1、Designation: B 63 07Standard Test Method forResistivity of Metallically Conducting Resistance andContact Materials1This standard is issued under the fixed designation B 63; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year o
2、f last revision. A number in parentheses indicates the year of last reapproval. A superscriptepsilon (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 method covers the determ
3、ination, 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, seeTest Method B 1
4、93.1.2 The values stated in inch-pound units are to be regardedas the standard. The values given in parentheses are forinformation only.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 be
5、come 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 health practices, and determine the applicability ofregulatory limitations prior to use.2. Referen
6、ced Documents2.1 ASTM Standards:2B 193 Test Method for Resistivity of Electrical ConductorMaterials3. Terminology3.1 Definitions:3.1.1 resistivity, nthat property of a material which deter-mines its resistance to the flow of an electric current, expressedas:r5RA/L (1)where R is the resistance in ohm
7、s of a specimen of thematerial of uniform cross section A and of a length L.Inreporting values of resistivity under this test A shall beexpressed in square centimeters and L in centimeters. Resis-tivity is measured in micro ohm-meter. English units of ohmscircular mil per foot are expressed as:? 5 1
8、2 3 106RA/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 heating ele-ments, a knowledge of resistivity is important in determiningwhether wire or strip of a specified are
9、a 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 resistancematerials.4.2 In the case of materials for electrical contacts, themeasurement of resistivity c
10、an 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 optional suitablespecimen holder for nonductile materials is shown in Fig. 1.5.2 A suitable bri
11、dge, 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 specimen,adequate to determine its length and its mean area of crosssection, each within 0.5 %.6. Te
12、st Specimen6.1 Ductile MaterialsThe test specimen for ductile ma-terials, including those used for contacts, shall be in the form1This test method is under the jurisdiction of ASTM Committee B02 onNonferrous Metals and Alloys and is the direct responsibility of SubcommitteeB02.10 on Thermostat Metal
13、s and Electrical Resistance Heating Materials.Current edition approved May 1, 2007. Published June 2007. Originallyapproved in 1926. Last previous edition approved in 2001 as B 63 90 (2001).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at servi
14、ceastm.org. For Annual Book of ASTMStandards 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.of a wire or a strip. In order to determine the resistiv
15、ity with aprecision of 2 %, it is necessary that the resistance, cross-sectional area, and length shall be measured with a limit oferror within 0.5 %. To ensure this limit of error each testspecimen shall conform to the following:6.1.1 It shall have a length of at least 15 cm (0.5 ft) betweenpotenti
16、al probes.6.1.2 It shall have a resistance of at least 0.001 V.6.1.3 If the cross section is to be determined by directmeasurement, the diameter of a wire specimen or the thicknessof a strip specimen shall not be less than the limits defined bythe 0.5 % criteria of 6.1, and this dimension throughout
17、 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 Nonductile MaterialsThe test specimen for nonductilematerials shall be made in accordance with Fig. 2 if thematerial
18、 is readily machinable. For materials which are notItemDescription 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, knurled head1032 by316 brass 24 Specimen clamp
19、 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 . . .NOTE 1Contact surfaces must be clean and free of
20、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 Machinable NonductileMaterialsB63072readily machina
21、ble, 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 following:6.2.1 The diameter of a specimen (Fig. 2), or the thicknessand width of a strip specimen, shall be uniform wit
22、hin 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 by any scale which willgive an accuracy of 0.5 % in the length measured. In casepotential leads are used, the length s
23、hall 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, shall not be more than 0.5 % ofthe distance between the potential contacts. In the case of thespecimen holder for nonduct
24、ile 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 micrometer or other suitablemeans shall be used for measuring this length.8. Cross-Sectional Area Measurements8.1 In
25、 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 measurements shall be made to obtain the meancross section to within 0.5 %.8.2 In case the diameter of the cylinder
26、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.8.3 When the density is unknown, it may be determined asfollows:8.3.1 For nonporous materials first weigh a sample of a
27、tleast 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 shallbe at room temperature to avoid errors due to convectioncurrents. For the accuracy required, no corrections are n
28、eces-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 bubblesfrom a specimen of fine wire, dip the wire, in the form of aloosely wound coil, in alcohol and rinse in water be
29、foreimmersing 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 = weight of specimen in water, gThe cross-sectional area, A, in square centimeters, may befound from the equation:A 5B
30、 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 approximately200 SUS at 37.8C (100F), held at a temperature of 82.2 65.5C (180 6 10F). Then cool the specimen to room tem-peratur
31、e 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 from the equation:D 5 B/C 2 E! (5)where:D = density, g/cm3B = weight of the unimpregnated specimen in air, gC = weight o
32、f 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 5C 2 E!/L (6)9. Leads9.1 Specimens with a resistance of less than 10 V shall beprovided with both current and potential
33、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 be introduced intothe specimen with current leads amply large to minimizeheating of the specimen. Specimens with a res
34、istance greaterthan 10 V do not require potential leads, though they may beused, if desired.10. Resistance Measurements10.1 Resistance of specimens provided with potential leadsshall be measured with a Kelvin bridge, potentiometer, digitalohmmeter, or equivalent capable of measuring the resistancebe
35、tween the potential contacts with a limit of error within0.5 %. Specimens with a resistance of more than 1 V may bemeasured with a limit of error within 0.5 % by means of asuitable Wheatstone bridge.11. Heating of Specimen11.1 In all resistance measurements, the measuring currentraises the temperatu
36、re 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 give the sensitivity necessary tomeasure to 0.5 % of the resistance shall be used. A convenienttest to determine whe
37、ther 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. If this change is as large as0.5 % of the measured value, a correction should be made. Fora material which has a po
38、sitive temperature coefficient ofresistance, the resistance at the temperature of the surroundingmedium shall be obtained by subtracting the measured changefrom the resistance as measured with the smaller current. ForB63073material with a negative temperature coefficient, this differenceshall be add
39、ed 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 nearly double the heating effect,and, for small changes in temperature, the rise in temperature.11.2 Measurements are to be in
40、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 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
41、of all micrometer read-ings, including average values and calculated cross-sectionalarea,12.1.5.2 If by weighing, a record of length, mass and densitydeterminations and calculated cross-sectional area,12.1.6 Method of measuring resistance,12.1.7 Value of resistance,12.1.8 Calculated value of electri
42、cal resistivity, and12.1.9 Previous mechanical and thermal treatments. (Sincethe resistivity of a material usually depends upon them, theseshall be stated whenever the information is available.)13. Precision and Bias13.1 The precision of this test method is within 2 %.13.2 The bias of this test meth
43、od is less than 1 %.14. Keywords14.1 contact materials; electrical conductors; heating ele-ments; resistivity; resistors; specific resistanceASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this
44、 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 be reviewed every five year
45、s 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 theresponsible technical committ
46、ee, 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, 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).B63074
