Electrical characterization of ceramics during Cold Sintering Process – ELECSIR

The development of low-temperature densification methods represents a major advance in the shaping of materials that were previously impossible to obtain by other processes. They allow the preparation of multi-materials whose sintering temperatures, stability or chemical nature are not compatible with high temperature sintering. They also allow the preparation of ultra-fine microstructures as well as the densification of materials with very low thermal stability. Densification under low temperature conditions is made possible by the chemical reactivity obtained by bringing together a solid phase and a (minor) liquid phase. Although the mechanisms are globally explained by dissolution-transport-precipitation phenomena, the details of these mechanisms remain poorly understood, limiting their use on all kind of materials.
Recent works have demonstrated the possibility of monitoring the solid/liquid system by electrochemical impedance spectroscopy during sintering. This allows to follow in real time the contribution of the different interfaces in the material (notably the grain boundaries and the solid/liquid interfaces) and has shown that beyond the densification and the microstructure, the quality of the grain boundaries plays a fundamental role on the overall properties.
The objective of this project is to develop this approach on various systems of increasing complexity (model material, ionic conductors with incomplete densification, then ceramic-polymer composites with multiple interfaces) in order to address two interests: i) a fundamental study of the influence of chemical and physical levers on low temperature sintering, and ii) an optimization of the performances of ionic conductor materials by sintering of ceramic-polymer composites through the reduction of the interface resistances during sintering.