1、Designation: B 663 94 (Reapproved 2006)Standard Specification forSilver-Tungsten Carbide Electrical Contact Material1This standard is issued under the fixed designation B 663; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the yea
2、r 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 specification covers elect
3、rical contact componentsmade from silver-tungsten carbide by powder metallurgicalprocedures.1.2 This specification covers compositions within the silver-tungsten carbide system normally specified by users of con-tacts.1.3 This standard does not purport to address all of thesafety concerns, if any, a
4、ssociated 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 health practices
5、, and determine the applicability ofregulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2B 328 Test Method for Density, Oil Content, and Intercon-nected Porosity of Sintered Metal Structural Parts andOil-Impregnated Bearings3. Significance and Use3.1 Proprietary methods for
6、 the manufacture of these mate-rials vary significantly among suppliers, and these methodsinfluence such properties as arc erosion, contact resistance, andthe tendency to weld in service. Since the performance ofcontacts in a device depends on numerous factors outside thecontact itself (opening spee
7、d, closing speed, contact pressure,contact bounce, environmental variations, assembly techniqueand variations, etc.), this specification cannot ensure perfor-mance control in the application.As part of the qualification oninitial samples, it is recommended that the user functionallyand electrically
8、test the materials for all devices applicable tothe materials use. This specification will provide a means forthe contact manufacturer and contact user to reach agreementon the details of the material to be supplied for a specific use,and reasonable assurance that future lots will be similar inprope
9、rties and microstructure to the initial test or samplecontacts supplied.4. Ordering Information4.1 Orders for this material under this specification shallinclude the following information:4.1.1 Dimensions (see Section 10),4.1.2 Chemical composition (see tables in the appendix as apossible guideline)
10、,4.1.3 Physical properties (see Section 6 and appendix as aguideline),4.1.4 Certification (see Section 13), and4.1.5 Other features as agreed upon between the manufac-turer and purchaser.5. Chemical Composition5.1 The material shall conform to composition limits asagreed upon between the manufacture
11、r and the purchaser.5.2 The chemical analysis shall be made in accordance withthe methods prescribed in the newest edition of Volume 01.02of the Annual Book of ASTM Standards or by any otherapproved method agreed upon between the manufacturer andthe purchaser.6. Physical Properties6.1 The manufactur
12、er and the purchaser shall agree onqualification tests for determination of physical properties.6.2 The tests shall be performed on production parts,wherever practical or applicable. (Small size contacts do notlend themselves to accurate conductivity measurement.)6.3 The tests shall be determined af
13、ter consideration of thefunction of the part.1This specification is under the jurisdiction of ASTM Committee B02 onNonferrous Metals and Alloys and is the direct responsibility of SubcommitteeB02.05 on Precious Metals and Electrical Contact Materials.Current edition approved June 1, 2006. Published
14、June 2006. Originallyapproved in 1979. Last previous edition approved in 2000 as B 663 94 (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 to the standards Docum
15、ent Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.4 The typical properties of three most common types ofsilver-tungsten contacts are given in the appendix.7. Dimensions, Mass, and Permissible Varia
16、tions7.1 Permissible variations in dimensions shall be within thelimits specified on drawings describing the contacts andaccompanying the order, or shall be within the limits specifiedin the purchase order.8. Finishing of Contacts8.1 The material shall be finished by such operations asnecessary to m
17、eet requirements agreed upon between themanufacturer and the purchaser of the contacts (braze alloybacking, tumbling to polish surfaces, special surface finish,silver-rich surface layer, cleaning, etc.).9. Workmanship, Finish, and Appearance9.1 The parts shall be free of defects in material or proce
18、ss-ing, that would seriously affect their performance.10. Sampling10.1 LotUnless otherwise specified, a lot shall consist ofparts of the same form and dimensions, made of powders of thesame particle size range and composition, processed under thesame conditions, and submitted for inspection at one t
19、ime.10.2 Chemical Analysis10.2.1 At least one sample for chemical analysis shall betaken from each lot. A representative sample of chips may beobtained by milling, drilling, or crushing at least two pieceswith dry tools, without lubrication. In order to obtain oil freechips, the parts selected for t
20、est shall have the oil extracted inaccordance with Test Method B 328, if necessary.10.2.2 These specification limits do not preclude the pos-sible presence of other unnamed elements, impurities, oradditives. Analysis shall be regularly made only for the minorelements listed in the table. However, if
