Metal surface treatment is inevitably oxidized during various heat treatment, machining, transportation and storage processes to produce a thick and uneven oxide layer. At the same time, it is also susceptible to various oil pollution and adsorption of some other impurities.
Metal surface treatment is inevitably oxidized during various heat treatment, machining, transportation and storage processes to produce a thick and uneven oxide layer. At the same time, it is also susceptible to various oil pollution and adsorption of some other impurities. For oil stains and certain adsorbates, the thinner oxide layer can be washed with solvent, chemically and mechanically, or directly with chemical treatment. For the surface treatment of severely oxidized metals, if the oxide layer is thick, it cannot be directly washed with solvents and chemically treated, and it is preferable to carry out mechanical treatment first.
The surface which is usually treated with a metal surface is highly active and is more susceptible to contamination by dust, moisture, and the like. For this reason, the metal surface treatment should be glued as quickly as possible.
The metal storage period after different treatments is as follows:
(1) wet sandblasted 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) blasted steel, 4h;
(6) Brass treated by wet blasting, 8h.
1. Aluminum and aluminum alloy are surface treatment solutions
[plan 1]
Degreaser treatment. Wipe with a damp cotton dampening solvent to remove the oil, then wipe it with a clean cotton cloth several times. Commonly used solvents are: trichloroethylene, ethyl acetate, acetone, methyl ethyl ketone and gasoline.
[Scenario 2]
After degreasing, chemically treat in the following solutions:
Concentrated sulfuric acid 27.3 potassium dichromate 7.5 water 65.2
After immersion at 60-65 ° C for 10-30 min, remove it with water, dry it or dry it below 80 ° C; or wash it in the following solution and then dry it:
Phosphoric acid 10 n-butanol 3 water 20
This method is suitable for phenolic-nylon glue and the like, and the effect is good.
[Scheme 3]
After degreasing, chemically treat in the following solutions:
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
It is immersed at 25-40 ° C for 4.5-6 min, that is, washed with water and dried. The method has high bonding strength and is glued within 4 hours after treatment, and is suitable for epoxy glue and epoxy-butyronitrile glue.
[Scheme 4]
After degreasing, chemically treat in the following solutions:
Phosphoric acid 7.5 chromium oxide 7.5 alcohol 5.0 formaldehyde (36-38%) 80
Immerse at 15-30 ° C for 10-15 min, then wash at 60-80 ° C, and dry.
[Scheme 5]
After degreasing, anodizing in the following solution:
Concentrated sulfuric acid 22g/l
The mixture was immersed for 10-15 min under a direct current intensity of 1-1.5 A/dm 2 , and further immersed in a saturated potassium dichromate solution at 95-100 ° C for 5-20 min, then washed with water and dried.
[Scheme 6]
After degreasing, chemically treat in the following solutions:
Potassium dichromate 66 sulfuric acid (96%) 666 water 1000
It was immersed at 70 ° C for 10 min, then washed with water and dried.
[Scheme 7]
After degreasing, chemically treat in the following solutions:
Nitric acid (d=1.41) 3 hydrofluoric acid (42%) 1
After immersing for 3 s at 20 ° C, it was washed with cold water, washed with hot water at 65 ° C, rinsed with distilled water, and dried. This method is suitable for cast aluminum alloys with higher copper content.
[Scheme 8]
After sandblasting or sanding, anodize in the following solution:
Chromium oxide 100 sulfuric acid 0.2 sodium chloride 0.2
Increase the voltage from 0V to 10V in 10min at 40 °C for 20min, then increase from 10V to 50V in 5min for 5min
, then washed with water and dried at 700C. Note: The free chromium oxide concentration should not exceed 30-35g/l.
[Scheme 9]
After degreasing, chemically treat in the following solutions:
Sodium silicate 10 non-ionic detergent 0.1
It was immersed at 65 ° C for 5 min, then washed at 65 ° C or lower, washed with distilled water and dried. Suitable for bonding aluminum foil.
[Scheme 10]
After degreasing, chemical treatment in the following solutions:
Sodium fluoride 1 concentrated nitric acid 15 water 84
Immerse for 1 min at room temperature, wash with water and then treat in the following solution:
Concentrated sulfuric acid 30 dichromate sodium 7.5 water 62.5
It was immersed for 1 min at room temperature, washed with water and dried.
Second, magnesium and magnesium metal surface treatment program
[plan 1]
Degreasing treatment. Commonly used solvents are: trichloroethylene, acetone, ethyl acetate and methyl ethyl ketone.
[Scenario 2]
After degreasing, immerse in the following solution at 70-75 ° C for 5 min:
Sodium hydroxide 12 water 100
Rinse with cold water and immerse in the following solution at 20 ° C for 5 min:
Chromium oxide 10 water 100 anhydrous sodium sulfate 2.8
Rinse with cold water, wash with distilled water, and dry at 40 °C.
[Scheme 3]
After degreasing, it was immersed in a 6.3% sodium hydroxide solution at 70 ° C for 10 min, washed with water, and then immersed in the following solution at 55 ° C for 5 min: chromium oxide 13.8 calcium sulfate 1.2 water 85
Wash with distilled water and immerse for 3 min at 55 ° C in the following solution
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