Chromium (VI)-free surface technology for hydraulic fittings

Transcription

1 Chromium (VI)-free surface for hydraulic fittings VOSS Fluid GmbH for hydraulic fittings Page 1 F-GM / Sl X

2 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 Cr (VI) ions Chromate coating Zinc Standard A3C surface of today Steel 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 SS) VOSS Fluid GmbH for hydraulic fittings Page 2 F-GM / Sl X

3 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 Cr (VI)-free surfaces Sealing coating Passivation Zinc Steel VOSS Fluid GmbH for hydraulic fittings Page 3 F-GM / Sl X

4 Summary: In the market there exists no passivation with a sealing coating capable 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. Cr (VI)-free surfaces As a result, the base coating must offer better corrosion protection for tube fittings! VOSS Fluid GmbH for hydraulic fittings Page 4 F-GM / Sl X

5 Cr (VI)-free surfaces Zinc-nickel base coating with passivation and sealing coating in accordance with VOSS specifications VOSS Fluid GmbH for hydraulic fittings Page 5 F-GM / Sl X

6 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 improving the friction properties Zinc-nickel does not produce any pronounced white rust like zinc does, but instead produces a slight grey haze Alternative surfaces Sealing coating Passivation Zinc-nickel Steel VOSS Fluid GmbH for hydraulic fittings Page 6 F-GM / Sl X

7 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 The facts White rust occurs only by way of a slight grey haze, no voluminous white corrosion decomposition product (zinc oxide): Efflorescence Proven better corrosion resistance than A3C Base coating (zinc-nickel) well proven for many years and being used as standard by European vehicle manufacturers VOSS Fluid GmbH for hydraulic fittings Page 7 F-GM / Sl X

8 Comparison of the coating structure of the different surfaces A3C Zn ZnNi Zinc Steel Zinc Steel Zinc-nickel Steel Coating structure 1 = Base metal; 2 = Base coating; thickness up to 12 µm 3 = Passivation resp. yellow chromation; coating thickness within the nanometer range Salt fog test after 120 hours. 4 = Sealing coating; coating thickness up to 2 µm VOSS Fluid GmbH for hydraulic fittings Page 8 F-GM / Sl X

9 Corrosion resistance until red rust appears [hours] Comparison of the base coatings Zinc Zinc-nickel nickel VOSS Fluid GmbH for hydraulic fittings Page 9 F-GM / Sl X

10 A3C A3C stainless steel A3C ZnNi ZnNi Comparison of the base coatings A3C A3C ZnNi Salt fog test in accordance with DIN h VOSS Fluid GmbH for hydraulic fittings Page 10 F-GM / Sl X

11 Comparison of the base coatings ZnNi 192h Zn 192h Salt fog test in accordance with DIN VOSS Fluid GmbH for hydraulic fittings Page 11 F-GM / Sl X

12 Corrosion resistance of surfaces with a zinc base coating Source, Internet: Experiment report by Battelle Final Report on CORROSION TEST RESULTS OF NON-HEXAVALENT CHROMIUM COATED PARTS to PARKER HANNIFIN CORPORATION, August 21, 2003, English VOSS Fluid GmbH for hydraulic fittings Page 12 F-GM / Sl X

13 Summer 2007 Be protected! VOSS chromium (VI)-free VOSS Fluid GmbH for hydraulic fittings Page 13 F-GM / Sl X