1、Designation: D7775 16 An American National StandardStandard 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 la
2、st revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This guide covers best practice for properties measure-ments on small (nonstandard) graphite specimens and require-ment
3、s for representing properties of 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. Theobjective of this guide is to provide advice on how theapplication of selected s
4、tandards under noncompliant condi-tions can be tested for suitability.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use.
5、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:2C559 Test Method for Bulk Density by Physical Measure-ments of Manufactured Ca
6、rbon and Graphite ArticlesC565 Test Methods for Tension Testing of Carbon andGraphite Mechanical MaterialsC611 Test Method for Electrical Resistivity of ManufacturedCarbon and Graphite Articles at Room TemperatureC651 Test Method for Flexural Strength of ManufacturedCarbon and GraphiteArticles Using
7、 Four-Point Loading atRoom TemperatureC695 Test Method for Compressive Strength of Carbon andGraphiteC714 Test Method for Thermal Diffusivity of Carbon andGraphite by Thermal Pulse MethodC747 Test Method for Moduli of Elasticity and FundamentalFrequencies of Carbon and Graphite Materials by SonicRes
8、onanceC748 Test Method for Rockwell Hardness of Graphite Ma-terialsC749 Test Method for Tensile Stress-Strain of Carbon andGraphiteC769 Test Method for Sonic Velocity in ManufacturedCarbon and Graphite Materials for Use in Obtaining anApproximate Value of Youngs ModulusC781 Practice for Testing Grap
9、hite 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 Flexural Strength of AdvancedCeramics at Ambient TemperatureC1259 Test Method for Dynamic Youngs Modu
10、lus, ShearModulus, and Poissons Ratio for Advanced Ceramics byImpulse Excitation of VibrationD7972 Test Method for Flexural Strength of ManufacturedCarbon and Graphite Articles Using Three-Point Loadingat Room TemperatureE228 Test Method for Linear Thermal Expansion of SolidMaterials With a Push-Rod
11、 DilatometerE1461 Test Method for 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
12、developed with the objectiveof optimizing 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 si
13、ze ranges, or both. The defaultposition 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 h
14、ow the application of selectedstandards under noncompliant conditions can be tested for1This guide is under the jurisdiction of ASTM Committee D02 on PetroleumProducts, Liquid Fuels, and Lubricants and is the direct responsibility of Subcom-mittee D02.F0 on Manufactured Carbon and Graphite Products.
15、Current edition approved Dec. 15, 2016. Published February 2017. Originallyapproved in 2011. Last previous edition approved in 2015 as D7775 11 (2015).DOI: 10.1520/D7775-16.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For A
16、nnual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis inter
17、national standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Com
18、mittee.1suitability. The ultimate objective is to provide guidance on theuse of each of the ASTM standards listed. The 2016 issue ofthis guide addresses nine standards: Test Method C559 forBulk Density by Physical Measurement of ManufacturedCarbon and Graphite Articles, Test Method C611 for Electric
19、alResistivity 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 for SonicVelocity in Manufactured Carbon and Graphite Materials forUse in Obtaini
20、ng Youngs Modulus, Test Method C749 forTensile Stress-Strain of Carbon and Graphite and Test MethodD7972 for Flexural Strength of Manufactured Carbon andGraphite Articles Using Three-Point Loading at RoomTemperature, Test Method E228 for Linear Thermal Expansionof Solid Materials with a Push-Rod Dil
21、atometer, and TestMethod E1461 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 outside the constraints imposed on size/volume inexisting ASTM standards for g
22、raphite (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 the user to demonstrate that the application ofa standard outside any specifi
23、ed 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 test specimens withrectangular parallelepiped or right circular cylinder geometry
24、.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. Grain size must be smaller than0.79 mm; while not specified, it is assumed that
25、 this refers toaverage grain size. The acceptable fracture zone shall be19 mm long with the centre of the zone at the point ofminimum diameter. The ratio of specimen diameter to grainsize or flaw size must be greater than 5.5.3 Test Method C611Applies to strip, rod, bar or tubegeometries. Specimen l
26、ength 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 minimum dimension should be greaterthan 5 times the largest grain dimension. Test s
