KAERI
Progress in Wire Technology YBCO wire - 1.2 micron thick YBCO on Ni substrate with textured YSZ buffer layer yields 1,200,000 A/cm 2 at 75 K and 0 T and 200,000 A/cm 2 at 75 K and 1 T (LANL) BSCCO wire - rolled, multifilamentary Bi-2223 wire yields 44,000 A/cm 2 at 77 K and 0 T (ASC/WDG) - short, pressed Bi-2223 wire yields 74,000 A/cm 2 at 77 K and 0 T (ANL) TBCCO wire - electrodeposited wire made from Tl-1223 on Ag foil yields Jc of 68,000 A/cm 2 at 77 K and 0 T (NREL) - spray pyrolyzed Tl-1223 on ceramic yields Jc of 325,000 A/cm 2 at 77 K and 0 T (GE/ORNL) Progress in Systems Technology Long-length wire - 1180 meters, Bi-2223/Ag powder-in-tube wire manufactured by ASC with Jc = 12,500 A/cm 2 (WDG) - 1260 meters, Bi-2223/Ag powder-in-tube wire manufactured by ASC with Jc = 12,000 A/cm 2 (ANL) Coils - ASC: Bi-2223 coils at 4.2 K, B = 3.3 T / at 30 K, B = 2.6 T / at 77 K, B = 0.6 T - IGC: Bi-2223 coils at 4.2 K, B = 3.2 T / at 27 K, B = 2.2 T / at 77 K, B = 0.38 T - Oxford: Bi-2212 coils at 4.2 K, B = 1.1 T / at 15 K, B = 1.0 T
80 70 60 S1 S2 S3 S4 C O Si S5 80 70 60 S1 S2 S3 S4 C O Si S5 50 50 Atomic % 40 30 Atomic % 40 30 20 10 20 10 0 0 0 1 2 3 4 5 6 7 8 Surface Center Distance (µm) 0 1 2 3 4 5 6 7 8 Surface Center Distance (µm)
PACKING density diameter length SHEATH strength chemical compatibility processability conductivity POWDER surface area size distribution impurities, additives stoichiometry FORMING % area reduction method of cold work speed of operation lubricant POST PROCESSING tape strain state current transfer length sample damage Ic criterion SINTERING temperature heat/cool rates atmosphere pressure time Fig. 2. Complexity surrounding Jc improvements.
0 Weight change (mg/cm 2 ) -2-4 -6 RBSC (48vol% SiC filler) RBSC (60vol% SiC filler) 360 o C, pure water Corrosion for 7 days -8 RBSC (35vol% SiC filler) Fig. 1-1-1. Weight change of RBSCs after corrosion test in pure water at 360 for 7 days. β-sic (A) RBSC (48 vol% SiC filler) Before corrosion test CPS (a.u.) Si α-sic α-sic β-sic α-sic Si α-sic Si β-sic α-sic β-sic α-sic β-sic 20 30 40 50 60 70 80 2θ (degree) β-sic RBSC (48 vol% SiC filler) Corrosion test, pure water, 400 o C, 7 days (B) CPS (a.u.) Si α-sic α-sic β-sic α-sic α-sic Si β-sic α-sic β-sic α-sic β-sic 20 30 40 50 60 70 80 2θ (degree) Fig. 1-1-2. XRD results of RBSC before (A) and after (B) corrosion test in pure water at 360 for 7 days.
(A) (B) (C) (D) (E) Fig. 1-1-3. Cross-sectional ((A), (C)) and surface ((B), (D)) microstructures of RBSC (48 vol% SiC filler) after corrosion test in pure water at 360 ((A), (B)) and in 35 ppm LiOH solution at 360 ((C), (D)) for 7 days. Surface microstructure of RBSC before corrosion test is also included (E).
Weight loss (mg/cm 2 ) 20 15 10 5 RBSC (35 vol% SiC filler) RBSC (48 vol% SiC filler) RBSC (60 vol% SiC filler) 0 Specimen type Fig. 1-1-4. Weight loss of RBSCs after corrosion test in 35 ppm LiOH solution at 360 for 7 days. 4.0 Weight loss (mg/cm 2 ) 3.5 3.0 2.5 2.0 1.5 1.0 CVD-SiC Sintered-SiC 0.5 0.0 0 2 4 6 8 10 Time (days) Fig. 1-1-5. Weight loss of sintered and CVD SiC after corrosion test at 360 C in pure water.
(A) (B) (C) (D) Fig. 1-1-6. Microstructures of as-received (a) and corroded sintered SiC specimens after corrosion at 360 for 1 (b), 5 (c), and 7 (d) days in pure water. Fig. 1-1-7. Microstructures of as-received (a) and corroded CVD SiC specimens after corrosion at 360 for 3 (b), 7 (c), and 10 (d) days in pure water.
0-2 -4 Weight change(mg/cm 2 ) -6-8 -10-12 -14 8Y 6Y2A 360 o C, pure water Corrosion for 7 days 4Y3A -16-18 (A) 4Y1S 0-5 Weight change(mg/cm 2 ) -10-15 -20-25 -30-35 (B) 8Y 6Y2A 4Y3A 360 o C, water + 70 ppm LiOH Corrosion for 7 days 4Y1S Fig. 1-1-8. Weight change of Si 3 N 4 specimens after corrosion test in pure water (A) and in 70 ppm LiOH solution (B) at 360 for 7 days.
