ASTM_C_372_-_94_2016.pdf

Designation:C37294(Reapproved 2016)Standard Test Method forLinear Thermal Expansion of Porcelain Enamel and GlazeFrits and Fired Ceramic Whiteware Products by theDilatometer Method1This standard is issued under the fixed designation C372;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 test method covers the determination of the linearthermal expansion of premelted frit(porcelain enamel andglaze)and ceramic whiteware products by the thermal dilatom-eter method.This test method is applicable to apparatusmeeting the reproducibility and accuracy requirements of thistest method,which are to produce percent linear expansionaccuracy of 63%or better and coefficient of linear expansionaccuracy of 65%or better.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:2E220 Test Method for Calibration of Thermocouples ByComparison TechniquesE228 Test Method for Linear Thermal Expansion of SolidMaterials With a Push-Rod DilatometerE230 Specification and Temperature-Electromotive Force(EMF)Tables for Standardized ThermocouplesE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Terminology3.1 Definitions:3.1.1 mean coeffcient of linear thermal expansionfromtemperature T1to temperature T2(T1 T2):,mm/mmC or in./in.C 50.01 PT22 T1where:=mean coefficient of linear thermal expansion fromtemperature T1to T2,andP=percent linear thermal expansion as defined in 3.1.2.3.1.2 percent linear thermal expansionfrom temperatureT1to temperature T2(T1 T2):P 5L22 L1L031001A5LL031001Awhere:P=percent linear thermal expansion from temperature T1to T2,L0=sample length at T0(T0between 20 and 30C),L1=sample length at T1,L2=sample length at T2,andA=instrument correction.4.Significance and Use4.1 Measurement of thermal expansion is useful for predict-ing stress within joined materials or single materials underconditions of changing or nonuniform temperature.It can alsoserve as an indicator of phase composition or changes instructure.5.Apparatus5.1 Thermal Dilatometer:5.1.1 General DescriptionA thermal dilatometer is anapparatus that provides means for varying the temperature of atest specimen in a controlled manner,measuring the specimenlength,and measuring the temperature of the specimen for eachreading of specimen length.There are several different types asfollows:5.1.1.1 ManualA manual dilatometer is one in which anyor all of the above are done by manual means and the correctedpercent linear thermal expansion curve is plotted by hand.1This test method is under the jurisdiction ofASTM Committee C21 on CeramicWhitewares and Related Productsand is the direct responsibility of SubcommitteeC21.03 on Methods for Whitewares and Environmental Concerns.Current edition approved Nov.1,2016.Published November 2016.Originallyapproved in 1955.Last previous edition approved in 2012 as C372 94(2012).DOI:10.1520/C0372-94R16.2For 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 5.1.1.2 RecordingA recording dilatometer is an apparatusby which the above are recorded by instrumental means but thefinal corrected percent linear thermal expansion curve isplotted by hand.5.1.1.3 Automatic RecordingAn automatic recordingdilatometer is a recording dilatometer with provision forautomatically plotting the corrected percent linear thermalexpansion curve.5.1.2 Any generally accepted apparatus that is capable ofmeasuring the length changes produced by thermal expansionmay be used in this method.The accuracy of the expansion-measuring apparatus including transducer,electronic,mechani-cal or optical amplification and readout device must be60.0001 in.(60.003 mm)and should be reproducible to60.00005 in.(60.0013 mm).A dilatometer may use a directmethod of sighting on either of the two ends of the testspecimen or suitable markings at the ends,by means of twotelescopes mounted on a measuring bank.Another methodtransmits the change in length of the specimen to a sensitivedial gage or transducer by means of members that are chemi-cally inert and free of phase transformations,having groundand polished surfaces at points of contact with the testspecimens.5.2 Scale or Caliper,capable of measuring the length of thespecimen with an accuracy of