1、Designation: B63 07 (Reapproved 2013)Standard Test Method forResistivity of Metallically Conducting Resistance andContact Materials1This standard is issued under the fixed designation B63; the number immediately following the designation indicates the year of originaladoption or, in the case of revi
2、sion, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscriptepsilon () 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 method co
3、vers the determination, to a precisionof 2 %, of the electrical resistivity of materials used inresistors, heating elements, and electrical contacts, as well asproducts of powder metallurgy processes which are used forother purposes.NOTE 1For determining the resistivity of electrical conductors, see
4、Test Method B193.1.2 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.3 This standard does not purport to address all of thesafety conce
5、rns, if any, associated with its use. It is theresponsibility of the user of this standard to become familiarwith all hazards including those identified in the appropriateMaterial Safety Data Sheet (MSDS) for this product/materialas provided by the manufacturer, to establish appropriatesafety and he
6、alth practices, and determine the applicability ofregulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2B193 Test Method for Resistivity of Electrical ConductorMaterials3. Terminology3.1 Definitions:3.1.1 resistivity, nthat property of a material which deter-mines its resist
7、ance to the flow of an electric current, expressedas: 5 RA/L (1)where R is the resistance in ohms of a specimen of thematerial of uniform cross section A and of a length L.Inreporting values of resistivity under this test A shall be ex-pressed in square centimeters and L in centimeters. Resistiv-ity
8、 is measured in micro ohm-meter. English units of ohmscircular mil per foot are expressed as: 5 12 3106RA/0.7854 L (2)where:R = resistance in ohmsA = uniform cross section area in square inchesL = length in inches4. Significance and Use4.1 In the case of materials for resistors and heatingelements,
9、a knowledge of resistivity is important in determin-ing whether wire or strip of a specified area of cross section andlength will have a required resistance. It serves as one basis forthe selection of materials for specific applications and itsmeasurement is a necessary acceptance test for resistanc
10、ematerials.4.2 In the case of materials for electrical contacts, themeasurement of resistivity can serve as a test for uniformity ofmaterials of nominally the same composition and structure.5. Apparatus5.1 Means for applying current and voltage terminals to thespecimen are specified in Section 9. An
11、 optional suitablespecimen holder for nonductile materials is shown in Fig. 1.5.2 A suitable bridge, potentiometer, digital ohmmeter, orequivalent, with necessary accessories for making resistancemeasurements with a limit of error of less than 0.5 %.5.3 Means for measuring the dimensions of the spec
12、imen,adequate to determine its length and its mean area of crosssection, each within 0.5 %.6. Test Specimen6.1 Ductile MaterialsThe test specimen for ductilematerials, including those used for contacts, shall be in the1This test method is under the jurisdiction of ASTM Committee B02 onNonferrous Met
13、als and Alloys and is the direct responsibility of SubcommitteeB02.10 on Thermostat Metals and Electrical Resistance Heating Materials.Current edition approved May 1, 2013. Published May 2013. Originallyapproved in 1926. Last previous edition approved in 2007 as B63 07. DOI:10.1520/B0063-07R13.2For
14、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,
