ISO 11997-3:2022

INTERNATIONAL ISO
STANDARD 11997-3
First edition
2022-07
Paints and varnishes — Determination
of resistance to cyclic corrosion
conditions —
Part 3:
Testing of coating systems on
materials and components in
automotive construction
Peintures et vernis — Détermination de la résistance aux conditions
cycliques de corrosion —
Partie 3: Essais de systèmes de revêtements sur matériaux et
composants en construction automobile
Reference number
© ISO 2022
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Principle . 2
5 Apparatus and test equipment . 2
6 Test specimen preparation . 4
7 Procedure .4
7.1 Test conditions – Test procedure . 4
7.2 Interruption of the test . 7
7.3 Positioning of test specimens in the chamber . 7
8 Method for evaluating chamber corrosivity . 8
9 Ev a luat ion . 8
10 Precision . 8
11 Test report . 9
Annex A (informative) Preparation and post-treatment of the mass-loss coupons.10
Annex B (normative) Climate data settings of the daily cycles .11
Annex C (informative) Sample of specified data for the programming of climate data .14
Annex D (informative) Details of interlaboratory testing .15
Annex E (informative) Additional information on the test specimen .22
Bibliography .23
iii
Foreword
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www.iso.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.
A list of all parts in the ISO 11997 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
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iv
Introduction
[9] [10]
This document was prepared on the basis of SEP 1850 and VDA 233-102 .
v
INTERNATIONAL STANDARD ISO 11997-3:2022(E)
Paints and varnishes — Determination of resistance to
cyclic corrosion conditions —
Part 3:
Testing of coating systems on materials and components in
automotive construction
1 Scope
This document specifies a method based on a cyclic corrosion test for testing the corrosion protection
of automobiles using coating systems on aluminium, steel or galvanized steel.
The test method uses corrosive conditions (temperature and humidity ramps and salt spray) to
create realistic corrosion patterns. These corrosion patterns are typical for automobiles, and they are
comparable in the case of sufficiently similar protective coating systems. In particular, the accelerated
test investigates the delamination/corrosion creep that results from defined artificial damage to
a coating. Investigations of surface and edge corrosion or investigations of adhesive specimens or
components are also covered. This cyclic corrosion test is also suitable for testing corrosion in flanged
areas or near gaps.
This document was developed for the assessment of coated substrates (test specimens, bodywork and
mounted parts) in the automotive industry. Other applications, such as components with unpainted
metallic coatings, were not part of the scope of the standardization work. This document was originally
developed for coating systems on aluminium, steel or galvanized steel but it can also be used for the
assessment of the corrosion resistance of coating systems on other metals and their alloys.
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 2409, Paints and varnishes — Cross-cut test
ISO 3574, Cold-reduced carbon steel sheet of commercial and drawing qualities
ISO 4618, Paints and varnishes — Terms and definitions
ISO 4628-1, Paints and varnishes — Evaluation of degradation of coatings — Designation of quantity
and size of defects, and of intensity of uniform changes in appearance — Part 1: General introduction and
designation system
ISO 4628-2, Paints and varnishes — Evaluation of degradation of coatings — Designation of quantity
and size of defects, and of intensity of uniform changes in appearance — Part 2: Assessment of degree of
blistering
ISO 4628-3, Paints and varnishes — Evaluation of degradation of coatings — Designation of quantity and
size of defects, and of intensity of uniform changes in appearance — Part 3: Assessment of degree of rusting
ISO 4628-4, Paints and varnishes — Evaluation of degradation of coatings — Designation of quantity
and size of defects, and of intensity of uniform changes in appearance — Part 4: Assessment of degree of
cracking
ISO 4628-5, Paints and varnishes — Evaluation of degradation of coatings — Designation of quantity and
size of defects, and of intensity of uniform changes in appearance — Part 5: Assessment of degree of flaking
ISO 4628-8, Paints and varnishes — Evaluation of degradation of coatings — Designation of quantity
and size of defects, and of intensity of uniform changes in appearance — Part 8: Assessment of degree of
delamination and corrosion around a scribe or other artificial defect
ISO 4628-10, Paints and varnishes — Evaluation of degradation of coatings — Designation of quantity
and size of defects, and of intensity of uniform changes in appearance — Part 10: Assessment of degree of
filiform corrosion
ISO 9227:2017, Corrosion tests in artificial atmospheres — Salt spray tests
ISO 17872, Paints and varnishes — Guidelines for the introduction of scribe marks through coatings on
metallic panels for corrosion testing
ISO 20567-1, Paints and varnishes — Determination of stone-chip resistance of coatings — Part 1: Multi-
impact testing
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 4618 apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Principle
WARNING — This document may involve hazardous materials, operations and equipment. This
document does not purport to address all of the safety concerns, if any, associated with its use.
