ASTM D6944-15(2020)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D6944 − 15 (Reapproved 2020)
Standard Practice for
Determining the Resistance of Cured Coatings to Thermal
Cycling
This standard is issued under the fixed designation D6944; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope D6132 Test Method for Nondestructive Measurement of Dry
Film Thickness of Applied Organic Coatings Using an
1.1 Thispracticedeterminestheresistanceofcuredcoatings
Ultrasonic Coating Thickness Gage
or coating systems to repeated thermal cycles and is designed
D6677 Test Method for Evaluating Adhesion by Knife
to assess the effect of thermal cycling on the properties of a
D7091 Practice for Nondestructive Measurement of Dry
coating or coating system. These properties may include
Film Thickness of Nonmagnetic Coatings Applied to
adhesion,resistancetochecking,cracking,blistering,orothers.
Ferrous Metals and Nonmagnetic, Nonconductive Coat-
This procedure is not intended to provide a quantitative
ings Applied to Non-Ferrous Metals
measure of the service life that can be expected from a specific
D7234 Test Method for Pull-OffAdhesion Strength of Coat-
coating system on a given substrate.
ings on Concrete Using Portable Pull-Off Adhesion Tes-
1.2 This standard does not purport to address all of the
ters
safety concerns, if any, associated with its use. It is the
G147 Practice for Conditioning and Handling of Nonmetal-
responsibility of the user of this standard to establish appro-
lic Materials for Natural and Artificial Weathering Tests
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
3. Summary of Test Methods
1.3 This international standard was developed in accor-
3.1 Test Method A—Cured test specimens are subjected to
dance with internationally recognized principles on standard-
30 thermal cycles of immersion, freezing and heating.
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
3.2 Test Method B—Cured test specimens are subjected to
mendations issued by the World Trade Organization Technical 30 thermal cycles of freezing and heating.
Barriers to Trade (TBT) Committee.
4. Significance and Use
2. Referenced Documents
4.1 The purpose of this test is to obtain information on the
2.1 ASTM Standards:
ability of a coating system to adhere to substrates under
D660 Test Method for Evaluating Degree of Checking of
thermal stress. It is assumed that the coating systems tested are
Exterior Paints
applied and cured according to the coating manufacturer’s
D661 Test Method for Evaluating Degree of Cracking of
instructions.
Exterior Paints
D714 Test Method for Evaluating Degree of Blistering of
TEST METHOD A—FREEZE/THAW/IMMERSION
Paints
D3359 Test Methods for Rating Adhesion by Tape Test
5. Apparatus
D4541 Test Method for Pull-Off Strength of Coatings Using
Portable Adhesion Testers 5.1 Thermal Cycling Apparatus:
5.1.1 The thermal cycling apparatus shall consist of a
suitable chamber or chambers in which the test specimens may
This practice is under the jurisdiction of ASTM Committee D01 on Paint and
undergo the specified cycle. Ideally, a chamber which contains
Related Coatings, Materials, and Applications and is the direct responsibility of
heatingandrefrigerationequipmentandimmersioncapabilities
Subcommittee D01.46 on Industrial Protective Coatings.
in the same unit should be used. This chamber shall have the
Current edition approved Feb. 1, 2020. Published February 2020. Originally
ability to maintain continuous reproducible cycles within the
approved in 2003. Last previous edition approved in 2015 as D6944 – 15. DOI:
10.1520/D6944-15R20.
specified temperature requirements. In the event that an appa-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
ratus having freezing, heating, and immersion capabilities is
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
not available, separate equipment for freezing, heating and
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. immersion may be used.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6944 − 15 (2020)
5.1.2 The chamber or chambers shall have the ability to
Condition Time (h)
50±3°C(122±5°F)inair 4
maintain a constant temperature during each of the respective
25 ± 3°C (77 ± 5°F) tap water immersion 4
temperature intervals as specified by the procedure.
-29 ± 3°C (–20 ± 5°F) in air 16
5.1.3 The samples shall be arranged to minimize contact
7.2 Repeat this cycle of heat/immersion/freeze for 30
with the chamber surfaces or any mounting racks, and to
cycles, or other agreed upon number of cycles. Leave the
maximize air flow.
surfaceofthepanelswetwhentransferringfromtheimmersion
5.1.4 The temperature of the thermal cycling apparatus shall
to the freeze cycle. Maintain panels in the freeze condition
give uniform readings at various locations within the chamber,
upon interruptions in the cycling (for example, weekends/
within 3°C (5°F) at any given time, except during the transition
holidays). Evaluate specimens either every 5 cycles or at the
between heating and freezing cycles. A two hour temperature
end of 30 cycles. Destructive tests are typically performed at
rampingperiodispermittedfortheequipmenttoreachthenext
the completion of all cycles.
temperature setting.
TEST METHOD B—FREEZE/THAW
6. Test Specimens
8. Apparatus
6.1 Apply each coating or coating system onto the substrate
type and thickness as agreed upon. Preparation of the substrate
8.1 Thermal Cycling Apparatus:
(that is, surface cleanliness and roughness) prior to application
8.1.1 The thermal cycling appa
...