Ca3Co4O9 ceramics consolidated by SPS process: Optimisation of mechanical and thermoelectric properties
Résumé
Ca3Co4O9 (349) thermoelectric (TE) oxide ceramics were successfully prepared by Spark Plasma Sintering process. The effects of the uniaxial pressure (30-100 MPa), the dwell temperature (700-900 °C) and the cooling rate were investigated. Microstructure analyses have revealed strong enhancements of the bulk density as the pressure level and the applied temperature during the SPS process are increased. Mechanical properties were investigated by using instrumented nanoindentation and three point bending tests. Hardness, elastic modulus, strength and fracture toughness were shown to improve drastically and depend on the processing parameters. Thermal expansion measurements reveal a noticeable anisotropy induced by unidirectional hot pressing. The mechanical, thermal and thermoelectric properties were correlated to the microstructure and crystallographic texture of the resulting ceramics. © 2010 Elsevier Ltd. All rights reserved.
Mots clés
A. Ceramics
A. Oxides
Bulk density
Cooling rates
Crystallographic textures
D. Mechanical properties
Microstructure analysis
Optimisations
Oxide ceramics
Pressure level
Processing parameters
Spark plasma sintering process
Strong enhancement
Thermal expansion measurements
Thermoelectric properties
Three-point bending test
Uniaxial pressures
Bending tests
Calcium
Ceramic materials
Fracture toughness
Hot pressing
Microstructure
Nanoindentation
Single crystals
Spark plasma sintering
Thermal expansion
Thermal stress
Thermoelectric equipment
Mechanical properties