1、Designation: D7775 11Standard Guide forMeasurements on Small Graphite Specimens1This standard is issued under the fixed designation D7775; 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 paren
2、theses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide covers best practice for properties measure-ments on small (nonstandard) graphite specimens and require-ments for representing properties o
3、f the bulk material. Thisguide is aimed specifically at measurements required onnuclear graphites, where there may be constraints on thegeometry or volume of the test specimen, or both.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in this
4、standard.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. Ref
5、erenced Documents2.1 ASTM Standards:2C559 Test Method for Bulk Density by Physical Measure-ments of Manufactured Carbon and Graphite ArticlesC565 Test Methods for Tension Testing of Carbon andGraphite Mechanical MaterialsC611 Test Method for Electrical Resistivity of Manufac-tured Carbon and Graphit
6、e Articles at Room TemperatureC651 Test Method for Flexural Strength of ManufacturedCarbon and Graphite Articles Using Four-Point Loading atRoom TemperatureC695 Test Method for Compressive Strength of Carbon andGraphiteC714 Test Method for Thermal Diffusivity of Carbon andGraphite by Thermal Pulse M
7、ethodC747 Test Method for Moduli of Elasticity and Fundamen-tal Frequencies of Carbon and Graphite Materials by SonicResonanceC748 Test Method for Rockwell Hardness of GraphiteMaterialsC749 Test Method for Tensile Stress-Strain of Carbon andGraphiteC769 Test Method for Sonic Velocity in Manufactured
8、Carbon and Graphite Materials for Use in ObtainingYoungs ModulusC781 Practice for Testing Graphite and Boronated GraphiteMaterials for High-Temperature Gas-Cooled Nuclear Re-actor ComponentsC886 Test Method for Scleroscope Hardness Testing ofCarbon and Graphite MaterialsC1161 Test Method for Flexura
9、l Strength of AdvancedCeramics at Ambient TemperatureC1259 Test Method for Dynamic Youngs Modulus, ShearModulus, and Poissons Ratio for Advanced Ceramics byImpulse Excitation of VibrationE228 Test Method for Linear Thermal Expansion of SolidMaterials With a Push-Rod DilatometerE1461 Test Method for
10、Thermal Diffusivity by the FlashMethod3. Summary of Guide3.1 There is currently a suite of ASTM standards (see 2.1)that can be applied to graphite covering a range of physical,mechanical, electrical and thermal property measurements.Each of these standards has been developed with the objectiveof opt
11、imizing the method of measurement in the absence of anyconstraints on test specimen production. Without exception,these standards specify limits on the ratio between test speci-men dimensions and coke and filler grain sizes or prescribe testspecimen geometries or size ranges, or both. The defaultpos
12、ition for any user should be to follow these standardsexactly as described. However, in some applications, availabletest material or experiment design constraints on test specimensizes may result in noncompliance. The objective of this guideis to provide advice on how the application of selectedstan
13、dards under noncompliant conditions can be tested forsuitability. The ultimate objective is to provide guidance on theuse of each of the ASTM standards listed. The 2011 issue of1This guide is under the jurisdiction of ASTM Committee D02 on PetroleumProducts and Lubricants and is the direct responsib
14、ility of Subcommittee D02.F0 onManufactured Carbon and Graphite Products.Current edition approved Dec. 1, 2011. Published January 2012. DOI: 10.1520/D777511.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of AS
15、TMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.this guide addresses eight standards: Test Method C559 forBulk Density by Physical Measur
16、ement of ManufacturedCarbon and Graphite Articles, Test Method C611 for ElectricalResistivity of Manufactured Carbon and Graphite Articles atRoom Temperature, Test Method C747 for Moduli of Elasticityand Fundamental Frequencies of Carbon and Graphite Mate-rials by Sonic Resonance, Test Method C769 f
17、or SonicVelocity in Manufactured Carbon and Graphite Materials forUse in Obtaining Youngs Modulus, Test Method C749 forTensile Stress-Strain of Carbon and Graphite and PracticeC781 for Testing Graphite and Boronated Graphite Materialsfor High-Temperature Gas-Cooled Nuclear Reactor Compo-nents, Test
18、Method E228 for Linear Thermal Expansion ofSolid Materials with a Push-Rod Dilatometer, and Test MethodE1461 for Thermal Diffusivity by the Flash Method.4. Significance and Use4.1 The purpose of this guide is to report considerations,which should be included in testing nonstandard specimensthat lie
