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Hot Dip Aluminizing Process for TBM applications - An Overview

Hot Dip Aluminizing Process for TBM applications - An Overview. Nirav I. Jamnapara , S. Mukherjee, P. M. Raole, E. Rajendrakumar INSTITUTE FOR PLASMA RESEARCH Gandhinagar – 382044, India. About LLCB. Solid + Liquid Breeder Concept

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Hot Dip Aluminizing Process for TBM applications - An Overview

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  1. Hot Dip Aluminizing Process for TBM applications- An Overview Nirav I. Jamnapara, S. Mukherjee, P. M. Raole, E. Rajendrakumar INSTITUTE FOR PLASMA RESEARCH Gandhinagar – 382044, India Workshop on Steels & Fabrication Technologies 2008 21-22 July, 2008 Organized by: IPR & IGCAR

  2. About LLCB • Solid + Liquid Breeder Concept • Li2TiO3 pebbles as solid breeder & Pb-17Li Eutectic as liquid breeder. Fig 1: Open view of LLCB TBM N.I. Jamnapara, S. Mukherjee, P. M. Raole, E. Rajendrakumar WS&FT ’08, 21-22 July, 2008

  3. Schematic 450-900 C 460 C PbLi out 325 C PbLi in 2 N.I. Jamnapara, S. Mukherjee, P. M. Raole, E. Rajendrakumar WS&FT ’08, 21-22 July, 2008

  4. Environment & Challenges • Liquid Pb-17Li @ 1.2 MPa, 325-460 C, 0.5-1 m/s velocities [1]– Hot Corrosion-erosion • T generation in CB & Pb-Li circuits [1] – Tritium permeation through FMS • Thermal Cycles [1] • MHD effects [1]– Insulation needed N.I. Jamnapara, S. Mukherjee, P. M. Raole, E. Rajendrakumar WS&FT ’08, 21-22 July, 2008

  5. Why coating? Fig 3: T permeation into coolant from Pb-17Li blanket by Reiter [2] Fig 4: Permeability of several metals by P.S. Korinko [3] Crsn N.I. Jamnapara, S. Mukherjee, P. M. Raole, E. Rajendrakumar WS&FT ’08, 21-22 July, 2008

  6. Ideal Coating Should… • Protect FMS against corrosion from Pb-17Li (> 10,000 hrs) [5, 6] • Resist Tritium permeation through FMS (PRF > 75 in Pb-17Li conditions) [4] • Maintain thermal compatibility () • be Electrically insulating (to resist MHD effects) • not affect heat transfer • be easy to apply on substrates N.I. Jamnapara, S. Mukherjee, P. M. Raole, E. Rajendrakumar WS&FT ’08, 21-22 July, 2008

  7. Candidate coatings N.I. Jamnapara, S. Mukherjee, P. M. Raole, E. Rajendrakumar WS&FT ’08, 21-22 July, 2008

  8. Why Aluminide coating? • Good resistance to T permeation* • Good corrosion resistance of FMS against liquid Pb-Li (480 – 550 C) • Thermally compatible • Electrically Insulating top layer (Al2O3) Volume resistivity: 0.01  m *EU Fusion Technology Program has considered aluminide coatings as ‘reference coating’ (HDA & CVD) as tritium permeation barriers. Ref # 09: J. Konys et. al., FZK Germany N.I. Jamnapara, S. Mukherjee, P. M. Raole, E. Rajendrakumar WS&FT ’08, 21-22 July, 2008

  9. Comparison N.I. Jamnapara, S. Mukherjee, P. M. Raole, E. Rajendrakumar WS&FT ’08, 21-22 July, 2008

  10. Why Hot Dip Aluminizing? • Aluminizing possible by solid, liquid & gas processing [3] • Better PRFs with H2 as compared to CVD (J. Konys; FZK, Germany, [4]) • Ease of processing complex geometries • Scalable • Adherent alumina by oxidation of surface N.I. Jamnapara, S. Mukherjee, P. M. Raole, E. Rajendrakumar WS&FT ’08, 21-22 July, 2008

  11. Targeted Aluminide Coating • Intermetallic Fe-Al + Al2O3 1-10 m Al2O3 (for resistance to corrosion, MHD and Erosion) 150-180 m Intermetallic Fe-Al (for Tritium Permeation Resistance) Ref: J. Konys et. al., FZK [4,5] N.I. Jamnapara, S. Mukherjee, P. M. Raole, E. Rajendrakumar WS&FT ’08, 21-22 July, 2008

  12. HV 320 270 240 FeAl -Fe(Al) F82H-mod. Targeted Microstructures Parameters for hot dipping: temperature at 700°C and dipping time of 30 s Microstructure of hot dipped surface Microstructure after heat treatment Al Fe2Al5 F82H-mod. The alloyed surface layer consists of brittle Fe2Al5, covered by solidified Al Heat treatment at 1040°C/0.5 h + 750°C/1 h and an applied pressure of >250 bar (HIPing) reduces porosity and transforms the brittle Fe2Al5-phase into the more ductile phases FeAl and -Fe(Al) Ref: J. Konys et. al., FZK [4,5] N.I. Jamnapara, S. Mukherjee, P. M. Raole, E. Rajendrakumar WS&FT ’08, 21-22 July, 2008

