1、Designation: B 712 93 (Reapproved 2006)Standard Guide forDetermination of Sodium and Potassium Content For Silver-Cadmium Oxide Contact Materials1This standard is issued under the fixed designation B 712; the number immediately following the designation indicates the year oforiginal adoption or, in
2、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 describes procedures for use in conductinganalysis of silver-cadmium oxi
3、de materials for sodium andpotassium content. The exact methods for the performance ofthis testing are not stated since many different procedures areequally applicable. This guide points out specific proceduresfor decreasing the chance of recognized potential errors andspecifies methods for increasi
4、ng the sensitivity of the testing.1.2 This standard may involve hazardous materials, opera-tions, and equipment. This standard does not purport toaddress all of the safety concerns, if any, associated with itsuse. It is the responsibility of the user this standard to becomefamiliar with all hazards
5、including those identified in theappropriate Material Safety Data Sheet (MSDS) for thisproduct/material as provided by the manufacturer, to establishappropriate safety and health practices, and determine theapplicability of regulatory limitations prior to use. For specificprecautions see Sections 4
6、and 6.1.3 Whoever uses this standard should consult the MaterialSafety Data Sheet concerning the products involved.2. Referenced Documents2.1 ASTM Standards:2E 50 Practices for Apparatus, Reagents, and Safety Consid-erations for Chemical Analysis of Metals, Ores, andRelated MaterialsE 663 Practice f
7、or Flame Atomic Absorption Analysis32.2 Other Document:Operation Guide for Chemical Analysis of Metals andMetal Bearing Ores by Atomic Absorption Spectropho-tometry43. Significance and Use3.1 This guide is recommended for use in analyzing thesodium and potassium content of silver-cadmium oxide mate-
8、rials and is meant to be used in conjunction with standardmethods of atomic absorption spectroscopy. The recommendedprocedures cite methods for minimizing extraneous sodiumand potassium contamination through use of specific handlingprocedures and shorter sample preparation methods. This guidealso re
9、commends procedures that prevent the formation ofnonstable and potentially hazardous silver-acetylene com-pounds.4. Precautions4.1 Since silver nitrate reacts with acetylene to form silveracetylide, the guide recommends either alternative flames toairacetylene or the removal of silver from solution.
10、 Silveracetylide is unstable and may explode violently upon beingdisturbed.5. Sampling5.1 Handle the sample so as to avoid contamination bysodium and potassium; avoid contact with hands.6. Procedures6.1 First clean the sample in nitric acid and distilled ordeionized water to remove extraneous surfac
11、e contamination.Test powder samples as received. Then store the samples insuch a manner as to minimize contamination.6.2 Use a sample size of approximately2gormore for eachtest.6.3 Handle the samples with gloves and utensils, never withbare hands.6.4 The use of TFE-fluorocarbon or other suitable sub
12、sti-tutes for glassware is recommended. If glass is used, aged glass1This guide is under the jurisdiction of ASTM Committee B02 on NonferrousMetals and Alloys and is the direct responsibility of Subcommittee B02.05 onPrecious Metals and Electrical Contact Materials.Current edition approved June 1, 2
13、006. Published June 2006. Originallyapproved in 1982. Last previous edition approved in 1999 as B 712 93 (1999).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
14、standards Document Summary page onthe ASTM website.3Withdrawn.41982 Annual Book of ASTM Standards, Part 12 (see Related MaterialsSection).1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.rather than new glass is recommended. Clean the
15、 glasswarewith ammonia and rinse with deionized water. Avoid the use ofdetergents.6.5 Calibrate the instrument and determine the optimumcalibration-solution concentration in accordance with PracticeE 663 and other standards as cited in Section 2.6.6 Fully dissolve the sample in a nitric acid solutio
16、n inaccordance with standard procedures and concentrations rec-ommended for the atomic absorption procedures and instru-ments used. Also prepare a reagent blank.6.7 An air-propane or air-hydrogen flame is recommendedrather than air-acetylene in order to prevent the formation ofsilver acetylide. (War
17、ningSilver acetylide may explodeviolently if disturbed.) The silver then may be left in solution.6.8 If an air-acetylene flame is used, a precipitation andsettling procedure is recommended over filtrations for removalof silver. A settling time of 24 h is recommended in laboratoryware that will not c
18、ontribute to contamination followed bycareful aspiration of the supernatant solution into the air-acetylene flame. If the choice is made to remove the silver fromsolution, the possibility of some of the sodium and potassiumbeing removed with the precipitate should be recognized.7. Report7.1 Since sl
19、ight variations in technique can easily causediscrepancies between laboratory results, the exact methodused shall be listed. The report statement shall include suchitems as follows:7.1.1 Sample size,7.1.2 Type of solution containers used,7.1.3 Whether silver was precipitated, and7.1.4 Specific type
20、of gas flame used.7.2 Supplier and user shall reach agreement concerning allvariables in technique and procedure before attempting tocompare results of specific samples.8. Precision8.1 The precision is based on the tests performed bycompetent operators of a number of different laboratories; seeTable
21、 1 and Table 2. All the laboratories were given the basicguidelines as described in this guide.9. Keywords9.1 analysis; cadmium oxide; contacts; potassium; silver;silvercadmium oxide; sodiumASTM International takes no position respecting the validity of any patent rights asserted in connection with
22、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 responsible technic
23、al 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 careful consideration
24、 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 International, 100 Barr Harbo
25、r 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 ASTM website(www.astm.org).TABLE 1 Sodium AnalysisMean, ppmsppm %745735 8 23190 26 14500 94 19TABLE 2 Potassium AnalysisMean, ppmsppm %6 11 18012 4 33B 712 93 (2006)2