19、outside the constraints imposed on size/volume inexisting ASTM standards for graphite (noting that there aresome generic ASTM standards with no such constraints).These constraints may be real or may be an artifact of theround-robin test program that supported the standard. It is theresponsibility of
20、 the user to demonstrate that the application ofa standard outside any specified constraints is valid andreasonably provides properties of the bulk material from whichthe nonstandard specimen was extracted.5. Test Specimen Volume/Size Constraints in CurrentStandards5.1 Test Method C559Applies to tes
21、t specimens withrectangular parallelepiped or right circular cylinder geometry.The minimum test volume is specified as 500 mm3. Theminimum test specimen dimension should be 10 times thelength of the largest visible grain.5.2 Test Methods C565Applies to reduced diameter uni-axial tensile specimens. G
22、rain size must be smaller than 0.79mm; while not specified, it is assumed that this refers toaverage grain size. The acceptable fracture zone shall be 19mm long with the centre of the zone at the point of minimumdiameter. The ratio of specimen diameter to grain size or flawsize must be greater than
23、5.5.3 Test Method C611Applies to strip, rod, bar or tubegeometries. Specimen length to maximum cross-sectional di-mension should be 6:1. No dimension should be smaller than 5times the length of the largest visible grain.5.4 Test Method C651Applies to rectangular parallelepi-ped geometries. The minim
24、um dimension should be greaterthan 5 times largest grain dimension. Test specimen length tothickness should be greater than 8. The ratio of test specimenwidth to thickness should be less than or equal to 2.5.5 Test Method C695Applies to right cylinder geometry.The test specimen diameter should be gr
25、eater than 10 times themaximum grain size. The test specimen height to diameterratio should be in the range 1.9 to 2.1. The minimum test sizeis specified as 9.5 mm diameter and 19.1 mm height.5.6 Test Method C714Applies to circular disks, 2 to 4 mmthick and 6 to 12 mm in diameter. The diameter must
26、not be toolarge relative to the flash source as the front surface needs to beheated uniformly. The specimen thickness must be selectedsuch that t/t1/2is smaller than 0.02, where t is the pulse timeand t1/2is the time for the rear surface temperature to rise toone half of its maximum value.5.7 Test M
27、ethod C747Applies to slender rod or bargeometries. The test specimen length to thickness ratio shouldlie in the range 5 to 20:1.5.8 Test Method C748Applies to flat specimens of mini-mum thickness 6.35 mm. The grain size of the test materialshould be less than 0.8 mm, with a hardness range 0 to 120Ro
28、ckwell L.5.9 Test Method C749Applies to reduced-diameter uni-axial tensile test geometries as defined in Fig. 9 of thatstandard. Gage diameter must be greater than 3 to 5 times themaximum grain size.5.10 Test Method C769Applies to right cylinder geom-etry. The user should minimize attenuation of the
29、 sonic pulseby selecting a wavelength appropriate to the grain size of thetest material. If the test specimen is a few grains thick,acceptability of application should be tested over a range oflengths. Specimen should have a diameter of at least a factor oftwo and ideally a factor of five greater th
30、an the wavelength ofsound within the material.5.11 Test Method C886Can be applied to any convenienttest specimen size, but test surfaces smaller than 5 by 5 mm arenot recommended. The material must have a grain size lessthan 0.8 mm. The minimum specimen thickness is 5 mm.5.12 Test Method E228Applies
31、 to right cylinder (prefer-able) or slab geometries. Ideally, test specimens should be 25to 60 mm long and 5 to 10 mm in diameter or equivalent(although there is no fundamental limitation provided theinstrument controls the maximum thermal gradient to betterthan 62C/50 mm). The specimen length shoul
32、d be such thatthe accuracy of determining the expansion DL/L0is at least620 mm/m.5.13 Test Method E1461Applies to thin circular diskspecimens with the front surface area less than that of theenergy beam. Typically, test specimens should be 10 to 12.5mm in diameter and 1 to 6 mm in thickness.5.14 Tes
33、t Method C1259Can be applied to graphite testspecimens with both round and rectangular cross sections. Theratio of test specimen length to minimal cross-sectional dimen-sion should be greater than 10, and preferably greater than 20.For shear modulus measurements, the test specimen width tothickness
34、ratio should be greater than 5.5.15 Test Method C1161Applies to rectangular parallel-epiped geometries and can be adapted for graphite. Theaverage grain size should be less than 2% of the beamthickness. For beam lengths of 25, 45, and 90 mm, specifiedwidths are 2, 4, and 8 mm, respectively, and spec
