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Chromium-6 free;
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Excellent adhesion, corrosion protection and cost effective processing
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Meets the GSB and Qualisteelcoat standards, Qualicoat certified
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Multi-metal application
AD has developed a chromium(VI)-free pre-treatment system for hot dip galvanized steel prior to the coating process, the so called DUPLEX coating. In specific PreCoat Z31 enables perfect paint adhesion and corrosion protection on galvanized surfaces. It also provides a passivation against white rust (passivation layer) on the bare substrate.
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Chromium(VI)- free pretreatment of galvanized steel
PreCoat Z31 is developed for the needs of galvanizers that also offer a powdercoating or wet-painting service to their customers. PreCoat Z31 is a complete chromium(VI)-free pretreatment system (including etching, cleaning, conversion coating) .
PreCoat Z31 product characteristics:
- Chromium(III) based
- Spray, dip or cascade application
- Free of substances of very high concern (SVHC
- Multi-metal, suitable for all zinc and aluminum based alloys
- Meeting the performance requirements of GSB and Qualisteelcoat
- Qualicoat approved
- Superior corrosion protection (up to 2000 hours salt spray testing)
- Excellent paint adhesion
Customer case: Weert Groep (Netherlands)
AD Chemicals and Weert Group are introducing an innovative chromium (VI)- free pretreatment system prior to powder coating on galvanized steel (Duplex-system). Weert Group is the first galvanizer in Europe to implement this new technology that complies with both the GSB and Qualicoat (Approval No. A-119) standard.
For making this innovation possible, there has been a joint research and development trajectory of more than 8 years. The uniqueness of the PreCoat Z31 pretreatment lies in the fact that it is a 1-on-1 replacement for chromium (VI), meaning that all the qualitative properties are sustained (corrosion protection, paint adhesion, passivation). This results in a corrosion protection and paint adhesion of more than 2000 hours of NSS, a performance to be proud of. The expectation of AD Chemicals and Weert Group is that this new system will become the (global) market standard in chromium (VI) free pretreatments on galvanized steel.
Test Results
PreCoat Z31 has been thoroughly tested according to the highest test standards. PreCoat meets the following standards:
Paint adhesion
- Cross hatch, according EN ISO 2409 / ASTM D3359
- Boiling water test/wet adhesion
- Impacttest, according EN ISO 6272-1 / ASTM D2794 / EN 13523-5.
Corrosion protection
- Machu-test
This is an accelerated corrosion test on test panels and construction parts according to Qualicoat specifications. The test is made in a warm environment. To create this environment the test panels are placed in the plastic container, which is placed in the Machu Test Bath. The test panels need to be scratched crosswise with a 1mm cutting tool before placing them in the warm moisture test chamber. The fluid content, temperature and remain time are specified. - Salt spray test
Salt spray according to ISO9227/ Din50021/ ASTM B117.
Below image shows the test resultts after 500 hours of Neutral Salt Spray Test (NSS) in comparison to a chromium(VI) based pretreatment.
PreCoat Z31 versus Chromate conversion coating
Below table shows an overview comparison between PreCoat Z31 and a chromate conversion coating.
| Chromate conversion coating | PreCoat Z31 | |
|---|---|---|
| Environmental impact | -/- | ++ |
| Corrosion protection and paint adhesion | ++ | ++ |
| Multi-Metal | -/+ | ++ |
| Robust proces | ++ | ++ |
| Meets quality standards | Qualisteelcoat, GSB, Qualicoat | Qualisteelcoat, GSB, Qualicoat |
Exceeding the market standard
HDG Pre-treatments have a huge range of requirements on a complex combination of zinc based alloys. This drives the need for close working relationships, consultation, testing and pilot line experimentation. With PreCoat Z31 AD Chemicals shows that replacing chromium-6 while maintaining the highest quality is possible.
Discover more
General galvanizing (HDG)
AD Chemicals supplies a range of products for passivation of HDG and pre-treatment prior to coating (DUPLEX). Next to that it offers specialty additives to assist the galvanizing process.
Pre-treatment HDG
AD Chemicals has developed a hexavlent chrome free pre-treatment process that are specifically designed to the high demands of HDG and Zinc-alloy processing companies.
Specialty additives
AD Chemicals has the perfect product for every step in the hot-dip galvanising process. The range of products includes degreasing agents, cleaning/etch additives, inhibitors and other pickling additives.
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