SIST EN ISO 10271:2002
(Main)Dental metallic materials - Corrosion test methods (ISO 10271:2001)
Dental metallic materials - Corrosion test methods (ISO 10271:2001)
Migrated from Progress Sheet (TC Comment) (2000-07-10): New TD given by Keller's email on 980824 (TA/980826)
Dentale metallische Werkstoffe - Korrosionsprüfverfahren (ISO 10271:2001)
Diese Internationale Norm legt Prüfverfahren und Prüfpläne zur Bestimmung des Korrosionsverhaltens aller metallischer Werkstoffe fest, die in der restaurativen Zahnheilkunde, der Prothetik und der Kieferorthopädie in der Mundhöhle verwendet werden, einschließlich gegossener, maschinell hergestellter und vorgefertigter Produkte.
Diese Internationale Norm gilt nicht für Instrumente und Geräte.
Produits dentaires métalliques - Méthodes pour les essais de corrosion (ISO 10271:2001)
La présente Norme internationale spécifie des méthodes et des protocoles d'essai permettant de déterminer le comportement à la corrosion de tous les produits métalliques utilisés en dentisterie, notamment en restauration, prothétique et orthodontie, dans la cavité buccale, y compris les dispositifs coulés, usinés et préfabriqués. La présente Norme internationale n'est applicable ni aux instruments, ni aux appareils.
Dental metallic materials - Corrosion test methods (ISO 10271:2001)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 10271:2002
01-maj-2002
Dental metallic materials - Corrosion test methods (ISO 10271:2001)
Dental metallic materials - Corrosion test methods (ISO 10271:2001)
Dentale metallische Werkstoffe - Korrosionsprüfverfahren (ISO 10271:2001)
Produits dentaires métalliques - Méthodes pour les essais de corrosion (ISO
10271:2001)
Ta slovenski standard je istoveten z: EN ISO 10271:2001
ICS:
11.060.10 =RERWHKQLþQLPDWHULDOL Dental materials
SIST EN ISO 10271:2002 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN ISO 10271:2002
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SIST EN ISO 10271:2002
EUROPEAN STANDARD
EN ISO 10271
NORME EUROPÉENNE
EUROPÄISCHE NORM
June 2001
ICS 01.006.10
English version
Dental metallic materials - Corrosion test methods (ISO
10271:2001)
Produits dentaires métalliques - Méthodes pour les essais Dentale metallische Werkstoffe - Korrosionsprüfverfahren
de corrosion (ISO 10271:2001) (ISO 10271:2001)
This European Standard was approved by CEN on 1 June 2001.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the Management Centre has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,
Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2001 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 10271:2001 E
worldwide for CEN national Members.
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SIST EN ISO 10271:2002
EN ISO 10271:2001 (E)
CORRECTED 2001-10-31
Foreword
The text of the International Standard ISO 10271:2001 has been prepared by Technical Committee ISO/TC 106
"Dentistry" in collaboration with Technical Committee CEN/TC 55 "Dentistry", the secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an identical text or by
endorsement, at the latest by December 2001, and conflicting national standards shall be withdrawn at the latest by
December 2001.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries
are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France,
Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland
and the United Kingdom.
Endorsement notice
The text of the International Standard ISO 10271:2001 was approved by CEN as a European Standard without any
modification.
NOTE: Normative references to International Standards are listed in annex ZA (normative).
2
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SIST EN ISO 10271:2002
EN ISO 10271:2001 (E)
Annex ZA (normative)
Normative references to international publications
with their relevant European publications
This European Standard incorporates by dated or undated reference, provisions from other publications.
These normative references are cited at the appropriate places in the text and the publications are listed
hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply
to this European Standard only when incorporated in it by amendment or revision. For undated references
the latest edition of the publication referred to applies (including amendments).
NOTE Where an International Publication has been modified by common modifications, indicated by (mod.),
the relevant EN/HD applies.
