Effects of accelerators, fluoride, Mn2+, Ni2+, Zn2+, PO4 and Fe2+ on phosphating process of aluminum materials were studied in detail by using SEM, XRD, potential-time curves, film weight changes and other methods. Studies have shown that guanidine nitrate has characteristics of good water solubility, low dosage, and rapid film formation. It is an effective accelerator for phosphating aluminum materials: fluoride can promote film formation, increase film weight, and refine grains; Mn2+ and Ni2+ can significantly refine grains, make phosphating film uniform and dense, and improve appearance of phosphating film; when Zn2+ concentration is low, film cannot be formed or film formation is poor. As Zn2+ concentration increases, film weight increases; PO4 content has a greater impact on phosphating film weight. Increasing PO4 content will increase phosphating film weight.

Conducted research on alkaline polishing solution system, compared effects of corrosion inhibitors, viscosity agents, etc. on polishing effect, successfully obtained an alkaline solution system with good polishing effect, and for the first time obtained additives that can reduce operating temperature, extend service life of solution, and improve polishing effect. Experimental results show that adding appropriate additives to NaOH solution can produce good polishing effects. Exploratory experiment also found that after DC constant voltage electrolytic polishing with glucose NaOH solution under certain conditions, surface reflectivity of aluminum material can reach 90%. However, due to instability factors in experiment, further research is needed. Feasibility of using DC pulse electrolytic polishing method to polish aluminum materials under alkaline conditions was explored. Results showed that pulse electrolytic polishing method can achieve leveling effect of DC constant voltage electrolytic polishing, but its leveling speed is slow.

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

Process, performance, morphology, composition and structure of ceramic-like amorphous composite conversion films formed by anodic oxidation deposition of aluminum and its alloys in neutral systems were preliminarily discussed. Film formation process and mechanism of film were preliminarily discussed. Process research results show that in Na2WO4 neutral mixed system, concentration of film-forming accelerator should be controlled to 2.5-3.0g/L, concentration of complexing film-forming agent should be 1.5-3.0g/L, and concentration of Na2WO4 should be 0.5-0.8g/L. , peak current density is 6~12A/dm~2, with weak stirring, a complete, uniform, and glossy gray series inorganic non-metallic film layer can be obtained. Film thickness is 5 to 10 μm, microhardness is 300 to 540HV, and corrosion resistance is excellent. This neutral system has good adaptability to aluminum alloys, and can form films well on various series of aluminum alloys such as rust-proof aluminum and forged aluminum.

YL112 aluminum alloy is widely used in structural parts of automobiles and motorcycles. Material requires surface treatment before application to improve its corrosion resistance and to form a surface layer that can easily bond with organic coatings for subsequent surface treatment.