pressureless sintering of zrb 2 with different amounts of sic
DESCRIPTION
PRESSURELESS SINTERING OF ZrB 2 WITH DIFFERENT AMOUNTS OF SiC. E. Padovano , W. Yang, A. Antonini , S. Biamino and M. Pavese. Outline. Processing of multilayer ceramic based on ZrB 2 /SiC composites: TAPE CASTING, DEBINDING and PRESSURELESS SINTERING. CHARACTERIZATION: - PowerPoint PPT PresentationTRANSCRIPT
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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