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Techniques for characterization of trace and tramp elements in advanced structural steels

Techniques for characterization of trace and tramp elements in advanced structural steels J.Arunachalam Head, National Centre for compositional Characterisation of Materials (CCCM), Bhabha Atomic Research Centre, Hyderabad. (aruncccm@rediffmail.com).

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Techniques for characterization of trace and tramp elements in advanced structural steels

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  1. Techniques for characterization of trace and tramp elements in advanced structural steels J.Arunachalam Head, National Centre for compositional Characterisation of Materials (CCCM), Bhabha Atomic Research Centre, Hyderabad. (aruncccm@rediffmail.com)

  2. CCCM has been setup by DAE as a national facility for analytical sciences Objectives: • R&D in basic analytical sciences • Specialized (inorganic) analytical services for the determinations elements down to sub-ppb levels • Validation support to analytical efforts in materials, environmental, and life sciences • Training in analytical techniques • Supply of reference materials • Consultancy services to industries in process optimization and product development

  3. Desired analytical competences in advanced technology • Direct analysis of refractory metals and ceramics for impurities in the bulk • Elemental concentrations in grain boundaries • Determination of elements/isotopes at sub-femtogram levels • Chemical state information • Speciation information • Spatial / depth distribution of gaseous elements • Techniques to characterize nanomaterials.

  4. ORGANIZATION • Bulk Analysis Laboratory • Surface and Profile Measurement Laboratory • Ultra Trace Analysis Laboratory • Service Facilities

  5. Analytical techniques • Bulk lab: FAAS, ICP-AES, GFAAS, Classical methods • SPML: Ion-beam Analysis ( RBS, NRA, PIXE/PIGE ( microbeam, HRBS and channelling studies) • UTAL: ICP-MS, GD-MS and GFAAS

  6. Some requirement of compositional analysis in fusion technology Bulk: Ferritic Steels; Oxide dispersion strengthened steels; Vanadium alloys; silicon carbide composites, H-3 breeding materials Surface: gaseous impregnation ( Hydrogen and its isotopes, Helium, Nitrogen); corrosion products migrated to surface; compositional degradation due exposure to coolants Elemental accumulation in grain boundaries

  7. IPR JAERI (95% Li-6) Al 925 <15 Ca 1203 <22 Cr 29 <29 Cu 2.3 n/a Fe 8.1 <31 Ni 5.3 n/a V 1.2 n/a Co 1.3 n/a Na 5.6 97 K 4.8 32 Mg 3.4 <13 Mn 5.1 n/a Si 1300* <15 Zr 60 <50 S n.d <18 (Silicon contamination due grinding in agate) Trace impurities in Lithium Titanate (indicative, in ppm, Analysis by GFAAS)

  8. Composition of some low activation steels

  9. Undesirable elements • Nb, Cu, Ni, Mo, N ( Nb < 1ppm required for activation consideration) • Tramp impurities include Ag, Ho, Bi, Co, Sm, Lu, Dy, Gd, and Cd.

  10. Chemical composition of V–4Ti alloy (% wt) Ti 3.99 Al / Si 0.014 W ≤0.5 (ppm) O 280 (ppm) N 30 (ppm) C 120 (ppm) V Rest

  11. Analysis of high purity elements by ICP-MS / GDMS

  12. Impurity analysis using ICP-MS

  13. Importance of trace element characterization Silver, niobium and molybdenum are the most important restrictive elements Steels produced up to now do not meet the criterion of activation criteria of shallow land burial of nuclear waste or recycling ( after a certain dose exposure followed by 100 y cooling) Considerable research and expense are required to meet these criteria. ( R.L.Kleuh et al, JNM, 280 (2000) 353-359.

  14. Ultra-Trace Analysis Laboratory Officer-In-Charge: Dr. J. Arunachalam, Head, CCCM

  15. Ultra Trace Analysis Laboratory • Designed and built totally indigenously • Provides dust free, metal free ultra clean working areas • Enables measurements down to parts per billion (ppb) and lower • Laboratory area is typically of class of 100 (based on US FED 209E) • Laminar flow clean benches better than class 10 (i.e., <10 particles in the size of >0.5 microns in one cubic feet)

  16. Requirements for ultra trace analysis • Ultra sensitive instruments • Clean rooms; protocols and strict implementation for contamination control • Clean lab ware • High purity reagents • Conscious analysts

