ASTM_D_6944_-_15.pdf

Designation:D694415Standard 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 revision.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 assess 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 specificcoating 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 limitations 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 by 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 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 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 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.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 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.In 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 intervals 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.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 2015.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 standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 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 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.Preparation 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 D613