CrO3 alternatives in decorative and functional plating alternative_Thiery.pdf600 Liters (IRT M2P) – 20 months of use > 130 Ah/L 800 Liters (Safran Turbomeca) – 6 months of use

CrO3 alternatives in decorative and functional plating25.01.2017

25.01.2017 - 2 CrO3 alternatives/Helsinki

CrO3 alternatives

Decorative platingChrome platingEtching of plastics

Functional plating


Decorative chrome plating from trivalent Chrome electrolyte

End use sectorAutomobile

Trims, emblems… plating on plasticsBuilding

Door handles, furnitures, door hinges : steel, zamakbase material

Cosmetics Perfume caps

Sanitary fittingsShower heads & holders : plating on plastics, on zamak,

or brass


Decorative chrome plating from trivalent Chrome electrolyte

Required propertiesAspect : colour (L*a*b* values as close as possible to CrVIreference)

Corrosion resistance propertiesNeutral Salt Spray Test (ISO 9227)CASS test (ISO 9227)Russian Mud (NISSAN NES M 4063…)Specific tests

PV 1073 A & B : Chrome and Nickel corrosion

Aspect of chrome deposits

ColourMeasured by spectrocolorimeterResults expressed in the CIE L*a*b* color space


L* ( 0 ÷ 100 )(Black ÷ White)

a* ( - 60 ÷ + 60 )(Green ÷ Red)

b* ( - 60 ÷ + 60 )(Blue ÷ Yellow)

TRISTAR 300 (chloride) 78 ÷ 80 -0.1 ÷ 0 0.5 ÷ 1

TRISTAR 300 AF serie(sulphate) 82 ÷ 84 -0.6 ÷ 0 -0,2 ÷ 0,5

CHROME 200 (CrO3) 82 ÷ 84 -0.6 ÷ 0.2 -0.5 ÷ 0.5

Table N°3 : Colour of different Chrome deposits (CIEL*a*b* coordinates)

Corrosion resistance of trivalent chrome vs hexavalent systems


CrVI reference TRISTAR 300 serie(Cl- based) + post treatment

TRISTAR 300 AF serie (SO42- based) + post treatment

NSST (ISO 9227) 480h wo stains 480 hours wo stains 480 hours wo stainsCASS test (ISO 9227)

72 hours 48 hours on microporous Ni72 hours on STRATA

48 hours on microporous Ni

Russian Mud (NESM 4063)

Doesn’t pass 96 h Pass 96 hours Doesn’t pass 96 h

PV 1073 A Doesn’t pass Pass Doesn’t passPV 1073 B Doesn’t pass Doesn’t pass Doesn’t pass

00.00.0000 - 7

POP Sequence-TRISTAR: Acid Copper thru Drying

Acid Copper

CUBRAC 2900

Rinse

Rinse

Rinse

Rinse

Rinse

Rinse

Rinse

Rinse

Rinse

Rinse Dry

POST

TREATMENT

TRISTAR 300

Micro-Porous Nickel

CRITERIONMP 250

SulphurFree Nickel CRITERION

SB 100

Bright Nickel CRYSTAL

103

Max 2 more steps than for CrVI

CrO3 alternatives/Helsinki


CrO3 alternatives


Functional plating


CrVI etching mechanism

Plating On Plastics with Non Chrome Etch

ASB

Cr3+ Pd colloid

Substrate ABS

Cr6+

After Etching CrO3/H2SO410-15 min, ~68°C

After Neutralization

1 min, ~45°C

After Catalyst

2-3 min, ~30°C

EN

After EN~10 min, ~30°C

Acc.

ABS – SEM picture – before and after etching

Before etching

Bare material

After low CrVI Etch

~80 g/L CrO3

After high CrVI Etch

~400 g/L CrO3

Plating On Plastics with Non Chrome Etch

CrO3 based etch versus non CrO3 etch on ABS


Surface structure after etching with SILKEN Bond and Cr VI etchCOMPARISON OF THE ETCHED SURFACE BY SEM

Adaptation in an existing line


Oxidation cell


Adhesion


Peeling test 90° following ASTM B533-85 (2004) in Newton per 25 mm width of strip peeledPeeling strength highlights the adhesion of the metallic layers on the plastic surface.Parts are 2.5 cm wide and measurement was done in OEM labs.

