of both inorganic and organic films, making the film layer Corrosion resistance and adhesion to the coating are significantly improved, but the passivation solution is rich in polymers, the stability of the solution is poor, the range of process parameters is narrow, the solution is difficult to maintain, and the corrosion resistance of the passivation film is still low. Poor, neutral salt spray resistance performance is far lower than 500h

Therefore, the existing passivation technology can only be used as a pre-painting treatment, and cannot be used alone as a terminal protective layer to replace the paint coating.