1、Designation: D 6944 09Standard Practice forResistance of Cured Coatings to Thermal Cycling1This standard is issued under the fixed designation D 6944; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A num
2、ber in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice determines the resistance of cured coatingsto repeated thermal cycles. This procedure is designed to assessthe influence of
3、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 standard does not purport to address all of thesafety concerns, if any,
4、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 ASTM Standards:2D 660 Test Method for Evaluating Degree of Checking o
5、fExterior PaintsD 661 Test Method for Evaluating Degree of Cracking ofExterior PaintsD 714 Test Method for Evaluating Degree of Blistering ofPaintsD 3359 Test Methods for Measuring Adhesion by Tape TestD 4541 Test Method for Pull-Off Strength of CoatingsUsing Portable Adhesion TestersD 6677 Test Met
6、hod for Evaluating Adhesion by KnifeG 147 Practice for Conditioning and Handling of Nonme-tallic Materials for Natural and Artificial Weathering Tests3. Summary of Test Methods3.1 Test Method ACured test specimens are subjected to30 thermal cycles of immersion, freezing and heating.3.2 Test Method B
7、Cured 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 is assumed that the coating systems used areapplied and cured
8、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 test specimens mayundergo the specified cycle. Ideally, a chamb
9、er 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. In the event that an appa-ratus having freezing, heating, and im
10、mersion 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 intervals as specified by the procedure.5.1.3 The samples shall be a
11、rranged 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) at any given time, except during the transitionbetween heating
12、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 substrate profile intoaccount when applied.1This practice is un
13、der 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. Published July 2009. Originally approvedin 2003. Last previous edition
14、approved in 2003 as D 6944 - 03.2For 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 to the standards Document Summary page onthe ASTM website.1Copyright ASTM International
15、, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.2 Apply each coating or coating system to a minimum oftwo specimens to determine repeatability. If the substrate ofchoice is concrete, then suitable encapsulation of the substratemust occur as agreed upon between
16、 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 specimens each time exposed materials are evalu-ated.6.2.2 Exposure of a similar material
17、 of known performance(a control) at the same time as the test materials is stronglyrecommended.6.3 Follow the procedures described in Practice G 147 foridentification, conditioning and handling of specimens of test,control, and reference materials prior to, during, and afterexposure.6.4 Unless other
18、wise 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 reference panel. TestMethods D 660, D 661, D 714, D 3359, and/or D 4541, and/orD 6677 are
19、 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 is shown in the table below.Other procedures as agreed upon between purchaser
20、 andsupplier may also be used.7.1.2 Thermal Cycling Procedure:Condition Time (h)50 6 3C (122 6 5F) in air 425 6 3C (77 6 5F) tap water immersion 4-29 6 3C (5 6 5F) in air 167.2 Repeat this cycle of freeze/thaw/immersion for 30cycles, or other agreed upon number of cycles. Leave thesurface of the pan
21、els 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 typically performed at the end of testing.TEST METHOD BFREEZE/THAW
22、8. 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 refrigeration in the same unit should be used. Thischamber shall have
23、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 freezing and another for heating may be used.8.1.2 The chamber or chambers
24、 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 mounting racks, and tomaximize air flow.8.1.4 The temperature of the ther
25、mal 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 the equipment to reach the nexttemperature setting.8.2 Reproducibil
26、ity 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 known performance (a control) at the same time asthe test materials is
27、 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 procedure is shown in the table below.Other procedures as agreed upon bet
28、ween purchaser andsupplier may also be used.10.1.2 Thermal Cycling Procedure:Condition Time (h)50 6 3C (122 6 5F) in air 8-29 6 3C (5 6 5F) in air 1610.2 Repeat this cycle of freeze/thaw for 30 cycles, or otheragreed upon number of cycles. Keep panels in the freezecondition upon interruptions in the
29、 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 the degree ofchecking of exterior paints as described i
30、n Test Method D 660.11.3 Visual evaluation of each panel for the degree ofcracking of exterior paints as described in Test Method D 661.11.4 Visual evaluation of each panel for the degree ofblistering of exterior paints as described in Test Method D 714.11.5 Results of adhesion testing from one or m
31、ore of TestMethods D 3359, D 4541, and D 6677.11.6 Identification of test specimens, including substrate,surface preparation, type and thickness of coating, and cureconditions.12. Keywords12.1 freeze/thaw; freezing; heating; immersion; thawing;thermal cycling; thermal stressD6944092ASTM Internationa
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33、wn 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 standard or for additional standardsand should be a
34、ddressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards,
35、at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D6944093