  13. HDA Setup - proposed Al2O3 - crucible Sample Holding chamber with protective environment Al-melt Furnace Melting chamber Coating conditions [4,5] Temperature: 700 – 750 °C Melt: Al or Al-Si (7-11% Si) Sample dimensions: 50 mm (l) x 30 mm (w) x 5 mm N.I. Jamnapara, S. Mukherjee, P. M. Raole, E. Rajendrakumar WS&FT ’08, 21-22 July, 2008

  14. HDA PROCESS          Steel sample (sheet or tube) Grinding Cleaning in acetone Coating, aq. flux-solution Pre-drying : 100°C Glove-box (Ar-5%H2) Heat Treatment (Standard process)    Coated sample   HIP-process (advanced process) Cleaning in water   Ref: Voltrag, et. al. FZK [4,5] Hot-dip-aluminizing, 700°C N.I. Jamnapara, S. Mukherjee, P. M. Raole, E. Rajendrakumar WS&FT ’08, 21-22 July, 2008

  15. Challenges • Wettability of sample in Al melt • Melt Composition (alloying, viz. Si) • Surface Activation (fluxes etc.) • Case composition – tailored (Fe-Al) • Post treatment (HIPing), dipping time, batch composition • No porosities (HIPing), Case depth • Adherent Al2O3 layer on top • Plasma oxidation process • Qualify for validation (performance related) N.I. Jamnapara, S. Mukherjee, P. M. Raole, E. Rajendrakumar WS&FT ’08, 21-22 July, 2008

  16. Plans for development • Development of homogenous aluminized coating after HDA • Generation of desired compositional profile by heat treatment & plasma oxidation • Hot Isostatic Pressing of aluminized samples (To be worked out in collaboration with other national insitutes) Hot Dip aluminizing 700 – 750 C HIPing 1050 C, 250 Bar 1 hr Validation Plasma Oxidation & H/T 1050 C N.I. Jamnapara, S. Mukherjee, P. M. Raole, E. Rajendrakumar WS&FT ’08, 21-22 July, 2008

  17. Validation: • Pb-17Li Loop testing • H2 / T permeation: • Initially the sample will be tested for Hydrogen permeation • Susequently the sample will be validated for Tritium permeation in Pb-Li environment Ref: Schematic of Permeation testing facility at ENEA, Italy N.I. Jamnapara, S. Mukherjee, P. M. Raole, E. Rajendrakumar WS&FT ’08, 21-22 July, 2008

  18. Present status • Design & generation of specs for furnace • Fabrication & installation of furnace • Preliminary trials for HDA – wettability & uniformity • Heat treatment optimization • Characterization • Hot Isostatic Pressing • Validation N.I. Jamnapara, S. Mukherjee, P. M. Raole, E. Rajendrakumar WS&FT ’08, 21-22 July, 2008

  19. Thank You N.I. Jamnapara, S. Mukherjee, P. M. Raole, E. Rajendrakumar WS&FT ’08, 21-22 July, 2008

  20. References: • Design Description Document for Indian Lead Lithium cooled ceramic breeder (LLCB) Blanket • G. W. Hollenberg et. al., Tritium / Hydrogen Barrier Development, June 1994, 3rd Intl. Symposium on Fusion Nuclear Technologies, LA, California • P.S. Korinko et. al., ‘Dev. of aluminide coatings for Hydrogen isotope permeation resistance’, Tritium 2001, Tsukaba, Japan, 11-16 Nov, 2001 • J. Konys et. al., ITER TBM Project Meeting, UCLA, Feb 23-25, 2004. • J. Konys et. al., J. Nucl. Mat. 367-370 (2007) 1144-1149 • H. Glasbrenner et. al., J. Nucl. Mat. 307-311 (2002) 1360-1363 BACK N.I. Jamnapara, S. Mukherjee, P. M. Raole, E. Rajendrakumar WS&FT ’08, 21-22 July, 2008

  21. Corrosion data Ref: W. Krauss et. al., Intl. workshop on breeder blankets, Russia June, 2006 BACK N.I. Jamnapara, S. Mukherjee, P. M. Raole, E. Rajendrakumar WS&FT ’08, 21-22 July, 2008

  22. Results of permeation testing in H2–gas in different facilitiesat ENEA Brasimone, Italy (PERI, CORELLI)Permeation Reduction Factors (PRF) cancelled pH2= 1 bar, steel: F82H-mod., Ref: J. Konys et. al. [4] BACK N.I. Jamnapara, S. Mukherjee, P. M. Raole, E. Rajendrakumar WS&FT ’08, 21-22 July, 2008

  23. HV 320 270 240 FeAl -Fe(Al) F82H-mod. FeAl HV 320 270 240 -Fe(Al) F82H-mod. WHY HIPPING? Microstructure after heat treatment Microstructure after HIP Heat treatment at 1040°C/0.5 h + 750°C/1 h and an applied pressure of >250 bar (HIPing) reduces porosity and transforms the brittle Fe2Al5-phase into the more ductile phases FeAl and -Fe(Al) Heat treatment at 1040°C/0.5 h + 750°C/1 h incorporates the solidified Al and transforms the brittle Fe2Al5-phase into the more ductile phases FeAl and -Fe(Al) BACK Ref: J. Konys et. al. [4] N.I. Jamnapara, S. Mukherjee, P. M. Raole, E. Rajendrakumar WS&FT ’08, 21-22 July, 2008

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