EN ISO 16773-4:2017

SLOVENSKI STANDARD
01-junij-2017
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SIST EN ISO 16773-4:2009
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Paints and varnishes - Electrochemical impedance spectroscopy (EIS) on coated and
uncoated metallic specimens - Part 4: Examples of spectra of polymer-coated and
uncoated specimens (ISO 16773-4:2017)
Elektrochemische Impedanzspektroskopie (EIS) an beschichteten und unbeschichteten
metallischen Proben - Teil 4: Beispiele für Spektren von polymerbeschichteten und
unbeschichteten Proben (ISO 16773-4:2017)
Spectroscopie d'impédance électrochimique (SIE) sur des éprouvettes métalliques
revêtues et non revêtues - Partie 4: Exemples de spectres d'éprouvettes revêtues de
polymères et non revêtues (ISO 16773-4:2017)
Ta slovenski standard je istoveten z: EN ISO 16773-4:2017
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 16773-4
EUROPEAN STANDARD
NORME EUROPÉENNE
April 2017
EUROPÄISCHE NORM
ICS 87.040 Supersedes EN ISO 16773-4:2009
English Version
Electrochemical impedance spectroscopy (EIS) on coated
and uncoated metallic specimens - Part 4: Examples of
spectra of polymer-coated and uncoated specimens (ISO
16773-4:2017)
Spectroscopie d'impédance électrochimique (SIE) sur Elektrochemische Impedanzspektroskopie (EIS) an
des éprouvettes métalliques revêtues et non revêtues - beschichteten und unbeschichteten metallischen
Partie 4: Exemples de spectres d'éprouvettes revêtues Proben - Teil 4: Beispiele für Spektren von
de polymères et non revêtues (ISO 16773-4:2017) polymerbeschichteten und unbeschichteten Proben
(ISO 16773-4:2017)
This European Standard was approved by CEN on 20 February 2017.

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, Serbia, 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
© 2017 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 16773-4:2017 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 16773-4:2017) 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 2017, and conflicting national standards shall
be withdrawn at the latest by October 2017.
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 16773-4:2009.
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, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 16773-4:2017 has been approved by CEN as EN ISO 16773-4:2017 without any
modification.
INTERNATIONAL ISO
STANDARD 16773-4
Second edition
2017-03
Electrochemical impedance
spectroscopy (EIS) on coated and
uncoated metallic specimens —
Part 4:
Examples of spectra of polymer-coated
and uncoated specimens
Spectroscopie d’impédance électrochimique (SIE) sur des éprouvettes
métalliques revêtues et non revêtues —
Partie 4: Exemples de spectres d’éprouvettes revêtues de polymères et
non revêtues
Reference number
ISO 16773-4:2017(E)
©
ISO 2017
ISO 16773-4:2017(E)
© ISO 2017, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
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Tel. +41 22 749 01 11
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copyright@iso.org
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ii © ISO 2017 – All rights reserved

ISO 16773-4:2017(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Theoretical background . 1
4.1 Basic considerations . 1
4.2 Examples of models . 2
4.2.1 Purely capacitive coating . 2
4.2.2 Randles equivalent circuit . 3
4.2.3 Extended Randles equivalent circuit . 3
Annex A (informative) Examples . 5
Annex B (informative) Composition of concentrated artificial rain water .35
Bibliography .36
ISO 16773-4:2017(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 voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO’s adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: w w w . i s o .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 35, Paints and varnishes, Subcommittee
SC 9, General test methods for paints and varnishes in collaboration with ISO/TC 156, Corrosion of metals
and alloys.
This second edition cancels and replaces the first edition (ISO 16773-4:2009), which has been
technically revised with the following changes.
a) The introductory element of the title, Paints and varnishes, has been omitted, because the scope has
been broadened to include metals and alloys. 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 and ASTM G106 for examples of spectra for low-impedance systems
(range from, e.g. 10 Ω to 1 000 Ω) has been added.
c) Examples for uncoated specimens have been added.
A list of all parts in the ISO 16773 series can be found on the ISO website.
iv © ISO 2017 – All rights reserved