  17. Element (in ng/ml) Ultra pure water Element (in ng/ml) Ultra pure water Na 0.3 Se 0.004 Mg <0.001 Cd 0.002 Al 0.06 In <0.0006 Ti 0.014 Sn 0.006 V 0.0001 Sb 0.001 Cr 0.003 Te 0.028 Mn <0.001 Pt <0.001 Co <0.0001 Au 0.0001 Ni 0.003 Pb <0.001 Cu 0.008 Bi <0.02 Zn 0.1 K 0.04 Typical levels of trace element impurities in Ultra pure water

  18. Typical Values of trace elements in normal and purified reagents prepared in the clean lab. (CCCM): Values in ng/ml Element MilliQ water Raw HNO3 Sub-boil HNO3 Raw HCl Sub-boil HCl Raw Ammonia ISP Ammonia Cr 0.007 53 0.7 17 2.2 1.8 0.25 Mn 0.006 14 0.21 13 0.21 16 0.016 Co 0.001 0.6 0.013 0.5 0.03 0.22 0.24 Ni 0.09 41 0.05 7.5 0.4 0.98 0.083 Cu 0.001 25 1.1 22 2.8 1.2 0.027 Zn 0.018 25 1.6 73 2.9 2.0 0.032 Mo 0.006 3.6 0.07 0.5 0.05 0.7 0.15 Cd 0.001 0.3 0.013 0.4 0.018 0.06 0.002 In 0.004 0.023 0.005 0.04 0.02 0.008 0.002 Pb 0.001 4.5 0.8 3.5 0.4 2.7 0.025

  19. Sensitive analytical techniques for analysis down to ppt levels • Inductively Coupled Plasma Mass Spectrometer (ICP-MS) • Glow-Discharge Quadrupole Mass Spectrometer (GD-QMS) • Graphite Furnace Atomic Absorption Spectrometer with Zeeman Background Correction (GFAAS) • Ion Chromatograph (IC)

  20. Inductively Coupled Plasma Mass Spectrometer Concentric nebulizer Cooled Scott type spray chamber Fassel torch Additional provision to handle organic matrices Time resolved acquisition mode to couple LC/GC Details of available equipment : Model VG PlasmaQuad 3

  21. Features • Very low, sub-ppb detection limits for most elements • Rapid throughput • Multi-elemental capability • Large linear dynamic range • Fewer matrix effects ( compared to AAS and AES ) • Isotopic ratio information

  22. Analysis of high purity arsenic; All values in mg/kg. Analysis by ICP-QMS Element Process Blank As-7 As-8 As-9 Cd 0.003 0.03 0.33 0.02 Co 0.001 0.028 0.005 0.016 Cr 0.003 0.06 0.19 0.47 Cu 0.018 0.25 0.28 0.23 Hg 0.007 0.19 0.17 0.18 Mn 0.001 0.29 0.10 0.16 Mo 0.008 0.09 0.08 0.03 Ni 0.009 0.09 0.09 0.08 Pb 0.007 0.42 0.75 0.68 Sb 0.23 0.37 0.81 0.26 Se 0.25 3.3 1.6 5.6 Te 0.039 0.12 0.14 0.13 Zn 0.009 0.58 0.50 0.58

  23. Speciation Analysis: Speciation of oxides dispersed in steel matrices ( Similar to free and bound carbon in boron carbide)

  24. Glow Discharge Quadrupole Mass Spectrometry Discharge Conditions: Voltage: 500 – 2000 V DC; Current: 0.2 – 10mA; Pressure: 0.1 – 10 Torr (Ar)

  25. Capabilities of GD-QMS • Direct Solid Analysis • No process blank • Multi-Elemental technique • Ability to measure majority of the elements • Major, minor and trace / ultra-trace level analysis in one cycle • Depth profiling of thin solid films • Rapid semi-quantitative analysis • DC/RF GD for conducting and non-conducting materials respectively

  26. A comparison of assay ( wet chemical vs GDMS Assay by GDMS = 100% - sum of all measured impurities

  27. Composition of a steel sample

  28. RSF Values used in steel analysis(NIST Steel standard NIST-1761 was used to generate RSFs)

  29. Determination of Chlorine in Zr-2.5Nb Alloy • Limit of Cl in Zr-2.5Nb alloy is <0.5ppm • Increase in Cl result in reduction of fracture toughness • Detection limits of the conventional techniques (Viz. Pyro-hydrolysis-IC) are not adequate

