ASTM_B_702_-_93_2015.pdf

Designation:B70293(Reapproved 2015)Standard Specification forCopper-Tungsten Electrical Contact Material1This standard is issued under the fixed designation B702;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This specification covers electrical contact componentsmade from copper tungsten by powder metallurgical proce-dures.1.2 This specification covers compositions within the cop-per tungsten system normally specified by users of contacts.1.3 The values stated in inch-pound units are to be regardedas standard.No other units of measurement are included in thisstandard.1.4 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 hazards including those identified in the appropriateData Safety Sheet(SDS)for this product/material as providedby the manufacturer,to establish appropriate safety and healthpractices,and determine the applicability of regulatory limi-tations prior to use.2.Referenced Documents2.1 ASTM Standards:2B328 Test Method for Density,Oil Content,and Intercon-nected Porosity of Sintered Metal Structural Parts andOil-Impregnated Bearings(Withdrawn 2009)33.Significance and Use3.1 Proprietary methods for manufacture of these materialsvary significantly among suppliers and these methods influencesuch properties as arc erosion,contact resistance,and tendencyto weld in service.Since the performance of contacts in adevice depends on numerous factors outside the contact itself(opening speed,closing speed,contact pressure,contactbounce,environmental variations,assembly technique andvariations,etc.)this specification cannot ensure performancecontrol in the application.As part of the qualification 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 for a specified use andreasonable assurance that future lots will be similar in proper-ties and microstructure to the initial test or sample contactssupplied.4.Ordering Information4.1 Orders for this material under this specification shallinclude the following information:4.1.1 Dimensions(see Section 8),4.1.2 Chemical composition(see reference tables in RelatedMaterial as possible guideline),4.1.3 Physical properties(see Section 6 and reference tablesas guideline),4.1.4 Certification(see Section 11),and4.1.5 Other features as agreed upon between the vendor andthe user.5.Chemical Requirements5.1 The material shall conform to composition limits asagreed upon between the manufacturer and the user.5.2 The chemical analysis shall be made in accordance withthe methods prescribed in the newest edition of Annual Book ofASTM Standards,or by any other approved method agreedupon between the manufacturer and the purchaser.6.Other Properties6.1 The manufacturer 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 after consideration of thefunction of the part.6.4 The typical properties of five most common types ofcopper-tungsten contacts are given in Appendix X1.1This 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 Oct.1,2015.Published October 2015.Originallyapproved in 1982.Last previous edition approved in 2010 as B702 93(2010).DOI:10.1520/B0702-93R15.2For 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 onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 7.Dimensions and Permissible Variations7.1 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.Workmanship,Finish,and Appearance8.1 The parts shall be free of defects in material orprocessing,which would seriously affect their performance.9.Sampling and Inspection9.1 LotUnless otherwise specified,a lot shall consist ofparts of the same form,and dim