Project Overview

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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_at_rediffmail.com)
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CCCM has been setup by DAE as a national facility
for analytical sciences

• Objectives
• RD 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

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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.

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ORGANIZATION

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

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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

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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

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Trace impurities in Lithium Titanate (indicative,
in ppm, Analysis by GFAAS)

• IPR JAERI (95 Li-6)
• Al 925 lt15
• Ca 1203 lt22
• Cr 29 lt29
• Cu 2.3 n/a
• Fe 8.1 lt31
• 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 lt13
• Mn 5.1 n/a
• Si 1300 lt15
• Zr 60 lt50
• S n.d lt18
• (Silicon contamination due grinding in agate)

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Composition of some low activation steels
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Undesirable elements

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

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Chemical composition of V4Ti alloy ( wt)

• Ti 3.99
• Al /
• Si 0.014
• W 0.5 (ppm)
• O 280 (ppm)
• N 30 (ppm)
• C 120 (ppm)
• V Rest

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Analysis of high purity elements by ICP-MS / GDMS
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Impurity analysis using ICP-MS
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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.

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Ultra-Trace Analysis Laboratory
Officer-In-Charge Dr. J. Arunachalam, Head, CCCM
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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., lt10 particles in the size of gt0.5 microns
  in one cubic feet)

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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

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Typical levels of trace element impurities in
Ultra pure water  
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Typical Values of trace elements in normal and
purified reagents prepared in the clean lab.
(CCCM) Values in ng/ml
 
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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)

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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
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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 )
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• Isotopic ratio information

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Analysis of high purity arsenic All values in
mg/kg. Analysis by ICP-QMS
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Speciation Analysis

• Speciation of oxides dispersed in steel matrices
• ( Similar to free and bound carbon in boron
  carbide)

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

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A comparison of assay ( wet chemical vs GDMS
Assay by GDMS 100 - sum of all measured
impurities
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Composition of a steel sample
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RSF Values used in steel analysis(NIST Steel
standard NIST-1761 was used to generate RSFs)
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Determination of Chlorine in Zr-2.5Nb Alloy

• Limit of Cl in Zr-2.5Nb alloy is lt0.5ppm
• Increase in Cl result in reduction of fracture
  toughness
• Detection limits of the conventional techniques
  (Viz. Pyro-hydrolysis-IC) are not adequate

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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.
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Analysis of boron in Zircaloy (NIST) standards
Zr-Nb samples(GD-QMS)
 
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Analysis of chlorine in Zr-2.5 Nb samples from
NFC (GD-QMS)
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Specifications of super alloys
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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

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Depth Profile of Hydrogen in Si implanted with 30
keV protons
Hydrogen Depth Profile of Si3N4 layer on GaAs
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Micro area elemental distribution in SS 316L
exposed to LBE
Bi
Pb
Fe
Cr
Ni
Mo
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RBS spectra of virgin and exposed (LBE) SS316L
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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.
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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.
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• 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