Publication Year Title EN Year
ISO 1562 1993 Dental casting gold alloys EN ISO 1562 1995
ISO 3696 1987 Water for analytical laboratory use – EN ISO 3639 1995
Specification and test methods
ISO 8891 1998 Dental casting alloys with noble metal EN ISO 8891 1998
content of at least 25 % but less than
75 %
ISO 9333 1990 Dental brazing alloys EN 29333 1991
ISO 9693 2000 Metal-ceramic dental restorative sytems EN ISO 9693 2000
3
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SIST EN ISO 10271:2002
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SIST EN ISO 10271:2002
INTERNATIONAL ISO
STANDARD 10271
First edition
2001-06-01
Dental metallic materials — Corrosion test
methods
Produits dentaires métalliques — Méthodes pour les essais de corrosion
Reference number
ISO 10271:2001(E)
©
ISO 2001
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SIST EN ISO 10271:2002
ISO 10271:2001(E)
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ii © ISO 2001 – All rights reserved
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SIST EN ISO 10271:2002
ISO 10271:2001(E)
Contents Page
Foreword.iv
Introduction.v
1 Scope .1
2 Normative references .1
3 Terms and definitions .1
4 Test methods.3
Annex A (informative) Corrosion test method development .12
Bibliography.18
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SIST EN ISO 10271:2002
ISO 10271:2001(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO
member bodies). The work of preparing International Standards is normally carried out through ISO technical
committees. Each member body interested in a subject for which a technical committee has been established has
the right to be represented on that committee. International organizations, governmental and non-governmental, in
liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 10271 was prepared by Technical Committee ISO/TC 106, Dentistry, Subcommittee
SC 2, Prosthodontic materials.
This first edition cancels and replaces ISO/TR 10271:1993 which has been technically revised, in particular by the
inclusion of a wider range of test methods.
Annex A of this International Standard is for information only.
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SIST EN ISO 10271:2002
ISO 10271:2001(E)
Introduction
ISO 10271 was developed from the original Technical Report (ISO/TR 10271) as a result of worldwide demand for
standard test methods to determine acceptability of metallic materials for oral restorations in relation to corrosion.
The testing of the corrosion behaviour of metallic materials in dentistry is complicated by the diversity of the
materials themselves, their applications and the environment to which they are exposed. Variation occurs between
devices and within the same device during the exposure time. The type of corrosion behaviour or effect may also
vary with exposure time. Accordingly, it is not possible to specify a single test capable of covering all situations, nor
is it a practical proposition to define a test for each situation. This International Standard therefore gives detailed
protocols for test methods which have been found to be of merit as evidenced by considerable use.
In addition, an informative annex (annex A) is provided that sets out a protocol for each element of the test system
such that a consistent approach may be taken for the development of further test methods. Equally, it is recognized
that any element can only represent the current recommendation, but changes in the future are unlikely to change
the framework
It is not the purpose of this International Standard to propose corrosion test methods for specific applications or to
set limits as precise as those in the standard relating to the type of product and its application.
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SIST EN ISO 10271:2002
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SIST EN ISO 10271:2002
INTERNATIONAL STANDARD ISO 10271:2001(E)
Dental metallic materials — Corrosion test methods
1 Scope
This International Standard provides test methods and protocols to determine the corrosion behaviour of all metallic
materials used in restorative, prosthetic and orthodontic dentistry in the oral cavity, including cast, machined and
prefabricated devices.
This International Standard is not applicable to instruments and appliances.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this International Standard are encouraged to
investigate the possibility of applying the most recent editions of the normative documents indicated below. For
undated references, the latest editions of the normative documents referred to applies. Members of ISO and IEC
maintain registers of currently valid International Standards.
ISO 1562, Dental casting gold alloys.
ISO 3585, Borosilicate glass 3.3 — Properties.
ISO 3696:1987, Water for analytical laboratory use — Specification and test methods.
ISO 7183-2:1996, Compressed air dryers — Part 2: Performance ratings.
ISO 8891, Dental casting alloys with noble metal content of at least 25 % but less than 75 %.
ISO 9333, Dental brazing materials.
ISO 9693, Metal-ceramic dental restorative systems.
3 Terms and definitions
For the purposes of this International Standard, the following terms and definitions apply.
