Zinc Phosphate Pre-Treatment

Technical Data Sheet

Gardobond® Z 3400

Zinc phosphate pre-treatment

Scope

Gardobond Z 3400 is a phosphating process on the basis of zinc phosphate for iron materials and serves as a pre-treatment prior to cold forming. It is particularly suited for tube drawing.

Gardobond Z 3400 is applied by immersion.

The weight of the phosphate coating amounts to 1 - 6 g/m².

Physical propertiesGardobond Gardobond Gardobond

Z 3400 A Z 3400 E Z 3400 E1

Appearance:...colourless liquidcolourless liquidcolourless liquid

Density (20ºC):..1,55 g/cm³.1,55 g/cm³.1,45 g/cm³

pH value (concentrate, 20ºC):<1..<1..<1

pH value (75 g/l, 20ºC):.1,8..n/a..n/a

Flash point (DIN 51755 / 53213):non-flammablenon-flammablenon-flammable

Other chemicals required

Gardobond-Additive H 7004 (accelerator)

Gardobond-Additive H 7030 (18% hydrogen peroxide solution)

Gardobond-Additive H 7141 (neutralising agent)

Process sequence

Cleaning (if necessary) rinsing (if cleaning must be done) pickling rinsing prerinsing phosphating rinsing neutralizing after-treatment (depending on the type of cold forming) drying (if necessary)

Bath make-up

For 1000 litres of phosphating solution, add:

Variant 1 / Variant 2
Gardobond Z 3400 A / 50 litres (80 kg) / 53 litres (85 kg)
Gardobond-Additive H 7004 / 0.6 litres (0,8 kg) / 1.3 litres (1,5 kg)
Gardobond-Additive H 7141 / - / 1,6 litre (2,2 kg)

[cont]

A company of mg chemical group Dynamit Nobel

Gardobond Z 3400

[Bath make-up – cont]

Immediately before the first throughput of material through Gardobond Z 3400 variants 1 and 2 add Gardobond-Additive H 7004; for Gardobond Z 3400 variant 3 add Gardobond-Additive H 7138, diluted in 10 times the amount of water.

Phosphating solutions made-up according to specification correspond to the following concentrations:

Gardobond Z 3400 variant 1:28 total acid points8 accelerator points

Gardobond Z 3400 variant 2:28 total acid points15 accelerator points

These are the normal make-up strengths. The Chemetall Field Support Engineer can recommend the precise conditions for any given installation.

Bath operation

Variant 1 / Variant 2
Immersion time (minutes) / 3 … 10 / 3 … 10
Temperature / 50 … 60ºC / 30 … 40ºC
Total acid points / 22 … 33 / 23 … 33
Accelerator points / 3 … 10 / 10 … 20

Bath control

Testing chemicals required

Indicator Solution #1 (phenolphthalein)

Testing Powder #18 (urea)

Testing Solution #1 (0.1N sodium hydroxide)

Testing Solution #6 (0.1N potassium permanganate)

Testing Solution #14 (50% sulfuric acid)

Testing Solution #44 (30% potassium oxalate)

5% disodium hydrogen phosphate solution

The concentration is controlled by determining the total acid points, the phosphate points and the accelerator points.

If necessary the total acid points HEHN are determined.

Fill the tank with water to operating level and stir thoroughly.

Total acid points

Pipette 10 ml of phosphating solution into an Erlenmeyer flask. Dilute with approximately 50ml of distilled water and add 10 drops of Indicator Solution #1. Titrate with Testing Solution #1 until the colour changes to pink.

The ml of Testing Solution #1 consumed indicate the total acid points.

Total acid points HEHN

Pipette 10 ml of bath solution into an Erlenmeyer flask, add approx. 20 ml of a 5 % disodium hydrogen phosphate solution and approx. 50 ml of water as well as 10 - 15 drops of Indicator Solution #1, titrate with Testing Solution #1 until the colour of the solution changes to pink.

The ml of Testing Solution #1 consumed indicate the total acid points HEHN.

[cont]

[Bath control – cont]

Phosphate points

The determination of phosphate points allows an exact control of the bath composition. The frequency of the control of the phosphate points will be determined by the Field Support Engineer upon startup. Prior to the determination of the phosphate points replenish the total acid points to nominal value.

Pipette 10 ml of bath solution into an Erlenmeyer flask, add 20 ml of Testing Solution 44 and 10 - 15 drops of Indicator Solution #1, titrate with Testing Solution #1 until the colour of the solution changes to red.

The ml of Testing Solution #1 consumed indicate the phosphate points.

Accelerator points

The accelerator points should be determined several times a day and at least prior to startup and following interruptions of the process.

Pipette 100 ml of bath solution into an Erlenmeyer flask, add 20 drops of Testing Solution #14 and titrate with Testing Solution #6 until a faint red colour persists for about 20 seconds.

The amount of ml of Testing Solution #6 consumed indicates the consumption "A".

Pipette 100 ml of bath solution into an Erlenmeyer flask, add 20 drops of Testing Solution #14 as well as 2 g of Testing Powder #18 and let it rest for approx. 3 minutes. Titrate with Testing Solution #6 until a faintly red colour persists for about 20 seconds.

