Simple process, no need to adjust the surface. Filming fast. Phosphate coating is thin.
1. Process flow
1.1 Degreasing(alkaline) → Water Rinsing → Rust Cleaning → Phosphating → Water Rinsing → Drying
1.2 Degreasing(acid) → Rust Cleaning → Water Rinsing → Phosphating → Water Rinsing → Drying
1.3 Grease and Rust Cleaning → Water Rinsing → Phosphating → Water Rinsing → Drying
2. Solution preparation (1 ton)
The weight ratio of phosphate coating agent and water is 1 : 9, that means there are phosphating solution of 100 kg and water of 900 kg in working solution of 1 ton. The pH of working fluid is 3 to 4.
3. Performance indicators
Code number | Items | Indicators |
1 | Processing Mode | Dipping or Spraying |
2 | the Weight of Phosphate Coating | 1 to 2 vm |
3 | the Scope of total acid (TA) | 25 to 50 |
4 | the Scope of free acid (FA) | 1 to 3 |
5 | Temperature | Dipping: Room Temperature Spraying: 20 to 45 degrees |
6 | Time | Dipping: 5 to 15 min Spraying: 2 to 3 min |
7 | Coating Adhesion (level) | 0 |
8 | Wearing Quality 3 % NaCl (H) | > 1 |
9 | The handling capacity of concentrated phosphating liquid (m*m/kg ) | > 80 |
4. Detection method
4.1 Total acidity (points)
Taking 10 ml working fluid to the conical flask, and adding phenolphthalein indicator of 3 to 5 drops. Titrating above-mentioned solution by 0.1 M sodium hydroxide standard solution from colorless to red. The quantity (ml) of 0.1 M sodium hydroxide standard solution is called the points of total acidity.
4.2 Free acidity (points)
Taking 10 ml working fluid to the conical flask, and adding bromophenol blue indicator of 2 to 4 drops. Titrating above-mentioned solution by 0.1 M sodium hydroxide standard solution from yellow to blue. The quantity (ml) of 0.1 M sodium hydroxide standard solution is called the points of free acidity.
5. Additions and adjustments (1 ton)
After using a period of time, phosphating working solution will lose activity. When total acidity is normal, but free acidity is too low, phosphate coating agent can be added.
Theoretical calculations: Adding phosphate coating agent of 5 kg can improve one point of the points of free acidity, and 4.2 kg can improve a total acid points.
steel phosphate coating
