EN ISO 16773-2:2016

SLOVENSKI STANDARD
01-julij-2016
1DGRPHãþD
SIST EN ISO 16773-2:2007
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Paints and varnishes - Electrochemical impedance spectroscopy (EIS) on coated and
uncoated metallic specimens - Part 2: Collection of data (ISO 16773-2:2016)
Elektrochemische Impedanzspektroskopie (EIS) an beschichteten und unbeschichteten
Proben - Teil 2: Datenerfassung (ISO 16773-2:2016)
Spectroscopie d'impédance électrochimique (SIE) sur des éprouvettes métalliques
revêtues et non revêtues - Partie 2: Recueil des données (ISO 16773-2:2016)
Ta slovenski standard je istoveten z: EN ISO 16773-2:2016
ICS:
87.040 Barve in laki Paints and varnishes
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 16773-2
EUROPEAN STANDARD
NORME EUROPÉENNE
April 2016
EUROPÄISCHE NORM
ICS 87.040 Supersedes EN ISO 16773-2:2007
English Version
Electrochemical impedance spectroscopy (EIS) on coated
and uncoated metallic specimens - Part 2: Collection of
data (ISO 16773-2:2016)
Spectroscopie d'impédance électrochimique (SIE) sur Elektrochemische Impedanzspektroskopie (EIS) an
des éprouvettes métalliques revêtues et non revêtues - beschichteten und unbeschichteten metallischen
Partie 2: Recueil des données (ISO 16773-2:2016) Proben - Teil 2: Datenerfassung (ISO 16773-2:2016)
This European Standard was approved by CEN on 11 March 2016.

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 CEN-CENELEC 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 CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2016 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 16773-2:2016 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
European foreword
This document (EN ISO 16773-2:2016) has been prepared by Technical Committee ISO/TC 35 “Paints
and varnishes” in collaboration with Technical Committee CEN/TC 139 “Paints and varnishes” 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 October 2016, and conflicting national standards shall
be withdrawn at the latest by October 2016.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent
rights.
This document supersedes EN ISO 16773-2:2007.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 16773-2:2016 has been approved by CEN as EN ISO 16773-2:2016 without any
modification.
INTERNATIONAL ISO
STANDARD 16773-2
Second edition
2016-04-01
Electrochemical impedance
spectroscopy (EIS) on coated and
uncoated metallic specimens —
Part 2:
Collection of data
Spectroscopie d’impédance électrochimique (SIE) sur des éprouvettes
métalliques revêtues et non revêtues —
Partie 2: Recueil des données
Reference number
ISO 16773-2:2016(E)
©
ISO 2016
ISO 16773-2:2016(E)
© ISO 2016, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
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Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2016 – All rights reserved

ISO 16773-2:2016(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Electrochemical cell . 2
5.1 General . 2
5.2 Electrodes . 3
5.3 Exposed area . 3
5.4 Electrolyte . 3
6 Procedure. 4
6.1 Grounding . 4
6.2 Shielding . 4
6.3 Cell cable ground contacts . 4
6.4 Local conditions . 4
6.5 Measurement equipment characteristics . 5
6.6 Confidence test . . 5
6.6.1 General. 5
6.6.2 Use of interlaboratory test cells for confidence test . 6
6.6.3 Error estimate and accuracy . 6
6.7 Specimens . 6
6.7.1 Preconditioning of specimens . 6
6.7.2 Environmental control . 6
6.8 Evaluation of laboratory and field coating specimens . 6
6.9 Number of specimens and repeatability of results . 7
7 Instrumental parameters . 7
7.1 General . 7
7.2 Conditioning potential and conditioning time . 8
7.3 Frequency spectrum . 8
7.4 Data point spacing and points per decade . 8
7.5 D.C. potential control . 8
7.6 Amplitude of perturbation . . 9
7.7 Current range settings . 9
7.8 Data averaging settings . 9
8 Data presentation . 9
8.1 General . 9
8.2 Bode plot . 9
8.3 Nyquist plot.10
9 Exchange file format .11
10 Test report .11
Annex A (informative) Determination of maximum measurable impedance with the open-
lead test .13
Annex B (normative) Data exchange file format .15
Annex C (informative) Considerations about the precise determination of the exposed area .19
Bibliography .24
ISO 16773-2:2016(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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical
Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 35, Paints and varnishes, Subcommittee SC 9,
General test methods for paints and varnishes.
