Designation:B748−90(Reapproved2016)StandardTestMethodforMeasurementofThicknessofMetallicCoatingsbyMeasurementofCrossSectionwithaScanningElectronMicroscope1ThisstandardisissuedunderthefixeddesignationB748;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thistestmethodcoversthemeasurementofmetalliccoatingthicknessesbyexaminationofacrosssectionwithascanningelectronmicrosope(SEM).1.2ThevaluesstatedinSIunitsaretoberegardedasstandard.Nootherunitsofmeasurementareincludedinthisstandard.1.3Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.2.ReferencedDocuments2.1ASTMStandards:2E3GuideforPreparationofMetallographicSpecimensE766PracticeforCalibratingtheMagnificationofaScan-ningElectronMicroscope3.SummaryofTestMethod3.1Atestspecimeniscut,ground,andpolishedformetal-lographicexaminationbyanSEMofacrosssectionofthecoating.Themeasurementismadeonaconventionalmicro-graphoronaphotographofthevideowaveformsignalforasinglescanacrossthecoating.4.SignificanceandUse4.1Thistestmethodisusefulforthedirectmeasurementofthethicknessesofmetalliccoatingsandofindividuallayersofcompositecoatings,particularlyforlayersthinnerthannor-mallymeasuredwiththelightmicroscope.4.2Thistestmethodissuitableforacceptancetesting.4.3Thistestmethodisforthemeasurementofthethicknessofthecoatingoveraverysmallareaandnotoftheaverageorminimumthicknessperse.4.4Accuratemeasurementsbythistestmethodgenerallyrequireverycarefulsamplepreparation,especiallyatthegreatermagnifications.4.5Thecoatingthicknessisanimportantfactorintheperformanceofacoatinginservice.5.Equipment5.1Thescanningelectronmicroscopeshallhavearesolu-tionofatleas...
