1、Designation: B 772 97 (Reapproved 2008)Standard Guide forSpecifying the Chemical Compositions for ElectricalContact Materials (Arcing and Nonarcing)1This standard is issued under the fixed designation B 772; the number immediately following the designation indicates the year oforiginal adoption or,
2、in the case of revision, the year 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.1. Scope1.1 This guide provides suggested methods for users andproducers of electrical conta
3、ct materials to specify the chemi-cal compositions of these materials.1.2 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 ap
4、propriateMaterial 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:2E 1282 Guide for Specifying the C
5、hemical Compositionsand Selecting Sampling Practices and Quantitative Analy-sis Methods for Metals, Ores, and Related Materials3. Significance and Use3.1 This guide should be used by committees or individualsin specifying the chemical composition of electrical contactmaterials.4. Procedure4.1 For Ba
6、sic Alloy Element(s) and Component(s):4.1.1 Specify the numerical limits of the elements as fol-lows:4.1.1.1 Major fractions of the alloy,4.1.1.2 Tighter tolerances, or4.1.1.3 Higher unit cost(s) or combination thereof.4.1.2 One of these elements may be chosen to be specifiedby “report by difference
7、.” List the minimum value of thiselement in a pair of parentheses before the clause “report bydifference.” Select this element or component according to oneor more of the following considerations:4.1.2.1 Least precious,4.1.2.2 Widest tolerance, and4.1.2.3 Requiring the least precise or most costly m
8、ethod toanalyze.4.2 For Impurities:4.2.1 Specify only the tolerance limits of the elementscommonly occurring with the major elements (for example,copper in silver); and the tolerance limits of the detrimentalelements (as recognized by the industry) which may be aresidue after fabrication (for exampl
9、e, sodium in Ag-CdOmaterial by the coprecipitation method).4.2.2 Specify the tolerance limits for total impurities of allthe impurity elements.4.3 Place the following note under the Table of ChemicalCompositions (see Table 1 for example) in the text of eachspecification:NOTE 1Analysis is regularly m
10、ade for the elements for which specificlimits are listed. If, however, the presence of “other” elements is suspectedor indicated in the course of routine analysis, further analysis shall bemade to determine that the total of these “other” elements and the listedimpurities is not in excess of the tot
11、al impurities limit.4.4 State under the section of Chemical Composition in thetext of each specification a clause as follows:4.4.1 These specification limits do not preclude the possiblepresence of other unnamed elements, impurities, or additives.Analysis shall be regularly made only for the minor e
12、lementslisted in the table. However if a user knows of elements thatmight be detrimental to their application or has other reasonsfor requiring analysis for specific elements, then agreementbetween manufacturer and purchaser for both limits andmethods of analysis should be required for elements nots
13、pecified.4.5 Additional guidelines for specifying the chemical com-positions and selecting sampling practices are covered in GuideE 1282.1This guide is under the jurisdiction of ASTM Committee B02 on NonferrousMetals and Alloys and is the direct responsibility of Subcommittee B02.05 onPrecious Metal
14、s and Electrical Contact Materials.Current edition approved May 1, 2008. Published May 2008. Originallyapproved in 1987. Last previous edition approved in 2003 as B 772 97 (2003).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org.
15、 For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.6 Example (For a hypothetical alloy):75A-24.5B-0.5Cwhere:A = prec
16、ious metal,B = base metal,C = base metal, andd, e, f, g = typical or detrimental impurities.5. Keywords5.1 analysis; chemical composition; contacts; electrical con-tact materials; impurities; tolerance limitsASTM International takes no position respecting the validity of any patent rights asserted i
17、n 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 infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the r
18、esponsible 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 for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive car
19、eful 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 known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM Internation
20、al, 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
21、ASTM website(www.astm.org).TABLE 1 Table of Chemical CompositionsNOTE 1Analysis is regularly made for the elements for which specificlimits are listed. If, however, the presence of “other” elements is suspectedor indicated in the course of routine analysis, further analysis shall bemade to determine that the total of these “other” elements and the listedimpurities is not in excess of the total impurities limit.Chemical CompositionLimitsImpuritiesA = 7476 d = 0.06 maxB = (23.5 Min.) Report by difference e = 0.05 maxf = 0.05 maxC = 0.350.65 g = 0.01 maxTotal: 0.15 maxB 772 97 (2008)2