1.0 0.8 pure water LiOH 35ppm Weight loss (mg/mm 2 ) 0.6 0.4 0.2 0.0 0 1 2 3 4 5 Time (day) Fig. 1-1-9. Weight loss as a function of corrosion time at 300 C pure water and LiOH solution. 800 700 pure water LiOH 35ppm Flexural strength(mpa) 600 500 400 300 200 100 304.2 0 0 1 2 3 4 5 Time (day) Fig. 1-1-10. Variation of 4-pt flexural strength as a function of corrosion time at 300 C pure water and LiOH solution.
(a) (b) (c) (d) (e) Fig. 1-1-11. SEM microstructures of Si 3 N 4 ceramics before corrosion test (a) and after corrosion at 300 C for 12 h in pure water ((b), (c)) and LiOH solution ((d), (e)).
specimen Rotating axis Autoclave wall Loading by MG coupler Rotating disk Wear-face 1-2-1. 1-2-2.
Specific wear rate (mm2/n) 1E-5 96% Al2O3 99.7% Al2O3 1E-6 1E-7 1E-8 1E-9 1E-10 20 40 60 80 100 120 140 160 180 200 220 240 Temperature (C) 1-2-3. 0.8 0.6 96% Al2O3 99.7% Al2O3 Friction coefficient 0.4 0.2 0.0 0 20 40 60 80 100 120 140 160 180 200 220 240 Temperature (c) 1-2-4.
(a) (b) (c) 1-2-5. 99.7% SEM ( 50 micro- m) (a) (30oC), (b) 100oC, (c) 200oC (a) (b) (c) 1-2-6. 96 % SEM ( 50microm) (a) (30oC), (b) 100oC, (c) 200oC
(a) (b) (c) 1-2-7. SN300 Si3N4 SEM ( 50 micro-m) (a) (30oC), (b) 100oC, (c) 200oC 1E-4 Specific wear rate (mm2/n) 1E-5 1E-6 1E-7 1E-8 1E-9 Ssanyong SN300 20 40 60 80 100 120 140 160 180 200 220 240 Temperature (C) 1-2-8. Si3N4
1-3-1. 99.7 wt% EDX 2.0 1.8 Si composition (wt%) 1.6 1.4 1.2 1.0 0.8 0.6 0.4 99.7% Al2O3 96% Al2O3 0.2 0.0 0 10 20 30 40 50 Time (h) 1-3-2. 100oC Si
Flexural strength (kgf/mm^2) 33 32 31 30 29 28 27 26 25 24 23 22 AR G B GB Kind of specimens Mean 1-3-3.,, 100 oc, 100 oc
1-3-4. 1-3-5. fluence cell V/Vmacro
1-3-6. (b) (a) 1-3-7 (a) 300 gf loading, (b) 500 gf loading
o o o L i 2 T io 3 F : o n l y g l y c i n e o o o o o o o o o o E : o n ly c itr ic a c id D : U re a < c it. a c id C : U re a = c it. a c id B : U re a > c it. a c id A : o n ly u re a 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 2 T H E T A Fig. 2-1-1. XRD patterns of as-synthesized powders with various fuel type and compositions Fig. 2-1-2. SEM and TEM micrographs of the as-synthesized Li 2 TiO 3 powder with glycine fuel.
10 melting DSC (mw/mg) 0 ENDO EXO -10 0 100 200 300 400 500 600 700 800 900 1000 Temperature ( o C) Fig. 2-1-3. DSC curve of the glycine in air condition with heating rate of 10 o C/min 10 5 EXO DSC (mw/mg) 0-5 285 o C 330 o C -10 208 o C -15 0 100 200 300 400 Temperature ( o C) Fig. 2-1-4. DSC curve of the glycine-fueled LiNO 3 -TiO(NO 3 ) 2 precursor in air condition
20 0 200 400 600 800 1000 10 Weight loss (mg) 15 10 TG DTA 8 6 4 2 0-2 Thermal difference (uv) 5 0 200 400 600 800 1000 Temperature ( o C) -4 Fig. 2-1-5. Differential Thermal Analysis and Thermogravimetric Analysis patterns for the as-synthesized Li 2 TiO 3 powder (with glycine fuel) CPS fuel-rich (200% of stoi.) fuel-stoichiometric o o fuel-lean (50% of stoi.) o oo o 10 20 30 40 50 60 70 2 Theta Fig. 2-1-6. XRD patterns for Li 2 TiO 3 combusted under three glycine/nitrate ratio. (Stoichiometric and rich burn produced crystalline LT only and Fuel-lean produce mainly TiO 2 (open circle: anatase) and LT phase.
