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Five Kinds Of Commonly Used Aluminum Alloy Die Castings Surface Treatment Process
- Mar 20, 2018 -

Aluminum alloy die-casting products mainly used in electronics, automobile, motor, household appliances and some of the communication industry, etc., some of the high performance, high precision, high toughness quality products has also been used to requiring large planes, ships and other industries, the five kinds of commonly used technology for surface treatment of aluminum die casting.

1. Aluminum phosphating

The accelerant, fluoride, Mn2+,Ni2+,Zn2+ and PO4 were studied in detail by using SEM,XRD, potential time curve and membrane weight change. The effect of Fe2+ on aluminum phosphating process. The study shows that guanidine has the characteristics of good water solubility, low dosage and rapid film forming. It is an effective promoter of aluminum phosphating: fluoride can promote film, increase membrane weight and refine grain. Mn2+,Ni2+ can obviously refine grain, so that the phosphating membrane is uniform, dense and can improve the appearance of phosphating film. When the concentration of Zn2+ was low, it could not become film or film difference. As the concentration of Zn2+ increased, the aluminum alloy profiles increased. PO4 content has great influence on the phosphating film, and PO4 is improved. The content increased the phosphating film.

2. Basic electrolytic polishing process of aluminum

The alkaline polishing solution study, compared the corrosion inhibitor, viscosity agent on the polishing effect, successfully obtained the polishing effect is very good system of alkaline solution, and got to reduce the operating temperature for the first time, lengthen the service life of the solution, but also can improve the polishing effect of additives. The results showed that adding appropriate additives to NaOH solution produced good polishing effect. Exploratory experiment also found that: with NaOH solution under certain conditions of glucose after dc constant voltage electrolytic polishing, aluminum surface reflectance can reach 90%, but as a result of the experiment also exists instability, needs further research. Explores the dc pulse electrochemical polishing method, the feasibility of polished aluminium in alkaline conditions, the results show that the pulse electrochemical polishing method can achieve dc constant voltage electrolysis polishing leveling effect, but the leveling speed slower.

3. Environment-friendly chemical polishing of aluminum and aluminum alloy profiles

The new technology of environmentally friendly chemical polishing with phosphoric acid as base solution is determined to realize zero emission of NOx and overcome the quality defect of similar technology in the past. The key to the new technology is to replace nitric acid with compounds that have special effects in the base solution. For this reason, it is necessary to analyze the polishing process of aluminum triacylation, especially the role of nitric acid. The main effect of nitric acid in aluminum chemical polishing is to restrain the corrosion and improve the polishing brightness. In pure chemical polishing experiments in a sulfuric acid, phosphate think add special material should be in a sulfuric acid phosphate can inhibit corrosion, reduce total corrosion, and must have a better effect on the whole peaceful and bright

4. Electrochemical surface hardening treatment of aluminum and its alloys

Aluminum and its alloy anodic oxidation deposit formed in neutral system class ceramic conversion of amorphous composite membrane process, properties, morphology, composition and structure, preliminary discussion on the film-forming process and the mechanism of the film. Technology research results show that in Na_2WO_4 neutral mixed system, control film promoter concentration is 2.5 ~ 3.0 g/l, complexing film-former concentration is 1.5 ~ 3.0 g/l, Na_2WO_4 concentration is 0.5 ~ 0.8 g/l, the peak current density for 6 ~ 12 a/dm ~ 2, weak stirring, uniform and can get a complete, good gloss gray series of inorganic non metal film layer. The thickness of the film is 5 ~ 10 mu m, the microhardness is 300 ~ 540HV, and the corrosion resistance is excellent. The neutral system has a good adaptability to aluminum alloy profiles, and can be well formed in aluminum, aluminum, wrought aluminum and other series of aluminum alloy profiles.

5. Surface treatment technology of aluminum alloy castings

Aluminum alloy castings are widely used in automobile and motorcycle structural parts. The material needs surface treatment before application to improve its corrosion resistance and form a surface layer that is easy to combine with organic coating to facilitate the subsequent surface.