VAN MARUM MINI-SYMPOSIUMUNIVERSITEIT LEIDEN

Faculteit der Wiskunde en Natuurwetenschappen

Contamination by nickel from coins:

Does the euro represent an increased risk or an improvement in regard to nickel allergy?

May 27, 2003

Thomas R. Govers

P.-G. Fournier, Orsay

M. Abani, El Jadida, Morocco

K. Berrada, Marrakech, Morocco

T. Govers, Paris

and collaborators (see publications)

« euro coins » page at www.aecono.com

ANNEX '28. Nickel CAS No 7440-0-20 EINECS No 2311114 and its compoundsMay not be used: ..2. in products intended to come into direct and prolonged contact with the skin such as:- earrings,- necklaces, bracelets and chains, anklets, finger rings,- wrist-watch cases, watch straps and tighteners,- rivet buttons, tighteners, rivets, zippers and metal marks, when these are used in garments

if the rate of nickel release from the parts of these products coming into direct and prolonged contact with

the skin is greater than 0,5 μg/cm²/week

31994L0027 European Parliament and Council Directive 94/27/EC of 30 June 1994 amending for the 12th time Directive 76/769/EEC on the approximation of the laws, regulations and administrative provisions of the Member States relating to restrictions on the marketing and use of certain dangerous substances and preparationsOfficial Journal L 188 , 22/07/1994 P. 0001 - 0002

EN 1811:1999

The Reference Test Method for Nickel Release

REFERENCE TEST METHOD FOR RELEASE 0F NICKEL FROM PRODUCTS

INTENDED TO COME INTO DIRECT AND PROLONGED CONTACT WITH THE

SKIN

Introduction

This is a summary of the test method. Due to copyright regulations the full test method must be purchased from the nominated National Standards Body. This method is used to determine whether the nickel released from products intended to come into direct and prolonged contact with the skin will not exceed 0.5 micrograms per square centimetre per week.

Scope

This European Standard specifies a method for simulating the release of nickel from consumer items in direct and prolonged contact with the skin in order to determine whether such items release nickel at a rate greater than 0.5 μg/cm2/week.

Principle

The item to be tested for nickel release is placed in an artificial sweat test solution for 1 week. The concentration of dissolved nickel in the solution is determined by atomic absorption spectrometry or other appropriate analytical methodology. The nickel release is expressed in micrograms per square centimetre per week (μg/cm2/week).

http://news.excite.ca/news/r/011126/09/odd-eurocoins-dc Nov. 26, 2001

Euro Coins Could Cause Skin Disease - Mon, Nov 26 9:21 AM EST STOCKHOLM (Reuters) - Two of the eight euro coins due to come into circulation in January release so much nickel that people allergic to the metal could develop hand eczema, according to a study obtained by Reuters on Friday…

…study by a Swedish dermatologist and British laboratory scientist said. Earlier studies which tested French, British and Swedish coins containing nickel were also found to have the potential to cause nickel allergies, it said…

…Fifteen percent of all women and two to five percent of men in the industrialized world are prone to nickel allergy.

…The study, published earlier this year in the journal Contact Dermatitis, was written by dermatologist Carola Liden at Sweden's Karolinska Institute and Stephen Carter of Britain's Laboratory of the Government Chemist in Middlesex. The one- and two-euro coins have a potential nickel release up to 100 times greater than the EU directive's upper limit, the study found.

Allergie te wijten aan nikkel in euro's

Door een onzer redacteuren

ROTTERDAM, 10 JUNI. In Naarden zijn twee mensen getroffen

door een 'euroallergie'. De vrouwen - een drogiste en een caissière -

hebben last van jeukende rode uitslag op hun handen en wijten dit

aan de nieuwe munt. Aanvankelijk werd aangenomen dat de

klachten niets met de euro te maken had, maar nu is gebleken dat het

eczeem wordt veroorzaakt door nikkel, één van de bestanddelen van

de munt.

,,Het begon gelijk in januari,'' verklaart Anke Zeldenrijk, caissière

bij de Edah en één van de slachtoffers. ,,Eerst zag ik het alleen op

mijn vingers, maar al snel werd het rood tot aan mijn onderarmen.

Daarna kreeg ik ook uitslag in mijn gezicht.''

Aangezien nikkelallergie vooral voor komt bij blonde mensen pleitte

de Zweedse delegatie bij de EU er al in 1997 voor om de euro

nikkelvrij te maken.

