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Do the structural design, the work will certainly encounter aluminum die-casting process, the following is the aluminum die-casting parts of the surface treatment method summary

One, aluminum phosphating

Accelerators, fluoride, Mn2+, Ni2+, Zn2+, PO4 were studied in detail by means of SEM, XRD, potential time curve, membrane weight change, etc. And Fe2+ on the phosphating process of aluminum. The results show that guanidine nitrate is characterized by good water solubility, low dosage and rapid film formation, and is an effective accelerator and fluoride for phosphating aluminum, which can promote film formation, increase film weight and refine grain. Mn2+ and Ni2+ can obviously refine grain, make phosphating film uniform and compact, and improve the appearance of phosphating film. When the concentration of Zn2+ is low, the film cannot be formed or the film is poor. With the increase of Zn2+ concentration, the increase of O4 content in the film weight has a great influence on the phosphating film weight, while the increase of PO4 content increases the phosphating film weight.

Second, the alkaline electrolytic polishing process of aluminum

The alkaline polishing solution system was studied, and the influence of corrosion inhibitor and viscosity agent on the polishing effect was compared, and the alkaline solution system with good polishing effect was obtained successfully, and the additives that could reduce the operating temperature, prolong the service life of the solution and improve the polishing effect were obtained for the first time. The experimental results show that adding proper additives to NaOH solution can produce good polishing effect. The exploratory experiment also found that the surface reflectivity of aluminum can reach 90% after using NaOH solution with glucose under certain conditions, but due to the unstable factors in the experiment, further study is needed. The feasibility of using DC pulse electropolishing method to polish aluminum under alkaline condition was explored. The results show that the pulse electropolishing method can achieve the leveling effect of DC constant pressure electropolishing, but the leveling speed is slow.

Environmental protection chemical polishing of aluminum and aluminum alloy

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 the quality defects existing in previous similar technologies. The key to the new technique is to replace nitric acid with specific compounds in the base solution. Therefore, it is necessary to analyze the triacidizing polishing process of aluminum, especially to study the role of nitric acid. The main function of nitric acid in chemical polishing of aluminum is to inhibit point corrosion and improve the brightness of polishing. Combined with the chemical polishing test in simple phosphoric acid monosulfuric acid, it is considered that the special substances added in phosphoric acid monosulfuric acid should be able to inhibit the point corrosion, slow down the overall corrosion, and at the same time have a good leveling and shining effect.

Electrochemical surface strengthening treatment of aluminum and its alloys

The process, properties, morphology, composition and structure of ceramic amorphous composite conversion film formed by anodic oxidation of aluminum and its alloy in neutral system were discussed. The results showed that in Na_2WO_4 neutral mixed system, the concentration of controlled film forming accelerator was 2.5-3.0g/L, the concentration of complexing film forming agent was 1.5-3.0g/L, the concentration of Na_2WO_4 was 0.5-0.8g/L, the peak current density was 6-12a/DM ~2, and the gray inorganic non-metallic film with good luster could be obtained by weak stirring. The thickness of the film is 5 ~ 10 m, the microhardness is 300 ~ 540HV, and the corrosion resistance is excellent. The neutral system has good adaptability to aluminum alloy, and can form film well on various series of aluminum alloy, such as antirust aluminum, forging aluminum, etc.

V. Surface oxidation treatment technology of YL112 aluminum alloy

Yl112 aluminum alloy is widely used in automobile and motorcycle structural parts.

Metal surface in various heat treatment, mechanical processing, transportation and storage process, will inevitably be oxidized, resulting in a layer of uneven thickness of the oxide layer. At the same time, it is also prone to various oil pollution and adsorption of some other impurities.

For oil and some adsorbents, the thinner oxide layer may be cleaned by solvent, chemically treated, mechanically treated, or chemically treated directly. For heavily oxidized metal surface, the oxidation layer is thicker, can not be cleaned directly with solvent and chemical treatment, but the best mechanical treatment.

Usually treated metal surfaces are highly reactive and are more prone to re-contamination by dust, moisture, etc. Therefore, the treated metal surface should be bonded as quickly as possible.

The metal storage period after different treatments is as follows:

(1) Wet sandblasting aluminum alloy, 72h;

(2) Chromic acid-sulfuric acid treated aluminum alloy, 6h;

(3) Anodized aluminum alloy, 30 days;

(4) Sulfuric acid treated stainless steel, 20 days;

(5) Sandblasted steel, 4h;

(6) Wet-sandblasted brass, 8h.

Vi. Surface treatment methods for aluminum and aluminum alloys

(Method 1)

Degreasing treatment. Wipe with absorbent cotton wet solvent, remove grease, and then wipe with clean cotton cloth for several times. Common solvents are trichloroethylene, ethyl acetate, acetone, butanone and gasoline, etc.

(Method 2)

After degreasing, chemical treatment in the following solution:

Concentrated sulfuric acid 27.3 potassium dichromate 7.5 water 65.2

Soak for 10-30min at 60-65°C, then rinse with water, dry or dry below 80°C; Or wash in the following solution before drying:

Phosphate 10 n-butanol 3 water 20

This method is suitable for phenolic aldehyde - nylon rubber, etc

(Method 3)

After degrease, it is chemically treated in the following solution: ammonium hydrogen fluoride 3-3.5 chromium oxide 20-26 sodium phosphate 2-2.5 concentrated sulfuric acid 50-60 boric acid 0.4-0.6 water 1000

Soak for 4.5-6min at 25-40°C, then wash and dry. This method has high adhesive strength and is suitable for epoxy adhesive and epoxy-Butyl adhesive within 4h after treatment.

(Method 4)

After degreasing, chemical treatment in the following solution:

Phosphoric acid 7.5 chromium oxide 7.5 alcohol 5.0 formaldehyde (36-38%) 80

Soak at 15-30°C for 10-15min, then wash and dry at 60-80°C.

(Method 5)

After degreasing, anodized in the following solution:

Sulfuric acid 22 g/l

Macerate at dc strength of 1-1.5A/dm2 for 10-15min, then macerate in saturated potassium dichromic solution at 95-100°C for 5-20min, then wash and dry.

(Method 6)

After degreasing, chemical treatment in the following solution:

Potassium dichromate 66 sulfuric acid (96%) 666 water 1000, soak at 70°C for 10min, then wash and dry.

(Method 7)

After degreasing, chemical treatment in the following solution:

Nitric acid (D =1.41) 3 hydrofluoric acid (42%) 1

Soak 3s at 20°C, rinse with cold water, then wash with hot water at 65°C, rinse with distilled water, and dry. This method is suitable for casting aluminum alloy with high copper content.

(Method 8)

After sand blasting or grinding, positive polarization in the following solutions:

Chromium oxide 100 sulfate, 0.2 sodium chloride, 0.2

The voltage was raised from 0V to 10V within 10min at 40°C and kept for 20min. The voltage was raised from 10V to 50V within 5min and kept for 5min. Then the water was washed and dried under 700C. Note: the concentration of free chromium oxide should not exceed 30-35g/ L.

(Method 9)

After degreasing, chemical treatment in the following solution:

Sodium silicate 10 non - ionic detergent 0.1

Soak for 5min at 65°C, then wash with water below 65°C, then wash and dry with distilled water. Suitable for adhesive bonding of aluminum foil.

(Method 10)

After degreasing, it is chemically treated in the following solution:

Sodium fluoride 1 concentrated nitric acid 15 water 84

Soak it at room temperature for 1min, then rinse it and treat it in the following solution:

Concentrated sulfuric acid 30 sodium dichromate 7.5 water 62.5

Soak for 1min at room temperature, wash and dry.

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