INTERNATIONAL STANDARD ISO 16773-4:2017(E)
Electrochemical impedance spectroscopy (EIS) on coated
and uncoated metallic specimens —
Part 4:
Examples of spectra of polymer-coated and uncoated
specimens
1 Scope
This document gives some typical examples of impedance spectra of polymer-coated and uncoated
specimens (see Annex A). Some guidance on interpretation of such spectra is also given. Further
examples of spectra of low-impedance systems (range from, e.g. 10 Ω to 1 000 Ω) are given in
ISO/TR 16208 and in ASTM G106. ISO 16773-2 gives guidelines for optimizing the collection of EIS data
with focus on high-impedance systems.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. 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.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at http:// www .iso .org/ obp/
4 Theoretical background
4.1 Basic considerations
A basic introduction to electrochemical impedance spectroscopy, especially in connection with
corrosion, is given in ASTM G106.
It is not intended to limit the interpretation of EIS measurements to the models given below. Other
interpretations may be valid. The choice of the proper model requires other experimental and
theoretical considerations to be taken into account.
ISO 16773-4:2017(E)
4.2 Examples of models
4.2.1 Purely capacitive coating
A metal covered with an undamaged coating generally has a very high impedance. The equivalent
circuit for such a situation is shown in Figure 1.
Figure 1 — Equivalent circuit for a purely capacitive coating
The model includes a resistor representing the resistance R , of the solution and, connected in series
s
with it, a capacitor representing the capacitance C , of the coating.
c
In practice, the resistance of a perfect coating can often not be seen in the given frequency range. Any
deviation from the graph given in the Bode plot in Figure 2 indicates either a modified model or the
input limits of the impedance device (see ISO 16773-2:2016, Annex A).
Key
X1 frequency, f, in Hz X2 frequency, f, in Hz
Y1 impedance, Z, in Ω Y2 phase angle, φ, in degrees
Figure 2 — Bode plot for a perfect coating
2 © ISO 2017 – All rights reserved

ISO 16773-4:2017(E)
4.2.2 Randles equivalent circuit
The Randles equivalent circuit includes the resistance of the solution R , the capacitance of the coating
s
C and the ohmic resistance of the coating R , as shown in Figure 3.
c c
Figure 3 — Randles equivalent circuit
The Bode plot for a Randles equivalent circuit is shown in Figure 4.
Key
X logf (f in Hz)
Y1 log|Z| (Z in Ω)
Y2 |φ| (degrees)
1 impedance, Z
2 phase angle, φ
Figure 4 — Bode plot for a Randles equivalent circuit
4.2.3 Extended Randles equivalent circuit
Quite often, fitting experimental data to the model shown in Figure 3 results in systematic errors. In such
cases, the literature shows that it is possible to use the model shown in Figure 5 to obtain a better fit.
ISO 16773-4:2017(E)
Figure 5 — Extended Randles equivalent circuit
NOTE This model is not necessarily the most appropriate and other models are not excluded.
In most cases of high-impedance coatings, R and C are the charge-transfer resistance R and double-
B B ct
layer capacitance C , respectively, in the extended Randles circuit corresponding to properties of the
dl
coating rather than to corrosion processes in the underlying metal.
The Bode plot shown in Figure 6 clearly shows the additional contribution of these two added elements.
Again, the Bode plot does not go high enough in frequency to measure the solution resistance. In
practice, this is not a problem because the solution resistance is a property of the test solution and the
test cell geometry and not a property of the coating.
Key
X logf (f in Hz)
Y1 log|Z| (Z in Ω)
Y2 |φ| (degrees)
1 impedance, Z
2 phase angle, φ
Figure 6 — Bode plot for an extended Randles equivalent circuit
4 © ISO 2017 – All rights reserved