Daar werd vanaf gezien omdat het goedkoper was om het nikkel uit

de voormalige Europese munten te hergebruiken.

Europa liet de Zweden niet helemaal in de kou staan en verwerkte

alleen nikkel in de munten van één en twee euro. Met ongeveer

twintig procent maakt de stof maar een klein deel van de

geldstukken uit. De guldenmunten bestonden voor meer dan 99

procent uit nikkel.

Met het relatief lage nikkelgehalte van de euro is echter niet alles

gezegd. ,,Het gaat niet om de hoeveelheid nikkel die een munt bevat,

maar om de hoeveelheid die vrij komt bij gebruik,'' legt huidarts

Rustemeyer van de Vrije Universiteit in Amterdam uit. ,,Bij een

lichte beschadiging komt kennelijk genoeg vrij voor irritaties.''

Volgens demissionair minister Zalm van Financiën is niet bewezen dat euro's meer nikkel afgeven dan guldenmunten.

In een brief aan de Tweede Kamer relativeerde hij bijna een maand geleden de huidklachten die mensen door de euro's hebben. De irritaties zouden met een zalfje kunnen worden verholpen.

Bovendien is de euro volgens de bewindsman niet gevaarlijker dan veel andere gebruiksvoorwerpen. In veel bh-sluitingen en deurknoppen zit bijvoorbeeld meer nikkel dan in de euromunten, aldus Zalm.

,,Ik heb van deurknoppen of bh-sluitingen totaal geen last,'' reageert Zeldenrijk, die haar werk als drogiste nu met

handschoenen doet. ''Maar ik raak geen euromunt meer aan.''

NRC Handelsblad - Nieuws: Economie: Allergie te wijten aan nikkel in euro's

10 juni 2002

PARIS, 12 sept (AFP) - Des scientifiques français ont mis en cause jeudi une étude suisse publiée dans la revue Nature, selon laquelle les pièces de 1 et 2 euros présenteraient des risques pour les personnes allergiques au nickel.

Dans un communiqué à l'AFP, Thomas Govers et Paul-Guy Fournier, du CNRS, co-auteurs d'un article sur "la contamination par le nickel et d'autres métaux lors de la manipulation des pièces de monnaie", assurent que "les tests utilisés par les chercheurs de Zurich ne sont pas appropriés pour évaluer le risque allergique dû au nickel".

"En effet, selon le communiqué, ces tests sont des tests de solubilisation sur des périodes longues alors que la manipulation courante d'une pièce de monnaie ne dure que quelques secondes. Dans ce cas, le transfert de contamination métallique est surtout dû au frottement et non pas à un phénomène de dissolution".

Selon les chercheurs français, dont l'étude a été publiée ce mois-ci aux Comptes Rendus de l'Académie des Sciences où elle a été présentée par le prix Nobel de physique Pierre-Gilles de Gennes, "des tests qui simulent de manière réaliste la manipulation journalière montrent que les pièces de 1 et 2 euros transfèrent environ deux fois moins de nickel que les anciennes pièces françaises en nickel"."Notre article (...) montre que si l'on évalue l'ensemble des pièces euro, toutes dénominations confondues, celles-ci transfèrent quatre fois moins de nickel aux mains que les francs français", affirme M. Govers pour qui "il serait regrettable que des conclusions basées sur des tests non-représentatifs soient utilisés comme argument contre l'euro"…

Surface SurfaceDenomination Appearance Composition rim incl. rim excl.

( cm²) ( cm²)

Francs

10 F "Génie" yellow outer ring aluminum bronze Cu92Al6Ni2 5.63 4.19white centre pure nickel 4.12 4.12

1 F; 2 F white pure nickel 10.4 ; 12.5 9.0 ; 11.0

Euros

1 € yellow outer ring nickel-brass Cu75Zn20Ni5 5.92 4.22white centre copper-nickel Cu75Ni25 4.28 4.28

nickel core

2 € white outer ring copper-nickel Cu75Ni25 7.11 5.33yellow centre nickel brass Cu75Zn20Ni5 5.09 5.09

nickel core

CONTACT DERMATITIS 2001 : 44 : 160 - 165

Nickel release from coins CAROLA LIDÉN1AND STEPHEN CARTER2

1Occupational and Environmental Dermatology, Department of Medicine, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden

2Laboratory of the Government Chemist (LGC), Queens Road, Teddington, Middlesex, TW11 OLY, UK

