Mechanics of Nano, Micro and Macro Composite Structures 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: SEM microanalysis Relative densities Elastic modulus Bending strenght Conclusions

Milling (24h) Processing of multilayer ceramic based on ZrB 2 /SiC composites: TAPE CASTING On a moving Mylar support Blade gap: 1 mm Casting speed: 100 mm/min Solvents Powders Binder Plasticizer Milling (48h) Casting

Processing of multilayer ceramic based on ZrB 2 /SiC composites: TAPE CASTING Drying at room temperature Stacking (“Glue made of water/ethanol/PVA) 60 mm 12 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 ZrB 2 /SiC composites: DEBINDING and SINTERING

Processing of multilayer ceramic based on ZrB 2 /SiC composites: SAMPLE COMPOSITION Sample composition  100vol% SiC  90vol% SiC+10vol% ZrB 2  80vol% SiC+20vol% ZrB 2  60vol% SiC+40vol% ZrB 2  40vol% SiC+60vol% ZrB 2  20vol% SiC+80vol% ZrB 2  10vol% SiC+90vol% ZrB 2  100vol% ZrB 2 1wt% B + 3wt% C as sintering aids for SiC

Microstructural analisys of ZrB 2 /SiC composites: polished surfaces sintered composites 40vol% SiC-60vol% ZrB 2 60vol% SiC-40vol% ZrB 2 100vol% SiC 100vol% ZrB 2 20µm

ZrB Si Microstruttura EDS (Energy Dispersive Spectroscopy) 60vol% SiC-40vol% ZrB 2

Mechanical properties : Relative density

Grindosonic ASTM E1876 Mechanical properties : Elastic modulus

Mechanical properties : Bending strenght Three-point bending tests

Mechanical properties : Microhardness Vickers microindentation

CONCLUSIONS  Pure ZrB 2 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 ZrB 2.  Young’s modulus shows a similar growing trend (respect the relative density) with increasing ZrB 2 content.  Flexural strenght of ZrB 2 -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 ZrB 2 /SiC multilayer composite. Oxidation resistance and passivating behaviour in dependence on different relative amount of ZrB 2.

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

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