ASTM_E_1937_-_97.pdf

Designation:E 1937 97Standard Test Method forDetermination of Nitrogen in Titanium and Titanium Alloysby the Inert Gas Fusion Technique1This standard is issued under the fixed designation E 1937;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 This test method provides a procedure for the determi-nation of nitrogen in titanium and titanium alloys in concen-trations from 0.007 to 0.11%.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 establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.Specific hazardsstatements are given in 7.8 and Section 8.2.Referenced Documents2.1 ASTM Standards:E 50 Practices for Apparatus,Reagents,and Safety Precau-tions for Chemical Analysis of Metals2E 173 Practice For Conducting Interlaboratory Studies ofMethods For Chemical Analysis of Metals23.Summary of Test Method3.1 This test method is intended for use with automated,commercially available inert gas fusion analyzers.3.2 The test sample,plus flux,is fused in a graphite cruciblein a flowing helium gas stream at a temperature sufficient torelease nitrogen.The nitrogen is swept by the helium gasstream into a thermal conductivity detector.The detectorresponse is compared to that of calibration standards and theresult is displayed as percent nitrogen.3.3 In a typical instrument(Fig.1)the sample gases areswept with helium through heated rare earth/copper oxidewhich converts CO to CO2and H2to H2O.The CO2isabsorbed on sodium hydroxide impregnated on clay,and theH2O is removed with magnesium perchlorate.The nitrogen,asN2,enters the measuring cell and the thermistor bridge outputis integrated and processed to display percent nitrogen.4.Significance and Use4.1 This test method is primarily intended as a refereemethod for compliance with compositional specifications.It isassumed that all who use this test method will be trainedanalysts capable of performing common laboratory proceduresskillfully and safely.It is expected that the work will beperformed in a properly equipped laboratory.5.Interferences5.1 The elements usually present in titanium and its alloysdo not interfere.6.Apparatus6.1 InstrumentThe general features of the typical instru-ment are shown in Fig.1.6.2 Graphite Crucibles,made of high-purity graphite of thedimensions recommended by the instrument manufacturer.6.3 FluxWire baskets consisting of platinum or high-purity nickel of dimensions that meet the requirements of the1This test method is under the jurisdiction of ASTM Committee E-1 onAnalytical Chemistry for Metals,Ores and Related Materials and is the directresponsibility of Subcommittee E01.06 on Titanium,Zirconium,Tungsten,Molyb-denum,Tantalum,Niobium,Hafnium,and Rhenium.Current edition approved Dec.10,1997.Published August 1998.2Annual Book of ASTM Standards,Vol 03.05.FIG.1 Apparatus for Determination of Nitrogen by the Inert GasFusion-Thermal Conductivity Method1AMERICAN SOCIETY FOR TESTING AND MATERIALS100 Barr Harbor Dr.,West Conshohocken,PA 19428Reprinted from the Annual Book of ASTM Standards.Copyright ASTMautomatic sample drop,if present,on the instrument(Note 1).NOTE1In some instruments,nitrogen and oxygen are run sequen-tially and platinum is the required flux for nitrogen.High purity platinumcan be substituted for nickel in the same weight ratio of flux to sample.When using platinum as a flux,graphite powder should not be added to thecrucible.6.4 TweezersSix inch solvent and acid-resistant plastic.7.Reagents7.1 AcetoneResidue after evaporation must be 0.0005%.7.2 Graphite Powder,of purity specified by the instrumentmanufacturer.7.3 Helium,of purity and type specified by the instrumentmanufacturer.7.4 Magnesium Perchlorate,AnhydrousUsed in the in-strument to absorb water.Use the purity specified by theinstrument manufacturer.(Known commercially as Anhy-drone.)7.5 Nickel Flux Cleaning SolutionPrepare a fresh solutionof nickel cleaning solution by combining 75 mL of acetic acid,25 mL of HNO3and 2 mL of HC1.7.6 Rare Earth/Copper OxideReagent used in the instru-ment to oxidize CO to CO2.Use the purity specified by theinstrument manufacturer.7.7 Sodium Hydroxide on ClayReagent used in someinstruments to absorb CO2.Use a purity specified by theinstrument manufacturer.(Known commercially as AscariteII.)7.8 Titanium Sample Pickle SolutionPrepare a fresh solu-tion of 3 parts 30%H2O2and 1 part 48%HF.(WARNING:HF causes serious burns which may not be immediatelypainful;refer to the paragraph about HF in the Safety Precau-tions section of Practices E 50.)8.Hazards8.1 Use care when handling hot crucibles and operatingfurnaces to avoid personal inj