ASTM_C_674_-_13.pdf

Designation:C67413Standard Test Methods forFlexural Properties of Ceramic Whiteware Materials1This standard is issued under the fixed designation C674;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 These test methods cover determination of the modulusof rupture and the modulus of elasticity of fired ceramicwhitewares bodies,formed by any fabrication method,and areapplicable to both glazed and unglazed test specimens.1.2 The values stated in inch-pound units are to be regardedas the standard.The metric equivalents of inch-pound unitsmay be approximate.1.3 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.Summary of Test Methods2.1 The specimens,either cylindrical,or rectangular,aresupported on knife edges over a suitable span and a direct loadis applied at the midpoint between the supports at a uniformrate until breakage occurs.The modulus of elasticity may bedetermined by halting the applied load at definite intervals andmeasuring the deflection of the specimen at the midpoint to thenearest 0.001 in.(0.025 mm).3.Significance and Use3.1 These test methods provide a means for determining themodulus of rupture and the modulus of elasticity,which maybe required in product specifications.4.Apparatus4.1 Testing MachineAny suitable testing machine may beused,provided uniform rates of direct loading can be main-tained.4.1.1 For all specimens the loading rate should be such thatthe specimen should fail in approximately 1 min.Table 1 listsloading rates that shall be used for each size specimen.Forstrengths of specimens intermediate of those specified,inter-polation can be used to obtain the equivalent loading rate.4.1.2 For the prescribed rectangular specimens the loadingrate shall be 1000 6 150 lbs(454 6 68 kg)/min.4.2 Bearing EdgesFor the support of the test specimen,two steel(or high-strength ceramic)knife edges rounded to aradius of 0.125 in.(3.18 mm)shall be provided.The load shallbe applied by means of a third steel knife edge rounded to aradius of 0.125 in.When testing rectangular specimens,thesupporting members for the bearing edges shall be constructedto provide a means for alignment of the bearing surfaces withthe surfaces of the test specimen(it being possible that therectangular specimen may be wedge-shaped or twisted).Theapparatus shown in Figs.1 and 2 are suggested as suitabledevices for ensuring proper spacing and alignment of thebearing edges for rectangular test specimens.5.Test Specimens5.1 Preparation of SpecimensForm,fire,and finish thespecimens by the appropriate methods,following practicesused in actual production.5.2 DimensionsThe specimens shall be approximately1.125 in.(28.6 mm),0.750 in.(19.2 mm),0.500 in.(12.7 mm),or 0.250 in.(6.4 mm)in diameter,whichever diameter is mostcomparable to that of the finished product.The length shall be6 6 0.50 in.(153 6 12.7 mm)to permit an overhang of at least0.25 in.(6.4 mm)at each end when mounted on the supports.Note that the 0.25-in.specimens may be 3.75 6 0.25 in.(95 67 mm)long.5.2.1 The dry-pressed specimens shall be rectangular barsapproximately 1 in.(25.4 mm)by 0.50 in.(12.7 mm)in crosssection and at least 4.50 in.(114 mm)in length to permit anoverhang of at least 0.25 in.at each end when mounted on thesupports.5.3 HandlingObserve all due precautions in the forming,drying,and firing to produce straight test specimens of uniformcross section.5.4 StorageCool test specimens taken warm from the kilnin a desiccator.If the testing must be delayed,store the bars inthe desiccator,or in an electric oven at 110C,and then cool ina desiccator before testing.When removing specimens from ahot kiln,take care to avoid thermal shock which will lead toerroneous results.1These test methods are under the jurisdiction of ASTM Committee C21 onCeramic Whitewares and Related Productsand are the direct responsibility ofSubcommittee C21.03 on Methods for Whitewares and Environmental Concerns.Current edition approved March 1,2013.Published March 2013.Originallyapproved in 1971.Last previous edition approved in 2006 as C674 88(2006).DOI:10.1520/C0674-13.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 MODULUS OF RUPTURE6.Procedure6.1 Test at least ten dry specimens at room temperature.NOTE1The modulus of elasticity may be determined as described inSections 10 11 on the same type specimens used for the modulus ofrupture test.6.2 Place the cylindrical specimen on the bearing edges,spaced 5 in.(127 mm)6 2%between centers,with thespecimen overha