Mechanics of Nano, Micro and Macro Composite Structures 20121

PRESSURELESS SINTERING OF ZrB2

WITH DIFFERENT AMOUNTS OF SiC.

E. Padovano, W. Yang, A. Antonini, S. Biamino and M.

Pavese

Outline

• Processing of multilayer ceramic based on ZrB2/SiC composites:

TAPE CASTING, DEBINDING and PRESSURELESS SINTERING• CHARACTERIZATION:

SEM microanalysisRelative densitiesElastic modulusBending strenght

• Conclusions

Milling (24h)

Processing of multilayer ceramic based on ZrB2/SiC composites:

TAPE CASTING

On a moving Mylar supportBlade gap: 1 mmCasting speed: 100

mm/min

Solvents Powde

rs

Binder

Plas

ticize

r

Milling (48h)

Casting

Processing of multilayer ceramic based on ZrB2/SiC composites:

TAPE CASTING

Drying at room temperature

Stacking (“Glue made of water/ethanol/PVA)

60 mm12 mm

10 layers ≈ 1 mm

Final multilayer structure

Debinding treatment

Both of treatment are in Argon controlled atmosphere

Sintering treatment

350 °C/hours up to 2200 °C

Isotherm at 2200 °C for 30 minutes

200 °C/hours up to a 20 °C

Processing of multilayer ceramic based on ZrB2/SiC composites:

DEBINDING and SINTERING

Processing of multilayer ceramic based on ZrB2/SiC composites:

SAMPLE COMPOSITION

Sample composition

100vol% SiC

90vol% SiC+10vol% ZrB2

80vol% SiC+20vol% ZrB2

60vol% SiC+40vol% ZrB2

40vol% SiC+60vol% ZrB2

20vol% SiC+80vol% ZrB2

10vol% SiC+90vol% ZrB2

100vol% ZrB2

1wt% B + 3wt% Cas sintering aids for SiC

Microstructural analisys of ZrB2/SiC composites:

polished surfaces sintered composites 

40vol% SiC-60vol% ZrB2

60vol% SiC-40vol% ZrB2

100vol% SiC

100vol% ZrB2

20µm 20µm

20µm 20µm

Zr B

Si

MicrostrutturaEDS (Energy Dispersive Spectroscopy)

60vol% SiC-40vol% ZrB2

0 10 20 30 40 50 60 70 80 90 10070

75

80

85

90

95

100Relative density

Relative amount of ZrB2 [%]

Rela

tive d

en

sity

[%

of

theore

tica

l]

Mechanical properties : Relative density

0 10 20 30 40 50 60 70 80 90 100150

200

250

300

350

400

450

500Elastic modulus

Relative amount of ZrB2 [%]

E (

GP

a)

0 20 40 60 80 10070

75

80

85

90

95

100Relative density

Relative amount of ZrB2 [%]

Rela

tive

den

sity

[% o

f the

oreti

cal]

Grindosonic

ASTM

E1876

Mechanical properties : Elastic modulus

Mechanical properties : Bending strenght

0 10 20 30 40 50 60 70 80 90 1000

50

100

150

200

250

300

350

400Bending strenght

Relative amount of ZrB2 [%]

Ben

din

g s

tren

gh

t [M

pa]

Three-point bending tests

Mechanical properties : Microhardness

0 10 20 30 40 50 60 70 80 90 1000

500

1000

1500

2000

2500

3000Microhardness

Relative amount of ZrB2 [%]

HV

Vickers microindentation

CONCLUSIONS

Pure ZrB2 sintered without pressure assistance shows not satisfactory density and consequently not good mechanical properties.

Pressureless sintering let to obtain medium relative density of 90,9%, with an increasing trend with high relative amount of ZrB2.

Young’s modulus shows a similar growing trend (respect the relative density) with increasing ZrB2 content.

Flexural strenght of ZrB2-based seems to be not significantly dependent on different amount of added SiC. Similar considerations can be made for microhardness trend.

Further work

Study the role of different sintering aids in pressureless sintering of ZrB2/SiC multilayer composite.

Oxidation resistance and passivating behaviour in dependence on different relative amount of ZrB2.

The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 262749 (Project SMARTEES)

Acknowledgements

16

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