Passivators
We offer a range of passivation materials to meet the varying requirements of different galvanised products. Our passivation materials are classified into single component passivators and two component passivators. The brand name of our passivators is Guangdu. The characteristics and uses are as follows:
|
Single Action Passivators |
Double Action passivators |
|
Type |
Characteristic |
Type |
Characteristic |
|
GD-D101 |
Economic |
GD-D201 |
Economic |
|
GD-D102 |
Improved |
GD-D202 |
Improved |
|
GD-D103 |
High Strength |
GD-D203 |
High Strength |
|
GD-D104 |
Immersion |
GD-NZ201 |
Economic anti-fingerprint |
|
GD-D105 |
High-Temperature |
GD-NZ202 |
Improved Anti-fingerprint |
|
GD-D109 |
Inner Pipe |
GD-NZ203 |
High Strength Anti-fingerprint |
Passivators of the Single action series react chemically with the galvanised layer to improve the corrosion resistance of galvanizing layer. The double action series not only reacts chemically with the galvanised layer but also forms a film on it. The corrosion resistance of the double action passivators are much better than the single action types but are more expensive
Guangdu brand Single action passivators（GD-D101～103）
(1) Introduction
- Characteristics
The single action GD-D1XX passivator series is the newest passivator range developed by our company. The passivation layer of this product is colorless, bright and conveys excellent corrosion resistance. This material improves corrosion resistance by 8 to 20 times compared to the standard hexavalent chrome passivation
- Use
Used for passivation of all types of galvanized products. Efficiently prevents formation of both white rust and black spot on the product surface.
- Application
Spraying, immersion and rolling can be used to apply the passivator to the work. 。
- Types
- （GD-D101） Economic grade：Salt-spray test - 48 hours. Product stability in use is high but product brightness is not as good as with the other grades. GD-S100 Economic grade passivator is suitable for immersion application.
- （GD-D102）Normal grade：Salt-spray test - 60 hours. Stability is good and product brightness is good. The passivation film’s brightness is good and the stability is excellent. GD-D102 Normal grade passivator is suitable for both spray and immersion application.
- （GD-D103）High strength grade：Salt-spray test - 72 hours, the passivation film’s brightness is good and lasts. Stability is good and product brightness is good. GD-D102 high strength grade passivator is suitable for both spray and immersion application.
There are small differences in the quality of the three kinds of passivation Clients can select them according to the requirement of their product.
(2) Operating instructions
- Preparation ratio：one part of passivator to 12～17 parts of water
- Temperature range：5～45℃
- Process time：1～20 seconds
- To be mixed with soft or distilled water only. The conductance of the mixing water must be below 200μs/cm. Preferred passivator bath materials are stainless steel and glass fiber.
- When chromium concentration is reduced by one point, 8～10 Kg of reagent per tonnes of solution should be added.
- The pH value of solution should be between 2 and 3.5. If the pH value is near to 4, reagent or new solution must be added into the tank.
(3) Recommendations
- 1) Galvanized pipes are best passivated by spraying. This eliminates the need to discharge contaminated passivation material.
- Galvanized sheet should be passivated by roll coating. Immersion is a second choice.
- Before take-up, sheet must be hot air blow dried to assure good corrosion resistance. Suggested process temperature is 90-150℃ to achieve 50-80℃ on the sheet
- Customers should determine whether products for immersion coating require to be pre-washed.
- Determination of the chromium point: Place10 ml solution into a 250 ml conical flask. Add 100 ml de-ionized water. Add 10 ml of sulphuric acid (1:3) and three drops of N-phenylanthranilic acid indicator. Titrate with 0.1M Fe4SO4 standard solution until the purple color is replaced by green. 1 Ml of titrate = 1 unit of chrome
- Storage temperature: Above 0℃.
- Twenty-four hours after application, the coating will be completely reacted and have reached full corrosion resistance.
Guangdu Brand double action passivators(GD-D201～202)
1. Introduction
GD-D201~202 series are the latest fourth-generation passivation product developed by this company. It consists of two reagents-A&B. A is a brownish red liquid; B is a light green liquid. The mixed solution is a yellow liquid.
2. Characteristics:
This double action passivation material incorporates a special organic polymer along with a trivalent chromium product to provide excellent film forming and hardness. The treated product has an intense brightness and much better corrosion resistant property. The salt-spray test results are 10 - 30 times (170 hours) greater than for the traditional passivation material. It is environmental-friendly with little dross make in the use of this passivator.
3. Application
This product effectively prevents formation of white rust and macula. It is more efficient than competing products. Galvanized products that have been treated with this passivator can be painted, welded and withstand fingerprints.
4. Solution preparation
A:B=1:3; (A+B):H2O:1:4-6. Avoid mixing A and B directly. There are two methods to mix A&B:
Add A to water while stirring followed by B. (eg: for 400 Kg of passivator-- add 300 Kg of water into the tank. While stirring, add 25 kg of A followed by 75 Kg of B)
5. Coating procedures
Procedure 1: Temperature of the work—about 50℃. Spray the passivator on the work and then remove the excess passivator using air knife or compressed air wiping. This procedure eliminates need for a drier.
Procedure 2: Products - cold or cannot dry itself. Spray the passivator on the work and then remove the excess passivator with air knife or compressed air wiping then pass the product into a drier. Drier temperature ranges from 30 to 50℃.
6. Usage
Following is an example of a procedure for passivating pipe—0,2~0.3Kg passivator is used for one tonne passivated work.
7. Recommended ratio (The following table is only for your reference. Changes can be flexibly made according to local weather conditions)
|
ratio |
concentration of Cr6+ |
PH value |
Salt-spry test |
|
|
1：3：3 |
19~21 |
1.5 |
120h |
Used in summer |
|
1：3：4 |
16~18 |
1.8 |
96h |
Used in spring and autumn |
|
1：3：5 |
12~14 |
2.0 |
72h |
Used in Winter |
8. Precautions:
l Soft water or deionized water should be used for diluting the passivator. The electric conductivity of the water should be less than 200μs/cm.
l For an optimum passivation effect, the diluted solvent should be stilled for 24 hours before it is applied to the work.
l A non-reversible polymer is formed after the film is dried
l Solvent in the tank can be recycle
l The passivator must be stored at 0℃～40℃
9. Safety of this product：
l Spraying does not have generate liquid waste and there is no waste solution to be discharged.
l Most Cr6+ in the passivation has been transformed into Cr3+. The film on the product is innocuous.
l No direct discharge of the passivator. If it has to be discharged, it must comply with the environmental rules.
l The acid in this product is corrosive to the skin and Cr6+ is toxic. Safety equipment should be worn when handling. In the event of skin contact, wash it off immediately with clean water. I
l It is not volatile--No air pollution to the environment.
The measurement of concentration Cr6+
Put 10ml passivator liquid into the bottle of 250ml，and then put another 100ml pure water into the bottle ，1：3H2SO410ml，titrating 3 drops of 0.1% Phenylanthranilic acid into the bottle. Titrate 0.1N Ammonium ferrous sulfate solution to the bottle until the purple disappears and the green comes out. The value of the concentration of Cr6+ is milliliter consumption of the Ammonium ferrous sulfate solution.