ISO 16773-4:2017(E)
Annex A
(informative)
Examples
A.1 General
This annex contains a collection of spectra obtained from materials described briefly in the relevant
clause. The examples were obtained from various laboratories using a range of different equipment and
materials.
This collection of spectra is not intended to imply that all the materials mentioned necessarily give
spectra similar to those shown or that the spectra given here are free of experimental errors. The
collection does not represent the complete range of coating materials.
A.2 Example 1
This example shows how a smaller than usual thickness of a high-build coating material can be used to
investigate the influence of immersion time on EIS measurements (see Figure A.1).
Details: Two-component epoxy coating, typically used for (maritime) steel constructions, above
and below the water level. Airless spray application. Dry film thickness (DFT) recommended by the
manufacturer: 1 000 µm to 3 000 µm.
Measurements were performed on one coat on steel, DFT 200 µm, on an area of 10 cm at 21 °C using
concentrated artificial rainwater (see Annex B). A vertical three-electrode setup, with a saturated
Ag/AgCl reference electrode, was used. Spectra were recorded after defined periods of immersion.
ISO 16773-4:2017(E)
Key
X frequency, f, in Hz
Y1 modulus of the impedance, |Z|, in Ω⋅cm
Y2 modulus of the phase angle, |φ|, in degrees
t = 0 h
t = 2 h
t = 24 h
t = 168 h
t = 504 h
Figure A.1 — Bode plot for a high-build coating material under immersion conditions
A.3 Example 2
This example concerns a surface-tolerant coating material which does not require the same amount of
surface pretreatment as that in Example 1 (see Figure A.2). Usually, de-rusting with mechanical tools is
used rather than grit blasting.
Details: Surface-tolerant two-component epoxy coating for (maritime) steel constructions, above and
below the water level, can be applied on corroded steel, grit-blasted steel and old (undamaged) paint
coatings. Application by airless spray, conventional spray, brushing or rolling. DFT recommended by the
manufacturer: 100 µm to 200 µm.
Measurements were performed on one coat on steel, DFT 250 µm, on an area of 10 cm at 21 °C using
concentrated artificial rainwater (see Annex B). A vertical three-electrode setup, with a saturated
Ag/AgCl reference electrode, was used. Spectra were recorded after defined periods of immersion.
6 © ISO 2017 – All rights reserved

ISO 16773-4:2017(E)
Key
X frequency, f, in Hz
Y1 modulus of the impedance, |Z|, in Ω⋅cm
Y2 modulus of the phase angle, |φ|, in degrees
t = 0 h
t = 2 h
t = 24 h
t = 168 h
t = 504 h
Figure A.2 — Bode plot for a surface-tolerant coating material under immersion conditions
A.4 Example 3
This example represents a high-build, solvent-free coating material with high abrasion resistance,
applied as a single coat (see Figure A.3).
Details: Solvent-free two-component epoxy coating for grit-blasted metals, concrete and fibreglass in
aggressive environments. High abrasion resistance and corrosion protection. Application by airless
spray or brush. DFT recommended by the manufacturer: 500 µm to 1 000 µm as one coat.
Measurements were performed on one coat on steel, DFT 230 µm, on an area of 10 cm at 21 °C using
concentrated artificial rainwater (see Annex B). A vertical three-electrode setup, with a saturated
Ag/AgCl reference electrode, was used. Spectra were recorded after defined periods of immersion.
ISO 16773-4:2017(E)
Key
X frequency, f, in Hz
Y1 modulus of the impedance, |Z|, in Ω⋅cm
Y2 modulus of the phase angle, |φ|, in degrees
t = 0 h
t = 2 h
t = 24 h
t = 168 h
t = 504 h
Figure A.3 — Bode plot for a solvent-free coating material under immersion conditions
A.5 Example 4
This example concerns a representative powder coating applied by spray on aluminium (see Figure A.4).
The quite large measurement area of 16,5 cm allowed a three-electrode setup to be used, but the
open-circuit potential was not delivered with the spectra. The discontinuities in the phase-angle plot
are due to potentiostat current range changes combined with the low capacitance of the system being
examined, indicating incorrect setting of the measurement device.
Details: Polyester powder coating material sprayed on chromatized
...