Densification of nanostructured functional materials: innovative combinations of low-temperature strategies
Résumé
The development of high-performance materials faces the challenge of implementing low-temperature densification processes which can offer new opportunities in a context of sustainable development. Advanced sintering methods such as Spark Plasma Sintering, Cold Sintering process and Hydrothermal Sintering have contributed significantly to recent breakthroughs. The strategies associated with the search for enhanced diffusion and mobility pathways through defect chemistry and chemical reactivity, will be emphasized. We will underline the central role of initial nanoparticles regarding crystallinity, size, size distribution, surface chemistry, hydroxyls. Illustrations will be given on zirconia and lead-free piezoelectric oxides, for which crystalline structure, nanostructure and properties are intimately linked. The control of this interplay depends on the synthesis route and nanoparticle features. We will show the potential of supercritical fluid method for zirconia towards low-temperature sintering. Combined processes, SPS and screen-printing, towards the co-sintering of metallic- polymer/piezoelectric ceramic multilayers for processing vibration energy harvesters, will be discussed.