Acid Corrosive

Acid corrosive can be used in the surface treatment of aluminum alloy. The technology was introduced from aluminum surface processing technology in Japan, and later on, it was put into practice and improved by and by. Now it yields good results.

1. Characteristic:
1.1 The operation is simple and safe. The trough liquid has a good stability and long service longevity.
1.2 The components are unique. And the operation conditions are flexible and controllable.
1.3 The corrosion is even, and the amount of dissolved aluminum is low. The aluminum consumption for one ton of aluminum items is less than 8kg (about one fourth of the aluminum consumption of alkali corrosion), thus the production cost is reduced.

2. Technical Parameters and Operation Conditions:
2.1 Process and Solution Composition
Degreasing— water-washing — acid corrosion — water-washing — alkali corrosion— water-washing — neutralization — water-washing — oxidation
Ammonium acid fluoride: 50-60g/1
Accelerant: 40-50g/1
Stabilizer: 60-70g/1
Operation temperature: 40-45⁰C
Treatment time: about 4-6min (the treatment time can be changed when needed)
Fixed work points: 6.5-8.5

Due to that there will exist the floating matters and deposits during the production process, it is required that the following ancillary facilities should be set and the sketch map is as follows:

2.3 Trough Liquid Maintenance:
2.3.1 Control the operation points to be between 6.5-8.0 according to the analysis result. Add 4-6kg of stabilizer and 2-4kg of accelerant accordingly while adding ammonium acid fluoride.
2.3.2 For each production batch under normal conditions, add ammonium acid fluoride, stabilizer and accelerant for at least two times.
2.3.3 Keep the suspension in acid corrosion trough to the least degree, and control the operation temperature according to the technical requirements.

3. Related Products:
For convenience, stabilizer and accelerant are packed in a mixed way, and the product No. is (F200-1).

3.1 Technical Parameters:
Ammonium acid fluoride: 55-65g/1
F200-1 acid corrosive: 65-75g/1
Intermediate: 1g/1
Operation temperature: 40-45⁰C
Treatment time: about 4-6min
Fixed work points: 6.5-8.0

3.2 Production Consumption: 3-3.5kg of acid corrosive is consumed to produce one ton of section bars, or add 8-12kg of acid corrosive when 100kg ammonium acid fluoride is consumed. The operation points can be determined according to the method for the first type of products.

4. Analysis Method:
Add 10ml of trough liquid to a 250ml conical flask, and add 50-100ml of pure water. Rock the conical flask and make them mix evenly. Then drip 3-4 drops of phenolphthalein, and then titrate the trough liquid with 1N NaOH standard solution till the end point (when the solution turns pink).
Calculation of operation points: N_NaOH V_NaOH

5. Suggestions for Requirement of Environment Protection: (Waste Water Treatment)
The waste water contains fluorine ions when ammonium acid fluoride is used in the aluminum surface treatment process. Therefore, the fluorine ions should be treated in the waste water treatment. The suggestions are as follows:

5.1 The waste water is discharged into the neutralization tank. pH value is adjusted at 3-4 with NaOH and then adjusted at 7-8 with CaO.
5.2 The waste water is drawn to the higher tank, and polyacrylamide diluent (about 20-30g polyacrylamide/m3) is added.
5.3 The sedimentation at the bottom of sedimentation tank is separated from water by percolator, and the sedimentation is packed in a bag, and the water is discharged into the neutralization tank.
5.4 Users can treat the waste water according to the company’s criterion, and discharge the waste water when it meets the related contamination-discharging criterion of the country.