Chromium (VI)-free surface technology for hydraulic fittingsdoc.voss.de/Marketing/Fluid/information/presentation_voss_fluid... · © VOSS Fluid GmbH Surface technology for hydraulic

01.11.2006 Page 1 F-GM / Sl X© VOSS Fluid GmbH Surface technology for hydraulic fittings

Chromium (VI)-free surface technology for hydraulic fittings

© VOSS Fluid GmbH Surface technology for hydraulic fittings 01.11.2006 Page 2 F-GM / Sl X

Surface technology

Standard A3C surface of today

Structure of the A3C surface (with hexavalent chromium)

Zinc coating applied by electroplating (8 - 12 µm) with chromate coating (0,3 µm)

Optimum surface for parts subjected to mechanical stress

The Cr (VI) ions “flow” towards the harmed spot and seal it off.Self-healing effect when the chromate coating is damaged.

Only chromium (VI) offers this property and therefore A3C only!

Good results in connection with corrosion protection tests up to 100 hours compared to white rust (salt fog test in accordance with DIN 50021-SS)

Cr (VI) ionsChromate coatingZinc

Steel


Surface technology

Cr (VI)-free surfaces

Zinc with passivation and sealing

Same base coating of zinc as for yellow chromation

Instead of yellow chromation, passivation and additional sealing is used

If the sealing coating is harmed, a rapid reduction in corrosion resistance is the result

An equivalent self-healing effect does not exist here

Sealing coatingPassivationZinc

Steel


Summary:

In the market there exists no passivation with a sealing coatingcapable of attaining the properties of yellow chromation

The base coating of zinc with passivation and sealing coating is not suited in practice for the purpose of attaining the required degree of corrosion protection for pipe fittings.

As a result, the base coating must offer better corrosion protection for tube fittings!


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Zinc-nickel base coating with passivation and sealing coating in accordance with VOSS specifications


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Alternative surfaces

The chromium (VI)-free alternative from VOSS Fluid:

The zinc-nickel base coating offers a degree of corrosion protection which is many times higher compared to zinc

Passivation plus sealing coating serve the purpose of improvingthe friction properties

Zinc-nickel does not produce any pronounced white rust like zinc does, but instead produces a slight grey haze

Zinc-nickel

Passivation

Sealing coating

Steel


The facts

Zink–Nickel

The properties at a glance:

Very high degree of corrosion resistance, also after handling and assembly!

The zinc-nickel base coating offers a degree of corrosion resistance which is many times higher compared to zinc

White rust occurs only by way of a slight grey haze, no voluminous whitecorrosion decomposition product (zinc oxide): “Efflorescence”

Proven better corrosion resistance than A3C

Base coating (zinc-nickel) well proven for many years and being used asstandard by European vehicle manufacturers

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Coating structure

44

SteelSteel

Zinc Zinc3322

11Steel

Zinc-nickel

Comparison of the coating structure of the different surfaces

A3C Zn ZnNi

1 = Base metal;1 = Base metal;

2 = Base coating; 2 = Base coating; thickness up to 12 thickness up to 12 µm

3 = Passivation resp.3 = Passivation resp.yellow chromation; yellow chromation; coating thickness within coating thickness within the nanometer rangethe nanometer range

4 = Sealing coating;4 = Sealing coating;coating thickness coating thickness up to 2 up to 2 µm Salt fog test after 120 hours.


Comparison of the base coatings

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Zinc Zinc ZincZinc--nickelnickel

Corrosion resistance until red rust appears [hours]Corrosion resistance until red rust appears [hours]


Salt fog test in accordance with DIN 50021 840 h

A3C A3C stainlesssteel

A3C ZnNi ZnNi

A3C A3C ZnNi

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ZnNi 192h

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Zn 192h

Salt fog test in accordance with DIN 50021


Corrosion resistance of surfaces with a zinc base coating

Source, Internet: Source, Internet: www.chromium6free.com/ www.chromium6free.com/ Experiment report by Experiment report by Battelle Final Report on CORROSION TEST RESULTS OF NONBattelle Final Report on CORROSION TEST RESULTS OF NON--HEXAVALENT CHROMIUM COATED HEXAVALENT CHROMIUM COATED PARTS to PARKER HANNIFIN CORPORATION, August 21, 2003, EnglishPARTS to PARKER HANNIFIN CORPORATION, August 21, 2003, English

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VOSS chromium (VI)-free

Summer 2007Be protected!

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Chromium (VI)-free surface technology for hydraulic fittingsdoc.voss.de/Marketing/Fluid/information/presentation_voss_fluid... · © VOSS Fluid GmbH Surface technology for hydraulic