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 download the product sheet
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GEOBLACK®
GEOBLACK® is a black non-electrolytic thin-film coating composed of zinc and aluminium flakes in a chromium free mineral binder, for the corrosion protection of parts made from steel, cast iron or other iron metals.
This thin coating (approximately 10-12µm) consists of 2 products applied successively on bulk parts:
- GEOMET® 321, 1 or 2 coats, metallic silver in appearance, chromium free (no hexavalent chrome nor trivalent chrome), according to the process used and performances required.
- PLUS® ML BLACK, one coat, 1 or 2 coats, black colour, according to the process used and performances required.
The GEOBLACK® coating is obtained by the application of aqueous dispersions by cold immersion or spray. |
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CHARACTERISTICS
The corrosion resistance of GEOBLACK® depends upon the thickness of the coating and is due to the combination of several mechanisms:
• a barrier effect due to the tile-like structure of the GEOMET® undercoat,
• controlled sacrificial protection of the zinc in relation to the metal substrate,
• the film passivation which reduces the speed at which the zinc and aluminium are consumed.
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PROPERTIES
1/No hydrogen embrittlement
When surface preparation is done according to recommended techniques, the non-electrolytic application of the film does not induce hydrogen embrittlement. GEOBLACK® is therefore especially indicated for protecting security parts.
2/ Corrosion resistance
GEOBLACK® provides excellent corrosion protection to mechanical parts.
2.1/ Salt spray test (ISO 9227)
> 800 hours without red rust.
> 240 hours without white rust
2.2/ Salt spray test after 1 hour thermal shock at 120°C:
ditto
2.3/ Cyclical corrosion tests
VDA-test 621-415 > 10 cycles without red rust.
2.4/ Bimetallic corrosion resistance
GEOBLACK® behaves very well in contact with aluminium and performs better than other zinc-based coatings in contact with copper, stainless steel or magnesium.
3/ Humidity (DIN 50017 KK)
240 hours + scratch grid: good adherence
4/ Resistance to automotive fluids:
Standardised test fuel, diesel fuel, motor oil, cooling fluid: no coating alteration (VDA 621-412).
5/ Coefficient of friction on nuts and screws
• test method DIN 946: µ average between 0,10 and 0,16
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HOMOLOGATIONS
GEOBLACK® is a chromium free corrosion protective coating made from water-based chemicals free of harmful substance. It anticipates the European legislation as regards health, safety and environment.
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APPLICATION
GEOBLACK® is applied to bulk parts and to parts on racks by GEOMET® licensees equipped with an appropriate line.
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