Nickel allergy is the most frequent contact allergy and is also one of the major background factors for hand eczema. The clinical significance of nickel release from coins was discussed when the composition of euro coins was decided. Current European coinage is dominated by cupro-nickel coins (Cu 75; Ni 25); other nickel-containing and non-nickel alloys are also used. Nickel release from used coinage from the UK, Sweden and France was determined. It was shown that nickel ions are readily available on the surface of used coins. After 2 min in artificial sweat, approximately 2 μg of nickel per coin was extracted from cupro-nickel coins. Less nickel was extracted from non- nickel coins. Nickel on the surface was mainly present as chloride. After 1 week in artificial sweat approximately 30 μg /cm2 was released from cupro-nickel coins: less nickel was released from coins made of other nickel alloys. Theoretically, several ug of nickel salts may be transferred daily onto hands by intense handling of high-nickel-releasing coins.

Key words: chemical analysis; coin alloys; contact allergy; cupro-nickel; euro coin; nickel; nickel release; bioavailability. © Munksgaard, 2001.

Accepted for publication 11 September 2000

June 2002

Phys. Chem. News 6 (2002) 82-92

CONTAMINATION PROVOQUEE PAR DES MONNAIES EN EUROS ET EN FRANCS FRANÇAIS DUE A LA LIXIVIATION ET AU FROTTEMENT

P.-G. Fournier, T. Govers, M. Abani, H. Boughaleb, M. Monkade

Nickel concentration after 24 h (µg/l)

1.0E+01

1.0E+02

1.0E+03

1.0E+04

1.0E+05

1.0E-07 1.0E-06 1.0E-05 1.0E-04 1.0E-03 1.0E-02

Initial HCl concentration (Mole/l)

Ni 2 € Ni 1 € Ni 10 F Ni 2 F

Leaching rates for an initial HCl concentration of 10E-7 M

1 10 100 1000

2 Euro 24 h

2 Euro 168 h

1 Euro 24 h

1 Euro 168 h

10 F 24 h

10 F 168 h

2 F 24 h

2 F 168 h

Microgram/week

Ni Cu Zn Al

Leaching rates for an initial HCl concentration of 10E-2 M

10 100 1 000 10 000 100 000

2 Euro 24 h

2 Euro 168 h

1 Euro 24 h

1 Euro 168 h

10 F 24 h

10 F 168 h

2 F 24 h

2 F 168 h

Microgram/week

Ni Cu Zn Al

24 h 1 week

Ni Cu Zn Ni Cu Zn

2 € 9.6 6.7 3.1 38.4 34.1 19.31 € 7.5 6.6 3.9 24.5 31.6 17.1

10 F 1.2 18.2 0.6 2.6 42.4 0.052 F 2.9 3.2 0.7 5.3 5.9 0.3

Metals dissolved after immersing coins during 24 h and during 1 week, respectively, in a dilute HCl solution.Average of data for intial HCl concentrations of 10-5, 10-6 and 10-7 M. Results in μg per coin.

Solv. 2 F Solv. 2 €

Ni 8.7E-05 2.9E-04Cu 9.6E-05 2.0E-04Zn 2.2E-05 9.2E-05

μg dissolv. in 2.6 sec

Ambient

2.9 ± 0.98.4 ± 5.0

15 ± 6

μg on 3 fingers

C. R. Physique 3 (2002) 749–758

Contamination par le nickel et d’autres métaux lors de la manipulation des pièces de monnaie – comparaison entre francs français et euros

P.-G. Fournier , T.R. Govers , J. Fournier , M. Abani

Reçu le 1er mars 2002 ; accepté le 26 juin 2002

Note présentée par Pierre-Gilles de Gennes.

Ambient contamination of the fingers

0

20

40

60

80

100

120

En

fan

t sco

laris

é

Re

pr.

Co

mm

erc

ial

Em

plo

yé b

ure

au

Ch

erc

he

ur

1

Inst

itute

ur

Jou

rna

liste

Aid

e m

én

ag

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Etu

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nt

Ve

nd

eu

se 1

Ve

nd

eu

se 2

Co

iffe

use

Ch

erc

he

ur

2

Ave

rag

e a

mb

ien

t

Am

ou

nt

(mic

rog

ram

)Ni Cu Fe Zn Al

Ambient contamination of the fingers

0%

20%

40%

60%

80%

100%

En

fan

t sco

laris

é

Re

pr.

