1、Designation: D6944 091Standard Practice forResistance of Cured Coatings to Thermal Cycling1This standard is issued under the fixed designation D6944; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A numb
2、er in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEEditorial corrections were made in 7.1.2 and 10.1.2 in March 2014.1. Scope1.1 This practice determines the resistance of cured coatingsto repeated
3、 thermal cycles. This procedure is designed to assessthe influence of thermal cycling on adhesion and other prop-erties of coatings. This procedure is not intended to provide aquantitative measure of the service life that can be expectedfrom a specific coating system on a given substrate.1.2 This st
4、andard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1
5、 ASTM Standards:2D660 Test Method for Evaluating Degree of Checking ofExterior PaintsD661 Test Method for Evaluating Degree of Cracking ofExterior PaintsD714 Test Method for Evaluating Degree of Blistering ofPaintsD3359 Test Methods for Measuring Adhesion by Tape TestD4541 Test Method for Pull-Off S
6、trength of Coatings UsingPortable Adhesion TestersD6677 Test Method for Evaluating Adhesion by KnifeG147 Practice for Conditioning and Handling of Nonmetal-lic Materials for Natural and Artificial Weathering Tests3. Summary of Test Methods3.1 Test Method ACured test specimens are subjected to30 ther
7、mal cycles of immersion, freezing and heating.3.2 Test Method BCured test specimens are subjected to30 thermal cycles of freezing and heating.4. Significance and Use4.1 The purpose of this test is to obtain information on theability of a coating system to adhere to substrates underthermal stress. It
8、 is assumed that the coating systems used areapplied and cured according to the given specifications of thecoating manufacturer.TEST METHOD AFREEZE/THAW/IMMERSION5. Apparatus5.1 Thermal Cycling Apparatus:5.1.1 The thermal cycling apparatus shall consist of asuitable chamber or chambers in which the
9、test specimens mayundergo the specified cycle. Ideally, a chamber which containsheating and refrigeration equipment and immersion capabilitiesin the same unit should be used. This chamber shall have theability to maintain continuous reproducible cycles within thespecified temperature requirements. I
10、n the event that an appa-ratus having freezing, heating, and immersion capabilities isnot available, separate equipment for freezing, heating andimmersion may be used.5.1.2 The chamber or chambers shall have the ability tomaintain a constant temperature during each of the respectivetemperature inter
11、vals as specified by the procedure.5.1.3 The samples shall be arranged to minimize contactwith the chamber surfaces or any mounting racks, and tomaximize air flow.5.1.4 The temperature of the thermal cycling apparatus shallgive uniform readings at various locations within the chamber,within 3C (5F)
12、at any given time, except during the transitionbetween heating and freezing cycles. A two hour temperatureramping period is permitted for the equipment to reach the nexttemperature setting.6. Test Specimens6.1 Apply each coating onto the substrate as agreed upon.Minimum film thicknesses should take
13、substrate profile intoaccount when applied.1This practice is under the jurisdiction of ASTM Committee D01 on Paint andRelated Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.46 on Industrial Protective Coatings.Current edition approved July 1, 2009. Publishe
14、d July 2009. Originally approvedin 2003. Last previous edition approved in 2003 as D6944 03. DOI: 10.1520/D6944-09E01.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer t
15、o the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States16.2 Apply each coating or coating system to a minimum oftwo specimens to determine repeatability. If the substrate ofchoice is co
16、ncrete, then suitable encapsulation of the substratemust occur as agreed upon between purchaser and supplier.6.2.1 When destructive tests are run, it is recommended thata sufficient number of reference specimens be retained so thatthe property of interest can be determined on unexposedreference spec
17、imens each time exposed materials are evalu-ated.6.2.2 Exposure of a similar material of known performance(a control) at the same time as the test materials is stronglyrecommended.6.3 Follow the procedures described in Practice G147 foridentification, conditioning and handling of specimens of test,c
