Lili Nadaraia, Nikoloz Jalabadze, Levan Khundadze, Levan Lortkipanidze and Givi Sharashenidze

Spark Plasma Sintering of Ultra High Temperature ceramics

Georgian Technical University,

Republic Center for Structure Researches (RCSR) nadaraia@gtu.ge

Carbides Compositions

TiC

SiCB4C

TiB2

ZrB2

HfB2

TiB2-TiC, B4C-SiC, Ti3SiC2

Borides

Ultra-High Temperature CeramicsUHTC

Applicationlow density

high hardness

wear resistance

high melting poin thermal stability

as neutron radiation absorbent

Abrasion resistanceUHTC

Armor

NozzlesAbrasives

Nuclear applications

Refractory applications

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…..

Advantages and disadvantages of spark plasma sintering

Advantages 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

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.

Spark plasma between powder particle

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);

SPS Device

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

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, 36- 44.

Self-propagating high-temperature synthesis (SHS), (combustion synthesis CS)

Poly SHS

Borides

2TiB2+4CO

3C

B4C2TiO2

2HfB2+4CO

3C

B4C2HfO2

2ZrB2+4CO

3C

B4C2ZrO2

TiB2

ZrB2

HfB2

Titanium Diboride

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

TiB2

Zirconium Diborides ZrB2

X-Ray and SEM images of Zirconium Diborides

a- ZrB2 powder synthesis at 10000C 1h,

b- sintered via SPS at 16000C ;

C- sintered via SPS at 17000C

SEM images of Zirconium Diborides sintered via SPS at 17000C

Hafnium Diborides

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

HfB2

Carbides

CTi

CSi

C4B

TiC

SiC

B4C

Carbides

TiC SiC

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;

Boron Carbide

a- XRD pattern of B4C powder (SPS 14000C-3 min)

b- SEM image of B4C bulk material (SPS 17000C-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).

B4C

Composition

B4C - SiC

2C

Si 4B

SiC

B

4

C

50%

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.

Composition

Ti3SiC2

2C

Si 3Ti Ti Si C

0,77

0.14

0.12

X –Ray of Ti3SiC2 composition of sintered via SPS at 14500C

Composition

TiB2 - TiC

3C

B4C2TiO2

TiC

TiB2

X –Ray and SEM images of TiB2 - TiC composition of sintered via SPS at 14500C

Vickers hardness 29.5 Gpa

Sample#

Regime

SPS-B4Cpowder

SPS-B4C

SPSHfB2

SPSTiB2

SPS-B4C-SiC

SPS- TiB2- TiC

SPS Ti3SiC2

SPSCurrent (V/A) 9/1370 9.2/2060 10/2700 9/2700 9.5/2300 10/2700 9/2700

Temp. (0C) 1600 1700 1800 1600 1700 1700 1450

Holding Time (min) 5 10 5 5 5 5 6

Pressure MPa 0 20 20 25 20 30 30

Density(% of theoretical)

- 94 85 92 95 98 97

SPS OPERATING MODES WITH RELATIVELY DENSITY

Shapes of materials sintered via SPS

Ballistic Testing

¤  Size of the plate -120x120mm;

¤ Size of the plate fragments

60x60mm; Weight - 50-100g.¤ 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.

Backing material Plastic (Ti-6Al-4V)/textile

Hard Blend (B4C, SiC, B4C-TiB2, B4C-SiC )

Bullet direction

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.http://www.bodyarmornews.com/

Ballistic testing

120mm

NIJ requirements - Max Back face signature (BFS) depth is 44mm

BFS 40mm

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.

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.

ACKNOWLEDGEMENT

Thank you for attention

nadaraia@gtu.ge