1、Designation: C760 90 (Reapproved 2015)Standard Test Methods forChemical and Spectrochemical Analysis of Nuclear-GradeSilver-Indium-Cadmium Alloys1This standard is issued under the fixed designation C760; the number immediately following the designation indicates the year oforiginal adoption or, in t
2、he case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 These test methods cover procedures for the chemicaland spectrochemical analysis of n
3、uclear grade silver-indium-cadmium (Ag-In-Cd) alloys to determine compliance withspecifications.1.2 The analytical procedures appear in the following order:SectionsSilver, Indium, and Cadmium by a Titration Method 715Trace Impurities by Carrier-Distillation Spectro-chemical Method16221.3 The values
4、stated in SI units are to be regarded as thestandard.1.4 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 o
5、f regulatory limitations prior to use. For specific hazardand precautionary statements, see Section 5 and Practices E50.2. Referenced Documents2.1 ASTM Standards:2C752 Specification for Nuclear-Grade Silver-Indium-Cadmium AlloyD1193 Specification for Reagent WaterE50 Practices for Apparatus, Reagent
6、s, and Safety Consid-erations for Chemical Analysis of Metals, Ores, andRelated MaterialsE115 Practice for Photographic Processing in Optical Emis-sion Spectrographic Analysis (Withdrawn 2002)32.2 Other Document:NBS Circular 60243. Significance and Use3.1 Silver-indium-cadmium alloy is used as a con
7、trol mate-rial in nuclear reactors. In order to be suitable for this purpose,the material must meet the specifications for assay and impu-rity content. These test methods are designed to show whetheror not a given material meets the specifications as given inSpecification C752.3.1.1 An assay is perf
8、ormed to determine whether thematerial has the chemical composition specified.3.1.2 The impurity content is determined to ensure that themaximum concentration limit of impurities is not exceeded.4. Purity of Reagents4.1 Reagent grade chemicals shall be used in all tests.Unless otherwise indicated, i
9、t is intended that all reagents shallconform to the specifications of the Committee on AnalyticalReagents of the American Chemical Society,5where suchspecifications are available. Other grades may be used, pro-vided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its
10、 use without lessening the accuracy ofthe determination.4.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water conformingto Specification D1193.5. Hazards5.1 Proper precautions should be taken to prevent inhalationor ingestion of heavy element (si
11、lver, indium, or cadmium)powder or dust during handling.5.2 Workers should observe precautions as specified invendor-supplied Material Safety Data Sheets (MSDS).1These test methods are under the jurisdiction of ASTM Committee C26 onNuclear Fuel Cycle and are the direct responsibility of Subcommittee
12、 C26.03 onNeutron Absorber Materials Specifications.Current edition approved Jan. 1, 2015. Published January 2015. Originallyapproved in 1971. Last previous edition approved in 2007 as C760 90 (2007).DOI: 10.1520/C0760-90R15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcon
13、tact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.4Available from National Institute of Standards and
14、Technology (NIST), 100Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http:/www.nist.gov.5Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Stand
15、ards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K. and the United States Pharmacopeia andNational Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States16. Samplin
16、g6.1 Suggestions for sampling this alloy are given in Speci-fication C752.SILVER, INDIUM, AND CADMIUM BY A TITRATIONMETHOD7. Scope7.1 This test method is applicable to the determination ofsilver, indium, and cadmium in alloys of approximately 80 %silver, 15 % indium, and 5 % cadmium used in nuclear
17、reactorcontrol rod applications. The titrimetric methods presented6,7will yield results with a bias of the order of 0.1 %.8. Summary of Test Method8.1 A weighed sample is dissolved in nitric acid and dilutedto a known volume, and aliquots are removed for analysis.Silver is determined first by titrat
18、ing with standardized sodiumchloride solution to the potentiometric endpoint indicated by achloride-selective ion electrode. Following the silver titration,the solution is boiled to coagulate the silver chloride. The pHis adjusted to 2.5 and the indium content is titrated with EDTA,using PAN (1-(2-p
19、yridylazo)-2-naphthol) indicator. The pH isthen raised to 6.0 and the cadmium is titrated with EDTAusingthe same indicator. The entire process requires approximately20 min per aliquot, exclusive of sample weighing and disso-lution.9. Interferences9.1 No interferences have been observed from any elem
20、entsnormally encountered as impurities in nuclear grade silver-indium-cadmium alloy over the concentration ranges expected.10. Apparatus10.1 Burets, precision, two, 25-mL capacity, preferablySchellbach type with TFE-fluorocarbon stopcock and auto-matic zero. They shall be certified or tested to conf