Co

mm

erc

ial

Em

plo

yé b

ure

au

Ch

erc

he

ur

1

Inst

itute

ur

Jou

rna

liste

Aid

e m

én

ag

ère

Etu

dia

nt

Ve

nd

eu

se 1

Ve

nd

eu

se 2

Co

iffe

use

Ch

erc

he

ur

2

Ave

rag

e a

mb

ien

t

Rel

ativ

e ab

un

dan

ceNi Cu Fe Zn Al

Contamination from counting 58 franc coins

0

20

40

60

80

100

1 2 3 4 5 6 7 8 9

10

Av

era

ge

F

mic

rog

ram

Ni Cu Fe Zn Al

Contamination from counting 58 franc coins

0%

20%

40%

60%

80%

100%

1 2 3 4 5 6 7 8 9

10

Av

era

ge

F

Rel

ativ

e ab

un

dan

ceNi Cu Fe Zn Al

Contamination from counting 58 euro coins

0

40

80

120

160

200

1 2 3 4 5 6 7 8 9

10

11

Av

era

ge

€

mic

rog

ram

Ni Cu Fe Zn Al

Contamination from counting 58 euro coins

0%

20%

40%

60%

80%

100%

1 2 3 4 5 6 7 8 9

10

11

Av

era

ge

€

Rel

ativ

e ab

un

dan

ceNi Cu Fe Zn Al

Relative abundances (corrected)

0%

20%

40%

60%

80%

100%A

mb

ien

t

Co

un

tin

g F

Pla

yin

g F

Co

mp

.b

as

ke

t F

Co

un

tin

g €

Pla

yin

g €

Co

mp

.b

as

ke

t €

Ni Cu Fe Zn Al

Ambient F €

Ni 2.9 ± 0.9 0.45 ± 0.24 0.25 ± 0.13Cu 8.4 ± 5.0 0.26 ± 0.17 1.3 ± 0.6Fe 10 ± 3 0.05 ± 0.04 0.06 ± 0.04Zn 15 ± 6 0.08 ± 0.08 0.17 ± 0.09Al 14 ± 3 0.09 ± 0.08 0.10 ± 0.08

Contamination resulting from the manipulation of one franc coinor one euro coin, in μg per manipulation. Ambient contaminationof three fingers is given in the first data column, for comparison.

Les tests de manipulation des pièces de monnaie montrent que la contamination des mains est plutôt induite par le frottement que par un transfert par solubilisation. Ce type de test nous paraît approprié pour évaluer les risques d’allergie potentiels dus aux maniements des pièces de monnaies, alors que la normeEN 1811 est plus adaptée pour

évaluer les objets en contact direct et prolongé avec la peau.

Les pièces de 1 et de 2 € récemment mis en circulation libèrent près de deux fois moins de nickel au contact des mains que les pièces françaises en nickel pur, alors qu’on pouvait s’attendre à une

réduction par un facteur six. En extrapolant nos résultats on peut prévoir que des tests utilisant l’ensemble des pièces en euros mis en

circulation, montreraient une diminution significative de la contamination des mains par le nickel. En contrepartie, les pièces de 1 et de 2 € donnent lieu à une contamination en cuivre sensiblement

accrue..

Solv. 2 F Solv. 2 € Manip. F Manip. €

Ni 8.7E-05 2.4E-04 0.45 ± 0.24 0.25 ± 0.13Cu 9.6E-05 2.0E-04 0.26 ± 0.17 1.3 ± 0.6Zn 2.2E-05 9.2E-05 0.08 ± 0.08 0.17 ± 0.09

μg from handling 1 coinμg dissolv. in 2.6 sec

Contamination by Nickel, Copper and Zinc during the Handling

of Euro Coins.

PAUL-GUY FOURNIER1 AND THOMAS R. GOVERS

2

1Laboratoire de Spectroscopie de Translation, Université Paris-Sud, 91405 Orsay, France;

2Aecono Consulting, 59 rue de Prony, 75017 Paris, France.