3.1
breakdown potential
E
p
least noble potential at which pitting or crevice corrosion, or both, will initiate and propagate
3.2
corrosion
physicochemical interaction between a metal or an alloy and its environment that results in a partial or total
destruction of the material or in a change of its properties
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SIST EN ISO 10271:2002
ISO 10271:2001(E)
3.3
corrosion potential
E
corr
open-circuit potential measured under either service conditions or laboratory conditions that closely approximate to
service conditions
3.4
corrosion product
substance formed as a result of corrosion
3.5
crevice corrosion
corrosion associated with and taking place in or near a narrow aperture or crevice
3.6
current density
value of electric current per unit surface area flowing through a conductor
3.7
electrochemical corrosion
degradation occurring in an electrolyte as a result of electrochemical reactions
3.8
electrolyte
solution or liquid which will conduct an electrical current by means of ions
3.9
electrode potential
potential difference between the sample and a reference electrode
3.10
dynamic immersion test
test in which the sample is exposed to a corrosive solution under conditions of relative motion between sample and
solution
3.11
static immersion test
test in which the sample is exposed to a corrosive solution under conditions of minimum relative motion between
sample and solution
3.12
open-circuit potential
E
ocp
potential of an electrode measured with respect to a reference electrode or another electrode when no current
flows
3.13
pitting corrosion
localized corrosion which results in pits
3.14
potentiodynamic test
test in which the electrode potential is varied at a pre-programmed rate and the relationship between current
density and electrode potential is recorded
3.15
potentiostatic test
test in which the electrode potential is maintained constant
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SIST EN ISO 10271:2002
ISO 10271:2001(E)
3.16
stress corrosion
corrosion resulting from the combined action of static tensile stress and an electrolyte
3.17
synthetic saliva
test medium that simulates natural saliva
3.18
tarnish
surface discolouration due to the interaction between metal and its environment
3.19
zero-current potential
potential at which cathodic and anodic currents are equal
4 Test methods
4.1 Static immersion test
4.1.1 Information required
Composition, including hazardous elements, in accordance with the appropriate ISO material standard.
4.1.2 Application
Dental metallic materials and devices covered by the scope of ISO 1562, ISO 8891, ISO 9333 or ISO 9693.
4.1.3 Reagents
4.1.3.1 Lactic acid (C H O ), 90 % analytical grade.
3 6 3
4.1.3.2 Sodium chloride (NaCl), analytical grade.
4.1.3.3 Water, complying with grade 2 of ISO 3696:1987.
4.1.3.4 Ethanol or methanol (C H OH or CH OH), analytical grade.
2 5 3
4.1.4 Apparatus
4.1.4.1 Borosilicate glass container, complying with ISO 3585.
4.1.4.2 pH meter.
4.1.4.3 Analytical instrumentation.
4.1.4.4 Micrometer.
4.1.5 Solution preparation
Prepare a fresh immersion solution for each test. Dissolve 10,0� 0,1 g 90 % C H O (4.1.3.1) and 5,85� 0,005 g
3 6 3
NaCl (4.1.3.2) in approximately 300 ml of water (4.1.3.3). Dilute to 1 000 � 10 ml with water. The pH shall be
2,3 � 0,1. If not, the solution shall be discarded and reagents checked.
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SIST EN ISO 10271:2002
ISO 10271:2001(E)
4.1.6 Samples
4.1.6.1 Fabrication
4.1.6.1.1 Casting alloys
Samples shall be cast in accordance with the manufacturer's recommendations.
4.1.6.1.2 Prefabricated
Prefabricated parts/devices shall be used in the as-received condition.
4.1.6.1.3 Other
Samples prepared by other methods, e.g. machined, sintered, eroded, etc., shall be tested in the as-manufactured
condition after suitable cleaning.
4.1.6.2 Number of samples
The number of samples shall be sufficient to provide at least two parallel sets. (The number of specimens in a set
can vary.)
4.1.6.3 Size
2
The total surface area of samples shall be at least 10 cm .
4.1.6.4 Preparation
4.1.6.4.1 Cast samples
Remove any sprues, runners or other projections from sample surface. Blast surfaces with 125�m pure alumina.