The amount of ml of Testing Solution #6 consumed indicates the iron points.

Titration "A" - iron points = accelerator points

Replenishment

Total acid points

The total acid points is maintained by adding Gardobond Z 3400 E or Gardobond Z3400E1. The optimum replenisher solution will be determined by the Field Support Engineer.

For each total acid point consumed add, per 1000 litres of phosphating solution:

1.0 litres (1,7 kg) Gardobond Z 3400 E, or

0.85 litres (1.38kg) Gardobond Z 3400 E1.

Accelerator point

The accelerator points are maintained by replenishing the bath solution with Gardobond-Additive H 7004 in the case of Gardobond Z 3400 variants 1 and 2.

For each accelerator point consumed add 0,07 litres (0,08 kg) of Gardobond-Additive H 7004 in the case of Gardobond Z 3400 variants 1 and 2 per 1000 litres of phosphating solution.

Phosphate points

In order to obtain the correct titration ratio for the bath replenishment, divide the total acid points by the phosphate points.

[cont]

[Replenishment – cont]

If the titration ratio is between 1.4 and 2.8 replenish with Gardobond Z 3400 E or Gardobond Z 3400E1.

If the titration ratio is below 1.4 replenish with Gardobond Z 3400 A.

For each total acid point add 1.6 litres (2.6 kg) Gardobond Z 3400 A per 1000 litres of bath solution.

If the titration ratio is above 2.8 replenish with Gardobond Z 3400 E or Gardobond Z3400E1; in this case please contact our Technical Service.

Iron content

If more than 0.5 iron points are titrated or if the amount of iron points is about equal to the consumption A, the bath solution has absorbed iron which has to be eliminated with the addition of Gardobond-Additive H 7030 diluted in 10 times the amount of water.

Then the bath has to stand at operating temperature for 2 - 3 hours without throughput of material. After this add anhydrous sodium carbonate according to the following table and diluted in a 10 % aqueous solution:

For 1000 litres of bath solution
Iron points / Iron (II) content / g/l / Gardobond-Additive H7030 / litres / sodium carbonate/ kg
1 / 0.056 / 0.091 / 0.053
2 / 0.112 / 0.182 / 0.106
3 / 0.168 / 0.274 / 0.159
4 / 0.224 / 0.365 / 0.212
5 / 0.280 / 0.456 / 0.265
10 / 0.560 / 0.912 / 0.530
20 / 1.120 / 1.824 / 1.060
30 / 1.680 / 2.735 / 1.590
40 / 2.240 / 3.647 / 2.120
over 40 / over 2.240 / new bath makeup necessary

Desludging of the bath may become necessary after iron precipitation.

Prior to further operation, the total acid points and the accelerator points should be determined and replenished up to their nominal value.

Desludging

We recommend to remove the sludge accumulating during phosphating by means of a filter. To this effect the tank bottom has to be equipped with pointed cones.

If not, the sludge must be removed from time to time. To this effect fill the phosphating solution into a settling tank or pump the solution above the sludge into a rinsing or reserve tank.

After returning the clear solution fill the tank with water to operating level and stir thoroughly. Then titrate the total acid points and replenish to their nominal value.

Bath replenishment after desludging

For each total acid point consumed add 1.6 litres (2.6 kg) Gardobond Z 3400 A per 1000litres of bath solution.

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Gardobond Z 3400

Equipment materials

Tank

Chromium nickel steel, material No. 1.4541

Chromium nickel molybdenum steel, material No. 1.4571

Generalpurpose constructional steels to DIN EN 10025, with rubber lining

Generalpurpose constructional steels to DIN EN 10025, lap-welded, limited suitability

Heating element

Chromium nickel molybdenum steel, material No. 1.4571

Watercooling jacket

Fluorocarbon resins

General information

Chemetall supplies a wide range of chemical products and associated equipment for cleaning, sanitising, descaling, paint and carbon removal, metal protection and forming, paint denaturing and non-destructive testing. Field Support Engineers are available to advise on specific problems and applications.

Chemetall also supplies products within the glass, polymer, fine chemical and aerospace fields.

Safety and handling guidance

Before using the product it is important that this complete document, together with any relevant safety data sheet(s), have been read and understood. The safety data sheet(s) will advise on all precautions, safety equipment and procedures necessary in the safe use and disposal of the product.

Environmental guidance

All local and national regulations on the transport, storage, use and waste treatment of chemicals in concentrated or diluted form, or as working solutions, plus any by-products and contamination occurring as part of the process, must be obeyed.

All waste waters must be treated in accordance with national legislation and local regulations prior to discharge to the sewer.

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The above data have been compiled to the best of our knowledge on the basis of thorough tests and with regard to the current state of our long practical experience. No liabilities or guarantee deriving from or in connection with this leaflet can be imputed to us. Reproduction, in whole or in part, only with our express permission. / Chemetall PLC
Denbigh Road, Bletchley, Milton Keynes MK1 1PB
Tel: (01908) 649333 • Fax: (01908) 373939
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Gardobond Z 3400

LC Juni 2002