ASTM_F_29_-_97_2012.pdf

Designation:F2997(Reapproved 2012)Standard Specification forDumet Wire for Glass-to-Metal Seal Applications1This standard is issued under the fixed designation F29;the number immediately following the designation indicates the year of originaladoption or,in the case of revision,the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This specification covers round,copper-coated 42%nickel-iron wire,commonly known as dumet,intended primar-ily for sealing to soft glass.1.2 The values stated in inch-pound units are to be regardedas standard.The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.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 establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2B170 Specification for Oxygen-Free Electrolytic CopperRefinery ShapesD1535 Practice for Specifying Color by the Munsell SystemD1729 Practice for Visual Appraisal of Colors and ColorDifferences of Diffusely-Illuminated Opaque MaterialsE3 Guide for Preparation of Metallographic SpecimensE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE53 Test Method for Determination of Copper in UnalloyedCopper by GravimetryE228 Test Method for Linear Thermal Expansion of SolidMaterials With a Push-Rod DilatometerF14 Practice for Making and Testing Reference Glass-MetalBead-Seal3.Ordering Information3.1 The wire is usually supplied with a surface coatingconsisting of a mixture of copper oxides and fused sodiumtetraborate(borax)which retards oxidation of the wire duringsealing in glass and further aids wetting of the wire by theglass.The composite wire may also be purchased as bare wirefor specific applications.3.2 The size of the wire,if applicable,the borate color rangedesignated as light,medium(regular),or dark,shall bespecified on each purchase order.3.3 Package sizes shall be agreed upon between the pur-chaser and the seller.4.Chemical Composition4.1 The copper used in the manufacture of dumet shall be99.90%minimum copper.Silver shall be included with thecopper.The material shall be free of reducible oxides.4.2 The chemical composition of the nickel-iron core shallbe as shown in Table 1.5.Oxide Coating5.1 The primary standards for the entire range of colors aredivided into three groups covering light,medium(regular),anddark as shown,with their respective limits,in Fig.1 and Table2(Note 1).The color range of the specimens shall bedetermined in accordance with 9.2.NOTE1Color chip 2.5R 3.90/8.0 may be included in the dark rangemerely to extend the color series for assisting the viewer in making abetter decision regarding the cut-off point between medium(regular)anddark dumet.6.Thermal Expansion6.1 The nominal values for the average coefficient of linearthermal expansion shall be as follows when determined inaccordance with 9.1:6.1.1 Core63 to 72 107in./in.deg C(mm/mmdegC)over the temperature range of 30 to 400C.6.1.2 Copper177 6 3.5 107in./in.C(mm/mmdegC)over the temperature range of 30 to 300C.7.Dimensional Tolerances7.1 The specified diameters shall conform to the tolerancesgiven in Table 3.8.Workmanship and Finish8.1 Internal ConditionThe internal structure of the com-posite material,including the bond area,shall be sound and1This specification is under the jurisdiction of ASTM-Committee F01 onElectronics and is the direct responsibility of Subcommittee F01.03 on MetallicMaterials.Current edition approved July 1,2012.Published August 2012.Originallyapproved in 1963.Last previous edition approved in 2009 as F29 97(2009).DOI:10.1520/F0029-97R12.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 free from pipes,porosity,or discontinuities which mightprevent the making of a satisfactory seal.8.2 Surface Condition:8.2.1 There shall be no areas of exposed core evident on thesurface of the wire.8.2.2 The wire shall contain no longitudinal scratches,folds,or lines of a depth greater than the width.8.2.3 There shall be no oil,grease,or other surface contami-nants on the wire.8.2.4 The wire shall be looped or coiled over a mandrel fivetimes the diameter of the wire.At least 75%of the dumet areashall be free from defects consisting of damaged borate,exposing the copper,when observed at 10 magnification.8.2.5 The nickel-iron core shall be uniformly covered with18%to 28%copper(by