35、ified depthsare 1.5, 3, and 6 mm, respectively.6. General Principle for Measurements Outside SpecifiedSpecimen Volume/Size Constraints in CurrentStandards6.1 The default position for any user should be to followthese standards exactly as described.D7775 1126.2 Specimen size and volume constraints ma
36、y be set by aparticular measurement technique and hence apply to any testmaterial, but some may depend upon the microstructure andcomposition of the material. In such cases, it is preferable toprovide technical data and basis to support the choice of theadapted measurement technique and test specime
37、n dimensionsused.6.3 A simple, general principle should be applied to anyproposed measurements that are noncompliant with respect tovolume/size.6.3.1 The user must first specify the level of accuracyrequired for the measurements together with tolerable repeat-ability, tolerance, and bias uncertainti
38、es associated with themeasured properties. This may need to take into account thenumber of specimens used for the measurements.6.3.2 These qualifying measurement criteria must be dem-onstrated using representative material in a manner compliantwith the ASTM standard. The user should take account ofi
39、n-service changes to test material (for example, irradiation,oxidation) when selecting representative material for such ademonstration; as-manufactured material may not be suffi-ciently representative for such purposes.6.3.3 The measurements should then be repeated on thesame material, progressively
40、 reducing the volume/size of thespecimen and repeating the measurements. Ideally, this proce-dure would involve the successive re-sizing of the startingspecimen. This would ensure that no specimen to specimenvariability affected the results. Consideration should be givento within specimen variabilit
41、y and any potential effects ofspecimen preparation that might affect the property measure-ment. This process should be continued until there are suffi-cient compliant data to benchmark the measurement techniqueagainst the material; there should be sufficient data at andbelow the desired test specime
42、n geometry to characterize thedependence of the measured property upon volume/size. It maybe necessary to study more than one parameter and theseshould be varied singly in order not to confound the results.6.3.4 The results should be analyzed to establish either thestandard can be applied directly t
43、o an extended specimenvolume/size range or it can be applied with volume/sizecorrections. In both cases, the accuracy and uncertainty of themeasurement at the desired specimen volume/size should beevaluated and assessed for acceptability against the originalspecification.6.3.5 It is good practice to
44、 retain the test specimens aschecks or secondary standards in the subsequent measurementcampaigns.7. Bulk Density by Physical Measurement (Test MethodC559)7.1 Test Method C559 requires a mass measurement and avolume determination by mensuration on a test specimen witheither a rectangular parallelepi
45、ped or right cylinder geometry.The standard specifies that the specimen volume should not beless than 500 mm3and the minimum dimension must be atleast ten times the length of the largest visible grain. Theminimum dimension should also be more than 2000 times theresolution of the measuring device. Th
46、e volume determinationinvolves four length measurements (longest dimension) eitherat the centre of each long face in the case of the rectangularparallelepiped or 90 apart on the periphery of the circular endfaces in the case of the right cylinder. For the rectangularparallelepiped, width and thickne
47、ss at each end and at twointermediate points along the length are required. For the rightcylinder, two sets of diameter measurements are required, eachset consisting of four measurements, one at each end and twoat two intermediate points along an axial line.7.2 The accuracy of contact measuring devi
48、ces must beassessed in the context of point and flat contact options.7.3 Principal sources of mensuration error will arise fromgeometry irregularity and from surface condition.7.4 For specimens of regular geometry, mensuration couldbe carried out with automated multi-measurement contactdevices that
49、record and analyze results for prescribed measure-ment patterns.7.5 Non-contact scanning devices can also be used todetermine volumes of both regular and non-regular geometryspecimens. Such devices need careful qualification before useto ensure the detectors respond consistently for graphitesurfaces. The calibration and accuracy of the device must betested on volume standards made from materials that respondto the scanning beam in a simple manner to graphite.7.6 Bulk density can also be determined using ArchimedesPrinciple, as an alternative to mensuration techn