It is the responsibility of the user of this document to establish appropriate safety and health
practices and determine the applicability of regulatory limitations prior to use.
The test specimens are tested in a cyclic test that involves salt spray, humidity ramps and temperature
ramps. In this way, realistic corrosion patterns are created for coated substrates of steel, galvanized
steel and aluminium. The results of the tests are assessed based on subjective criteria that are agreed
beforehand between the contractual partners.
5 Apparatus and test equipment
The typical laboratory and glass or plastics apparatus, together with the following.
5.1 Corrosion test chamber
All parts of the test chamber that come into contact with salt spray, condensate or test solutions shall
be made of a material that is resistant to attack by the test solutions and does not itself affect the action
of the test solutions or the salt spray/condensate on the test specimens.
The test may be carried out in separate chambers as long as the climatic conditions for the cycles are
met. Chambers that can perform all conditions are available and recommended.
Test chambers shall consist of a cooling unit, heating, pressure equalization as well as the necessary
measurement and control equipment to set and maintain the climate data described in Annex B
(temperature ±2 °C, relative humidity ±5 %) as measured at a reference point in the closed chamber
at defined temperature/relative humidity values. When passing through temperature ramps in phases
with constant relative humidity, deviations in relative humidity of −8 % to +5 % are permitted.
The test chamber shall be designed in such a way that no drops fall from the ceiling or side walls onto
the test specimens positioned below them. A test solution that has already been sprayed shall not be
returned to the storage container.
The usable space for the test and/or the space for positioning the test specimens and test specimen
holders is only that part of the test chamber that is outside of the direct spray jet. In this space, it is
possible to demonstrate that there is a uniform distribution of the spray jet in accordance with 5.4.
The holders for the test specimens are to be produced from a durable, non-metallic non-conductive
material. The holder should be designed as such that the gathering of test solution on the holder
is prevented as much as possible. No conductive bridge is allowed between test specimens. If it
is necessary to hang up test specimens, the material used shall be a durable, non-metallic and non-
conductive material. The connection points on the test specimen should be at least 20 mm to the left or
right from the scribe.
5.2 Spray nozzle(s)
Nozzles that are suitable for the temperature range of the test and that fulfil the conditions in 5.4 are
used to generate the spray. Nozzles that use compressed air (see 5.5) to atomize the droplets shall be
used. It is necessary to set the flow rate to be constant so that it is within the limits specified in 5.4. It is
to be noted that the spray jet shall not point directly at the test specimens to be tested. The number and
arrangement of the spray nozzles are to be selected in such a way that the specifications in 5.4 for the
usable space are fulfilled.
The spray nozzles shall be made from a durable material such as glass or plastic.
5.3 Test solution
The initial solution in the storage container is a preparation of NaCl in distilled, demineralized or
deionized water with a maximum conductivity of 20 μS/cm at (25 ± 2) °C in accordance with ISO 9227
but having a NaCl concentration of 10 g/l. The purity of sodium chloride shall be as specified in ISO 9227.
This solution is to be used in such a way that the sodium chloride concentration of the sprayed and
collected test solution is (10 ± 1) g/l, as this can deviate from the prepared solution depending on the
chamber. The density of a corresponding solution is (1,005 ± 0,000 5) g/cm at 25 °C. The pH value
(6,5 to 7,2) is to be maintained. Use hydrochloric acid or sodium hydroxide to adjust the pH if necessary.
WARNING — Hydrochloric acid (CAS No. 7647-01-0) solution is toxic, corrosive, irritating and
very toxic to aquatic life. Refer to Safety Data Sheet for details. Handling of hydrochloric acid
solution shall be restricted to skilled personnel or conducted under their control. Care shall be
taken in the disposal of this solution.
WARNING — Sodium hydroxide (CAS No. 1310-73-2) solution is toxic, corrosive and irritating.
Refer to Safety Data Sheet for details. Handling of sodium hydroxide solution shall be restricted
to skilled personnel or conducted under their control. Care shall be taken in the disposal of this
solution.
5.4 Quantity and distribution of the spray
The quantity of test solution to be sprayed over a defined period of time in accordance with 5.3 is
selected in such a way that (3,0 ± 1,0) ml/h of sprayed solution is collected on average in each of the
collecting devices that are used. The collected quantity in the test chamber should be controlled when
the chamber is loaded with specimens in a manner similar to the test procedure. A period of at least
16 h of constant salt spray operation is recommended before the test and during regular checks of the
salt spray phase.