Plating on plastics with non chrome etch

Rack platingConventional system : CrVI acts as a poison and prevents rack metallizationNon chrome etch system : specific rack conditioner* preventselectroless Nickel reduction on the racks

Bi injected partsBeta site test

Beta site test : 18 months of production in pilot line25.01.2017 - 14 CrO3 alternatives/Helsinki

* Patent pending


CrO3 alternatives


Functional plating

16

∎ Industrial context

CONTEXT

Chrome industry = 5000 to 10000 employees in France Hex Chrome use will be submitted to authorization

According REACH regulation EC N° 1907/2006 From September 2017

Hard Chrome = use of hexavalent chomium

For decorative appearance For functional aspect (hardness, thickness,

mechanical properties and corrosion)

Research project at the IRT‐M2P in order to develop an alternative to CrVIprocess based on CrIII electrolyte

HCTC Project → « Hard Chrome by Trivalent Chromium »

Develop an alternative from a REACH compliant CrIII based electrolyte Understanding of the deposition mechanisms from a CrIII electrolyte Evaluation of ageing of CrIII electrolyte Coatings characterization in comparison to those of the deposits obtained from CrVI

17

∎General information

PROJECT HCTC : « HARD CHROME BY TRIVALENT CHROMIUM »

∎ Project’s goals

Project duration: 48 months since Feb 2014 17 partners: 15 industrial and 2 laboratories Total budget: ≈ 3.35 million euros Multi‐scales : 40 liters to 800 liters

• Substrates– Representative of the final use

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SUBSTRATE

15CDV6 coupons(quenched and temperedsteel)Mechanical strength : 980 to 1180 MPa

15CDV6 & XC 48 steel cylinders

19

300

400

500

600

700

800

900

1E+04 1E+05 1E+06 1E+07Number of cycles

Stre

ss (M

Pa)

CrIII + Th T 4h at 200°C

CrVI + ThT 4h at 200°C

15CDV6 Better fatigue behaviour than

hex Chrome

Fatigue tests (rotative bending) ISO 1143:201015 CDV 6 (Moore type) samplesFrequency : 50 HzStress vs Number of cycles until 1E+07 cycles without complete failure

COATING CHARACTERIZATION

18

20

HEXAVALENT CHROME

TRIVALENT HARD CHROME

Ability to plate high thickness

Yes Yes (up to 400 µm tested)

Structure Micro cracked Presence of throughcracks – Increase withheat treatment – Last developments : low and thin cracks even afterthermal treatment

Hardness Decreases withtemperature

Increases withtemperature

Fatigue Good Superior to Hex Chrome

Wear resistance Good Comparable to HexChrome

Corrosion protection Medium Superior to Hex Chrome with a Ni underlayer

OVERVIEW OF THE COMPARATIVE PROPERTIES

21

CONCLUSIONS Bath is very stable:

2 x 40 Liters : Coventya and Utinam : > 1000 Ah/L 600 Liters (IRT M2P) – 20 months of use > 130 Ah/L 800 Liters (Safran Turbomeca) – 6 months of use 50 Ah/L

Comparison with CrVI on low Carbon steel : Optimization of electrolysis conditions Fatigue on steel : Confirmation of the superior behaviour of CrIII vs

CrVI Hardness : Yes Deposition rate : Yes Abrasion : Yes Adhesion : Improvement of adhesion and through cracks even after

thermal treatment Corrosion : No (but yes with Ni layer)

Simple parts (as automotive shock absorber) to be coated and characterized

Specific rectifier required Pre treatment sequence : substrate dependent

Conclusion

Alternatives to CrO3 in decorative chrome platingChrome plating electrolyte

Anti corrosion properties are achieved with chloride based electrolytesAspect is close to CrVI with sulfate based electrolytesSystems are in production phase since 3 years for automotive exterior

partsEtching of plastics

Permanganate based systems enable to obtain consistent results on ABS, ABS/PC parts

Bi components treatment in beta test

Alternatives to CrO3 in functional chrome platingTrivalent chrome with dedicated operating parameters

Representative parts to be plated first semester 2017


Documents

CrO3 alternatives in decorative and functional plating alternative_Thiery.pdf600 Liters (IRT M2P) – 20 months of use > 130 Ah/L 800 Liters (Safran Turbomeca) – 6 months of use