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FABRICATION OF SiC/SiCf COMPOSITE
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FABRICATION OF SiC/SiCf COMPOSITE

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This paper was presented on the ISASC 2008 (International symposium on new frontier of advanced Si-based ceramics and composites

This paper was presented on the ISASC 2008 (International symposium on new frontier of advanced Si-based ceramics and composites

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  • 1. 1 FABRICATION OF SiC/SiCf COMPOSITE BY VACUUM INFILTRATION AND HOT PRESSING Parlindungan Yonathan1, Jong-Hyun Lee1, Dang-Hyok Yoon1, Weon-Ju Kim2 and Ji-Yeon Park2 1School of Materials Science and Engineering, Yeungnam University 2Nuclear Materials Research Division, KAERI, Korea
  • 2. 2 Presentation Outline Background SiC/SiCff Experiment advantages SiC/SiC applications and Fusion reactors applications and issues Conclusion Main Goal Materials Process Composition Design Result
  • 3. 3 Background
  • 4. 4 SiC/SiCf Advantages High specific strength Good high-temperature properties Good fracture resistance Good thermal conductivity Corrosion and wear resistance Low induced radioactivity under nuclear environments
  • 5. 5 SiC/SiCf Applications
  • 6. 6 Fusion Reactors He bubbles First Wall Be, Be-alloy W, W-alloy SiC/SiCf,C/C Fusion reactor blanket concept: • TAURO, European Union (SiC/SiCf) • ARIES-AT, US (SiC/SiCf) • DREAM, Japan (Be-Li2O-SiC) ARIES-AT vertical cross-section *Fusion technology institute, University Wisconsin
  • 7. Permeability issue in SiC/SiCf 7 0.86Å Bombardment of high Point defect behavior in energetic neutrons in to ceramics composite surface He and H atoms will move to a Bubbles formation on the porous site, vacancy cluster, surface or blistering and grain boundary to start causing delamination issue * J.H Kim, Y.D Kwon, Parlindungan Yonathan, I. Hidayat, “The energetic of He and H atoms in the irradiated β-SiC: ab initio approach”
  • 8. 8 Main Goal To achieve a high density SiC/SiCf composite by maximizing SiC slurry infiltration into SiC woven fiber and finally to attain high structural strength composite material Process development high density composite material: Milling process Infiltration method Slurry composition Tape casting Evaluation of material performance Material characteristics and morphology Mechanical properties
  • 9. 9 Materials
  • 10. 10 SiC powder β-SiC, NanoAmor β-SiC, Marketech Average particle size: 52nm(NanoAmor), 30nm(Marketech) Fine & spherical β-SiC BET: 80 m2/g (NanoAmor), 109 m2/g (Marketech) Surface is covered with SiO2 layer thinner than 1.7nm 2nm
  • 11. 11 SiC Woven fiber (220nm) Top view Cross-section view Pyrolitic carbon-coated fiber TyrannoTM-SA Grade-3 Fiber Ube Industries, Ltd., Tokyo, Japan 2D woven fiber Properties Tyranno-SA Grade-3 Atomic composition (C/Si) 1.08, Al 0.005 PyC coated by KAERI Diameter (mm) 7.5 PyC coated design was Number of filaments/yarn 1600 based on CVI-SiC/SiCf Tensile strength (MPa) 2500 composite process Mass density (g/cm3) 3.1
  • 12. 12 Sintering Additives Alumina Oxide (Al2O3) Magnesium Oxide (MgO) Yttrium (III) Oxide (Y2O3) Sintering additives facilitate the densification of SiC due to its highly covalent bond structure Al2O3/Y2O3/MgO = (0.64/0.26/0.1) wt%* Liquid phase assisted sintering * KY Lim, DH Jang, YW Kim, JY Park, DS Park,quot; Effect of the processing parameters on the densification and strength of 2D SiC fiber-SiC matrix composites fabricated by slurry infiltration and stacking process
  • 13. 13 Process