15、West Conshohocken, PA 19428-2959. United States1form of a wire or a strip. In order to determine the resistivitywith a precision of 2 %, it is necessary that the resistance,cross-sectional area, and length shall be measured with a limitof error within 0.5 %. To ensure this limit of error each testsp
16、ecimen shall conform to the following:6.1.1 It shall have a length of at least 0.5 ft (15 cm) betweenpotential probes.6.1.2 It shall have a resistance of at least 0.001 .6.1.3 If the cross section is to be determined by directmeasurement, the diameter of a wire specimen or the thicknessof a strip sp
17、ecimen shall not be less than the limits defined bythe 0.5 % criteria of 6.1, and this dimension throughout thelength of the specimen shall not vary by more than 3 %.6.1.4 It shall show no surface cracks or other defectsobservable with normal vision, and shall be free from surfaceoxide.6.2 Nonductil
18、e MaterialsThe test specimen for nonductilematerials shall be made in accordance with Fig. 2 if theItemDescription Dimensions, in. (mm) Material NumberRequired1 Base block12 by 3 by 4 (12.7 by 76.2 by 101.6) micarta 12 Clamp block34 by 1 by 1 (19.0 by 25.4 by 25.4) copper 23 Current lead clamp screw
19、, knurled head1032 by316 brass 24 Specimen clamp screw, knurled head14 in.by40by1in. brass 25 Pivot bracket12 by1516 by 1716 (12.7 by 23.8 by 36.5) steel 26 Pivot . steel 27 Pivot block12 by 2332 by 3 (12.7 by 53.2 by 76.2) micarta 18 Potential knife-edge . steel 2 sets9 Specimen being tested . . .N
20、OTE 1Contact surfaces must be clean and free of visible oxide.FIG. 1 Specimen Holder for Nonductile MaterialsNOTE 1Metric equivalents are as follows.in. mm in. mm0.010 0.25 0.438 11.120.012 0.30 2.000 50.800.187 4.75 2.375 60.320.188 4.78 3.250 82.550.237 6.01FIG. 2 Resistivity Test Specimen for Mac
21、hinable Nonductile Ma-terialsB63 07 (2013)2material is readily machinable. For materials which are notreadily machinable, such as those containing graphite, a flatstrip may be used as a test specimen. In order to determine theresistivity with a precision of 2 %, each specimen shallconform to the fol
22、lowing:6.2.1 The diameter of a specimen (Fig. 2), or the thicknessand width of a strip specimen, shall be uniform within 1 %.6.2.2 It shall show no surface cracks or other defectsobservable with normal vision, and shall be free from surfaceoxide.7. Length Measurements7.1 The length may be measured b
23、y any scale which willgive an accuracy of 0.5 % in the length measured. In casepotential leads are used, the length shall be taken between thepotential contacts. In the direction of the length of specimen,the dimension of each potential contact, including solderingsurface or clamp contact area, shal
24、l not be more than 0.5 % ofthe distance between the potential contacts. In the case of thespecimen holder for nonductile materials shown in Fig. 1, thedistance between the potential contacts may be found bymeasuring from the outside flat of one potential knife edge tothe outside flat of the other. A
25、 micrometer or other suitablemeans shall be used for measuring this length.8. Cross-Sectional Area Measurements8.1 In general, the diameter of a specimen of circular crosssection, or the thickness and width of a strip specimen, shall bedetermined by micrometer measurements, and a sufficientnumber of
26、 measurements shall be made to obtain the meancross section to within 0.5 %.8.2 In case the diameter of the cylinder or the thickness ofthe strip cannot be measured to give the above accuracy withthe micrometer available, determine the cross section from theweight, density, and length of specimen.8.
