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Four Surface Treatment Methods for Aluminum Alloy Die Castings

Jul. 21, 2020

Die-casting aluminum parts factory shares this article with you.

1. Phosphating aluminum

The effects of accelerators, fluorides, Mn2+, Ni2+, Zn2+, PO4; and Fe2+ on the phosphating process of aluminum have been studied in detail by using SEM, XRD, potential-time curve, film weight change and other methods. Studies have shown that guanidine nitrate has the characteristics of good water solubility, low dosage, and rapid film formation. It is an effective accelerator for aluminum phosphating: fluoride can promote film formation, increase film weight, and refine grain; Mn2+, Ni2+ can be obvious Refine the grains to make the phosphating film uniform and compact and improve the appearance of the phosphating film; when the Zn2+ concentration is low, the film cannot be formed or the film formation is poor. As the Zn2+ concentration increases, the film weight increases; the content of PO4 affects the phosphating film Heavy impact is greater, increase PO4. The content increases the weight of the phosphating film.

Aluminum Alloy Tee

Aluminum Alloy Tee

2. The alkaline electrolytic polishing process of aluminum

Conducted research on alkaline polishing solution systems, compared the effects of corrosion inhibitors, viscosity agents, etc. on the polishing effect, successfully obtained an alkaline solution system with good polishing effect and obtained the first time that it can reduce the operating temperature and extend the use of the solution. Additives that improve the longevity of the polishing effect at the same time. The experimental results show that adding appropriate additives to the NaOH solution can produce good polishing effects. Exploratory experiments also found that after DC constant voltage electrolytic polishing with glucose NaOH solution under certain conditions, the reflectivity of the aluminum surface can reach 90%, but due to the unstable factors in the experiment, further research is needed. The feasibility of using the DC pulse electrolytic polishing method to polish aluminum under alkaline conditions is explored. The results show that the pulse electrolytic polishing method can achieve the leveling effect of DC constant voltage electrolytic polishing, but its leveling speed is slow.

3. Environmentally-friendly chemical polishing of aluminum and aluminum alloys

It is determined to develop a new environmentally friendly chemical polishing technology based on phosphoric acid-sulfuric acid as the base fluid. This technology must achieve zero emission of NOx and overcome the quality defects of similar technologies in the past. The key to the new technology is to add some special compounds to the base fluid to replace nitric acid. For this reason, it is necessary to analyze the three-acid chemical polishing process of aluminum, especially the role of nitric acid. The main function of nitric acid in aluminum chemical polishing is to inhibit pitting corrosion and improve polishing brightness. Combined with the chemical polishing test in simple phosphoric acid-sulphuric acid, it is believed that the special substances added to phosphoric acid-sulphuric acid should be able to inhibit pitting corrosion and slow down overall corrosion, and must have good leveling and brightening effects.

4. Electrochemical surface strengthening treatment of aluminum and its alloys

The process, performance, morphology, composition, and structure of the ceramic-like amorphous composite conversion film formed by anodic oxidation and deposition of aluminum alloy tee in a neutral system and the film formation process and mechanism of the film have been discussed. Process research results show that in the Na_2WO_4 neutral mixing system, the concentration of film-forming accelerator is controlled to be 2.5-3.0g/l, the concentration of complexing film agent is 1.5-3.0g/l, and the concentration of Na_2WO_4 is 0.5-0.8g/l, The peak current density is 6-12A/dm~2, and weak agitation can obtain a complete, uniform, and good-gloss gray inorganic non-metallic film. The film has a thickness of 5-10μm, a microhardness of 300-540HV, and excellent corrosion resistance. The neutral system has good adaptability to aluminum alloys and can form a good film on various series of aluminum alloys such as rust-proof aluminum and forged aluminum.

5. YL112 aluminum alloy surface treatment technology

YL112 aluminum alloy is widely used in structural parts of automobiles and motorcycles. The material needs to be surface treated before application to improve its corrosion resistance and form a surface layer that is easy to combine with the organic coating to facilitate the subsequent surface.