1、Designation: D6944 15Standard Practice forDetermining the Resistance of Cured Coatings to ThermalCycling1This 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 re
2、vision. A number 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 coatingsor coating systems to repeated thermal cycles and is designedto asse
3、ss the effect of thermal cycling on the properties of acoating or coating system. These properties may includeadhesion, resistance to checking, cracking, blistering, or others.This procedure is not intended to provide a quantitativemeasure of the service life that can be expected from a specificcoat
4、ing system on a given substrate.1.2 This standard 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 limitati
5、ons prior to use.2. Referenced Documents2.1 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 b
6、y Tape TestD4541 Test Method for Pull-Off Strength of Coatings UsingPortable Adhesion TestersD6132 Test Method for Nondestructive Measurement of DryFilm Thickness of Applied Organic Coatings Using anUltrasonic Coating Thickness GageD6677 Test Method for Evaluating Adhesion by KnifeD7091 Practice for
7、 Nondestructive Measurement of DryFilm Thickness of Nonmagnetic Coatings Applied toFerrous Metals and Nonmagnetic, Nonconductive Coat-ings Applied to Non-Ferrous MetalsD7234 Test Method for Pull-Off Adhesion Strength of Coat-ings on Concrete Using Portable Pull-Off Adhesion Tes-tersG147 Practice for
8、 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 thermal cycles of immersion, freezing and heating.3.2 Test Method BCured test specimens are subjected to30 thermal cycles
9、 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 tested areapplied and cured according to the coating manufacturersinstructions.T
10、EST 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 chamber which containsheating and refrigeration equipment and immersion
11、 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 immersion capabilities isnot available, separate equipment for freez
12、ing, 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 arranged to minimize contactwith the chamber surfaces or any mounti
13、ng racks, and tomaximize air flow.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, 2015. Published July 20
14、15. Originally approvedin 2003. Last previous edition approved in 2009 as D6944 091. DOI: 10.1520/D6944-15.2For 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 stand
15、ards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.1.4 The temperature of the thermal cycling apparatus shallgive uniform readings at various locations within the chamber,within 3C (5F) at
16、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 or coating system onto the substratetype and thickness as agreed upon. Pre
17、paration of the substrate(that is, surface cleanliness and roughness) prior to applicationof the coating or coating system shall be agreed upon. Measurethe thickness of each coating layer in accordance with PracticeD7091 (metallic substrates) or Test Method D6132 for non-metallic substrates.6.2 Appl
18、y 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 purchaser and supplier.6.2.1 When destructive tests (for example, adhesion) arerequired, a su
19、fficient number of reference specimens shall beretained so that the property of interest can be determined onnon-cycled reference specimens each time cycled test speci-mens are evaluated.6.2.2 Exposure of a similar material of known performance(a control) at the same time as the test materials is re
20、com-mended.6.3 Follow the procedures described in Practice G147 foridentification, conditioning and handling of specimens of test,control, and reference materials prior to, during, and aftercycling.6.4 Unless otherwise specified, cure each test specimen fora minimum of 7 days at 23 6 3C (73 6 5F) be
21、fore beginningthermal cycling.6.5 Prior to beginning the thermal cycling, determine rel-evant properties of the coating on a reference panel. TestMethods D660, D661, D714, D3359, and/or D4541, and/orD6677 and/or D7234 are recommended. Consider the intendedservice environment and product use requirem
22、ents when se-lecting appropriate evaluation methods.7. Procedure7.1 After the curing period, place the specimens into thethermal cycling apparatus or test chambers and begin thecycling procedure.7.1.1 A suitable procedure is shown in the table below.Other procedures/temperatures/immersion media as a
23、greedupon between purchaser and supplier 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 heat/immersion/freeze for 30cycles, or other agreed upon number of cycles. Leave thes
24、urface of the panels wet when transferring from the immersionto the freeze cycle. Maintain panels in the freeze conditionupon interruptions in the cycling (for example, weekends/holidays). Evaluate specimens either every 5 cycles or at theend of 30 cycles. Destructive tests are typically performed a
25、tthe completion of all cycles.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 refrigeration in
26、 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 freezing and another
27、 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 mounting racks, and
28、 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 the equipment
29、 to reach the nexttemperature setting.9. Test Specimens9.1 Test specimens shall be as described in Section 6.10. Procedure10.1 After the curing period, place the specimens into thethermal cycling apparatus or test chambers and begin thecycling procedure.10.1.1 A suitable procedure is shown in the ta
30、ble below.Other procedures/temperatures as agreed upon between pur-chaser and supplier 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 heat/freeze for 30 cycles, or otheragreed upon number of cycles. Maintain pa
31、nels in the freezecondition upon interruptions in the cycling (for example,weekends/holidays). Evaluate specimens either every 5 cyclesor at the end of 30 cycles. Destructive tests are typicallyperformed at the completion of all cycles.11. Report11.1 Test Method used and number of testing cycle(s).1
32、1.2 Cycle temperatures.11.3 Results of the visual evaluation of each coated panelfor the degree of checking as described in Test Method D660(if used).D6944 15211.4 Results of the visual evaluation of each coated panelfor the degree of cracking as described in Test Method D661 (ifused).11.5 Results o
33、f the visual evaluation of each coated panelfor the degree of blistering as described in Test Method D714(if used).11.6 Results of adhesion testing from one or more of TestMethods D3359, D4541, D6677, and/or D7234 (if used),compared to the adhesion properties of non-cycled coatedpanels.11.7 Descript
34、ion of test specimens, including substrate typeand thickness, surface preparation (degree of cleanliness androughness), coating type and thickness and cure time/conditions prior to cycling.12. Keywords12.1 freeze/thaw; freezing; heating; immersion; thawing;thermal cycling; thermal stressASTM Interna
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