1、Designation: C 695 91 (Reapproved 2005)An American National StandardStandard Test Method forCompressive Strength of Carbon and Graphite1This standard is issued under the fixed designation C 695; the number immediately following the designation indicates the year oforiginal adoption or, in the case o
2、f revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This test me
3、thod covers the determination of the com-pressive strength of carbon and graphite at room temperature.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 he
4、alth practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C 709 Terminology Relating to Manufactured Carbon andGraphiteE4 Practices for Force Verification of Testing MachinesE 177 Practice for Use of the Terms Precision and Bias
5、 inASTM Test MethodsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 Definitions: DefinitionsFor definitions of terms relat-ing to manufactured carbon and graphite, see TerminologyC 709.4. Significance and Use4.1 Carbon and graphite c
6、an usually support higher loads incompression than in any other mode of stress. This test,therefore, provides a measure of the maximum load-bearingcapability of carbon and graphite objects.5. Apparatus5.1 Test Machine, conforming to Practice E4 and to therequirements for speed of testing prescribed
7、in Section 8 of thistest method.5.2 Spherical Bearing Blocks attached to the upper or lowerhead of the machine in such a manner that the sphericalsurfaces are in full contact when not loaded. The center ofcurvative of the spherical surface shall lie on the surface thatcontacts the specimen and on th
8、e machine axis. The sphericalsurfaces shall be well-lubricated. The radius of the sphericalsurface shall be equal to or greater than the radius of the testspecimen.5.3 Steel Contact Blocks may be used above or below thespecimen, or both, to protect fixture and test machine surfacesfrom damage, as il
9、lustrated in Fig. 1 and Fig. 2. Contact blocksurfaces shall be plane and parallel to within 0.0005 in./in.(0.0005 mm/mm).5.4 All load-bearing machine and fixture surfaces shall havea minimum hardness of 45 HRC and surface finish of 16 in.(0.4 m) rms maximum. Surfaces in contact with the specimenshal
10、l be flat to less than 0.0005 in./in. (0.0005 mm/mm).5.5 Examples of arrangements of the load train are shownschematically in Fig. 1 and Fig. 2.6. Sampling6.1 Samples may be taken from locations and orientationsthat satisfy the objectives of the test.7. Test Specimen7.1 The test specimen shall be a
11、right cylinder with endsmachined to yield planar and parallel faces. These faces shallbe perpendicular to the cylindrical surface to within 0.001in./in. (0.001 mm/mm) of diameter total indicator reading. Allsurfaces shall have a surface finish visually comparable to 32in. (0.8 m) rms or better. Reas
12、onable care should beexercised to assure that all edges are sharp and without chips orother flaws.7.2 The diameter of the test specimen shall be greater thanten times the maximum particle size of the carbon or graphite.The ratio of height to diameter may vary between 1.9 and 2.1.The recommended mini
13、mum test specimen size is38 in. (9.5mm) diameter by34 in. (19 mm) high.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.F0 on Manufactured Carbon and Graphite Products.Current edition approved Ju
14、ne 1, 2005. Published August 2005. Originallyapproved in 1971. Last previous edition approved in 2000 as C 69591(2000).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
15、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.8. Procedure8.1 Center the specimen in the machine between the contactsurfaces. The deviation of the specimen axis from the mac
16、hineaxis shall be less than 5 % of the specimen diameter. Centeringcan be assisted by appropriate circles marked on the contactsurfaces.8.2 Place an appropriate guard around the specimen todeflect flying fragments at failure.8.3 Apply the load continuously, at a constant rate ofcrosshead or platen m
17、ovement, and without shock until ulti-mate failure. Choose the rate of movement so that averagerupture time is greater than 30 s.8.4 If the test machine is equipped with a load or strainpacing device, a constant load or strain rate may be used.9. Calculation9.1 Calculate the compressive strength of
18、each specimen asfollows:C 5 W/Awhere:C = compressive strength of specimen, psi (or MPa),W = total load on the specimen at failure, lbf (or N), andA = calculated area of the gage section of the specimen,in.2(or mm2).10. Report10.1 The report shall include the following:10.1.1 Type of testing machine,
19、 hydraulic or screw,10.1.2 Type and size of contact blocks,10.1.3 General description of material being tested,10.1.4 Dimensions, location, and orientation of specimens,10.1.5 Details of specimen preparation,10.1.6 Rate of crosshead or platen movement, or load rate,or strain rate,10.1.7 Load at fail
20、ure, failure mode, and compressivestrength of each specimen, and10.1.8 Mean compressive strength and standard deviationfor material tested.FIG. 1 Elements of Compressive Strength Load TrainFIG. 2 Compressive Test Arrangement with Spherical Blocks on BottomC 695 91 (2005)211. Precision and Bias311.1
21、PrecisionThe precision statements given in this sec-tion are based on the comparison of the mean strength by theStudent “t” test and carrying out the statistical analysis of thedata obtained in a round robin as recommended by PracticeE 691. The round robin was carried out on two materials.11.1.1 Com
22、parison of the MeansThe comparison of themeans by the Student “t” test leads to the conclusion that theaverage strength values measured by each laboratory on eachmaterial can be considered statistically equal at 95 % confi-dence level.11.1.2 Repeatability (Single Instrument) The precisionwithin labo
23、ratory of two single values of measured strengthusing Practice E 177 definition with the pooled standarddeviation calculated using Practice E 691:Repeatability within laboratory 5 2 Sr!jwhich yields a value for the materials used in the round robinof 469 psi (3.2 MPa) for one material and 522 psi (3
24、.6 MPa) forthe other. These values convert into strength percentages of 65for one material and 62.5 for the other.11.1.3 Repeatability (Multi-Instrument) The precision be-tween laboratories of two single values of measured strengthusing Practice E 177 definition with the component of variancebetween
25、 laboratories calculated using Practice E 691 is:Repeatability between laboratories 5 2 SL!jwhich yields a value for the materials used in this roundrobin of 347 psi (2.4 MPa) for one material and 135 psi (1MPa) for the other. This converts into strength percentages of63 for one material and 61 for
26、the other.11.2 BiasNo true statement on bias can be made becauseno reference carbon or graphite material exists.12. Keywords12.1 carbon; compressive strength; graphiteASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin th
27、is standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must b
28、e reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theres
29、ponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, W
30、est Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).3Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:C05-1010.C 695 91 (2005)3