L T L T : L i 2 T i O 3 L T (d ) L T L T L T L T L T L T L T (c ) (b ) o x o x : a n a t a s e ( T i O 2 ) : L i 2 C O 3 (a ) x x x x o o o o o o o o 1 0 2 0 3 0 4 0 5 0 6 0 7 0 2 T H E T A Fig. 2-1-7. XRD patterns of the Li 2 TiO 3 powder prepared by solid-state reaction; (a) after oven-drying, (b) after calcination at 550 o C for 3h (c) at 700 o C for 3h, and (d) at 1000 o C for 3h Fig. 2-1-8. Microstructure of the Li 2 TiO 3 compact made by solid state reaction (a) sintered at 700 o C for 3h, and (b) 1000 o C for 3h. And the Li 2 TiO 3 compact synthesized by combustion reaction (c) sintered at 550 o C for 3h, (d) 700 o C and (e) 1000 o C for 3h, respectively.
Fig. 2-1-9. Surface morphology of the Li 2 TiO 3 prepared by combustion reaction (a) after sintered at 550 o C for 3h, and (b) 700 o C for 3h, respectively. 100 90 Relative density (%) 80 70 60 J.M.Miller (4h, AECL) F.A. Pinn (4h, vacuum, ANL) sol-gel (2h, france) KAERI (2h, combustion) KAERI (4h, combustion) KAERI (10h, combustion) KAERI (2h, Aldrich Co.) KAERI (4h, Aldrich Co.) 50 600 800 1000 1200 1400 Sintering Temperature ( o C) Fig. 2-1-10. Effects of powder preparation method and sintering temperature on the relative density of sintered Li 2 TiO 3 compacts.
: Cu : CuO : Cu 2 O RELATIVE INTENSITY C B A 20 30 40 50 60 70 80 2 THETA Fig. 2-1-11. XRD patterns of as-synthesized ODC powders with various fuels ; (A) urea, (B) 1 urea + 1 glycine and (C) 2 urea + 1 glycine. Fig. 2-1-12. TEM micrographs of Al 2 O 3 -CuO powder prepared by the combustion process and EDS result.
A : as -s ynthes ized before re duc tion B : after s elective reduction RELATIVE INTENSITY : Cu : CuO B A Fig. 2-1-13. XRD patterns of Al 2 O 3 dispersed Cu powder ; (A) before reduction and (B) after reduction. 20 30 40 50 60 70 80 2 THETA (A) (B) (C) Fig. 2-1-14. Surface flaws of Al 2 O 3 dispersed Cu alloy extruded at (A) 550 o C, (B) 700 o C and (C) 750 o C
Fig. 2-1-15. Transmission electron micrograph (A) of the extruded Al 2 O 3 -Cu using the combustion synthesized powder, the magnified micrograph (B) of the white Particle, and EDS results ; (C) mark C particle in Fig. (A) and (D) mark D Grain in Fig. (A).
Tensile strength (Kg/mm 2 ) 60 50 40 30 20 10 KAERI (H.E 750 o C, annealing 600 o C/1h) AL-25 (as-hot extruded) AL-15 (as-hot extruded) AL-15 (T.J.Miller, H.E, annealing 600 o C/1h) pure copper 0 0 100 200 300 400 500 600 Temperature ( o C) Fig. 2-1-16. Tensile strength of pure copper and ODS Cu Fig. 2-1-17. Electrical conductivity of pure copper and Al 2 O 3 -dispersed Cu
Fig. 2-1-18.
Fig. 2-1-19. XRD patterns of as-synthesized powders made by ultrasonic mist combustion/pyrolysis process Fig. 2-1-20. Microstructure of the Li 2 TiO 3 powders made by ultrasonic mist combustion/pyrolysis process (A) ultrasonic mist combustion process (with fuel) and (B) ultrasonic mist pyrolysis process (without fuel), respectively.
Fig. 2-1-21. Thermogravimetric analysis patterns of the Li 2 TiO 3 powders made by ultrasonic mist combustion/pyrolysis process Fig. 2-1-22. Fracture morphology of the Li 2 TiO 3 pellets sintered at 1000 o C for 2h (A) ultrasonic mist combustion process (with fuel) and (B) ultrasonic mist pyrolysis process (without fuel), respectively.
3500 3000 2500 Intensity 2000 1500 1000 500 0 950 o C 900 o C 850 o C 800 o C 750 o C 700 o C 20 30 40 50 60 70 80 2 Fig. 2-1-23. XRD patterns of Al 2 O 3 dispersed Cu powder made by ultrasonic mist combustion process with various reduction temperature Fig. 2-1-24. Transmission electron micrograph and EDS results of the Al 2 O 3 - Cu powder after reducing process
Tensile strength (Kg/mm 2 ) 60 50 40 30 20 10 0 KAERI UMCP Al-15 Al-25 pure copper 0 100 200 300 400 500 600 Temperature ( o C) Fig. 2-1-25. Tensile strength of pure copper and ODS Cu 60 Electrical conductivity (Meg S/m) 50 40 30 20 10 KAERI (batch type) AL-15 AL-25 KAERI (UMCP) pure Cu 0 Specimen type Fig. 2-1-26. Electrical conductivity of pure copper and Al 2 O 3 -dispersed Cu
Fig. 2-1-27. XRD patterns of Cu-Ni alloy powders made by ultrasonic mist combustion process Fig. 2-1-28. SEM and TEM micrographs of the Cu-Ni alloy powders made by ultrasonic mist combustion process
(A) Ni (B) 0.1% Cr 2 O 3 -Ni (C) 0.3% Cr 2 O 3 -Ni (D) 0.5% Cr 2 O 3 -Ni (E) 7.0% Cr 2 O 3 -Ni O O O : Ni * : Cr 2 O 3 CPS * * * * * * (E) (D) (C) (B) (A) 20 30 40 50 60 2 THETA Fig. 2-1-29. X-ray diffraction patterns of the synthesized powders by the metal salt reduction process; (A) Ni, (B) 0.1% Cr 2 O 3 -Ni, (C) 0.3% Cr 2 O 3 -Ni, and (D) 0.5% Cr 2 O 3 -Ni powder, respectively. 100 95 Relative Density (%) 90 85 80 75 900 o C for 2h 1000 o C for 2h 70 Ni Ni-0.1Cr2O3 Ni-0.3Cr2O3 Ni-0.5Cr2O3 Fig. 2-1-30. Sintered density of the specimen with sintering temperature.