Glass or plastic funnels with a diameter of 100 mm which are fitted into a measuring cylinder made of
glass or plastic using a plug are examples of suitable collecting devices.
NOTE Funnels made of glass or plastic that have their pipe sections inside measuring cylinders have proven
themselves to be suitable collecting devices. Funnels with a diameter of 100 mm have a collection area of
approximately 80 cm .
To demonstrate the uniform distribution of the spray, at least two of the collecting devices – depending
on the size of the chamber – shall be placed in the zone where the test specimens are usually placed.
In the case of very large chambers (walk-in chambers), at least one collection device is to be used for
every 4 m of positioning area.
For calibration purposes and for the verification of the uniform distribution of the spray, follow the
procedure specified in ISO 9227:2017, 6.5.
5.5 Compressed air
The compressed air used to generate the salt spray shall be free of oil and solid contaminants. It shall be
at a suitable pressure depending upon the type of spray nozzle and adjusted so that the collection rate
of sprayed solution in the chamber and the concentration of sprayed solution collected are kept within
the specified limits.
NOTE Humidification of the spray air can be necessary to prevent evaporation of the spray during the test.
Saturation towers as described in ISO 9227 represent one common method to humidify the air.
5.6 Mass-loss coupons to demonstrate constant test conditions.
To test the apparatus, use at least three mass-loss coupons with dimensions of 150 mm × 70 mm and a
thickness of (0,9 ± 0,2) mm, made of CR4 steel in accordance with ISO 3574 with practically fault-free
surfaces (roughness Ra = 0,9 µm to 1,4 µm).
At least five mass-loss coupons should be used when the test chamber is being commissioned.
5.7 Balance, accurate to at least 0,001 g.
6 Test specimen preparation
If not otherwise specified, apply an artificial defect (prior damage) to the coating, for example:
— scribe in accordance with ISO 17872;
— stone impact in accordance with ISO 20567-1;
— cross cut in accordance with ISO 2409.
7 Procedure
7.1 Test conditions – Test procedure
The test duration is six test cycles (6 weeks), if not otherwise agreed. A test cycle lasts 7 days. It consists
of daily cycles A, B and C, the sequence of which is specified as shown in Figure 1.
Key
X test time, in hours
A, B, C daily cycle
Figure 1 — Test cycle with sequence of daily cycles A, B and C
The daily cycles are characterized by the following features:
— daily cycle A, in accordance with Figure 2 and Table B.1, with a salt spray phase of 3 h (10 g/l
NaCl solution);
— daily cycle B, in accordance with Figure 3 and Table B.2, with an assessment phase;
— daily cycle C, in accordance with Figure 4 and Table B.3, with a low-temperature phase.
NOTE The ramps specified in this document are based on the current status of the control technology for
the chambers. They are intended to ensure that the temperature and relative humidity loadings necessary for
the corrosion processes can be achieved. An example for the programming of the chambers is given in Table C.1.
The positioning of test specimens in the test chamber (or the removal of test specimens) is carried out
solely during the first daily cycle B of the assessment phase during the fourth, fifth and sixth hours
after the start of daily cycle B – see Figure 3.
Key
X time, in hours
Y1 temperature, in degrees Celsius (°C)
Y2 relative humidity, in percent (%)
1 temperature
2 relative humidity
3 salt spray phase (10 g/l NaCl solution)
Figure 2 — Daily cycle A with a salt spray phase of 3 h (10 g/l NaCl solution)
Key
X time, in hours
Y1 temperature, in degrees Celsius (°C)
Y2 relative humidity, in percent (%)
1 temperature
2 relative humidity
3 assessment phase
4 start of test after first placing test specimens in the chamber
Figure 3 — Daily cycle B with assessment phase
Key
X time, in hours
Y1 temperature, in degrees Celsius (°C)
Y2 relative humidity, in percent (%)
1 temperature
2 relative humidity
3 low-temperature phase (−15 °C),
4 temperature range <5 °C with undefined relative humidity
Figure 4 — Daily cycle C with low-temperature phase (−15 °C)
7.2 Interruption of the test
It is permitted to open the test chamber during the test cycle only in the assessment phases (fourth,
fifth and sixth hours) in daily cycle B. The test chamber shall not be switched off during this time.
7.3 Positioning of test specimens in the chamber
If not otherwise agreed, the surface to be assessed of the test specimen is positioned in the test chamber
at an angle of (20 ± 5)° to the vertical with the side to be tested facing upwards. The test specimens
shall not touch one another and shall not shield one another from the spray. The test specimens may
be arranged at different levels in the chamber if the solution does not drop from test specimens or test
specimen holders onto test specimens below them.
If two or
...