21、 a user knows ofelements that might be detrimental to their application or hasother reasons for requiring analysis for specific elements, thenagreement between manufacturer and purchaser for both limitsand methods of analysis should be required for elements notspecified.10.3 Physical TestsThe manufa
22、cturer and the purchasershall agree on a representative number of specimens forphysical tests including microstructure.11. Inspection11.1 Unless otherwise specified, inspection of parts suppliedon contract shall be made by the purchaser.12. Rejection12.1 Unless otherwise specified, rejections based
23、on testsmade in accordance with the specification shall be reported tothe manufacturer within 30 days of the receipt of the shipment.13. Certification13.1 A certification, when requested by the user, based onthe manufacturers quality control that the material conforms tothe requirements of this spec
24、ification, shall be furnished uponrequest of the purchaser, provided the request is made at thetime of cost quotation and at the time of order placement.14. Keywords14.1 arcing contacts; contacts; electrical contacts; powdermetallurgy; silver; silver tungsten carbide; tungsten carbide;tungsten carbi
25、de silverAPPENDIX(Nonmandatory Information)X1. TYPICAL PROPERTY VALUESX1.1 The following information provides guidelines forusers and manufacturers of silver-tungsten carbide contactmaterial. Typical ranges of chemistry and properties are givenfor the three most popular compositions, 40 % silver/60
26、%tungsten carbide, 50 % silver/50 % tungsten carbide, 65 %silver/35 % tungsten carbide. These properties are influencedby the particle size, shape, and distribution of tungsten carbide,homogeneity, impurities or additives, and other manufacturingprocess variablesNOTE X1.1Table X1.1 and Table X1.2 re
27、present the major manufac-turing techniques used in industry. The size and shape of the part isimportant in choosing the optimum technique as well as other consider-ations such as frequency of operation of the device, and how crucial is itsapplicationX1.1.1 The best choice for a given application sh
28、ould bemutually decided between the purchaser and the manufacturerusing their mutual experience and application engineeringknowledge.X1.2 With the knowledge that several types are available,care should be taken to ensure that production lots are the samein all respects as samples and that if a selle
29、r change is made,noticeable property or performance variations are possible.B 663 94 (2006)2TABLE X1.1 Typical Chemical Ranges Infiltrated Silver-Tungsten Carbide ContactsComposition,AWeight, %Class A Class B Class CSilver 38 to 42 48 to 52 63 to 67Tungsten carbide balance balance balanceCopper, max
30、 0.5 0.5 0.5Cobalt or nickel, max 0.5 0.5 0.5Total impurities, max 1 1 1Typical PropertiesClass A Class B Class CHardness, Rockwell B 95 to 105 86 to 96 50 to 65Density, Mg/m313.1 12.6 11.9Electrical conductivity, % IACS 35 to 40 45 to 50 55 to 60Theoretical density, min, % 96 96 96PropertiesClass A
31、 Class B Class CModulus of rupture:BpsiMPa120 00082795 00065580 000552Youngs modulus:BpsiGPa56 3 10638650 3 10634536 3 106248Tensile strength:BpsiMPa55 00037940 00027639 500272Coefficient of expansion:Bin./in.Fm/mK7.6 3 10613.7 3 1068.25 3 10614.8 3 1069.45 3 10617 3 106Thermal conductivity:BBtuin.h
32、ft2FW/mK280840543926334968716AAnalysis is regularly made for the elements for which specific limits are listed. If, however, the presence of “other” elements is suspected or indicated in the courseof routine analysis, further analysis shall be made to determine that the total of these “other” elemen
33、ts and the listed impurities are not in excess of the total impurities limit.BItems that are normally useful for engineering calculations in contact design but are not specified.TABLE X1.2 Typical Chemical Ranges Press, Sintered, and Repressed Silver-Tungsten Carbide ContactsCompositionAWeight, %Cla
34、ss A Class B Class CSilver 38 to 42 48 to 52 63 to 67Tungsten carbide balance balance balanceCopper, max 0.2 0.2 0.2Nickel or cobalt, max 0.2 0.2 0.2Total impurities, max 0.5 0.5 0.5Typical PropertiesClass A Class B Class CHardness, Rockwell B (as repressed) 60 to 70 60 to 70 40 to 55Hardness, Rockw
35、ell B (annealed) 55 to 65 55 to 65 35 to 45Density, Mg/m313.1 12.6 11.9Theoretical density, min,% 95 95 95Modulus of ruptureBpsi 70 000 62 000 60 000MPa 483 427 414AAnalysis is regularly made for the elements for which specific limits are listed. If, however, the presence of “other” elements is susp
36、ected or indicated in the courseof routine analysis, further analysis shall be made to determine that the total of these “other” elements and the listed impurities are not in excess of the total impurities limit.BItems that are normally useful for engineering calculations in contact design but are n
37、ot specified.B 663 94 (2006)3ASTM International takes no position respecting 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 inf
38、ringement 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 years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this stand
39、ard or for additional standardsand should be addressed to ASTM International 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 vi
40、ews 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).B 663 94 (2006)4