This second edition cancels and replaces the first edition (ISO 16773-2:2007), which has been
technically revised. The main changes are the following:
a) the introductory element of the title, Paints and varnishes, has been omitted, because the scope
is broadened to include metals and alloys and the main element of the title has been changed to:
Electrochemical impedance spectroscopy (EIS) on coated and uncoated metallic specimens;
b) a reference to ISO/TR 16208 has been added;
c) considerations about the precise determination of the exposed area have been added as an
informative annex;
d) a test report has been added.
ISO 16773 consists of the following parts, under the general title Electrochemical impedance spectroscopy
(EIS) on coated and uncoated metallic specimens:
— Part 1: Terms and definitions
— Part 2: Collection of data
— Part 3: Processing and analysis of data from dummy cells
— Part 4: Examples of spectra of polymer-coated and uncoated specimens
iv © ISO 2016 – All rights reserved

INTERNATIONAL STANDARD ISO 16773-2:2016(E)
Electrochemical impedance spectroscopy (EIS) on coated
and uncoated metallic specimens —
Part 2:
Collection of data
1 Scope
This part of ISO 16773 gives guidelines for optimizing the collection of EIS data with focus on high-
impedance systems. High impedance in the context of intact coatings refers to systems with an
9 2
impedance greater than 10 Ω⋅cm . This does not preclude measurements on systems with lower
impedance. For uncoated samples extra information can be found in ISO/TR 16208.
This part of ISO 16773 deals with the following:
— instrumental set-up: requirements and pit-falls;
— data validation: checking the measurement range and the accuracy of the data;
— performing an EIS measurement: specimen considerations and instrumental parameters;
— the experimental results: different methods of presenting EIS data.
These guidelines are intended to ensure the acquisition of EIS data that can be used to study the
performance of the specimen. This part of ISO 16773 does not give guidelines for the interpretation of
the data.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 16773-1, Electrochemical impedance spectroscopy (EIS) on coated and uncoated metallic specimens —
Part 1: Terms and definitions
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 16773-1 apply.
4 Principle
A so-called “confidence” test is described in order to check the suitability of the entire set-up
and recommendations are given as to how to perform EIS experiments. For convenience, only
potentiostatically controlled EIS measurements are described, although it is also possible to make EIS
measurements under galvanostatic control.
A potentiostat is connected either to a dummy cell or to an electrochemical cell (with working,
counter- and reference electrodes). A single-sinusoidal- or multi-sinusoidal-waveform potential,
either in conjunction with a d.c. offset or not, is applied by the potentiostat to the dummy cell or to the
electrochemical cell, and the resulting a.c. current is measured. Both potential and a.c. current data are
collected and analysed for amplitude and phase shift. This can be done in a variety of ways, depending
ISO 16773-2:2016(E)
on the type of equipment used. All data are presented and compared graphically or computed for
equivalent circuits. In the case of the dummy cell, the values of these equivalent components are
compared to the actual cell components connected to the potentiostat and evaluated for coherence.
5 Electrochemical cell
5.1 General
NOTE 1 Various types of measurement cell exist which are suitable for use with this part of ISO 16773.
Most commonly used are two-electrode and three-electrode arrangements for measurements in an aqueous
electrolyte.
The cell shall be constructed of materials that will not corrode, otherwise deteriorate or contaminate
the solution (e.g. PMMA, PTFE or glass). A material compatibility test should be carried out.
The cell shall be leak-proof to ensure that the geometrical surface of the specimen does not change
with time. Use an electrically insulating gasket material (O-ring, etc.) for the seal, i.e. with a through-
thickness resistance much greater than that of the coating.
The cell should preferably be designed to allow the following items to be inserted into the electrolyte
chamber: the working electrode, the reference electrode, the counter-electrode, a thermometer (for
temperature control) and gas inlet/outlet tubes to modify the oxygen content of the electrolyte. When
using an inert gas, a gas scrubber should be used.
