1、Designation: B 631 93 (Reapproved 2004)Standard Specification forSilver-Tungsten Electrical Contact Materials1This standard is issued under the fixed designation B 631; 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 (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This specification covers electrical contact componentsmade from silver-tungsten by powder-metallurgical proce-dures.1.
3、2 This specification covers compositions within the silver-tungsten system normally specified by users of contacts.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 become familiarwith all
4、 hazards including those identified in the appropriateMaterial Data Safety Sheet for this product/material as pro-vided by the manufacturer, to establish appropriate safety andhealth practices, and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Stan
5、dards:2B 328 Test Method for Density, Oil Content, and Intercon-nected Porosity of Sintered Metal Structural Parts andOil-Impregnated Bearings3. Ordering Information3.1 Orders for this material under this specification shallinclude the following information:3.1.1 Dimensions (see Section 7).3.1.2 Che
6、mical composition (see reference tables in theAppendix X1 as a possible guide).3.1.3 Physical properties (see Section 6 and Appendix X1 asguideline).3.1.4 Certification (see Section 13).3.1.5 Other features as agreed upon between the purchaserand manufacturer.4. Chemical Composition4.1 The material
7、shall conform to composition limits asagreed upon between the manufacturer and purchaser.4.2 The chemical analysis shall be made in accordance withthe methods prescribed in the newest edition of the AnnualBook of ASTM Standards, or by any other approved methodagreed upon between the manufacturer and
8、 purchaser.5. Other Requirements5.1 The manufacturer and purchaser shall agree on qualifi-cation tests for determination of physical properties.5.2 The tests shall be performed on production parts,wherever practical or applicable (small size contacts do notlend themselves to accurate conductivity me
9、asurement).5.3 The tests shall be determined after consideration of thefunction of the part.5.4 The typical properties of the four most common types ofsilver-tungsten contacts are given in the appendix.6. Finishing of Contacts6.1 The material shall be finished by such operations asnecessary to meet
10、requirements agreed upon by the maker anduser of the contacts (braze alloy backing, tumbling to polishsurfaces, special surface finish, silver-rich surface layer, clean-ing, etc.).7. Permissible Variations in Dimensions7.1 Permissible variations in dimensions shall be within thelimits specified on d
11、rawings describing the contacts andaccompanying the order, or shall be within the limits specifiedin the purchase order.8. Workmanship8.1 The parts shall be free of defects in material or process-ing that would seriously affect their performance.9. Significance and Use9.1 Proprietary methods for man
12、ufacture of these materialsvary significantly among suppliers, and these methods influ-ence such properties as arc erosion, contact resistance, andtendency to weld in service. Since the performance of contactsin a device depends on numerous factors outside the contactitself (opening speed, closing s
13、peed, contact pressure, contact1This 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 May 1, 2004. Published May 2004. Origi
14、nallyapproved in 1977. Last previous edition approved in 1993 as B 631 93 (1998).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 Document Summary page
15、 onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.bounce, environmental variations, assembly technique andvariations, etc.) this specification cannot ensure performancecontrol in the application. As part of the qual
16、ification on initialsamples it is recommended that the user functionally electri-cally test the materials for all devices applicable to thematerials use. This specification will provide a means for thecontact manufacturer and contact user to reach agreement onthe details of material to be supplied f
17、or a specific use andreasonable assurance that future lots will be similar in proper-ties and microstructure to the initial test or sample contactssupplied.10. Sampling10.1 LotUnless otherwise specified, a lot shall consist ofparts of the same form and dimensions, made of powders of thesame particle
18、 size range and composition, processed under thesame conditions, and submitted for inspection at one time.10.2 Chemical AnalysisAt least one sample for chemicalanalysis shall be taken from each lot. A representative sampleof chips may be obtained by milling, drilling, or crushing atleast two pieces
19、with dry tools, without lubrication. In order toobtain oil-free chips, the parts selected for test shall have theoil extracted in accordance with Test Method B 328.10.2.1 These specification limits do not preclude the pos-sible presence of other unnamed elements, impurities oradditives. Analysis sha
20、ll be regularly made only for the minorelements listed in the table. However, if 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 ana
21、lysis should be required for elements notspecified.10.3 Physical TestsThe manufacturer and purchaser shallagree on a representative number of specimens for physicaltests including microstructure.11. Inspection11.1 Unless otherwise specified, inspection of parts suppliedon contract shall be made by t
22、he purchaser.12. Rejection12.1 Unless otherwise specified, rejections based on testsmade in accordance with the specification shall be reported tothe manufacturer within 30 days of the receipt of shipment.13. Certification13.1 A certification, when requested by the purchaser, basedon the manufacture
23、rs quality control, that the material con-forms to the requirements of this specification, shall befurnished upon request of the purchaser, provided the request ismade at the time of cost quotation and at the time of orderplacement.14. Keywords14.1 contacts; powder metallurgy; silver; silver-tungste