18、ontrol, and reference materials prior to, during, and afterexposure.6.4 Unless otherwise specified, cure each test specimen fora minimum of 7 days at 23 6 3C (73 6 5F) before beginningthermal cycling.6.5 Prior to beginning the thermal cycling, determine rel-evant properties of the coating on a refer
19、ence panel. TestMethods D660, D661, D714, D3359, and/or D4541, and/orD6677 are recommended. Consider product use requirementswhen selecting appropriate methods.7. Procedure7.1 After the curing period, place the specimens into the testchamber and begin the cycling procedure.7.1.1 A suitable procedure
20、 is shown in the table below.Other procedures as agreed upon between purchaser andsupplier may also be used.7.1.2 Thermal Cycling Procedure:Condition Time (h)50 3C (122 5F) in air 425 3C (77 5F) tap water immersion 4-29 3C (20 5F) in air 167.2 Repeat this cycle of freeze/thaw/immersion for 30cycles,
21、 or other agreed upon number of cycles. Leave thesurface of the panels wet when transferring from the immersionto the freeze cycle. Keep panels in the freeze condition uponinterruptions in the agreed upon cycle. Evaluate specimenseither every 5 cycles or at the end of 30 cycles. Destructivetests are
22、 typically performed at the end of testing.TEST METHOD BFREEZE/THAW8. Apparatus8.1 Thermal Cycling Apparatus:8.1.1 The thermal cycling apparatus shall consist of asuitable chamber or chambers in which the test specimens mayundergo the specified cycle. Ideally, a chamber which containsheating and ref
23、rigeration in the same unit should be used. Thischamber shall have the ability to maintain continuous repro-ducible cycles within the specified temperature requirements.In the event that an apparatus having freezing and heatingcapabilities is not available, separate equipment, one chamberfor freezin
24、g and another for heating may be used.8.1.2 The chamber or chambers shall have the ability tomaintain a constant temperature during each of the respectivetemperature intervals as specified by the procedure.8.1.3 The samples shall be arranged to minimize contactwith the chamber surfaces or any mounti
25、ng racks, and tomaximize air flow.8.1.4 The temperature of the thermal cycling apparatus shallgive uniform readings at various locations within the chamber,within 3C (5F) at any given time, except during the transitionbetween freezing and heating.Atwo hour temperature rampingperiod is permitted for
26、the equipment to reach the nexttemperature setting.8.2 Reproducibility of test results between laboratories hasbeen shown to be good when the stability of materials isevaluated in terms of performance ranking compared to othermaterials or to a control. Therefore, exposure of a similarmaterial of kno
27、wn performance (a control) at the same time asthe test materials is strongly recommended.9. Test Specimens9.1 Test specimens shall be as described in Section 6.10. Procedure10.1 After the curing period, place the specimens into thetest chamber and begin the cycling procedure.10.1.1 A suitable proced
28、ure is shown in the table below.Other procedures as agreed upon between purchaser andsupplier may also be used.10.1.2 Thermal Cycling Procedure:Condition Time (h)503C(1225F)inair 8-29 3C (-20 5F) in air 1610.2 Repeat this cycle of freeze/thaw for 30 cycles, or otheragreed upon number of cycles. Keep
29、 panels in the freezecondition upon interruptions in the agreed upon cycle. Evaluatespecimens either every 5 cycles or at the end of 30 cycles.Destructive tests are typically performed at the end of testing.11. Report11.1 Test Method used and testing cycle(s).11.2 Visual evaluation of each panel for
30、 the degree ofchecking of exterior paints as described in Test Method D660.11.3 Visual evaluation of each panel for the degree ofcracking of exterior paints as described in Test Method D661.11.4 Visual evaluation of each panel for the degree ofblistering of exterior paints as described in Test Metho
31、d D714.11.5 Results of adhesion testing from one or more of TestMethods D3359, D4541, and D6677.11.6 Identification of test specimens, including substrate,surface preparation, type and thickness of coating, and cureconditions.12. Keywords12.1 freeze/thaw; freezing; heating; immersion; thawing;therma
32、l cycling; thermal stressD6944 0912ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk
33、of infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this
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