  • 14. 14 Process focus Milling (dispersion) Solid volume fraction in green body Infiltration Rate of infiltration and densification Sinterability (pressure, temperature) Effective infiltration Controllable infiltration
  • 15. 15 Ball milling vs. High Energy Milling @ Ball mill High energy mill The most conventional Recently introduced mechanical milling (MiniCer, Netzsch) 2–200 mm spherical or 0.01 – 0.8 mm ZrO2 beads cylindrical balls Rotation up to 4200rpm Rotation under 200 rpm Very effective in milling
  • 16. 16 Why HEM Milling time (min) Herring’s scalling laws: 0 20 40 60 80 100 120 n 15000 t1 ⎛ r1 ⎞ High energy milling =⎜ ⎟ ⎜r ⎟ ⎝ 2 ⎠ 12000 t2 Viscosity(mPa.s) 9000 At constant temp Ball milling Rumpf’s Equation: 6000 1.1φ A 3000 σ= . 0 1 − φ 12rl 2 0 20 40 60 80 100 120 Milling time (hr) All proposed mechanisms of sintering and densification of ceramic powder compacts agree that the particle size is one of the most important parameters in the rate of progress of these processes. * Nono Darsono a, Dang-Hyok Yoon a,*, Jaemyung Kim b, “Milling and dispersion of multi-walled carbon nanotubes in texanol”
  • 17. 17 Vacuum Infiltration Enhance the infiltration by vacuum absorption force Enhance the composite density in fiber
  • 18. 18 Vacuum Infiltration The slurry is infiltrated as the vacuum pressure Vacuum release Vacuum on progressively released to return to surrounding pressure, thereby causing the slurry to be forced through the fiber pores. Advantages: SiC Slurry Using vacuum force to help infiltration process SiC Fiber Infiltration can be controlled by altering the vacuum pressure and release of vacuum time. Vacuum pressure 0.1Pa Pumping speed 120L/min
  • 19. 19 Vacuum Infiltrated fiber - SEM Top view Cross-section view Normal infiltration (dipping) Vacuum infiltration
  • 20. 20 Composition
  • 21. 21 Composition Two types of slurry Infiltration slurry Tape casting (binder 40% wt% wrt. powder) Two composition variables Sintering additives (2/6/10 wt% wrt. powder) Binder (PVB B-98, 0/5/10/45% wrt. powder)
  • 22. 22 Effect of sintering additives Relative density & Flexural strength 500 Sintering Solvent 100 Flexural Strength (MPa) additives (Ethanol) 400 Relative Density (%) 80 300 High Energy Milling 60 Drying 200 40 Sintering SiC 20 100 Marketech Density additives Powder Marketech Flexural Strength Nanostructure Density TEM SEM Nanostructure Flexural Strength 0 0 High Energy Milling 2 4 6 8 10 Additive (wt%) Sintering additives Density Powder Type Density (%) Drying (% w.r.tpowder) (g/cm3) Marketech 2 2.215 69.21% Hot Pressing Marketech 6 3.178 99.29% Marketech 10 3.187 99.55% NanoAmor 2 2.529 79.02% Bending test Density SEM (4-point) (Archimedes) NanoAmor 6 3.174 99.16% NanoAmor 10 3.198 99.89%
  • 23. 23 Effect of binder Infiltration slurry viscosity ( β− SiC NanoAmor) Binder solution 50 0 5 High energy milling 40 10 45 Viscosity (cP) 30 Shear Rate at 42.24/sec Vacuum infiltration Sintering additives 6% 20 Drying Cryo-fracture 10 Binder burn-out SEM 0 -5 0 5 10 15 20 25 30 35 40 45 50 Binder (% wrt powder) Hot Pressing Binder percentage No. Powder Type (w.r.t. powder) 1 NanoAmor 45% 2 NanoAmor 10% Bending test Density SEM 3 NanoAmor 5% (4-point) (Archimedes) 4 NanoAmor 0%
  • 24. 24 SEM pictures of infiltrated fibers after binder burn-out Top-view Top-view Top-view Top-view 0% binder 5% binder 10% binder 45% binder Fiber cross-section Fiber cross-section Fiber cross-section Fiber cross-section 0% binder 5% binder 10% binder 45% binder
  • 25. 25 SEM pictures of hot-pressed infiltrated fiber Cross-section view Cross-section view Cross-section view Cross-section view 0% binder 5% binder 10% binder 45% binder Fiber cross-section Fiber cross-section Fiber cross-section Fiber cross-section 0% binder 5% binder 10% binder 45% binder