Contact Dermatitis, in press (2003)

μg

from circul. washed from circul. washedNi 0.38 ± 0.10 0.46 ± 0.16 0.23 ± 0.06 0.26 ± 0.07Cu 0.44 ± 0.10 0.24 ± 0.07 1.4 ± 0.2 1.3 ± 0.2Zn 0.14 ± 0.03 0.12 ± 0.04 0.26 ± 0.03 0.28 ± 0.05

2F 2 €

Metal release by rinsing (2€ coin)

0

4

8

12

16

20

24

28

32

0 20 40 60 80

Time (minutes)

Qu

anti

ty r

elea

sed

per

co

in (

μg

)

Ni Cu Zn

μg

from circul. polished from circul. polishedNi 0.38 ± 0.10 0.009 ± 0.004 0.23 ± 0.06 0.012 ± 0.006Cu 0.44 ± 0.10 0.013 ± 0.004 1.4 ± 0.2 0.10 ± 0.01Zn 0.14 ± 0.03 0.012 ± 0.003 0.26 ± 0.03 0.07 ± 0.03

2 €2F

μg 2F 2 € 3 fingers

accessible accessible ambientNi 12 ± 1 5.0 ± 0.7 3.0 ± 0.5Cu 13 ± 8 38 ± 5 11 ± 2Zn 2 ± 2 8 ± 2 18 ± 3

Participant A B C D Average

Ni 0.24 0.21 0.26 0.24 0.24 ± 0.02

Cu 1.42 1.34 1.54 1.50 1.45 ± 0.07

Zn 1.00 1.16 1.36 1.44 1.24 ± 0.17

Ni+Cu+Zn 1.06 1.05 1.25 1.15 1.13 ± 0.08

Ratios of euros to francs obtained with "baskets" containing 10 coins of each of the 8 denominations

Ongoing

Evolution of nickel contamination averaged over 25 successive manipulations

0

0.2

0.4

0.6

0.8

1

1 - 25 26 - 50 51 - 75 76 - 100 101 - 125

Successive manipulations

Ra

tio

to

fir

st

25

ma

nip

ula

tio

ns

Denomin. Test duration Appearance(hours)

1 FF 24 ; 72 white pure nickel Ni100

1 SFr 24 ; 72 white copper-nickel Cu75Ni25

2 SFr 72 white copper-nickel Cu75Ni25

0.25 $ 24 ; 72 white copper-nickel Cu75Ni25

1 $ 72 white copper-nickel Cu75Ni25

50 Öre (1973) 24 white copper-nickel Cu75Ni25

10 p 24 white copper-nickel Cu75Ni25

1 £ 24 yellow nickel-brass Cu70Zn24.5Ni5.5

yellow outer ring nickel-brass Cu75Zn20Ni51 € 24 ; 72 Cu75Ni15Zn10 surface average

white centre copper-nickel Cu75Ni25

white outer ring copper-nickel Cu75Ni252 € 72 Cu75Ni15Zn10 surface average

yellow centre nickel-brass Cu75Zn20Ni5

0.50 € 72 yellow nordic gold Cu89Al5Zn5Sn1

Surface composition

Total amounts collected (skin + coin)

0

20

40

60

80

100

120

1 FF* 1 FF 1 SFr* 1 SFr 2 SFr 0.25 $* 0.25 $ 1 $ 50 Öre* 10 p* 1 £* 1 €* 1 € 2 € 0.50 €

mic

rog

ram

/we

ek

/cm

²

Ni Cu Zn

"Monolayer" ≈ 1015 atoms/cm2 ; MW Ni = 58.7

Accessible nickel on 2€ ≈ 5µg on 2*2.67 cm2

= (0.9E-6 g/cm2 * 6E23 atoms / 58.7 g) / 1015 atoms/cm2

≈ 9 monolayers

Nickel contamination from single manipulation of 2€ ≈ 0.25µg

on 2*2.67 cm2

≈ 0.5 monolayers

Or :

Density of nickel and of copper ≈ 9 g/cm 3

Spherical particle of 10 μm radius ≈ 3.8 E-8 g of which ≈ E-8 g

nickel if 25%

Accessible nickel on 2€ ≈ 5μg ≈ 500 particles of 10 μm

Nickel contamination from single manipulation of 2€ ≈ 0.25 μg

≈ 25 particles of 10 μm

"Monolayer" ≈ 1015 atoms/cm2 ; MW Ni = 58.7

Accessible nickel on 2€ ≈ 5µg on 2*2.67 cm2

= (0.9E-6 g/cm2 * 6E23 atoms / 58.7 g) / 1015 atoms/cm2

≈ 9 monolayers

Nickel contamination from single manipulation of 2€ ≈ 0.25µg

on 2*2.67 cm2

≈ 0.5 monolayers

AND / OR

In favour of particles hypothesis:

- Composition contamination new coins ≈ composition of coin- Copper on used pure-nickel coins

- « Playing » test contamination enhanced

and ≈ composition coins

- Handling cleans coins- Contamination upon air exposure builds up slowly, if at all

- In usage, rapid build-up of contamination-SEM results

If particles make up major part of contamination, two aspects

to allergic risk, which is due to dissolved ions:

- How much contamination is transferred ? This we know.