An example of an electrochemical cell is shown in Figure 1.
Key
1 reference electrode
2 counter electrode
3 electrolyte
4 O-ring
5 coating
6 working electrode
Figure 1 — Example of an electrochemical cell
NOTE 2 Other designs can be suitable.
For uncoated metallic specimens, IR drop should be considered.
2 © ISO 2016 – All rights reserved

ISO 16773-2:2016(E)
The components shown in Figure 1 are described in 5.2 to 5.4.
5.2 Electrodes
To perform EIS in aqueous solution, the more conventional set-up is composed of a three-electrode
arrangement: a working electrode, a reference electrode and a counter-electrode.
Working electrode: A conductive substrate covered by the coating to be investigated. A large surface
area is preferred to better take into account any defects and to decrease the impedance of the system to
give a better signal-to-noise ratio.
Counter electrode: Inert material such as platinum with a large surface area oriented parallel to the
working electrode in order to ensure a homogeneous current distribution.
Reference electrode: A low-impedance and low-noise reference electrode is recommended, according
to supplier’s user manual [when testing organic coatings, a salt bridge (e.g. Luggin capillary) is not
required]. The potential of the reference electrode should be checked periodically to control the
accuracy of the electrode and its stability with time. At very high frequencies, the presence of the
reference electrode can induce some spurious effects.
NOTE 1 To improve the quality of the high-frequency signal, a platinum wire with a capacitor may be placed in
parallel with the reference electrode. The capacitor ensures that the d.c. potential is coming from the reference
electrode and a.c. potential from the platinum wire.
NOTE 2 For specific applications, it can be acceptable to use a pseudo-reference electrode consisting of an
inert material such as a high-nickel alloy or a chloridized silver wire. Pseudo-reference electrodes are useful for
measurements in the field, where a reference electrode can be easily broken.
5.3 Exposed area
The exposed area should be known, constant with time, and should be adequate for the investigation.
The larger the exposed area the more sensitive the measurement is to single defects (pores) and the
better the signal-to-noise ratio.
If an O-ring is used, the precise exposed area shall be determined under compression (see Annex C for a
recommended technique).
NOTE For example, when using an O-ring with a diameter of 1,2 cm and an approximate exposed area of
1,13 cm², an error of up 37 % can occur. When using an O-ring with a diameter of 4,7 cm and an approximate
exposed area of 18 cm², an error of up 8 % can occur.
It is recommended that the user selects the largest possible area without defects. A typical area is in the
order of magnitude of 10 cm².
5.4 Electrolyte
The resistance of the solution should be low in comparison to the impedance of the investigated system.
Different types of electrolyte can be used. Non-aggressive electrolytes can be employed to characterize
the properties of the system without introducing corrosion. An aggressive solution may be selected to
characterize the corrosion resistance of the system. The electrolyte should be chosen with the end use
in mind.
NOTE 1 For the desired end-use, the pH value, the concentration and the composition of the electrolyte might
be important parameters.
When the oxygen content is influencing the corrosion, the preconditioning has to be chosen in a way
that a steady state is established.
NOTE 2 Purging with oxygen or an inert gas could be necessary to obtain steady state condition.
ISO 16773-2:2016(E)
6 Procedure
6.1 Grounding
An EIS instrument consists of a potentiostat, a computer and a module or instrument specifically
required for the impedance measurement.
Electrical grounding considerations between the instruments, the specimen and the environment are
important, both for the safety of the operator and the acquisition of as accurate and noise-free EIS data
as possible.
a) The safety of the operator is important. The chassis of the EIS instrument should be connected to
ground to avoid a potentially lethal electrical shock if the instrument malfunctions. The chassis is
normally grounded through the connection to the a.c. mains. Under no circumstances should this
connection to ground be bypassed.
b) In most cases, the coated specimen is tested in the laboratory in an electrochemical cell such as
that described in 5.1 in which the specimen is electrically isolated from ground, or “floating”. This
is the simplest case with no special consideration needed for connection of the instrument to the
specimen.
c) If, however, the coated specimen is grounded, then the grounding considerations become more
complex. This could happen if EIS is used to test coated structures in a field, such as vessels or
pipelines. If the coated specimen is grounded, then the EIS instrument should be electrically
isolated from ground to obtain accurate EIS data. This is not a trivial consideration and is generally
taken into account during the design of the EIS system. Floating the EIS system by bypassing the
protective ground connection to the mains is a safety hazard and is not acceptable.
d) When connecting up the various instruments and computers, it is possible to inadvertently ground
a floating instrument through the connection to a grounded instrument. This can give rise to noise
through “ground loops” or even result in improper operation.
