Degrigny, C. Test. 2010

8/7/2019 Degrigny, C. Test. 2010

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Leiden, 11-15 January 2010

SPAMT-TestUse of Ecorr vs time plots for the qualitativeanalysis of copper-based elements fromscientific and technical objects

Christian Degrigny


2/23


Need in conservation of simpleanalytical tools that are non-invasive and portable for the on-site

diagnosis of heritage metal artefacts

Spot tests: invasive and use of

corrosive chemicalsDynamometer

17th century, Lyce HocheVersailles, INRP

Clock, Louis XVI, Vauchez

Context


3/23


Preliminary research

artefactmultimeter

Referenceelectrode

COM V I

Device used:

- Objet : connected to the Voutput of a multimeter;- Reference electrode (with aknown potential): placed next tothe metal surface. Connected to

the COM output of the multimeter;- A drop of solution is placedbetween the object and theelectrode;- Measurement made (Ecorr) onthe multimeter- Monitoring vs time (5 10minutes): characteristic of themetal studied .


4/23


1st tests: brass alloys in sodiumsesquicarbonate

-reproducible results onpolished brass coupons;

- no alteration of themetal studied (no visiblemarks);

- requires a small surfaceof the metal and a smallvolume of solution: localspot test ;

- can be used for thequalitative analysis ofmetals;

-450

-400

-350

-300

-250

-200

-150

-100

-50

00 100 200 300 400

temps (secondes)

Ecorr (V/Ag-AgCl)

I3, S2 (I)

I2, S1 (II)I4, S2 (II)

Brass st

I5, S2 (III)

I1, S5 (IV)

I1, S6 (IV)

I1, S4 (V)

I4, S3 (V)

Zn


5/23


2nd tests: other families of copperalloys + 2 solutions

Objective : electrochemical behaviour of 16 referencecopper-based alloys in sodium sesquicarbonate (SS) andmineralised water

Conclusion-Family of alloys (tin bronzes, brass) are easy to identify;-The analysis is more difficult if the metal contains more than

2 elements.

60

70

80

90

100

110

0 100 200 300 400 500 600 700 800 900 1000

Time (seconds)

Ecorr

(V/She)

150

155

160

165

170

175

180

185

0 100 200 300 400 500 600 700 800 900 1000

Time (seconds)

Ecorr

(V/She)

Copper--arsenic95,4%Cu / 4.6%As Sodium sesquicarbonate

Mineral water


6/23


Advantages-Easy to use for conservators-Cheap-Portable , makes on-site measurements possible-Relatively non invasive

Drawbacks-High dependance towards the user-Need to define a protocol of measurement and a

thorough monitoring process-Results might be very close for 2 different materials-Need to work on polished metal artefacts

Advantages and drawbacks of thetechnique


7/23


The SPAMT-Test project

Objectives :

Increase the number of reference metalstestedAddition of a 3 rd testing solution

Definition of a precise protocol ofmeasurementConstruction of a database for copper-based alloys;Application to scientific, technical andhorology objects


8/23


Collection of reference materials (66)

1st step: setup of the methodology of theproject

Referencematerials

collected from:

EU IMMACO

project-EU EurekaE2210! Bronzartproject

-ICMPE-CECM-INSTN-V&A laboratory-CCI- ISC-Swissmetal

-private collectors-Foundation HAM-MIH

SDE analysis

Solutions testedKNO3 (1%(w/v), pH=6), mineral Swiss water Henniez (pH=7,6),sodium sesquicarbonate (pH=9,6)


9/23


Family Alloys

Arsenic-copper CuAs3.3S

Bronze (Cu/Sn) CuSn7.7, CuSn9.1Ni, CuSn10, CuSn14, CuSn15Pb, CuSn9.4Si3.6,CuSn9Si3.8Bi2.3, CuSn11Ni3.3, CuSn11Zn1.3Ni1.9, CuSn14Zn2.1

Silver bronze

(Cu/Sn/Ag)

CuSn5.6Ag12, CuSn5.7Ag5.9, CuSn6.5Ag

Leaded bronze(Cu/Sn/Pb)

CuSn12Pb11NiMn

Brass(Cu/Zn)

