The secret of the surface treatment process of aluminum alloy die castings

The influence of accelerator, fluoride, Mn2 +, Ni2 +, Zn2 +, PO4; through SEM, XRD, potential energy curve and film weight change method, the Fe 2+ and Fe 2+ in the phosphating process of aluminum were studied in detail . Studies have shown that guanidine nitrate has the characteristics of good water solubility, low dosage and fast film formation. It is an effective aluminum phosphide accelerator: fluoride can promote film formation, increase film weight, and refine grains; Mn2 + and Ni2 + are obvious. Refine the crystal grains, make the phosphating film uniform and compact, and improve the appearance of the phosphating film; when the Zn 2+ concentration is low, the film cannot be formed or the film formation is poor. As the concentration of Zn2 + increases, the weight of the film increases; the content of PO4 has a greater impact on the phosphating film, increasing PO4. This content increases the weight of the phosphating film.

The alkaline electrolytic polishing process of aluminum was studied in the alkaline polishing liquid system, and the influence of corrosion inhibitor and tackifier on the polishing effect was compared. An alkaline solution system with good polishing effect has been successfully obtained, and energy has been obtained for the first time. Additives that reduce the working temperature, prolong the service life of the solution and improve the polishing effect at the same time.

The experimental results show that: adding appropriate additives to the NaOH solution can produce a good polishing effect. Exploratory experiments also found that under certain conditions, after DC constant voltage electrolytic polishing with glucose NaOH solution, 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 DC pulse electrolytic polishing method to polish aluminum under alkaline conditions was discussed. The results show that the pulse electrolytic polishing method can achieve the leveling effect of DC constant voltage electrolytic polishing, but the leveling speed is relatively slow.

Aluminum and aluminum alloy environmentally friendly chemical polishing technology is determined to develop a new environmentally friendly chemical polishing technology based on phosphoric acid monosulfuric acid. This technology must achieve zero NOx emissions 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.

Therefore, we must first 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 a simple chemical polishing test in phosphoric acid-sulfuric acid, it can be considered that the special substances added to phosphoric acid-sulfuric acid should be able to inhibit pitting corrosion and slow down general corrosion, and must have better leveling and brightening effects. .

Electrochemical surface strengthening treatment of aluminum and its alloys. The process, properties, morphology, composition and structure of aluminum and its alloys forming ceramic amorphous composite conversion coatings through anodic oxidation and deposition in neutral systems are discussed. Membrane process and mechanism.