| Chromate
Treatment Reagent
(Product No.: YC-09)
The reagent is used in the coating pretreatment (also
called chromate treatment) of aluminum workpiece. A
loose spontaneous oxide membrane will form on the surface
of aluminum and aluminum alloy materials in a natural
environment, and the membrane thickness is less than
0.05mm. Chromate treatment can reinforce the anticorrosion
ability of oxide membrane and the adhesion of oxide
membrane with coating layer, which helps the thickness,
density and adhesion of membrane to meet the criterion
of coating treatment.
1. Chemical Characteristic and Operation Principle:
1.1 A brown liquid, containing oxidant and activating
reagent, pH=1.8-1.9 (3% diluent)
1.2 At normal temperature, the reagent reacts fast with
aluminum on the surface, and a buff invert membrane
results. The invert membrane has a strong anticorrosion
ability, and it can react with paint or resin powder
to form a hard solid.
2. Process and Technical Parameters:
2.1 Process:
degreasing — water-washing — water washing
— chromate treatment — water-washing —
water-washing — dry — coating treatment
2.2 Technical Parameters:
Chromate reagent (YC-09): 3-4%
Temperature: 10-350C
Time: 1-3min
3. Maintenance of Trough Solution:
Under normal production conditions, the operation index
of trough solution is 6-9, and pH is 1.7-2.0 (pH can
be adjusted by using technical grade nitric acid).
YC-09 chromate treatment reagent is based on the invert
membrane treatment technology, which is very popular
home and abroad. The product is improved to coexist
with foreign ions to a great degree, and it is no need
to renew the trough solution within a year (even if
the trough solution has aged).
4. Note:
When the product is used, the facilities or locations
may be different. The following information may be helpful:
4.1 Water quality of trough setting: The water quality
is various in different locations, and the foreign substance
in the water may affect the use life of trough solution.
As for YC-09 chromate treatment reagent, pure water,
drinkable tap water or soft water must be used in trough
setting, and the water with high concentration of Mg2+
,Ca2+ cannot be used.
4.2 The over-input of other trough solution should be
avoided, especially when the section bars or workpieces
are treated with alkali reagent, they must be cleaned
completely by water-washing before chromate treatment.
4.3 The optimum operation temperature is 15-25?. When
the trough temperature is too low, the chromate treatment
rate is slow, while high temperature will cause the
trough solution to decompose, which results in a larger
consumption of chromate treatment reagent. The installation
of air stirrer or circulation device may result in a
better chromate treatment effect.
5. Environment Protection:
During production, an ounce of YC-09 chromate treatment
reagent may be discharged along with washing water.
Therefore, when the chromate treatment is finished,
the waste water from the two water-washing troughs should
be reduced with FeSO4 first, and then discharged into
the waste water treatment station for final treatment.
6. Analysis Method:
Determination of pH: pH value is determined with calibrated
pH meter.
Determination of operation points: Add 5ml of test solution
to a 250ml volumetric flask, and add 100ml of water,
then add 3g of KI and rock the flask to make the KI
dissolve completely. Add 10ml of hydrochloric acid twice
(along the inner wall), and wash the wall with water,
then put on the lid and leave it for one minute, and
then titrate the solution with 0.1N Na2S2O3 standard
solution till the yellow color appears. Add 3-5ml of
fresh starch as indicator, and continue to titrate the
solution till the blue color disappears.
Calculation: operation points of trough solution=10NNa2S2O3VNa2S2O3
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