Fig. 2-1-31. Transmission electron micrograph (A) fo the 0.3% Cr 2 O 3 nickel and EDS results; (B) the nickel grain of (A), and (C) the Cr 2 O 3 dispersed particles of (A).
240 220 900 o C for 2h 1000 o C for 2h 200 180 Hardness (kg/mm 2 ) 160 140 120 100 80 60 40 NI Ni-0.1Cr2O3 Ni-0.3Cr2O3 Ni-0.5Cr2O3 Fig. 2-1-32. Microhardness values of sintered specimen with the Cr 2 O 3 content of Ni. Fig. 2-1-33.
CVD APPARATUS MFC (1) (2) (9) (11) MFC MFC P (5) (3) P (7) (8) (10) P.F (4) (6) SCRUBBER MTS P Ar H2 ICE BATH PUMP (12) EXHAUST Fig. 2-2-1. Schematic diagram of horizontal CVD reactor. -1.00 Ln Deposition Rate(mg/cm 2 /m in) -1.25-1.50-1.75-2.00-2.25-2.50-2.75-3.00-3.25 1.6torr 5torr 10torr 50torr 100torr -3.50 6.4 6.6 6.8 7.0 10 4 /T(K) Fig. 2-2-2. Deposition rate as a function of deposition temperature with various system pressure..
0.8 300 1150 o C Linear velocity(cm/s) 250 200 150 100 50 1200 o C 1250 o C 1300 o C 0.6 0.4 0.2 Residual time(s) 0 0.0 0 20 40 60 80 100 Total system pressure(torr) Fig. 2-2-3. Change of linear velocity and residence time as a function of total system pressure. 1150 o C 1250 o C 1300 o C 10torr 50torr 100torr Fig. 2-2-4. Microstructural change of SiC deposits with deposition temperature and system pressure.
Fig. 2-2-5. Microstructural map of SiC deposits. MTS Stainless steel chamber Graphite insulation Graphite heating elemen Constant temp. bath Substrate (graphite) Graphite isolation tube Furnace pressure control valve Vac. pump Gas scrubber Filter Fig. 2-2-6. Schematic diagram of large area CVD reactor.
Table 2-2-1. Experimental condition for large area CVD. Source : Methyltrichlorosilane (MTS) Diluent & carrier gas : H 2 Deposition temperature : 1200 ~1350 C, 1 h Chamber pressure : 25~50 torr MTS flow rate : 0.5 slm Total flow rate : 3.0 slm H 2 /MTS ratio : 5 Substrate rotation speed : 2~10 rpm Temperature uniformity : < 2 o C 50 Deposition rate (µm/h) 40 30 20 10 0 1200 1250 1300 1350 Deposition temperature ( o C) Fig. 2-2-7. Deposition rate as a function of deposition temperature for a graphite substrate with a diameter of 15 cm.
Deposition rate Kinetic limited Mass transport limited Thermodynamics limited Temp. Fig. 2-2-8. Different reaction regimes in a CVD process. G : graphite Indexed : β-sic (220) 1350 o C CPS (a.u.) (111) (311) 1300 o C G (222) G (111) G 1200 o C G 20 30 40 50 60 70 80 2θ (degree) Fig. 2-2-9. XRD patterns of SiC layer deposited at various temperatures.
Atomic percent (%) 100 90 80 70 60 50 40 30 20 Si C 10 O 0 0 50 100 150 200 Etch time (sec) Fig. 2-2-10. AES result of deposited SiC layer. 1200 C 1300 C 1350 C Fig. 2-2-11. SEM microstructures of deposited SiC.
4 Average grain size (µ m) 3 2 1 (A) horizontal vertical 0 7.5 5.0 2. 5 0 2. 5 5.0 7.5 Distance from center (cm) 10 Average grain size (µ m) 9 8 7 6 5 4 (B) horizontal ve rtica l 3 2 7.5 5.0 2.5 0 2.5 5.0 7.5 Distance from center (cm) Fig. 2-2-12. Grain size distribution of SiC layer deposited at (A) 1300 C and (B) 1350 C.
Deposition thickness (µ m) 40 30 20 10 (A) horizontal vertical 7. 5 5.0 2.5 0 2. 5 5.0 7.5 Distance from center (cm) Deposition thickness (µm) 90 (B) 80 70 60 50 40 30 horizontal vertical 7.5 5.0 2.5 0 2.5 5.0 7.5 Distance from center (cm) Fig. 2-2-13. Thickness distribution of SiC layer deposited at (A) 1300 C and (B) 1350 C.