  • 26. 26 Relative density & Flexural strength of SiC/SiCf 200 0% Density of infiltrated fiber 5% 10% 45% Infiltrated fiber hot-pressed density 100 2.8 90 Measured density/True Density (%) 2.7 Relative Density (%) Flexural Strength (MPa) Density (g/cm3) 2.6 75 150 2.5 80 2.4 Density Density Percentage FlexuralStrength 50 100 0% 5% 10% 45% 0% 5% 10% 45% Additive (wt%) Binder content (%) Binder Composition 0% 5% 10% 45% Density 2.493143 2.505714 2.5905 2.708 Percentage density 80.42% 80.83% 83.56% 87.35% Flexural Strength (MPa) 117.6 121.52 131 161.43
  • 27. 27 Composite design
  • 28. 28 Composite structure Composite formed by stacking SiC green tape the SiC green sheet and the Infiltrated SiC infiltrated SiC fibers fiber with SiC slurry Binder burn-out at 4000C for 2- hours at 1oC/min Hot pressed at 1750oC, 20MPa, Hot pressing 3-hours 5cm SiC infiltrated SiC infiltrated fiber (NanoAmor) fiber 20 infiltrated fibers and (Marketech) tapes SiC/SiCf composite [0o/45o] Green tape Green tape 62-72% fiber volume fraction (NanoAmor) (Marketech)
  • 29. 29 Effect of green tape Binder solution HEM (High energy milling) vacuum infiltration & stack with SiC Tapes Drying Cryo-fracture Binder burn-out SEM Tape casting Sintering (Hot Factors: Pressing) Slurry composition Dispersion Bending test Density SEM Zeta potential (4-point) (Archimedes) Viscosity DISPERSION STABILITY AND ITS EFFECT ON TAPE CASTING OF SOLVENT-BASED SiC SLURRY Jong-Hyun Lee, Parlindungan Yonathan, Dang-Hyok Yoon, Weon-Ju Kim* and Ji-Yeon Park* (Yeungnam University, Korea, * KAERI, Daejeon, Korea)
  • 30. Sintered SiC/SiCf 30 Relative density & Flexural strength of SiC/SiC f 100 300 Flexural Strength (MPa) Relative Density (%) 200 80 Sample 1 (Nano-tape) 100 60 Nano-tape Nano Marketech Powder type Sample 2 (Nano) Vacuum Other Hot infiltration & pressing CVI-PiP Hot pressing reported value Density (g/cm3) 3.161 2.9-3.0 2.5-2.8 Percent density (%) 98.78% 90-95% 80-90% Sample 3 (Mark-tape)
  • 31. 31 Mechanical 4point bending test NanoAmor (tape) NanoAmor (no tape) Sample 1 (Nano-tape) Marketech (tape) Sample 2 (Nano) Sample 3 (Marketech)
  • 32. 32 Sintered fracture cross-section NanoAmor+Tape NanoAmor+Tape NanoAmor+Tape (Before bending test) (Before bending test) (Before bending test) NanoAmor+Tape NanoAmor Marketech+Tape (After bending test) (After bending test) (After bending test)
  • 33. 33 XRD result XRD result of SiC/SiC f composite The phase structure were Marketech Sample 3 changed for both nano powder, Intensity (a.u.) Nano however phase Sample 2 change were not observed for marketech β− SiC phase Nanotape powder α− SiC phase Sample 1 20 30 40 50 60 70 80 2θ
  • 34. 34 Conclusion • High density of SiC/SiCf was achieved at 3.161g/cm3 (98.78%) by vacuum infiltration and hot pressing process. • Flexural strength of 230MPa was achieved with a brittle fracture mode showing very little fiber pull out. • Phase changed was observed after hot pressing at 1750oC- 20MPa-3hours, showing both alpha and beta-SiC phase in the composite. • SiC tape improved the sintered density and strength in the SiC/SiCf composite. • Slurry formulation including sintering additives plays an important role in vacuum infiltration and hot pressing process. • More intensive experiment on SiC/SiCf interface to improve the composite strength.
  • 35. 35 Acknowledgement This project is financial supports by: The Ministry of Knowledge Economy through a Materials & Components Technology R&D Program Highly appreciated