2 € Cu75Ni25 2 FF

Ni 0.48 ± 0.07 0.97 ± 0.37 1.1 ± 0.1Cu 3.7 ± 0.5 4.0 ± 1.1 1.2 ± 0.7Zn 0.8 ± 0.2 0.4 ± 0.2 0.2 ± 0.2

Accessible contamination devided by coin surface(2 faces), in μg/cm2.

If particles make up major part of contamination, two aspects

to allergic risk, which is due to dissolved ions:

- How much contamination is transferred ? This we know.- How fast do particles dissolve ?

If particles make up major part of contamination, two aspects

to allergic risk, which is due to dissolved ions:

- How much contamination is transferred ? This we know.- How fast do particles dissolve ?

« Educated guess » : assume small spheres with initial radius R0

and density d, small enough to be immersed in the sweat at the

surface of the skin, dissolving at a rate ρS time needed for

their weight to be reduced by half is given by :

t1/2 = 0.21 * R0d/ρ

where S is their surface area, ρ the dissolution rate per unit area.

The density d of nickel and of copper-nickel alloys is

about 9 g/cm3. Equating ρ to the sums of the metal

release rates obtained in our patch tests, one finds:

ρ ≈ 30 μg/cm2/week for pure nickel

ρ ≈ 85 μg/cm2/week for copper-nickel alloys.

If R0 is of the order of 1 μm

t1/2 ≈ 6 weeks for pure nickel

t1/2 ≈ 2 weeks for pure nickel

!!

TENTATIVE conclusion, depending on particle properties:

Particles will remain on the fingers until person washes hands

Relative risk of nickel allergy ≈ amount of nickel transferredtimes relative rate of solubilisation

1- and 2€ compared to other copper-nickel coins : Transfer twice as low, similar solubilisation 50% lower risk

1- and 2€ compared to pure-nickel coins : transfer twice as low, solubilisation three times faster

50% higher risk

Introduction of euro has reduced allergic risk mainly because 6 out of 8 coins do not contain nickel

There seems to be a discrepancy between the experimental and the calculated

stability of Ni(OH)2 in aqueous solutions. A passive film (NiO/Ni(OH)2/NiOOH

mixtures) is found at pH 5.0 and at 25°C on the surface of nickel and copper-

nickel alloys31,55, where according to our thermodynamic calculations the

thermodynamic solubilities are quite high. The aqueous system of nickel is

problematic not only because of the formation of higher oxides but also for its

very slow kinetics. The dissolution rate of nickel mono-oxide at pH = 1 and

60°C is just one monolayer per month56 and the discrepancy between the

experimental formation of a passive film in electrochemical experiments and its

thermodynamic stability might be due to kinetic considerations.

REVISED POURBAIX DIAGRAMS FOR NICKEL AT 25-300°C

B. BEVERSKOG* and I. PUIGDOMENECH†

Corrosion Science, Vol. 39, No. 5, pp. 969 - 980, 1997

Corrosion Science. Vol. 38, No. 8. pp. 1369 - 1383, 1996

SURFACE ANALYTICAL EXAMINATION 0F PASSIVE LAYERS

ON Cu-Ni ALLOYS PART II. ACIDIC SOLUTIONS

P. DRUSKA and H.-H. STREHBLOW*

The formation and chemical structure of passive layers on Cu-50Ni and Cu-20Ni in acidic electrolytes have been examined with X-ray photoelectron spectroscopy (XPS) and ion scattering spectroscopy (ISS). Phthatate buffer pH 5.0 and 0.005 M H2SO4 + 0.995 M K2SO4 pH 2.9 have been used for passivation. The corrosion behaviour of the alloys is characterized by the characteristic properties of both alloy components, i.e. increased dissolution of Cu and passivating properties of Ni in acidic electrolytes. A similar multilayer structure with an outer hydroxide and an inner oxide with lower valent cations in an inner position is found as for alkaline solutions...

TENTATIVErecommendation:

IF Ni maintained

ReplaceCu75Ni25

byNi100

ReplaceCu75Zn20Ni5

byCu92Al6Ni2

Thanks for your interest !