1.8 1.6 Relative thickness 1.4 1.2 1.0 0.8 0.6 Avg. t = 165 µm 0.4 0.2 7.5 5.0 2.5 0 2.5 5.0 7.5 Distance from center (cm) Fig. 2-2-14. Thickness distribution of SiC layer when the position of gas inlet nozzle is off-axis from the center of the substrate. (a) (b) Fig. 2-2-15. Surface and cross-sectional microstructures of the center region of SiC layer when the position of gas inlet nozzle is off-axis from the center of the substrate.
(a) (b) Fig. 2-2-16. Expected gas flow patterns when the position of gas inlet nozzle is off-axis (A) or on-axis (B) from the center of the graphite substrate. 1.4 1.2 Relative thickness 1.0 0.8 0.6 Avg. t = 76 µm 0.4 0.2 1 2 3 4 5 6 7 Position on substrate Fig. 2-2-17. Thickness distribution of SiC layer when the position of gas inlet nozzle is on-axis from the center of the substrate. Deposited at 1350 for 1 h.
1.4 Relative thickness 1.2 1.0 0.8 0.6 0.4 Avg. t = 25.7 µm 0.2 7.5 5.0 2.5 0 2.5 5.0 7.5 Distance from center (cm) Fig. 2-2-18. Thickness distribution of SiC layer when the position of gas inlet nozzle is on-axis from the center of the substrate. Deposited at 1300 for 1 h. Fig. 2-2-19. Macroscopic view of SiC-deposited graphite with a diameter of 25 cm.
1.4 Relative thickness 1.2 1.0 0.8 0.6 0.4 Avg. t = 93.8 µm 0.2 12.5 10.0 7.5 5.0 2.5 0 2.5 5.0 7.5 10.0 12.5 Distance from center (cm) Fig. 2-2-20. Thickness distribution of SiC layer deposited on 25 cm graphite substrate at 1300 for 4 h. Fig. 2-2-21. Cross-sectional microstructures of rim (A) and center (B) region of SiC layer deposited on 25 cm graphite substrate.
3.0 2.5 MTS:C 2 H 2 = 100:100 SiC Graphite Equilibrium yield (mole) 2.0 1.5 1.0 0.5 0.0 400 600 800 1000 1200 1400 1600 1800 Temperature ( o C) Fig. 2-2-22. Calculated relation between deposition temperature and yield of PyC and SiC. 100 C/(C + SiC) (vol%) 80 60 40 20 0 0.1 1 10 log(c 2 H 2 /CH 3 SiCl 3 ) Fig. 2-2-23. Calculated relation between the input gas ratio and C/(C+SiC) at 1300, 10torr.
SiC C/SiC C/C Fig. 2-2-24. Polished cross-sectional morphology of C/SiC compositionally graded layers (back scattered electron image). 30 Vickers hardness (GPa) 25 20 15 10 5 Theoretical Measured 0 0.1 1 10 log(c 2 H 2 /CH 3 SiCl 3 ) Fig. 2-2-25. Comparison between calculated (line) and measured (symbols) hardness of C/SiC layers.
Carbon β-sic PyC MTS20 MTS50 MTS70 MTS80 MTS100 20 30 40 50 60 70 80 2 θ Fig. 2-2-26. XRD patterns of the C/SiC layers by changing the input gas ratio. 100 C/(C + SiC) (vol%) 80 60 40 20 Theoretical composition Measured composition 0 0.1 1 10 log(c 2 H 2 /CH 3 SiCl 3 ) Fig. 2-2-27. Comparison between calculated (line) and measured (points) composition of C/SiC layers deposited at 1300, 10torr
Fig. 2-2-28. X-ray mapping of Si for C/SiC compositionally graded layers. 1.75 Crack length/unit area(cm/cm 2 ) 1.63 1.50 1.38 1.25 1.13 1.00 non-fgm 2 step FGM 5 step FGM 10 step FGM Fig. 2-2-29. Effect of FGM interlayer on the cracking behavior of SiC-coated C-C composites.
60 50 Hardness (GPa) 40 30 20 Faceted microstructure 10 0 60 0 50 100 150 200 250 300 Displacement (nm) 50 Hardness (GPa) 40 30 20 Round-top microstructure 10 0 0 50 100 150 200 250 300 Displacement (nm) Fig. 2-2-30. Hardness of CVD SiC with different microstructure measured by nanoindentation.
50 40 Hardness (GPa) 30 20 10 d = 70 µm 0 d = 50 µm 0 2 4 6 8 10 12 Indentation load (N) Fig. 2-2-31. Hardness as a function of indentation load in microhardness test of SiC/graphite at coating thickness of 70 µm and 50 µm, respectively. Fig. 2-2-32. Surface views of microhardness contact damage in SiC/graphite structure with coating thickness, d = 50 µm: at indentation load (a) P = 2 N showing radial cracks and (b) P = 3 N showing ring crack.
