ASTM_E_121_-_83_1996.pdf

Designation:E 121 83(Reapproved 1996)Standard Test Methods forChemical Analysis of Copper-Tellurium Alloys1This standard is issued under the fixed designation E 121;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(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 These test methods cover procedures for the chemicalanalysis of copper-tellurium alloys having chemical composi-tions within the following limits:Copper,A%98 and overTellurium,%0.04 to 0.6AIncludes silver.1.2 The analytical procedures appear in the following order:SectionsCopper by the Electrolytic Method8 to 12Tellurium by the Dichromate(Volumetric)Method13 to 172.Referenced Documents2.1 ASTM Standards:E 29 Practice for Using Significant Digits in Test Data toDetermine Conformance With Specifications2E 50 Practices for Apparatus,Reagents,and Safety Precau-tions for Chemical Analysis of Metals3E 55 Practice for Sampling Wrought Nonferrous Metals andAlloys for Determination of Chemical Composition33.Significance and Use3.1 These test methods for the chemical analysis of metalsand alloys are primarily intended to test such materials forcompliance with compositional specifications.It is assumedthat all who use these test methods will be trained analystscapable of performing common laboratory procedures skill-fully and safely.It is expected that work will be performed ina properly equipped laboratory.4.Apparatus and Reagents4.1 Apparatus and reagents required for each determinationare listed in separate sections preceding the procedure.Theapparatus,standard solutions,and certain other reagents usedin more than one procedure are referred to by number and shallconform to the requirements prescribed in Practices E 50.5.Precautions5.1 For precautions to be observed in these test methods,reference shall be made to Practices E 50.6.Sampling6.1 Sampling shall conform to Practice E 55.7.Rounding Calculated Values7.1 Calculated values shall be rounded to the desired num-ber of places in accordance with the rounding method given in3.4 and 3.5 of Practice E 29.COPPER BY THE ELECTROLYTIC TEST METHOD8.Summary of Test Method8.1 Copper is deposited electrolytically on a platinum cath-ode.The addition of manganese nitrate to the electrolyteprevents the deposition of tellurium.9.Apparatus9.1 Electrodes for ElectroanalysisApparatus No.9.10.Reagents10.1 Manganese Nitrate Solution(20 g/L)Dilute 4 mL ofthe commercially available Mn(NO3)2solution(50%)to 100mL with water.10.2 Potassium Permanganate Solution(20 g/L)Dissolve2 g of KMnO4in water and dilute to 100 mL.10.3 Sulfuric-Nitric Acid MixtureAdd slowly,while stir-ring,300 mL of H2SO4to 750 mL of water.Cool and add 210mL of HNO3.11.Procedure11.1 Transfer 2.00 g of the sample to a 300-mL electrolysisbeaker.Add 30 mL of H2SO4-HNO3mixture,cover,and allowto stand a few minutes until reaction has nearly ceased.Heat at80 to 90C until dissolution is complete and brown fumes havebeen expelled.Wash down the cover glass and the sides of thebeaker and dilute to about 200 mL.Add KMnO4solutiondropwise until a faint,permanent pink color is produced andthen add 5 mL of Mn(NO3)2solution.11.2 Insert the electrodes,cover the solution with a pair ofsplit watch glasses,and electrolyze at a current density of about0.6 A/dm2for about 16 h or at a current density of 4 A/dm2for1These test methods are under the jurisdiction of ASTM Committee E-1 onAnalytical Chemistry for Metals,Ores,and Related Materials and are the directresponsibility of Subcommittee E01.05 on Cu,Pb,Zn,Cd,Sn,Be,their Alloys andRelated Metals.Current edition approved Feb.25,1983.Published April 1983.Originallypublished as E 121 56 T.Last previous edition E 121 60(1978).2Annual Book of ASTM Standards,Vol 14.02.3Annual Book of ASTM Standards,Vol 03.05.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.about 2.5 h.Wash down the cover glasses,the sides of thebeaker,and the electrode stems,and continue electrolysis forabout 15 min.If no copper plates on the newly exposedcathode surface,copper deposition may be considered com-pleted.11.3 Quickly withdraw the cathode from the electrolytewhile directing a gentle stream of water from a wash bottleover its surface.Rinse the cathode in a water bath and then dipin two successive baths of ethanol or acetone.Dry in an ovenat 110C for 3 to 5 min,cool,and weigh.11.4 Strip the copper deposit from the cathode by immer-sion in HNO3(1+1)for a few minutes.When dissolution of thecopper is complete,rinse the cathode in a water bath and thendip in two successive baths of ethanol or acetone.Dry in anoven at 110C for 3 to 5 min,cool,and reweigh.12.Calculation12.1 Calculate the percentage of copper as follows:Copper,%5A 2 B!/C#3 100(1)where:A=weight of copper plus cathode,B=weight of cathode,an