24、n;tungsten; tungsten-silverAPPENDIX(Nonmandatory Information)X1. Typical Property ValuesX1.1 ScopeX1.1.1 The following information provides guidelines forusers and manufacturers of silver-tungsten contact material.Typical ranges of chemistry and properties are given for thethree most popular composi
25、tions, 27 silver/73 tungsten, 35silver/65 tungsten, and 50 silver/50 tungsten. These propertiesare influenced by the particle size, shape, and distribution oftungsten, homogeneity, impurities or additives, and othermanufacturing process variables (Note). The best choice for agiven application should
26、 be decided mutually between thepurchaser and supplier using their mutual experience andapplication of engineering knowledge.NOTE X1.1 Table X1.1, Table X1.2, Table X1.3, and Table X1.4represent the major manufacturing techniques used in industry. The sizeand shape of the part is important in choosi
27、ng the optimum technique aswell as other considerations such as frequency of operation of the device,and how crucial is its application.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 ve
28、ndor change is made,noticeable property or performance variations are possible.B 631 93 (2004)2TABLE X1.1 Typical Chemical Ranges for Infiltrated Silver-Tungsten ContactsComposition,Aweight %Class A Class B Class CTungsten remainder remainder remainderSilver 2529 3337 4751Copper, max 0.2 0.2 0.2Coba
29、lt or nickel, max 1.0 1.0 1.0Carbon, max 0.2 0.2 0.2Total impurities, max 1.0 1.0 1.0PropertiesData for typical physical properties of infiltrated sintered silver-tungsten contacts are given in this table for contacts having a mean tungsten particle size asdetermined by a Fisher sub-sieve sizer of 1
30、 to 6.5 m.Class A Class B Class CHardness, Rockwell B 85105 7386 5060Density, Mg/m315.1415.74 14.5715.12 13.213.85Electrical conductivity, % IACS 4054 4560 5868Theoretical density, min, % 96 96 96Modulus of rupture,Bpsi 110 000130 000 108 000120 000 80 00082 000MPa 760900 740830 550570Youngs modulus
31、,Bpsi 39.00 3 10635 3 10628.00 3 106MPa 270 3 103240 3 103190 3 103Tensile strength,Bpsi 70 000 55 000 35 000MPa 480 380 240Coefficient of expansion,Bin./in.F 5.9 3 1066.75 3 1067.9 3 106m/mK 10.6 3 10612.15 3 10614.4 3 106Thermal conductivity,BBtuin./hft2F 2920 3130 3130W/mK 420 451 451AAnalysis is
32、 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” elements and the listed impurities are not in e
33、xcess 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 for High-Density Press and Sintered Silver-Tungsten ContactsComposition,Aweight %Class A Class B Class CTungsten remainder remai
34、nder remainderSilver 2529 3337 4246Nickel, cobalt, or copper, max 1.50 1.50 1.50Carbon, max 0.20 0.20 0.20Total impurities, max 0.50 0.50 0.50PropertiesData for typical physical properties of pressed and sintered silver-tungsten contacts are given in this table for contacts having a mean tungsten pa
35、rticle size asdetermined by a Fisher sub-sieve sizer, or 1 to 4 m.Class A Class B Class CHardness, Rockwell B 90105 70100 5085Density, Mg/m314.715.6 14.114.8 13.314.0Electrical conductivity, % IACS 3850 4560 5267Youngs modulus,Bpsi 32 3 10+630 3 10+625 3 10+6MPa 220 3 10+3210 3 10+3170 3 10+3Coeffic
36、ient of expansion,Bin./in.F 5.9 3 1066.77 3 1067.78 3 106m/mK 10.6 3 10612.2 3 10614.00 3 106Thermal conductivity,BBtuin./hft2F 2880 3160 3420W/mK 415 451 493AAnalysis is regularly made for the elements for which specific limits are listed. If, however, the presence of “other” elements is suspected
37、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 not spe
38、cified.B 631 93 (2004)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 infringem
39、ent 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 standard or
40、 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 views kn
41、own 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 AS
42、TM 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).TABLE X1.3 Typical Chemical Ranges for Pressed, Sintered and Repressed Silver-Tungsten ContactsComposition,Aweight %Class A Class B Class CTungsten remainder
43、remainder remainderSilver 2529 3337 4852Copper, max 0.2 0.2 0.2Carbon, max 0.2 0.2 0.2Total impurities, max 0.5 0.5 0.5PropertiesData for typical physical properties of repressed, sintered silver-tungsten contacts are given in this table for contacts having a mean tungsten particle size asdetermined
44、 by a Fisher sub-sieve sizer of 1 to 6.5 m.Class A Class B Class CHardness, Rockwell B 4570 5070 4055Density, Mg/m314.9515.31 14.1814.93 12.9213.67Electrical conductivity,% IACS 3845 4255 5065Theoretical density, min, % 95 95 95AAnalysis is regularly made for the elements for which specific limits a
45、re 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” elements and the listed impurities are not in excess of the total impurities limit.TABLE X1.4 Typical Chemi
46、cal Ranges for Low-Density Pressed and Sintered Silver-Tungsten ContactsComposition,Aweight %Class A Class B Class CTungsten remainder remainder remainderSilver 2529 3337 4652Copper, max 0.20 0.20 0.20Carbon, max 0.20 0.20 0.20Total impurities, max 0.50 0.50 0.50PropertiesData for typical physical p
47、roperties of pressed and sintered silver-tungsten contacts are given in this table for contacts having a mean tungsten particle size asdetermined by a Fisher sub-sieve sizer of 1 to 4 m.Hardness, Rockwell B 5570 4560 3550Density, Mg/m313.9715.2 13.7414.19 12.5212.93Electrical conductivity, % IACS 35
48、45 4555 5060Youngs modulus,Bpsi 32 3 10+630 3 10+625 3 10+6MPa 220 3 10+3210 3 10+3170 3 10+3Coefficient of expansion,Bin./in.F 5.9 3 1066.77 3 1067.78 3 106m/mK 10.6 3 10612.2 3 10614.00 3 106Thermal conductivity,BBtuin./hft2F 2880 3160 3420W/mK 415 451 493AAnalysis is regularly made for the elemen
49、ts 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” 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 not specified.B 631 93 (2004)4