27、pecimen lengthto thickness 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 greater than 10 times themaximum grain size. The test specimen height to dia
28、meterratio 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 not be toolarge relative to the flash source as the front surface needs to
29、 beheated uniformly. The specimen thickness must be selectedsuch that /t1/2is smaller than 0.02, where is the pulse timeand t1/2is the time for the rear surface temperature to rise toone half of its maximum value.5.7 Test Method C747Applies to slender rod or bargeometries. The test specimen length t
30、o 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 120Rockwell L.5.9 Test Method C749Applies to reduced-diameter uni-axial tensile te
31、st geometries as defined in Fig. 9 of thatstandard. Gauge 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 sonic pulseby selecting a wavelength appropriate to the grain size of thete
32、st 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 than the wavelength ofsound within the material.5.11 Test Method C886Can be ap
33、plied to any convenienttest specimen size, but test surfaces smaller than 5 mm by5 mm are not recommended. The material must have a grainsize less than 0.8 mm. The minimum specimen thickness is5 mm.5.12 Test Method C1161Applies to rectangular parallel-epiped geometries and can be adapted for graphit
34、e. Theaverage grain size should be less than 2 % of the beamthickness. For beam lengths of 25 mm, 45 mm, and 90 mm,specified widths are 2 mm, 4 mm, and 8 mm, respectively, andspecified depths are 1.5 mm, 3 mm, and 6 mm, respectively.5.13 Test Method C1259Can be applied to graphite testspecimens with
35、 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 ratio should be greater than 5.5.14 Test Method D7972Applie
36、s only to those specimensizes and geometries selected for the interlaboratory study thatunderwrites the standard. Reference should be made to thetable of specimen sizes and testing configurations included inthe standard. It is recommended that the size of the testspecimen is selected such that the m
37、inimum dimension of thespecimen is greater than 5 times the largest particle dimension.It is recommended that the test specimen has a length tothickness/diameter ratio of at least 6, and a width to thicknessratio not greater than 2.D7775 1625.15 Test Method E228Applies to right cylinder (prefer-able
38、) or slab geometries. Ideally, test specimens should be25 mm to 60 mm long and 5 mm to 10 mm in diameter orequivalent (although there is no fundamental limitation pro-vided the instrument controls the maximum thermal gradient tobetter than 62 C50 mm). The specimen length should besuch that the accur
39、acy of determining the expansion L/L0isat least 620 mmm.5.16 Test Method E1461Applies to thin circular diskspecimens with the front surface area less than that of theenergy beam. Typically, test specimens should be 10 mm to12.5 mm in diameter and 1 mm to 6 mm in thickness.6. General Principle for Me
40、asurements Outside SpecifiedSpecimen Volume/Size Constraints in CurrentStandards6.1 The default position for any user should be to followthese standards exactly as described.6.2 Specimen size and volume constraints may be set by aparticular measurement technique and hence apply to any testmaterial,
41、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 specimen dimensionsused.6.3 A simple, general principle should be applied to anyproposed m
42、easurements that are noncompliant with respect tovolume/size.6.3.1 The user must first specify the level of accuracyrequired for the measurements together with tolerablerepeatability, tolerance, and bias uncertainties associated withthe measured properties.This may need to take into account thenumbe
43、r 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 ofin-service changes to test material (for example, irradiation,oxidation) when selecting
44、 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 reducing the volume/size of thespecimen and repeating the measurements. Ideally, this
45、 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 variability and any potential effects ofspecimen preparation that might affect the property meas
46、ure-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 specimen geometry to characterize thedependence of the measured property upon volume/size. It
47、 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 to an extended specimenvolume/size range or it can be applied with volume/sizecorrectio
48、ns. 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 retain the test specimens aschecks or secondary standards in the subsequent measureme
49、ntcampaigns.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 parallelepiped 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. The volume determinationinvolves four length measu