CuZn5.3, CuZn5.8, CuZn7.8, CuZn12, CuZn11, CuZn14.84, CuZn24.9,CuZn30, CuZn32, CuZn34, CuZn35, CuZn36, CuZn46.1

Tin brass(Cu/Zn/Sn)

CuZn5.8Sn6PbNi, CuZn14Sn2.7PbFe, CuZn35Sn1, CuZn36Sn1.7

Leaded brass(Cu/Zn/Pb)

CuZn35Pb1.6Si, CuZn35Pb2.1Sn1.2Ni, CuZn35Pb3.1, CuZn36Pb1NiFe,CuZn37Pb1.7, CuZn38Pb0.7, CuZn38Pb3, CuZn39Pb1.6NiFe,CuZn39Pb2NiFe, CuZn39Pb2.6Fe, CuZn39Pb2.1, CuZn40Pb, CuZn40Pb1.3,CuZn40Pb1.8, CuZn42Pb2,3Al, CuZn43Pb

Nickel silver(Cu/Zn/Ni)

CuZn24Ni12PbFe, CuZn26Ni12Fe, CuZn34Ni14Mn4Pb1.2,CuZn34Ni14Mn5.3Pb, CuZn37Ni8.4Mn2.9Pb1.8

Quaternary bronze(Cu/Sn/Zn/Pb)

CuSn3.9Zn4.3Pb3.8, CuSn5.3Zn5.5Pb1.5NiFe, CuSn5.6Zn2.4Pb2.5,CuSn5.8Zn2.4Pb1.6Ni1.1Si, CuSn5.8Zn3.3Pb3.4Si1.3Ni1.1,CuSn9,1Zn7,5Pb5,6NiFeMn, CuSn11Zn1.7Pb2.7SiNi

Beryllium-copper CuBe2

Nickel-copper CuNi25Mn

Aluminium-copper CuAl8.5Ni2, CuAl11Ni1,5Fe1,2, CuAl13Ni5,8Fe3,8Mn

Materials tested

Somefamilies are

more

coveredthan

others


10/23


Experimental conditions for plottingEcorr vs time curves

-Prior testing of the reference electrode (RE);-Preparation of the test solution (stirred beforeuse), rinsing and filling the JPT with it (except inthe case of Henniez water);-Insertion of the RE into the JPT andovertightening with Teflon sealing tape. This stepmust be effected 30 minutes before beginningmeasurements, so as to ensure the stability of thesystem;-Polishing of the metallic surfaces of the studiedmaterials (handled with latex or vinyl gloves)before each plot is made with fine silicon carbidepaper (Struers 4000);-Placing of the RE/JPT system at a distance of2mm from the surface of the polished metal;-Application of the drop of solution (40L)between the membrane of the JPT and the metalsurface with a syringe (rinsed out with the testsolution (stirred before use));-Ecorr measurement for 5 and/or 15 minutes.


11/23


In total: more than 600 Ecorr vs time plots(2x5min + 1x15min) for 66 alloys in 3 solutions

-Binary alloys were done first (to appreciatethe effect of the major element)-Same operator to cover the same family ofcopper alloys-If reproducible plots were obtained (maximumdifference of 5mV accepted), we moved on tothe next material in the table of materialsstudied.-In case of lack of reproducibility (alloys

containing lead), increase of the number ofplots and change of the operator

2nd step: construction of the database

Electric contacts

to limit the impacton the reference

materials


12/23


-120

-100

-80

-60

-40

-20

0

20

40

0 2 4 6 8 10 12 14 16

Time (minutes)

Ecorr (

mV/Ag-AgCl)

CuSn3.9

-80

-60

-40

-20

0

20

40

60

80

0 2 4 6 8 10 12 14 16

Time (minutes)

Ecorr (

mV/Ag-AgCl)

CuSn3.9

-180

-160

-140

-120

-100

-80

-60

-40

-20

0 2 4 6 8 10 12 14 16

Time (minutes)

Ecorr

(mV/Ag-AgCl)

CuSn3.9

A few examples

-450

-400

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-250

-200

-150

-100

-50

0

0 2 4 6 8 10 12 14 16Time (minutes)

