Surface treatment method of aluminum die casting

1. Phosphating of aluminum materials: The effects of accelerators, fluorides, Mn2+, Ni2+, Zn2+, PO4; and Fe2+ on the phosphating process of aluminum materials have been studied in detail by using methods such as SEM, XRD, potential-time curve, and film weight change. influences. 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+ and 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.

2. Alkaline electrolytic polishing process of aluminum: Conducted research on alkaline polishing solution system, compared the effects of corrosion inhibitors, viscosity agents, etc. on polishing, and successfully obtained a very good alkaline solution system for polishing. And for the first time an additive that can lower the operating temperature, extend the service life of the solution, and improve the polishing accuracy. The experimental results show that: adding appropriate additives to the NaOH solution can produce good polishing**. 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.

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, which 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 first 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.

4. Electrochemical surface strengthening treatment of aluminum and its alloys: The process, performance, morphology, composition and structure of aluminum and its alloys in a neutral system by anodizing and forming ceramic-like amorphous composite conversion coatings are preliminarily discussed. The film formation process and mechanism of the layer. 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 5-10 μm, 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.