6.0 Toughness (MPam 1/2 ) 5.5 5.0 4.5 4.0 3.5 3.0 0 10 20 30 40 50 60 70 80 Coating thickness (µm) Fig. 2-2-33. Effects of coating thickness on toughness of SiC/graphite at indentation load of 2 N.
(a) (b) Section Grinding 300 µm Fig. 2-2-34. Micrographs of surface damage in SiC/graphite with different coating thickness; (a) d = 70 µm and (b) d = 50 µm after Hertzian indentation at load P = 50 N with WC ball r = 3.18 mm.
150 Indentation Stress, Po (kg f /mm 2 ) 100 50 E = 4900 kg f /mm 2 E = 694 kg f /mm 2 55 µ m coated 70 µ m coated 110 µm coated 140 µm coated 0 0.00 0.05 0.10 Indenatation Strain, a/r Fig. 2-2-35. Indentation stress-strain curves of SiC coated graphites with coating thicknes. 3500 3000 55 µm coated 70 µm coated 110 µm coated 140 µm coated Hardness (kg f /mm 2 ) 2500 2000 1500 1000 500 0 0 500 1000 1500 2000 Applied Load (g f ) Fig. 2-2-36. Hardness of SiC coated graphite with coating thickness.
Fig. 2-3-1. Schematics of crack propagation and stress-strain behavior in CFCCs. Fig. 2-3-2. Schematic diagram of the ceramic fiber/matrix interface in CFCCs. (a) typical result with uncontrolled interface and (b) that with the ideal interfacial system.
Fig. 2-3-3. Reactant and product gas concentrations as a function of axial position down a cylindrical pore: ( ) concentration under diffusion rate limiting conditions; ( ) concentration under chemical kinetic rate limiting conditions. Fig. 2-3-4. Geometrical features of the straight cylindrical model pore.
Fig. 2-3-5. Calculated thickness profiles of SiC based ceramics in the CH 3 SiCl 3 -H 2 system for various temperature, (b) total pressure, (c) aspect ratios L/ o with constant diameter o, and (d) diameters with constant L/ o.
Fig. 2-3-6. The five classes of CVI techniques.
Fig. 2-3-7. CVD diagram at 1atm (a) SiH4/CH4/H2, (b) SiCl4/CCl4/H2, (c) CH3SiCl3/H2, (d) (CH3)2SiCl2/H2
Fig. 2-3-8. Schematics of the silicon carbide whisker growth mechanisms. (a) vapor-solid growth mechanism, (b) two stage growth mechanism, (c) vapor-liquid-solid growth mechanism.
reactor reactor control console gas control console Fig. 2-3-9. Photograph of FCVI system. Fig. 2-3-10. Schematic diagram of reactor core.
Silicon Carbide fabric 2D Plain Woven Nicalon Interlayer Coating 950 o C, 5 torr, CH 4, for 4 hr Preform Matrix Filling 1000 o C, 100 torr, MTS/H 2, for 5 hr Matrix Filling 950~1100 o C, 100 torr, MTS/H 2, for 24 h XRD, SEM, Density, Bending test Fig. 2-3-11. Flow diagram of SiC/SiC composite fabrication
(a) (b) (c) Fig. 2-3-12. SEM photography of C/SiC composites fabricated with infiltration temperature using H 2 dilute gas ; (a) 1100, (b) 1200, (c) 1300.
(a) (b) (c) Fig. 2-3-13. SEM photography of C/SiC composites fabricated with infiltration temperature using N 2 dilute gas ; (a) 1100, (b) 1200, (c) 1300.
(a) (b) Fig. 2-3-14. SEM photography of C/SiC composites fabricated at 1100 ; (a) H 2 (2hr)-N 2 (6hr) (b) H 2 (2hr)-N 2 (2hr)-H 2 (2hr)-N 2 (2hr).
α=15 α=15 α=15 α=20 α=20 α=20 α=25 α=25 α=25 Fig. 2-3-15. SEM images of SiC f /SiC composites with reaction temperature and input gas ratio.
gas flow inlet outlet µ 6 5 4 3-2hr α = 20 α = 30 α = 40-4hr α = 20 α = 30 α = 40 µ 2 1-2hr α = 20 α = 30 α = 40-4hr α = 20 α = 30 α = 40 2 1 0 1 2 3 4 inlet outlet (a) 0 1 2 3 4 inlet outlet (b) Fig 2-3-16. The comparison of (a) whisker length (b) whisker diameter with variation of input gas ratio at 1100 µ 6 5 4 3-2hr α = 20 α = 25 α = 30 α = 40-4hr α = 15 α = 20 α = 25 µ 2 1-2hr α = 20 α = 25 α = 30 α = 40-4hr α = 15 α = 20 α = 25 2 1 0 1 2 3 4 inlet outlet (a) 0 1 2 3 4 inlet outlet (b) Fig 2-3-17. the comparison of (a) whisker length (b) whisker diameter with variation of input gas ratio at 1150
Fig. 2-3-18. SEM images of SiC / SiC composites which were prepared using hydrogen Dilute gas at 1100, = 20
Fig. 2-3-19. SEM images of SiC / SiC composites which were prepared using hydrogen dilute gas at 1150, = 20
(A) (B) Fig. 2-3-20. SEM images of SiC/SiC composites which were prepared by (A) two-step process and (B) four-step process.