21、orm withtolerances specified in NBS Circular 602.10.2 Reference ElectrodeSaturated calomel electrode.10.3 Glass pH ElectrodeStandard type.10.4 Chloride Specific Ion Electrode.10.5 Expanded Scale pH/millivolt Meter.11. Reagents11.1 Ammonium Hydroxide (sp gr 0.90)Concentrated am-monium hydroxide (NH4O
22、H).11.2 Buffer Solution, pH40.5 M sodium acetate0.5 Macetic acid.11.3 Cadmium (Cd)Metal, 99.99 % pure.11.4 Ethylenediaminetetraacetate Dihydrate Disodium Salt(EDTA) Solution (0.01000 M)Weigh 3.722 6 0.001 g ofEDTAinto a small plastic beaker. Dissolve with water, transferquantitatively to a 1-Lvolume
23、tric flask, and make up to volumewith water. Transfer the solution to a plastic storage bottle. Donot allow the EDTA solution to stand in contact with glasscontainers.11.5 Indium (In)Metal, 99.99 % pure.11.6 Nitric Acid (sp gr 1.42)Concentrated nitric acid(HNO3).11.7 PAN Indicator Solution (0.1 % PA
24、N in Methanol)Dissolve 100 mg of 1-(2-pyridylazo)-2-naphthol in 100 mL ofmethyl alcohol and mix until completely dissolved.11.8 Silver (Ag)Metal, 99.99 % pure.11.9 Sodium Chloride (NaCl).11.10 Sodium Chloride Solution (0.0500 M)Dry sodiumchloride (NaCl) at 120C, in a weighing bottle, to a constantwe
25、ight and cool to room temperature in a desiccator. Weigh2.922 6 0.001 g of the dried NaCl into a small plastic beaker.Dissolve in water, quantitatively transfer to a 1-L volumetricflask, and make up to volume with water.12. Standardization12.1 Silver-Indium-Cadmium Calibration Standard:12.1.1 Clean
26、approximately 8.0 g of silver metal, 1.5 g ofindium metal, and 0.5 g of cadmium metal with an organicsolvent and air dry.12.1.2 Weigh each metal accurately and transfer to a100-mL beaker.12.1.3 Add sufficient water to cover the metal pieces andadd HNO3(sp gr 1.42) dropwise until dissolution is compl
27、ete.12.1.4 Transfer quantitatively to a 100-mL volumetric flaskand dilute to volume with water.12.2 Calibration of NaCl and EDTA Titrants:12.2.1 Pipet 10 mL of the calibration standard into a100-mL volumetric flask and dilute to volume with water.(Retain this solution as a working standard.)12.2.2 P
28、ipet 10 mL of the diluted standard into a 100-mLbeaker and adjust the volume to about 25 mL with water.12.2.3 Adjust the pH to approximately 1 using NH4OH (spgr 0.90).12.2.4 Place a TFE-fluorocarbon-coated stirring bar in thesolution and insert the chloride specific ion electrode and thereference el
29、ectrode.12.2.5 Stir at a moderate rate and titrate the silver with NaClsolution. Record millivolt readings versus volume added.Allow sufficient time for equilibrium readings to be attained.12.2.6 The titration end point is taken as the termination ofthe rapidly rising segment of the millivolt versus
30、 volumetitration curve.12.2.7 Adjust to pH 2.5 6 0.2 by dropwise addition ofacetate buffer solution (pH4).12.2.8 Remove the electrodes and rinse thoroughly to avoidloss of indium and cadmium.12.2.9 Heat the solution to boiling on a hotplate until thesupernatant liquid is clear. Allow to cool.12.2.10
31、 Add 4 drops of PAN indicator solution.The solutionshould be deep purple.6Cheng, K. L., “Complexometric Titration of Indium,” Analytical Chemistry,Vol 27, 1955, p. 1582.7Cheng, K. L., “Complexometric Titration of Copper and Other Metals in aMixture,” Analytical Chemistry, Vol 30, 1958, p. 243.C760 9
32、0 (2015)212.2.11 Titrate the indium with standard EDTA solution tothe sharp transition from purple to yellow. The volume usedcorresponds to the indium content.12.2.12 Adjust to pH 6 6 0.2 with NH4OH (sp gr 0.90). Thecolor of the solution will change back to purple.12.2.13 Titrate the purple solution
33、 with standard EDTAuntilthe color again changes to yellow. The volume used corre-sponds to the cadmium content.13. Procedure13.1 Clean approximately 1.0 g of the sample with anorganic solvent and air dry.13.2 Weigh the cleaned sample accurately and transfer it toa 100-mL beaker.13.3 Cover the sample
34、 with water and add HNO3(sp gr1.42) dropwise until the sample is completely dissolved.13.4 Transfer the solution quantitatively to a 100-mL volu-metric flask and dilute to volume with water.13.5 Proceed with the determination of silver, indium, andcadmium as described in 12.2.2 12.2.13.14. Calculati
35、on14.1 Symbols:S = sample weight, mg,D.F. = dilution factor = 0.1,FS= calibration factor for silver, mg Ag/mL of titrant,FI= calibration factor for indium, mg In/mLof titrant, andFC= calibration factor for cadmium, mg Cd/mL of titrant.14.2 Calibration Calculations:FS5mg of Ag in calibration standard
36、 aliquotmL of standard NaCI solution added(1)FI5mg of In in calibration standard aliquotmL of standard EDTA solution added(2)FC5mg of Cd in calibration standard aliquotmL of standard EDTA solution added(3)14.3 Sample Calculations:Ag, % 5 mL of NaCl titrant 3 FS310/S (4)In, % 5 mL of EDTA titrant 3 F
37、I310/S (5)Cd,%5 mL of EDTA titrant 3 FC310/S (6)15. Precision and Bias15.1 PrecisionThe estimated standard deviation for asingle measurement of each element is 0.03 % for silver,indium, and cadmium.15.2 BiasThe estimated bias, measured using a known80 % Ag-15 % In-5 % Cd alloy, is as follows: Ag, 0.
