1、Designation:D699105(Reapproved 2010)Standard Test Method forMeasurements of Internal Stresses in Organic Coatings byCantilever(Beam)Method1This standard is issued under the fixed designation D6991;the number immediately following the designation indicates the year oforiginal adoption or,in the case
2、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 test method covers the procedure for measurementsof internal stresses in organic coatings by u
3、sing the cantilever(beam)method.1.2 This method is appropriate for the coatings for whichthe modulus of elasticity of substrate(Es)is significantlygreater than the modulus of elasticity of coating(Ec)and forwhich the thickness of substrate is significantly greater thanthickness of coating(see Note 4
4、 and Note 5).1.3 The stress values are limited by the adhesion values ofcoating to the substrate and by the tensile strength of thecoating,or both.1.4 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.5 This standard does not pu
5、rport 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 to determine theapplicability of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D823
6、 Practices for Producing Films of Uniform Thicknessof Paint,Varnish,and Related Products on Test PanelsD1186 Test Methods for Nondestructive Measurement ofDry Film Thickness of Nonmagnetic Coatings Applied toa Ferrous Base(Withdrawn 2006)3D1400 Test Method for Nondestructive Measurement of DryFilm T
7、hickness of Nonconductive Coatings Applied to aNonferrous Metal Base(Withdrawn 2006)33.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 cantilever,na beam or member securely fixed at oneend and hanging free at the other end.3.1.2 deflection,nthe displacement of a beam from itsorig
8、inal position by an applied force.3.1.2.1 DiscussionThe deflection of the beam is used tomeasure that force acting on the tip.3.1.3 internal stress,na stress system within a solid that isnot dependent on external forces.4.Test Method4.1 Internal stresses in coatings are determined by thecantilever m
9、ethod(Fig.1).Substrate A in the shape of arectangular cantilever beam is clamped by its end B in a specialfixture E.Coating(F)is applied to one side of the beam.Internal stresses occur in the film when it is being cured(drying,cross-linking,etc.).When there is sufficient adhesionbetween the coating
10、and the substrate,the stresses bend thecantilever beam,forcing its free end D to be deflected from itsoriginal position by a distance of h.The deflection of the beamis measured under an optical microscope and internal stress iscalculated using the equation for the cantilever method.See Eq1 in Sectio
11、n 9,(Formula 1).5.Significance and Use5.1 Stresses in coatings arise as a result of their shrinkage orexpansion if expected movements are prevented by coatingadhesion to its substrate.5.2 There are several causes leading to arrival of stresses inthecoatings:filmformation(cross-linking,solventevapora
12、tion,etc.);differences in thermal expansion coefficientsbetween coating and substrate;humidity and water absorption;environmental effects(ultraviolet radiation,temperature andhumidity),and others.5.3 Knowledge of the internal stresses in coatings is veryimportant because they may effect coating perf
13、ormance andservice life.If the internal stress exceeds the tensile strength ofthe film,cracks are formed.If stress exceeds adhesion between1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubc
14、ommittee D01.23 on Physical Properties of Applied Paint Films.Current edition approved Dec.1,2010.Published December 2010.Originallyapproved in 2005.Last previous edition approved in 2005 as D6991 05.DOI:10.1520/D6991-05R10.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact
15、 ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box
16、C700,West Conshohocken,PA 19428-2959.United States1 coating and substrate,it will reduce adhesion and can lead todelamination of coatings.Quantitative information aboutstresses in coatings can be useful in coating formulation andrecommendations for their application and use.5.4 This method has been found useful for air-dry industrialorganic coatings but the applicability has not yet been assessedfor thin coatings(thickness Es;the ratio between t and c should be carefullyselected.For example,if t
