Zinc-series phosphate coating agent as metal treatment Chemicals

1)Little-sediment. 2)Using at low-temperature. 3)Filming fast. 4)Parkerising film is thin and firm, dense and uniform.

1. Overview

PB-95 phosphate coating agent assigned two kinds of PB-95A for preparation and PB-95B for adding, which is little-sediment low-temperature phosphating agent for surface phosphating of iron and steel parts, cold-rolled sheet. There are some advantages, such as low-temperature, fast filming, little sediment, light pollution. Phosphate coating is thin and firm, dense and uniform, and nuclei is small. The product is suitable for large-scale spraying line or the combination of spraying and dipping with strong processing capability. It is the representative product of high-quality products bonderite developed by our company.

2. Using method

2.1 Tank liquor preparation (1 ton)

a. Reagent of tank

PB-95A zinc-series phosphate coating agent

PB-95B zinc-series phosphate coating agent

NT-125 neutralizer

AC-130 accelerator

b. First, add water to sink with 50 % of the capacity of sink. Second, 50 kg PB-95A was added to the sink. Third, 5.0 kg NT-125 neutralizer was dissolved in a small amount of water, and then add slowly to sink and stirring until flocculent precipitate was completely dissolved. Finally, add margin water, and stir evenly. Confirm process indicators.

Before using heated to processing temperature, add 1.3 kg AC-130 accelerator, and stir evenly.

2.2 Tank liquid management

Total acidity: 20 to 40

Free acid: 0.9 to 2.0

Accelerator: 4.0 to 6.0

Temperature: Dipping: 15 to 45 degrees 

                       Spraying: 30 to 45 degrees

Time: Dipping: 15 to 25 minutes       

           Spraying: 1 to 3 minutes

Spraying pressure: 0.6 to 1.0 kg/cm2.

3. Detection and analysis

3.1 Total acidity (points)(TA)

Pipet 10 ml tank fluid to the conical flask, and add 3 to 5 drops of phenolphthalein indicator. Titrate 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 as the points of total acidity.

3.2 Free acidity (points)(FA)

Pipet 10 ml tank fluid to the conical flask, and add 2 to 4 drops of bromophenol blue indicator. Titrate 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 as the points of free acidity.

 3.3 Accelerator (AC) detection

Take a certain amount of tank liquid to the fermentation tube, and putting 2 to 3 grams amino acid. A few minutes later, observing the amount of gases.

4. Supplement and adjustment of solution (1 ton)

4.1 After using a period of time, phosphating working liquid will lose activity. When the points of total acidity below 20 points, PB-95B should be added. 1.9 kg PB-95B can increase one point of total acidity. If the water level of tank dropped, water should be added to 1 ton. At this time total acidity below 20 points, PB-95A should be added, and 1.8 kg PB-95A can improve one point of total acidity.

4.2 When working liquid temperature was too low, or PB-95B was added not enough, the points of free acidity may reduce to less than 0.9. 1.1 kg PB-95B can increase free acidity of 0.1 points.

4.3 Even if the working liquid wasn’t used, accelerator was aslo gradually broke down. So before using the points of accelerator must be re-measured and added. Accelerator of 0.4 kg can increase accelerator of 1 point.

5. Notes

5.1 Degreasing and rust cleaning must be completely thorough. If phosphate film is not an ideal addition, the workpiece can be immersed in pickling bath to remove the film (must be remove completely), and then be re-phosphided.

5.2 After water rinsing process workpieces can’t be maintained too long time in the air to prevent rust, the water of washing tank should flow in order to ensure the quality of water.

5.3 Test TA and FA twice one day. Accelerator is consumed quickly, usually test it twice one day.

5.4 Phosphating workpieces should be stoved at 100 to 150 degrees after water rinsing process, can increase erosion resistance. Natural-drying isn’t a good method.

5.5 Copper sulfate spot test should be done after the workpiece was naturally dried and 12 hours after film was fully grown. Corrosion time is greater than 30 seconds.

Zinc-series phosphate coating agent as metal treatment Chemicals