Fig. 2-3-21. Microstructures of SiC f /SiC composites prepared by (a) 5h + 24h matrix filling and (b) 5 h whiskering +24 h matrix filling.
2.5 2.0 Density (g/cm 3 ) 1.5 1.0 0.5 0.0 950 1000 1050 Temp. ( o C) 2.5 2.0 Density (g/cm 3 ) 1.5 1.0 0.5 0.0 50 torr 100 torr Pressure(torr) whisker- filling Fig. 2-3-22. Bulk density of SiC f /SiC composites after the SiC matrix filling as a function of (a) reaction temperature and (b) reaction pressure. Load(kN) 0.15 0.10 Whiskher-filling 1000 O C 950 O C 1000 O C 1050 O C whisker-filling 0.05 1050 O C 950 O C 0.00 0.0 0.5 1.0 1.5 2.0 2.5 Crosshead Displacement(mm) Fig. 2-3-23. Comparison of three-point flexure curves of SiC f /SiC with varied matrix filling process.
250 200 Flexural Strength (MPa) 150 100 50 0 950 1000 Temperature ( o C) 1050 250 Flextural Strength (MPa) 200 150 100 50 0 50 torr 100 torr whisker-filling Fig. 2-3-24. Flexural strength of SiC f /SiC composites after the SiC matrix filling as a function of (a) reaction temperature and (b) reaction pressure. Fig. 2-3-25. Tubular SiC f /SiC composite and supporter for the preparation of it.
Fig.2-3-26. Microstructures of SiCf/SiC composites infiltrated (a) without the whisker growing at 1000 o C for 5 h and with the whisker growing for (b) 2 h, (c) 4 h and (d) 6 h at 1100 o C.
Fig. 2-3-27. Cross section of SiCf/SiC composites infiltrated (a)without the whisker growing at 1000 o C for 5 h and (b)with the whisker growing at 1100 o C for 4 h.
Fig. 2-3-28. Microstructures of SiC f /SiC composites prepared by (a) 5 h + 5 h matrix filling and (b) 6 h whiskering + 5 h matrix filling. (c) and (d) are the cross sections of (a) and (b), respectively.
Fig. 2-3-29. A schematic diagram of the whiskering process.
50 45 Nicalon (as-recieved) 50 45 Nicalon (1800 o C) 40 40 Frequency (number) 35 30 25 20 15 Frequency (number) 35 30 25 20 15 10 10 5 5 0 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Diameter (µm) 0 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Diameter (µ m) 50 45 Nicalon (1900 o C) 40 Frequency (number) 35 30 25 20 15 10 5 0 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Diameter (µm) 50 50 45 Nicalon (2000 o C) 45 Nicalon (2100 o C) 40 40 Frequency (number) 35 30 25 20 15 Frequency (number) 35 30 25 20 15 10 10 5 5 0 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Diameter (µ m) 0 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Diameter (µm)
15 14 13.8 Diameter (µm) 13 12 13.1 12.0 12.0 11.9 11 10 As-recieved 1800 1900 2000 2100 Heating temperature ( o C)
Mixing raw materials (Bi 2 O 3, PbO, SrCO 3, CaCO 3, CuO) Calcination in air Calcination in vacuum 700ºC, 12 h 800ºC, 8 h (X2) 720ºC, 5 h, 3 torr O 2 Degassing 760º~800ºC, 8 h (X2) 3 torr flowing O 2 PIT processing Heat treatment Analysis 840ºC, ~200 h, air Fig. 3-1-1. Experimental procedure.. 2212 2223 Ca 2 PbO 4 CuO AEC (B) (A) 32.5 33.0 33.5 34.0 (C) CPS (a.u.) (B) [0211] (A) 10 20 30 40 50 2θ (degree) Fig. 3-1-2. XRD patterns of the precursor powders calcined in (A) air and reduced oxygen pressure at (B) 760 C and (C) 780 C.
(A) (B) Fig. 3-1-3. SEM micrographs of the precursor powders calcined (a) in air at 800 C and (B) in low oxygen pressure at 760 C 18 16 Critical current density (ka/cm 2 ) 14 12 10 8 6 4 2 0 Air calcine Vacuum calcine 50 100 150 200 Cumulative annealing time (h) Fig. 3-1-4. Critical current densities of the tapes fabricated by the air-calcined and the vacuum-calcined powders. The tapes were sintered at 840 C.
2212 2223 CPS (a.u.) (B) (A) 10 20 30 40 50 2θ (degree) Fig. 3-1-5. XRD patterns of the tapes fabricated by (A) the air-calcined and (B) the vacuum-calcined powders after sintering at 840 C for 50 h. (A) (B) (C) (D) Fig. 3-1-6. Backscattered electron micrographs of the tapes fabricated by the air-calcined ((A), (B)) and the vacuum-calcined ((C), (D)) powders. (A) and (C): sintered at 840 C for 50 h; (B): 200 h; (D): 150 h.