Ecorr

(mV/Ag-AgCl)

CuZn40Pb1.8

-450

-400

-350

-300

-250

-200

-150

-100

-50

0

0 2 4 6 8 10 12 14 16Time (minutes)

Ecorr

(mV/Ag-AgCl)

CuZn40Pb1.8

-500

-450

-400

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-250

-200

-150

-100

-50

0

0 2 4 6 8 10 12 14 16Time (minutes)

Ecorr

(mV/Ag-AgCl)

CuZn40Pb1.8

Mineral water

Mineral water

KNO3

KNO3

Sodium sesquicarbonate

Sodium sesquicarbonate

Reproducible results

Non reproducible resultsin mineral water


13/23


General trends

Family General trend ofEcorr vs time plotsComments

Cu/As Depending on thesolution

- E KNO3>E EH>E SS- In SS: passivation (E corr increases vs time),- In KNO3 and HW: E corr first decreases and then increases

Bronze (Cu/Sn) Progressive passivationfor all solutions

- E KNO3>E EH>E SS- In HW and SS: 1 or 2 slopes (beyond 7-10 w% Sn, 1 st step is quick, 2 nd step is slow)

Silver bronze (Cu/Sn/Ag) Progressive passivationfor all solutions

- E KNO3>E EH>E SSAlmost no effect of Ag

Brass (Cu/Zn) Quick passivation (E corrgets stable between 5and 10 min.)

- E KNO3>E EH>E SS- In KNO3: decrease of E corr after a preliminary increase (10 min.) when cZn < 13w%- In HW and SS: 1 or 2 slopes (beyond 35 w% Zn, 1 st step is slow and 2 nd step is quick)

Tin brass (Cu/Zn/Sn) Quick passivation for all

solutions

- Quicker if cZn > 35w%

- In KNO3 and HSS: E corr is similar after 5 min.Leaded brass (Cu/Zn/Pb) Passivation for all

solutions- In HW and SS: E corr is more or less constant after 12min.- Poor reproducibility.

Nickel silver (Cu/Zn/Ni) Passivation - Slower passivation when cZn is between 24 and 37w%- 1 or 2 slopes

Quaternary alloy

(Cu/Sn/Zn/Pb)

Passivation - In most cases, E HW>ESS >EKNO3- In KNO3: 1 st values of E corr are very negative and slow passivation depending on the ratioCPb /CZn- Poor reproducibility

Cu/Be Progressive passivationfor all solutions

- E KNO3>E EH>E SS

Cu/Ni Depending on thesolution

- E KNO3>E EH>E SS- In HW: corrosion since E corr decreases steadily- In KNO3 and SS: passivation in 1 or 2 slopes

Cu/Ni/Al Depending on thesolution

- E KNO3>E EH>E SS- In HW: the passivation is favoured- In SS: more uncertain behaviour and passivation in KNO3


14/23


-220

-200

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-60

-40

0 2 4 6 8 10 12 14 16 18 20

Time (minutes)

Ecorr (mV/Ag-AgCl)

CuSn7.7

CuSn3.9Cu

CuSn14

Conc. Sn

CuSn10

In sodium sesquicarbonate

Tin bronzes: effect of Sn on the plots


15/23


16/23


Methodology followed on 2 examples

Condition survey

Stamped and cold worked:brass (35-40 Zn% (w/v) +Pb?

Cold worked: brass (30-40

Zn% (w/v))

Watch frame, IMH

Cartridge case, HAM


17/23


Use of the SPAMT-Test tool

On the watch frame

-300

-250

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-50

0

0 2 4 6 8 10 12 14 16

Temps (minutes)

Ecorr (mV/Ag-AgCl)

E78-MIH

CuZn39Pb1,6NiFe

-450

-400

-350

-300

-250

-200

-150

-100

-50

0

0 2 4 6 8 10 12 14 16

Temps (minutes)

Ecorr (mV/Ag-AgCl)

E78 - MIH

CuZn39Pb1,6NiFe

-550

-500

-450

-400

-350

-300

-250

-200

-150

-100

-50

0

0 2 4 6 8 10 12 14 16

Temps (minutes)

Ecorr (mV/Ag-AgCl)

E78-MIH

CuZn39Pb1,6

HW

KNO3

SS

Comments :

-Reproducible values;

-Measurements verysimilar to

CuZn39Pb1.6NiFe ofthe database;

-Higher potentials inSS at the start:certainly because ofthe remaining oxidelayer on the surfaceof the metal.


