Foshan Dechenghezhong Chemistry co.,LTD
No,12 Yuyang 2nd Road, Huchong Industrial District, Nanzhuang Town,
Chancheng District, Foshan City, Guangdong, China
Tel:0086-757-82012410
Fax:0086-757-82012430
Website:http://dchz.en.alibaba.com
E-mail:fsdchz@outlook.com
DCHZ-404 Trivalent Chromate Passivation for Aluminum
DCHZ-404 is a green liquid, hexavalent chromium-free passivation for aluminium, and contains
no lead, mercury, and nitrite,suitable as conversion coating of aluminum, produces an iridescent,
faintly blue to tan and visible layer.
Product Characteristic
1. The resulting finish complies with ROHS. Bath life is long. It is easy to control,easy to handle in
immersion, spray and wipe application.
2. Excellent bare corrosion protection,offers high salt spray resistance of over 100 hours.
3. The finish offers excellent corrosion resistance, complies with USA military specification MIL5541,
MIL-DTL-81706, JB/T10581-2006.
4. Wide application, can be used for chemical passivation protective, conductive oxidation stability
of contact resistance. It is also used as a conversion coating prior to powder coating,lacquering.
Operating Parameters
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pre-treatment before coating
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as corrosion protection
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layer weight:
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50-120mg/m2
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>110mg/m2
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make-up values:
spray:
immersion:
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Optimum Range
5% vol 3-25% vol
5% vol 3-20% vol
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Optimum Range
25% vol 10-30% vol
20% vol 10-30% vol
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Temperature
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25℃
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20-35℃
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30℃
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25-35℃
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pH
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3.5
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2.4-4.6
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3.5
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3.2-3.8
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application time:
spray:
immersion:
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Optimum Range
1min 0.5-3min
1 min 0.5-3 min
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Optimum Range
4min 2-8min
4min 2-8 min
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spraying pressure:
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Optimum Range
1 bar 0.5-2.5 bar
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Optimum Range
1 bar 0.5-1.5 bar
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agitation:
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not necessary
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not necessary
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make-up:
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Dilute DCHZ-404 with deionised water under vigorous stirring.
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tank material:
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stainless steel or steel with acid- and fluoride-resistant coating
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rack material:
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titanium, stainless steel (V4A), aluminium, plastic
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filtration:
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necessary (0.1-0.5 times the total bath volume per hour);
before coating: pore size ≤ 25μm
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heating:
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necessary; out of acid- and fluoride-resistant material
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exhaust:
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required for worker's protection
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pH control:
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Adjust the pH down with a 2% sulfuric acidc solution. Adjust the pH up using 2% sodium hydroxide solution
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Finishing Procedure
1. Before make up of a new bath, wash the tank with sulfuric acid solution thoroughly, the sulfuric
acid solution prepared with distilled water, the pH shoule be controlled in the range from 3.1 to 3.8.
2. Thoroughly clean and degrease pieces.
3. Cold water rinsing
4. Deoxidize: Etchant or chemical polishing
5. Cold water rinsing
6. Neutralizing
7. Rinse with distill water three times, the pH of the rinse water should be controlled in the range
from 4 to 5.
8. Conversion treatment: the length of time and the concentration of the DCHZ-404 solution will
determine the color of the finish.
9. Rinse with hot distill water (not to exceed 60℃) three times.
10. Drying: should be controlled the temperature lower 60℃.
Control Procedure
The treament time should be determined by the different operating temperature.The temperature
lower then the time should be prolonged. The finish with darker colors providing better corrosion
resistance.
The strength of the solution is maintained by adding the concentrate. Producing one square meter
will consume 20 to 25ml concentrate. The amount of additions determined by the consumption.
Caution
Avoid prolonged contact with skin. Do not get in eyes. In case of contact with skin or eyes, flush freely
with water for at least 15 minutes. For eyes, get medical attention. Avoid breathing dusts or mists.
When handling and working with solutions, wear glasses, goggles or face shield.
Packaging
25kg (net) in plastic bucket.