If recommended, heat-treat casting alloys following the manufacturer's instructions. Heat-treat all metal-ceramic
alloys for 10 min in air at the highest firing temperature recommended by the ceramic manufacturer (i.e. within the
range of 800 °C to 950 °C) and bench cool.
Remove at least 0,1 mm from each surface using standard metallurgical procedures unless samples are to be
tested in the as-received condition. Use fresh abrasive paper for each alloy. Finish with ASTM 600 or FEPA 1200
wet silicon carbide paper. Determine each sample area to the nearest 1 %. Clean surfaces ultrasonically for 2 min
in ethanol or methanol (4.1.3.4).
Rinse with water (4.1.3.3). Dry with oil- and water-free compressed air in accordance with ISO 7183.
4.1.6.4.2 Machined, sintered, eroded or electroformed samples
Heat-treat the samples if recommended.
Remove at least 0,1 mm, measured using a measuring instrument accurate to 0,01 mm [e.g. micrometer (4.1.4.4)]
from each surface using standard metallurgical procedures. If the samples are prefabricated parts these shall be
tested in the as-received condition. Use fresh abrasive paper for each alloy. Finish with ASTM 600 or FEPA 1200
2
wet silicon carbide paper. Determine each sample area to � 0,1 cm .
Clean surfaces ultrasonically for 2 min in ethanol or methanol. Rinse with water (4.1.3.3). Dry with oil- and water-
free compressed air.
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SIST EN ISO 10271:2002
ISO 10271:2001(E)
4.1.6.4.3 Prefabricated parts/devices
2
Determine each sample area to the nearest � 0,1 cm . Clean the surfaces ultrasonically for 2 min in ethanol or
methanol. Rinse with water (4.1.3.3). Dry with oil- and water-free compressed air.
4.1.7 Test procedure
Place each sample in a separate glass container (4.1.4.1) approximately 16 mm diameter � approximately 160 mm
such that the samples do not touch the glass surface except in a minimum support line or point. If a sample is
made up of two or more pieces, the pieces shall not touch each other.
Record the pH of the solution. Add the solution to each container sufficient to produce a ratio of 1 ml of solution
2
per 1 cm of sample surface area. Record the volume of solution to an accuracy of 0,1 ml. Close the container to
prevent evaporation of the solution. Maintain at 37 °C� 1 °Cfor 7d� 1 h. Remove the samples and record the pH
of the residual solution.
4.1.8 Elemental analysis
Use analytical instrumentation (4.1.4.3) of adequate sensitivity. Analyse the solution qualitatively and quantitatively.
Emphasis shall be on those elements listed in 4.1.1 but if impurities are found in a concentration greater than
0,1 %, they shall also be reported.
4.1.9 Test report
Report the method of analysis and detection limits of all observed elements. Report and justify any deviations from
sample preparation, 4.1.6.4, or test procedure, 4.1.7. Report the number of specimens making up a sample. Report
2
each element of each test separately in �g/cm �7 days. Each element listed in accordance with 4.1.1 shall be
reported as well as any others found.
4.2 Electrochemical test
4.2.1 Information required
Composition, including hazardous elements, in accordance with the appropriate material standard.
4.2.2 Application
Dental metallic materials and devices covered by the scope of ISO 1562, ISO 8891, ISO 9333 or ISO 9693.
4.2.3 Reagents
4.2.3.1 Lactic acid (C H O ), 90 % analytical grade.
3 6 3
4.2.3.2 Sodium chloride (NaCl), analytical grade.
4.2.3.3 Sodium hydroxide (NaOH), analytical grade.
4.2.3.4 Water, complying with grade 2 of ISO 3696:1987.
�6
4.2.3.5 Argon or nitrogen gas, with oxygen contentu 5 � 10 .
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SIST EN ISO 10271:2002
ISO 10271:2001(E)
4.2.4 Apparatus
4.2.4.1 Temperature-controlled borosilicate glass test cell, complying with ISO 3585 (a double-walled cell
is unnecessary if the test is carried out at 23 °C � 2 °C).
