1. Spark Plasma Sintering of Ultra High Temperature ceramics
Lili Nadaraia, Nikoloz Jalabadze,
Levan Khundadze, Levan Lortkipanidze and Givi Sharashenidze
Georgian Technical University,
Republic Center for Structure Researches (RCSR)

2. Ultra-High Temperature Ceramics
UHTC
Carbides
Compositions
TiC
SiC
B4C
TiB2
ZrB2
HfB2
TiB2-TiC, B4C-SiC, Ti3SiC2
Borides

3. Refractory applications
Armor
low density
high hardness
 wear resistance
 high melting poin
 thermal stability
as neutron radiation absorbent
 Abrasion resistance
Nozzles
Abrasives
UHTC
Nuclear applications
Refractory applications

4. Manufacturing methods of UHTC
Methods producing the Powder
reaction of elemental boron and carbon powder between reagents
carbothermal synthesis,
carbothermal vapor–liquid–solid growth mechanism
self-propagating high-temperature synthesis (SHS) = Combustion Synthesis (CS),
arc melt process,
etc…
Methods producing the
Dense bodies
hot press,
hot isostatic pressing (HIP),
Cold compaction and high temp. sintering
pressureless sintering,
self-propagating high-temperature synthesis (SHS) under the pressure,
Spark Plasma Sintering,
etc…..

5. Advantages and disadvantages of spark plasma sintering
Fast sintering process;
Uniform sintering;
Low grain growth (nano-grain materials may be prepared);
Compaction and sintering stages are combined in one operation;
Binders are not necessary;
Better purification and activation of the powder particles surfaces;
Different materials (Metals, Ceramics, composites) may be processed;
High energy efficiency;
Easy operation.
Disadvantages of spark plasma sintering:
Only simple symmetrical shapes may be prepared;
Expensive pulsed DC generator is required.
Expensive SPS device

6. Spark plasma between powder particle
Fig.1. Scheme of the SPS the process of sintering – PDC - pulsed DC, GD - graphite die, S – powder sample, P – pressure loading, EC- electric current, s – spark, sp – spark plasma and p- powder particles.
SPS mechanism by SPS SYNTEX INC Company;
(a) I- Flow direction of electrons during DC current,
(b) I- Flow directions of electrons during AC current.

7. DC current shapes
Pulse DC current Shape in the developed device: a- at the frequency of 400 Hz, b- during different frequencies (T), different duration pulses (t) and different duration pauses (T-t);
Current Shapes to be used after retrofitting the SPS device: during different frequencies (T), different duration pulses (t) and different duration pauses (T-t);

8. SPS Device
Press molds for synthesize nanopowder (a) and sintering dense bodies (b) of composite materials 1-upper plug, 2-lower plug, 3-Matrix.

9. Self-propagating high-temperature synthesis (SHS), (combustion synthesis CS)
Poly SHS
Sintering process a: Self-Propagating High-Temperature Synthesis (SHS), b: SPS accompanied with poly SHS.
A. G. Merzhanov. 2006, Advances in Science and Technology, 45,

10. Borides 2HfB2+4CO 2TiB2+4CO 2ZrB2+4CO HfB2 TiB2 ZrB2 2TiO2 B4C 2ZrO2
2HfO2
2TiB2+4CO 3C
B4C
2TiO2
2ZrB2+4CO 3C
B4C
2ZrO2
HfB2
TiB2
ZrB2

11. Titanium Diboride TiB2 X-Ray and SEM images of Titanium Diborides
a- TiB2 powder synthesis at 10000C 1h,
b- sintered via SPS at 16000C ;
C- SEM image of sintered via SPS at 16000C

12. Zirconium Diborides ZrB2 X-Ray and SEM images of Zirconium Diborides
a- ZrB2 powder synthesis at C 1h,
b- sintered via SPS at C ;
C- sintered via SPS at C
SEM images of Zirconium Diborides sintered via SPS at 17000C

