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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:
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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 microanalysis • Relative densities • Elastic modulus • Bending strenght • Conclusions
Solvents Powders On a moving Mylar support Blade gap: 1 mm Casting speed: 100 mm/min Processing of multilayer ceramic based on ZrB2/SiC composites:TAPE CASTING Milling (24h) Binder Plasticizer Milling (48h) Casting
Processing of multilayer ceramic based on ZrB2/SiC composites:TAPE CASTING Stacking (“Glue made of water/ethanol/PVA) Drying at room temperature Final multilayer structure 10 layers ≈ 1 mm 12 mm 60 mm
Processing of multilayer ceramic based on ZrB2/SiC composites: DEBINDING and SINTERING Debinding treatment Sintering treatment • 350 °C/hours up to 2200 °C • Isotherm at 2200 °C for 30 minutes • 200 °C/hours up to a 20 °C Both of treatment are in Argon controlled atmosphere
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% C as sintering aids for SiC
Microstructuralanalisys of ZrB2/SiC composites: polished surfaces sintered composites 20µm 20µm 100vol% SiC 60vol% SiC-40vol% ZrB2 20µm 20µm 40vol% SiC-60vol% ZrB2 100vol% ZrB2
Microstruttura EDS (Energy Dispersive Spectroscopy) Si 60vol% SiC-40vol% ZrB2 Zr B
Mechanical properties : Elastic modulus Grindosonic ASTM E1876
Mechanical properties : Bending strenght Three-point bending tests
Mechanical properties : Microhardness Vickers microindentation
CONCLUSIONS • Pure ZrB2 sinteredwithoutpressureassistanceshowsnotsatisfactory density and consequentlynotgoodmechanicalproperties. • Pressurelesssinteringlettoobtain medium relative density of 90,9%, withanincreasing trend with high relative amountof ZrB2. • Young’s modulusshows a similargrowing trend (respect the relative density) withincreasing ZrB2content. • Flexuralstrenghtof ZrB2-based seemstobenotsignificantlydependent on differentamountofaddedSiC. Similarconsiderations can bemadeformicrohardness trend.
Further work • Study the role of different sintering aids in pressureless sintering of ZrB2/SiC multilayer composite. • Oxidationresistance and passivatingbehaviour in dependence on different relative amountof ZrB2.
Acknowledgements 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)