ASTM_B_662_-_94_2012.pdf

Designation:B66294(Reapproved 2012)Standard Specification forSilver-Molybdenum Electrical Contact Material1This standard is issued under the fixed designation B662;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 silver-molybdenum by powder metallurgical pro-cedures.1.2 This specification covers compositions within the silver-molybdenum 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 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.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for Density,Oil Content,and Intercon-nected Porosity of Sintered Metal Structural Parts andOil-Impregnated Bearings(Withdrawn 2009)33.Ordering Information3.1 Orders for this material under this specification shallinclude the following information:3.1.1 Dimensions(see Section 10),3.1.2 Chemical composition(see tables in the appendix as aguideline),3.1.3 Physical properties(see Section 5 and the appendix asa guideline),3.1.4 Certification(see Section 13),and3.1.5 Other features as agreed upon between the manufac-turer and purchaser.4.Chemical Composition4.1 The material shall conform to composition limits asagreed upon between the manufacturer and the purchaser.4.2 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.5.Physical Properties5.1 The manufacturer and the purchaser shall agree onqualification 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 measurement.)5.3 The tests shall be determined after consideration of thefunction of the part.5.4 The typical properties of two most common types ofsilver-molybdenum contacts are given in the appendix.6.Finishing of Contacts6.1 The material shall be finished by such operations asnecessary to meet 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.).7.Dimensions,Mass,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 or process-ing that would seriously affect their performance.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 May 1,2012.Published May 2012.Originallyapproved in 1979.Last previous edition approved in 2006 as B662 94(2006).DOI:10.1520/B0662-94R12.2For 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 9.Significance and Use9.1 Proprietary methods for 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 speed,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 test the materials for all devices applicable tothe materials use.This specification will provide a means forthe contact manufacturer and contac