–9 –1
4.2.4.2 Scanning potentiostat, potential range� 1 600 mV, current output range 10 Ato10 A.
11
4.2.4.3 Potential measuring instrument, with input impedance � 10 � and sensitivity/accuracy able to
detect a change of 1 mV over a potential change of �1600mV.
4.2.4.4 Current-measuring instrument, capable of measuring a current to within 1 % of the absolute value
–9 –1
over a current range between 10 A and 10 A.
4.2.4.5 Working electrode (sample holder).
4.2.4.6 Counter electrode(s), composed of high purity vitreous carbon or platinum.
4.2.4.7 Reference electrode, either saturated calomel electrode (SCE) or Ag/AgCl electrode (saturated silver
chloride electrode [SSE]).
4.2.4.8 pH meter.
4.2.5 Electrolyte preparation
Dissolve 9,0 g NaCl (4.2.3.2) in approximately 950 ml water (4.2.3.4). Adjust to pH 7,4� 0,1 using 1 % C H O
3 6 3
(4.2.3.1) or 4 % NaOH (4.2.3.3). Dilute with water to 1 000 ml.
4.2.6 Sample
4.2.6.1 Fabrication
4.2.6.1.1 Casting alloys
Samples shall be cast in accordance with the manufacturer’s recommendations.
4.2.6.1.2 Prefabricated samples
Prefabricated parts/devices shall be used in the as-received condition.
4.2.6.1.3 Other
Samples prepared by other methods, e.g. machined, sintered, eroded, etc., shall be tested in the as-manufactured
condition after suitable cleaning.
4.2.6.2 Number of samples
At least four samples shall be tested and these may be cut from one cast rod.
4.2.6.3 Size
2
The surface area of the samples shall be not less than 0,1 cm .
4.2.6.4 Preparation
If the sample is cast, blast its surfaces with 125�m pure alumina to remove investment.
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SIST EN ISO 10271:2002
ISO 10271:2001(E)
Heat substrate alloys for ceramic veneering for 10 min in air at the highest firing temperature recommended by the
manufacturer of the ceramic (800 °Cto950 °C) and bench cool. If recommended, heat-treat casting alloys
following manufacturer's instructions.
Samples shall be prepared with one flat surface exposed. A suitable contact shall be provided for connection to the
electrochemical apparatus.
The working electrode shall be prepared in a way that ensures the absence of crevices. The recommended
procedure is that of embedding in epoxy or acrylic resin, which does not exhibit loss of electrical insulation during
immersion. Instead of embedding, a sample holder (4.2.4.5) may be used if the absence of crevices is confirmed
by sample examination after the test.
Use fresh paper for each alloy. Remove at least 0,1 mm from the free surface. Use a measuring instrument
(micrometer) to measure the change in thickness. Finish using standard metallurgical procedures with wet silicon
carbide papers, ending with 1�m diamond paste.
Examine with a light microscope at � 50 for cracks or crevices at the sample/resin interface. Replace the sample if
2
any cracks or crevices are found. Determine the exposed area of the sample to an accuracy of 0,01 cm . Clean
surfaces ultrasonically for 2 min in water. Store in water (4.1.3.3) until transfer to test cell.
4.2.7 Test procedure
An example of an electrochemical measuring circuit is shown in Figure 1.
An example of an electrolytic cell is shown in Figure 2.
Key
a
1 Potentiostat
Current measurement
b
2 Counter electrode
Potential measurement
3 Reference electrode
4 Working electrode
Figure 1 — Schematic diagram of measuring circuit
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SIST EN ISO 10271:2002
ISO 10271:2001(E)
Key
1 Thermometer 6 Reference electrode (saturated calomel electrode) [SCE] 11 Magnetic agitator (motor)
2 Counter electrode 7 Saturated solution of KCl 12 Double-walled vessel
3 Working electrode 8 Lugging capillary 13 Electrolyte
4 Gas outlet 9 Magnetic stirrer (PTFE-coated) 14 Water outlet
5 Electrolytic bridge 10 Water inlet 15 Bubbler (using nitrogen)
Figure 2 — Schematic diagram of electrolytic cell
Fill test cell with electrolyte.