  30. Element (ug/kg) Al Pr.Blk Sample 1 Sample 2 Sample 3 ICPMS GFAAS ICPMS GFAAS ICPMS GFAAS Al 2 18 11 7.4 6 5.3 5 Ag 9.3 11 8.3 As 22 13 12.2 Cd <0.03 5.2 0.3 0.19 <0.05 <0.1 <0.05 Co <0.3 2.1 <5 1.6 <5 1.5 <5 Cr <3 60 <5 60 <3 51 <3 Cu <2 8.4 <5 5.9 <5 5.6 <5 Fe 25 <5 <5 <5 In <10 0.5 <10 0.13 <10 0.98 <10 Mn <0.5 20 13 <0.5 16.5 <0.5 Ni* 3 490 <3 683 <3 741 <3 Pb <3 11 <5 4 <3 Nd <3 Zn 10 35 <5 39 <5 37 <5 Ca 30 100 20 22 K <5 35 <5 <5 Na <5 55 <5 <5 Trace Element Impurities in Tellurium: ( in ppb) * Higher values for nickel by ICP-MS is due to possible contamination from sampler cone made of nickel.

  31. NIST Code NIST (indicated values) mg/kg GD-QMS values (mg/kg) CCCM Zircaloy 1237 0.4 0.42  0.02 Zircaloy 1238 2.0 2.31  0.05 Zircaloy 1239 0.25 0.24  0.01 Zr-2.5% Nb (NFC) < 0.5  0.1 (DC arc, NFC) 0.33  0.01 Zr- 1% Nb alloy 3(NFC) < 0.5  0.1 (DC Arc, NFC) 0.10  0.01 Analysis of boron in Zircaloy (NIST) standards & Zr-Nb samples(GD-QMS)

  32. Zr-Nb 2.5 alloy samples GD-QMS values (n=6) in mg/kg %RSD 1st Melt ingot 12.25  0.14 1.2 2nd Melt ingot 2.93  0.23 7.8 3rd Melt ingot 0.82  0.09 10.5 4th Melt ingot 0.08  0.01 11.6 Analysis of chlorine in Zr-2.5 Nb samples from NFC (GD-QMS)

  33. Elements Specification limit (ppm) Elements Specification limit (ppm) B 50-150 Nb 0.1-0.5% C 500-1500 Ag <50 N <10 Cd <50 O <10 In <50 Na <50 Sn <15 Mg <80 Sb <50 Al 4.8-6% Te <0.3 Si <500 Hf 0.8-1.8% P <50 Ta 6-9% S <10 W 5-7.5% K <50 Re 4.8-7.5% V <0.1% Au <50 Cr 1.4-4.4% Hg <50 Mn <100 Tl <0.3 Fe <0.15% Pb <2 Ni 53-74% Bi <0.3 Co 3-8% Cu <50 Zn <50 Ge <50 As <50 Se <1 Specifications of super alloys:

  34. Ion beam Analysis aproaches • RBS/ HRBS : multi layered films • NRRA: for H • PIXE: Multi-element analysis • PIGE: Low Z elements like F • ERDA: eg. Hydrogen isotopes using high energy heavy ion beams • Microbeam approaches for probing micron dimensions using micro-RBS and micro-PIXE; surface elemental mapping

  35. Depth Profile of Hydrogen in Si implanted with 30 keV protons Hydrogen Depth Profile of Si3N4 layer on GaAs

  36. Micro area elemental distribution in SS 316L exposed to LBE Bi Pb Fe Cr Ni Mo

  37. RBS spectra of virgin and exposed (LBE) SS316L

  38. End User Preferences: Trace element profiles determined using direct Instrumental methods like RF-GD-MS are preferred by the end-users, than those based on chemical separations. As many as 60 impurities need to be specified for assessing the purity of the material but approaches based on chemical separations cannot meet this requirement.

  39. Sharing the cost and instrument time: In view of the small number of users/producers of high purity materials the cost of these sophisticated analytical equipment can be shared on a “ consortium basis” They can be located in a centralized facility, which has the necessary infrastructure, experience and access. The country has the necessary expertise in developing sophisticated analytical instruments, which has to be pooled together and supported for a sustained period. In the absence of such indigenous effort our progress in meeting the material requirements of high technology will be severely hampered.

  40. We have the capability to meet all the compositional analysis requirements of structural steels and other metals and alloys. • We need to develop the competence to carry out the analysis of ceramics. • In addition, considerable efforts need to be put on: • Producing certified reference materials (CRMs) of high purity matrices (metals, alloys, ceramics) • Organizing Proficiency Tests among the laboratories • Generating adequate trained manpower in high purity material production and characterization. • Thank You

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