13. Hafnium Diborides
HfB2
X-Ray and SEM images of Hafnium Diborides sintered via SPS at 18000C ;

14. Carbides C Si C 4B C Ti
SiC
B4C
TiC

15. Carbides
SiC
TiC
X-Ray images of Titanium Carbide sintered via SPS at 14000C -3 min;
X-Ray images of Silicium Carbide sintered via SPS at 18000C -1 min;

16. Boron Carbide B4C a- XRD pattern of B4C powder (SPS 14000C-3 min)
b- SEM image of B4C bulk material (SPS C-10min)
A-XRD patterns of B4C powder materials obtained by standard (a), SPS methods (b) ;
B- SEM image of nanopowder B4C obtained by SPS method (14000C-3min).

17. Composition 4B Si 2C SiC B4C 50% SPS sintered B4C – SiC (17000C-5min):
a-X-ray diffraction pattern; c- SEM image B4C – SiC Sintered via SPS
b- SEM image of B4C – SiC powder produce via SPS.

18. Composition 3Ti Si 2C Ti3SiC2 Ti Si C 0,77 0.14 0.12
X –Ray of Ti3SiC2 composition of sintered via SPS at C

19. Composition Vickers hardness 29.5 Gpa TiB2 - TiC TiB2 TiC
B4C
2TiO2
TiB2
TiC
Vickers hardness Gpa
X –Ray and SEM images of TiB2 - TiC composition of sintered via SPS at C

20. SPS OPERATING MODES WITH RELATIVELY DENSITY
Sample#
Regime
SPS-B4C
powder
SPS-
B4C
SPS
HfB2
TiB2
B4C-SiC
TiB2- TiC
SPS Ti3SiC2
SPSCurrent
(V/A)
9/1370
9.2/2060
10/2700
9/2700
9.5/2300
Temp. (0C)
1600
1700
1800
1450
Holding Time (min) 5 10 6
Pressure MPa 20 25 30
Density
(% of theoretical) - 94 85 92 95 98 97
Shapes of materials
sintered via SPS

21. Plastic (Ti-6Al-4V)/textile
Ballistic Testing
Test is conducting according Standards of National Institute of Justice (NIJ) (type-IV)
Additional energy is absorbed by each successive layer of material in the ballistic panel.
 Size of the plate -120x120mm;
Size of the plate fragments
60x60mm; Weight g.
The plate presented a package armored with ballistic textile (Kevlar, tvarin, denima); Weight of the package was 0,6 – 0,8 kg;
Fire tests were provided by shooting from the Mosin’s Rifle;
Bullets - armor-piercing
Bullet Mass – 10.8±0,1;
Bullet speed - 869±10 m/sec.
Standard shooting method, distance - 10m towards a plasticine target.
Bullet direction
Backing material
Plastic (Ti-6Al-4V)/textile
Hard Blend
(B4C, SiC, B4C-TiB2, B4C-SiC )

22. Ballistic testing 120mm BFS  40mm
NIJ requirements - Max Back face signature (BFS) depth is 44mm

23. Conclusion
There was developed new technology for manufacturing of nanocrystalline composite materials.
Poly SHS process were detect during SPS and were use for UHTC materials fabrication
Diborides of transaction metals Ti, Zr, Hf, were produced
Nanocrystalline Powders of carbides of metals Ti, Si, and B were obtain after Poly SHS process
Effective composition materials TiB2 - TiC, Ti3SiC2, B4C - SiC were developed.
Ballistic testing gives promising results and further effort will be directed to improve the characteristics.
Modernization of SPS device is undergoing process (replacing of pulse DC current unit with pulse AC current unit).
Further work will be directed to detect impacte of DC current at the sintering process and at the materials properties.

24. Acknowledgement
The part of research described in this presentation was made possible in scope of projects funded by Shota Rustaveli National Science Foundation. Project # 12/34 Presidential Grants for Young Scientists.

25. Thank you for attention