27、3 When the density is unknown, it may be determined asfollows:8.3.1 For nonporous materials first weigh a sample of atleast 10 g in air and then in water. The density in grams percubic centimetre is equivalent to the weight in air divided bythe loss of weight due to submergence in water. The water s
28、hallbe at room temperature to avoid errors due to convectioncurrents. For the accuracy required, no corrections are neces-sary for the temperature of the water or for the buoyancy of theair. However, exercise care to remove all air bubbles from thespecimen when weighing it in water. To remove air bu
29、bblesfrom a specimen of fine wire, dip the wire, in the form of aloosely wound coil, in alcohol and rinse in water beforeimmersing it in the water to be used in weighing. Thencalculate the density from the following equation:D 5 B/B 2 E! (3)where:D = density, g/cm3B = weight of specimen in air, gE =
30、 weight of specimen in water, gThe cross-sectional area, A, in square centimeters, may befound from the equation:A 5 B 2 E!/L (4)8.3.2 For porous materials such as products of powdermetallurgy, weigh a specimen of at least 10 g in air. Immersethe specimen for at least4hinoil(viscosity of approximate
31、ly200 SUS at 37.8C (100F), held at a temperature of 82.2 65.5C (180 6 10F). Then cool the specimen to room tem-perature by immersing it in oil at room temperature. Afterremoving excess oil from the specimen by means of a softcloth, weigh the specimen in air and then in water. Calculatethe density fr
32、om the equation:D 5 B/C 2 E! (5)where:D = density, g/cm3B = weight of the unimpregnated specimen in air, gC = weight of the specimen impregnated with oil (in air), gE = weight of the impregnated specimen in water, gThe cross-sectional area, A, in square centimetres, may befound from the equation:A 5
33、 C 2 E!/L (6)9. Leads9.1 Specimens with a resistance of less than 10 shall beprovided with both current and potential leads. The minimumdistance between each potential contact and the adjacentcurrent lead shall be at least three times the diameter of thewire or the width of the strip. Current shall
34、be introduced intothe specimen with current leads amply large to minimizeheating of the specimen. Specimens with a resistance greaterthan 10 do not require potential leads, though they may beused, if desired.10. Resistance Measurements10.1 Resistance of specimens provided with potential leadsshall b
35、e measured with a Kelvin bridge, potentiometer, digitalohmmeter, or equivalent capable of measuring the resistancebetween the potential contacts with a limit of error within0.5 %. Specimens with a resistance of more than 1 may bemeasured with a limit of error within 0.5 % by means of asuitable Wheat
36、stone bridge.11. Heating of Specimen11.1 In all resistance measurements, the measuring currentraises the temperature of the specimen above that of thesurrounding medium. If this is sufficient to change the resis-tance by 0.5 %, a correction shall be made. In general, thesmallest current that will gi
37、ve the sensitivity necessary tomeasure to 0.5 % of the resistance shall be used. A convenienttest to determine whether a correction should be applied is toincrease the current to 1.4 times the value it had when themeasurement was made (Note 2) and then to measure theresulting change in resistance. I
38、f this change is as large as0.5 % of the measured value, a correction should be made. Fora material which has a positive temperature coefficient ofresistance, the resistance at the temperature of the surroundingmedium shall be obtained by subtracting the measured changefrom the resistance as measure
39、d with the smaller current. ForB63 07 (2013)3material with a negative temperature coefficient, this differenceshall be added to the resistance obtained by measurements withthe smaller current.NOTE 2Increasing the current to 1.4 times the value it had when themeasurement was made serves to very nearl
40、y double the heating effect,and, for small changes in temperature, the rise in temperature.11.2 Measurements are to be in a controlled temperatureenvironment.12. Report12.1 Report the following information:12.1.1 Identification of test specimen,12.1.2 Material type,12.1.3 Temperature of surrounding
41、medium,12.1.4 Length of specimen used,12.1.5 Method of obtaining cross-sectional area:12.1.5.1 If by micrometer, a record of all micrometerreadings, including average values and calculated cross-sectional area,12.1.5.2 If by weighing, a record of length, mass and densitydeterminations and calculated
42、 cross-sectional area,12.1.6 Method of measuring resistance,12.1.7 Value of resistance,12.1.8 Calculated value of electrical resistivity, and12.1.9 Previous mechanical and thermal treatments. (Sincethe resistivity of a material usually depends upon them, theseshall be stated whenever the information
43、 is available.)13. Precision and Bias13.1 The precision of this test method is within 2 %.13.2 The bias of this test method is less than 1 %.14. Keywords14.1 contact materials; electrical conductors; heating ele-ments; resistivity; resistors; specific resistanceASTM International takes no position r
44、especting the validity of any patent rights asserted in connection with any item mentionedin this 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.Thi
45、s standard is subject to revision at any time by the responsible technical committee and must be 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 Inte
46、rnational Headquarters. Your comments will receive careful consideration at a meeting of theresponsible 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
47、below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West 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). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).B63 07 (2013)4
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