Test at room temperature (23 °C � 2 °C). If there is a phase transition between room temperature and 37 °C, then a
test temperature of 37 °C � 1 °C shall be used.
Place counter electrode(s) in the test cell followed by the reference electrode. Then place the working electrode in
the test cell without immersion. Activate the magnetic stirrer. Bubble oxygen-free nitrogen or argon at a rate of
3 –1
about 100 cm min through the electrolyte for at least 30 min. Immerse the working electrode in the electrolyte.
Adjust the reference electrode. Adjust gas flowrate to give a slight bubbling. Begin measurement procedure.
4.2.7.1 Open-circuit potential measurement
Record the open-circuit potential vs. time curve for 2 h. Determine the open-circuit potential (E )in mV (SCE)
ocp
after immersion for 2 h� 6 min. An example of a potential vs. time curve is shown in Figure 3.
4.2.7.2 Potential measurements (anodic polarization)
Start the potentiodynamic scan 5 min after finishing the open-circuit potential measurement at E minus 150 mV.
ocp
–1 –3 –2
The potentiodynamic sweep rate should be 1 mV�s up to a current density of 10 A�cm or a potential of
� 1 000 mV (SCE) [or breakdown potential (E ) � 300 mV]. Record the curve of potential vs. logarithm of current
p
density. A reverse scan back to the original potential may be used to obtain information on pitting corrosion. An
example of a potential vs. log current density curve is shown in Figure 4.
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SIST EN ISO 10271:2002
ISO 10271:2001(E)
Figure 3 — Open-circuit potential vs time
Figure 4 — Log current density vs potential
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SIST EN ISO 10271:2002
ISO 10271:2001(E)
4.2.8 Test report
The test report shall contain the following information:
a) identity of the test alloy;
b) details of heat-treatment, if applicable;
c) test temperature (23 °C � 2 °C);if37 °C is used, the reason for this choice;
d) description of any deviations from sample preparation or test procedure;
e) open circuit potential (E )inmV(SCE);
ocp
f) potential vs. log current density curve or potential vs. current density curve;
g) zero current potential E in mV (SCE);
z
–2
h) breakdown potential E in mV (SCE), with the corresponding current density I in A�cm ;
p p
–2
i) active peak potentials E in mV (SCE) between E and E with the corresponding current density I in A�cm ;
c z p c
–2
j) current density I in A�cm at potential of (E � 300) mV (SCE);
300 z
k) description of any significant changes of the electrolyte or the alloy surface.
If a reference electrode other than a saturated calomel electrode (SCE) is used, the reported potential values shall
be converted to mV (SCE).
4.3 Tarnish test (cyclic immersion)
4.3.1 Information required
Composition, including hazardous elements in accordance with the appropriate ISO material standard.
4.3.2 Application
This test method is applicable only to noble and low noble alloys, e.g. alloys containing silver, copper and/or gold.
4.3.3 Reagents
4.3.3.1 Sodium sulfide hydrate (approximately 35 % Na S), analytical grade.
2
4.3.3.2 Water, complying with grade 2 of ISO 3696:1987.
4.3.3.3 Ethanol or methanol (C H OH or CH OH), analytical grade.
2 5 3
4.3.4 Apparatus
4.3.4.1 Dipping device, that dips each sample in the test solution for 10 s to 15 s every minute with the
temperature controlled at 23 °C� 2 °C.
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SIST EN ISO 10271:2002
ISO 10271:2001(E)
4.3.5 Solution preparation
Prepare a fresh solution for each test. Dissolve 22,3 g sodium sulfide hydrate (4.3.3.1) in water. Dilute to 1 000 ml
with water.
4.3.6 Samples
4.3.6.1 Fabrication
Fabricate the samples in accordance with the manufacturer’s recommendations.
4.3.6.2 Number of samples
At least two samples shall be tested.
4.3.6.3 Size
2
The surface area of the samples shall be approximately 1 cm .
4.3.6.4 Preparation
Remove any sprues, runners or other projections from sample surface. Blast surfaces with 125�m pure alumina.
If recommended, heat-treat casting alloys following the manufacturer's instructions. Heat-treat all metal-ceramic
all
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