6.2 Shielding
Shielding is very important for noise considerations in EIS measurements of high-impedance specimens.
Proper shielding will ensure that the cell electrodes and cables will not pick up electromagnetic
radiation from the surroundings. The electrochemical cell should be placed inside a Faraday cage and
the Faraday cage connected to an appropriate ground connection of the potentiostat. If the potentiostat
has an externally mounted electrometer, the electrometer should also be put inside the Faraday cage.
The manufacturer’s manual should be consulted to ensure proper wiring.
6.3 Cell cable ground contacts
The connections between the cell cables and the cell should be clean and the length of the cables should
be as short as possible to minimize stray capacitance.
6.4 Local conditions
The following conditions in the vicinity of the EIS experiment can affect the quality of the measurement.
a) The incoming a.c. power to the EIS instrument can be noisy or exhibit large voltage transients, both
of which can result in noise in the electrochemical data. If severe, the user may install an a.c. line
conditioner. The raw potential and current data are usually averaged by the EIS instrument and are
not as susceptible to line noise as d.c. experiments.
b) Electromagnetic noise from electrical devices (e.g. computer monitors) in the local vicinity of
the EIS experiment can also contribute to noise in the experiment. Again, data processing will
discriminate against this noise. Instruments or appliances that operate intermittently (e.g. freezers,
ovens, ultrasonic cleaners, magnetic stirrers, water baths) are particularly troublesome because
4 © ISO 2016 – All rights reserved

ISO 16773-2:2016(E)
they can introduce noise in the electrical circuit when they are activated. These devices should be
operated on a different circuit, if possible. Because of the low current levels which are typically
observed in EIS experiments on coated specimens, the specimen should always be contained in a
Faraday cage that is connected to the appropriate instrument ground.
c) The relative humidity in the environment can also be of concern. If the relative humidity is high,
then micro-condensation can occur in the electronics of the EIS instrument, providing a low-
impedance leakage path. At the low current levels typically encountered in EIS experiments on
coated specimens, this can result in errors in the current measurement.
6.5 Measurement equipment characteristics
An electrochemical cell has impedance values that can range from 1 mΩ to more than 1 TΩ (10 Ω).
The measured impedance of coated specimens can range up to 10 Ω.
A specimen with high impedance will exhibit very low current flow during the EIS experiment.
Therefore, the instrument used to measure the EIS of coated specimens needs to be capable of
measuring these low currents. The test described in 6.6 is useful to make sure an EIS instrument is
capable of measuring coated specimens.
All equipment should be able to measure the dummy cell described in 6.6.1.
Sometimes, it might be desirable to perform an open-lead test in order to find the limits of the entire
set-up under the given conditions. A method of estimating the maximum measurable impedance with
the open-lead test is given in Annex A.
NOTE EIS measurements on high-impedance coatings are not limited to the above-mentioned cell designs.
6.6 Confidence test
6.6.1 General
In order to obtain confidence in the entire experimental set-up, it is recommended that a confidence test
be carried out prior to measurements of real specimens. Confidence can be obtained by carrying out
reference tests using hard-wired dummy circuits with known values for capacitance and resistance.
These values should be in the order of magnitude which can be expected for the actual coated specimen
under investigation. As high-impedance coatings easily reach values of several gigaohms, combined
with low capacitance of about 100 pF, it is recommended that the circuit in Figure 2 be used as a
reference.
Rs
R1
Key
R1 50 GΩ
C1 150 pF
Rs 50 Ω
Figure 2 — Dummy cell for confidence test
...