Mixing raw materials 24 h in alcohol Calcination & Grinding 700ºC, 12 h 800ºC, 8 h (X2) Addition of 2223 particles Ball milling Mixing 8 h in alcohol 24 h in alcohol Drying & Degassing 720ºC, 5 h, 3 torr O 2 PIT processing Air-quenching Heat treatment 840ºC, ~200 h, air Analysis Fig. 3-1-7. Experimental procedure. 2212 2223 Ca 2 PbO 4 (C) CPS (a.u.) (B) (A) 10 20 30 40 50 2θ (degree) Fig. 3-1-8. X-ray diffraction patterns of the precursor powders containing (A) 0, (B) 1, and (C) 5 wt% 2223 seed particles.
Critical current density (ka/cm 2 ) 14 12 10 8 6 4 2 no seed 1 wt% seed 3 wt% seed 5 wt% seed 10 wt% seed 0 20 40 60 80 100 Annealing time (hrs.) Fig. 3-1-9. Critical current density of the tapes containing various amounts of 2223 seed particles. The tapes were sintered up to 100 h without intermediate mechanical deformation. 2212 2223 CPS (a.u.) (B) (A) 20 30 40 2θ (degree) Fig. 3-1-10. X-ray diffraction patterns of the tapes containing (A) 0 and (B) 1 wt% 2223 seed particles after sintering at 840 C for 50 h.
16 24 Critical current density (ka/cm 2 ) 14 12 10 8 6 4 2 0 (A) no seed 1 wt% seed 3 wt% seed 5 wt% seed Critical current density (ka/cm 2 ) 20 16 12 8 4 0 (B) 50 100 150 200 Cumulative annealing time (hrs.) 50 100 150 200 Cumulative annealing time (hrs.) Fig. 3-1-11. Critical current density of the tapes containing various amounts of 2223 seed particles. The tapes were sintered three times at 840 C for a total time of 200 h with two intermediate pressing steps. The soaking period in the first sintering step was controlled to (A) 50 h or (B) 35 h. (A) (B) (C) (D) Fig. 3-1-12. Microstructures of the tapes containing (A) no seed, (B) 1, (C) 5, and (D) 10 wt% seed particles after sintering at 840 C for 200 h.
Volume fraction of 2223 phase (%) 100 80 60 40 20 0 no seed 1 wt% seed 5 wt% seed 1 10 100 Annealing time (hrs.) Fig. 3-1-13. Transformed fraction of 2223 phase as a function of annealing time for the tapes containing 0, 1, and 5 wt% seed particles. 1 0 no seed 1 wt% seed 5 wt% seed ln [-ln(1-f)] -1-2 0.86-3 -4 1.26 2.12-5 4 5 6 7 8 9 ln (t) Fig. 3-1-14. Kinetics of 2223 phase formation for the tapes containing 0, 1, and 5 wt% seed particles.
(A) (B) Fig. 3-1-15. Microstructures of (A) the spray dried powder and (B) the calcined powder.. Fig. 3-1-16. TG/DTA curve of the spray dried powder.
14 12 Critical current (A) 10 8 6 4 2 spray dried powder solid-state reacted powder 0 50 100 150 200 Cumulative annealing time (h) Fig. 3-1-17. Critical current of the tapes fabricated by the spray dried powder and solid-state reacted powder. Annealing time: 150h total 14 12 Critical current (A) 10 8 6 4 838 839 840 841 842 843 844 Annealing temperature ( o C) Fig. 3-1-18. Critical current of the 37 multifilamentary tapes sintered at different temeratures.
(A) As-rolled (B) Final tape Fig. 3-1-19. Transverse and longitudinal microstructures of the 37 multifilamentary tapes before and after sintering. 14 12 1 wt% seed 10 Ic (A) 8 6 4 2 0 1 2 3 4 5 6 7 8 9 10 11 12 13 Tape Number Fig. 3-1-20. Summary of critical current of the 25m long 37 multifilamentary tapes.
Fig. 3-1-21. Photographs of the 100m long multifilamentary tapes.
Ic/Ico 1.1 1.0 0.9 0.8 0.7 H : parallel to tape surface 0.6 0.5 0.4 0.3 0.2 H : perpendicular to tape surface 0.00 0.05 0.10 0.15 Back-up field (T) 3-2-1. PIT Bi-2223 (77.3 K) 3-2-2. double pancake
Voltage drop (V) 3-2-3. 0.07 0.06 0.05 total magnet 0.04 0.03 0.02 2nd DPC 0.01 0.00-0.01 mid DPC 0 2 4 6 8 10 12 14 Transport current (A) 3-2-4. 77.3 K ( 160 m )
z- directional field intensity (T) 0.130 0.125 0.120 9A : Fz max = 0.123 (T) 0.115 0.110 0.105 0.100 8A : Fzmax = 0.113 (T) 0.095 0.090 1 2 3 4 5 6 7 location along center axis (cm) 3-2-5. z z
3-3-1.
3-3-2. ( 25 K, 45K, 80K,85k, zero field cooling, 5 mm )
3-3-3.
3-3-4. 3-3-5. 20,000 rpm
3-3-6. ring type (a) (b). 3-3-7 (a) Halbach array, (b) Halbach (2 )
3-3-8. ( ) 11000 10000 9000 8000 RPM 7000 6000 5000 4000 3000-200 0 200 400 600 800 1000 1200 1400 1600 Time (sec) 3-3-9.