18/23

Leiden, 11-15 January 2010-400

-350

-300

-250

-200

-150

-100

-50

0

0 2 4 6 8 10 12 14 16Temps (minutes)

Ecorr (mV/Ag-AgCl)

E83-SAM

CuZn24,9

-300

-250

-200

-150

-100

-50

0

0 2 4 6 8 10 12 14 16

Temps (minutes)

Ecorr (mV/Ag-AgCl)

E83-SAM

CuZn24,9

-200

-180

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-140

-120

-100

-80

-60

-40

-20

0

0 2 4 6 8 10 12 14 16

Temps (minutes)

Ecorr (mV/Ag-AgCl)

E83-SAM

CuZn24,9

HW

KNO3

SS

Comments :

-Reproducible values;

-Measurements verysimilar to CuZn24.9

of the database;-Higher potentials inSS at the start:certainly because of

the remaining oxidelayer on the surfaceof the metal.

On the cartridge case


19/23


Composition proposedby the SPAMT-Test

tool

Composition obtainedby EDS

MIH E77 CuSn14Zn2.1 CuSn18Zn1.4FeMnMIH E78 CuZn39Pb1.6NiFe CuZn39Pb1.7

MIH E79 CuZn30-34 CuZn30SiNiFe

MIH E80 CuSn5.3Zn5.5Pb1.5NiFe CuSn4.3Zn24Pb2.9Fe

MIH E86 CuSn6Zn5.8PbNi CuSn9Zn6Pb1.5FeSi

HAM E37 CuZn30 CuZn30

HAM E81 CuZn5.3-7.8 CuZn8

HAM E82 CuZn30 CuZn30HAM E83 CuZn24.9 CuZn28

HAM E85 CuZn26Ni12Fe CuZn27Ni8

EDS analysis of the artefacts

Comparison

between proposalsand analysis:

-Rather accurate forbinary alloys

-Major elements arerevealed for alloyscontaining morethan one majorelements

To add to the database


20/23


Conclusion

The SPAMT-Test tool is adapted to the requirements ofconservation-restoration professionals:

-easy to use;-relatively non invasive;-easy to transport;-inexpensive.

Results :-Determination of the nature of the elements present inthe tested alloy;-In certain cases (binary alloys): accurate compositions ;-The precision of the tool depends on the databasecoverage.

Limitations :Need of a good surface preparation: adapted for technical,scientific, and horology objects which are rarely coveredwith a thick corrosion layer.


21/23


Throughout the project :measurements made by conservatorsspecialized in technical, scientific, andhorology objects (i.e. by potential end-users of the SPAMT-Test tool).

-Able to make initial suggestions

concerning the composition of theobjects (based on their technologicalknowledge of the objects and thematerials they are made of);

- Application of the ethics inconservation : minimal impact.

Input of end-users


22/23


23/23


Acknowledgements

-the Haute Ecole Spcialise de Suisse Occidentale (HES-SO -The University of Applied Sciences of Western Switzerland) forfinancially supporting the SPAMT-Test project,

-the research team at the Haute Ecole de Conservation-Restauration (HECR) Arc for their administrative support.

Colleagues who provided reference copper-basedmaterials for the construction of our database: A. Adriaens(Gent University, BE); K. Kreislova (SVUOM, Prague, CZ); L.Beck (Centre for Restoration and Conservation of FrenchMuseums, Paris, F); J. Muller (ICMPE-CECM, UPR 2801 / CNRS, Vitry-sur-Seine, F); G. Martin (Victoria & Albert Museum,

London, UK); L. Selwyn (CCI, Ottawa, Ca); P. Mottner (ISC,Bronnbach, D); M. Penna (Swissmetal, CH); T. Schenkel (HECRArc, La Chaux-de-Fonds, CH) and H. Habbeger (HAM, Thun,CH).

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Degrigny, C. Test. 2010

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