38、02 %;In, +0.09 %; Cd, 0.03 %, absolute.TRACE IMPURITIES BYCARRIERDISTILLATIONSPECTROCHEMICAL METHOD16. Scope16.1 This test method is applicable to the determination ofthe trace impurities listed in 19.1 in silver-indium-cadmiumalloys.17. Summary of Test Method17.1 The sample is cleaned, and a weighe
39、d quantity isdissolved in nitric acid. An equivalent weight of graphite isadded to the solution and it is evaporated to dryness at 85 65C. The residue is moistened with a few drops of water andmixed until a slurry is obtained. A dilute hydrochloric acidsolution is added and mixed well. The slurry is
40、 evaporated todryness at 85 6 5C in subdued light.17.2 The dried sample mixture is blended with a bariumfluoride-graphite carrier, weighed into graphite anode caps, andexcited in a d-c arc.The spectrum is recorded photographically,and the spectral lines of interest are compared visually withstandard
41、s exposed on the same plate.18. Apparatus18.1 SpectrographA spectrograph with sufficient resolv-ing power and linear dispersion to separate the analytical linesfrom other lines in the spectrum of the sample in the spectralregion from 220 to 400 nm is recommended. Instruments witha reciprocal linear
42、dispersion of 0.3 nm/mm or less aresatisfactory.18.2 Excitation SourceA d-c arc source capable of sus-taining a 12-A d-c arc.18.3 Excitation StandConventional type with adjustablewater-cooled electrode holders.18.4 BalanceAtorsion-type balance with a capacity of 1.0g and capable of weighing to the n
43、earest 0.5 mg.18.5 Pulverizer-MixerA mechanical mixer with a plasticvial and ball.18.6 ComparatorConventional type is satisfactory.18.7 Photographic Processing EquipmentPhotographicprocessing equipment conforming to the requirements ofPractices E115.18.8 Steam BathConventional type.18.9 Drying OvenC
44、onventional type, stainless steel con-struction.18.10 Beakers25 or 50-mL capacity TFE-fluorocarbonconstruction.18.11 Stirring RodsTFE-fluorocarbon construction.18.12 Venting ToolSee Fig. 1.C760 90 (2015)318.13 ElectrodesASTM Types S-1, S-2, and C-1.19. Reagents19.1 Barium Fluoride (BaF2)99.90 % puri
45、ty, 99.99 % purity.19.4 GraphiteSpectrographic grade, 200-mesh, nonpellet-izing type.19.5 Hydrochloric Acid (6 N)Dilute 500-mL of redistilledhydrochloric acid (HCl, sp gr 1.19) to 1 L with double-distilledwater.19.6 IndiumIndium metal, 99.99 % purity.19.7 Nitric Acid (8 N)Dilute 500 mL of redistille
46、d nitricacid (HNO3, sp gr 1.42) to 1 L with double-distilled water.19.8 SilverSilver metal, 99.99 % purity.20. Procedure20.1 Preparation of Standards:20.1.1 A minimum of four standards containing 1 to 1000g/g of each impurity element to be determined by blendingknown amounts of each impurity oxide o
47、r salt with a graphitematrix.820.1.2 Dissolve 20.00 g of silver metal, 3.75 g of indiummetal, and 1.25 g of cadmium metal in 75-mL of 8 N HNO3.Cool and dilute to 200-mL in a volumetric flask with double-distilled water.20.1.3 Pipet 2 mL of theAg-In-Cd solution (see 20.1.2) intoeach of five TFE-fluor
48、ocarbon beakers (25-mL capacity).Weigh 250 6 1 mg of graphite into the first beaker and 250 61 mg of each graphite base standard (see 20.1.1) into the fourremaining beakers, one standard in each of the beakers.20.1.4 Thoroughly mix the graphite and the solution using aTFE-fluorocarbon stirring rod a
49、nd carry through the samplepreparation procedure starting with 20.2.5.20.2 Preparation of Samples:20.2.1 Clean 0.5 to 1.0 g of sample with file, wash withorganic solvent, and air dry.20.2.2 Weigh the sample to the nearest 1 mg and transfer itto a 25-mL TFE-fluorocarbon beaker.20.2.3 Add 5 mLof 8 N HNO3and let stand until the sampleis completely dissolved.20.2.4 Weigh an amount of graphite equivalent to thesample weight 6 1.0 mg and transfer it to the TFE-fluorocarbon beaker. Thoroughly mix using a TFE-fluorocarbon stirring rod.20.2.5
