Synthesis and consolidation of high entropy ceramics

Title : Synthesis and consolidation of high entropy ceramics

Abstract:

The synthesis and consolidation of High Entropy-Ultra-High Temperature Ceramics (HE-UHTCs) based on transition metal borides is addressed in this work. This emerging class of ceramics is based on the combination, in near equimolar proportions, of at least four constituents to generate single-phase crystalline solid solutions with maximum configurational entropy, i.e. (Hf0.2Ti0.2Ta0.2Nb0.2Mo0.2)B2, (Hf0.2Ti0.2Ta0.2Zr0.2Mo0.2)B2, etc. The studies conducted so far evidenced that HE-UHTCs often exhibit superior oxidation resistance and mechanical properties, with respect to their individual constituents. Therefore, these materials have gained a significant interest for their high-temperature applications in several innovative and traditional industrial fields. Unfortunately, the obtainment of dense single phase HE-UHTCs represents quite a difficult goal. In this work, a two-steps process, consisting in the combination of the SHS technique with Spark Plasma Sintering (SPS), is successfully adopted for the preparation of various HE-UHTCs. In this regard, the use of the SHS method is found to highly promote the obtainment of the single-phase HE ceramic during the subsequent SPS stage. The introduction of different additives on SHS powder prior the SPS step is also considered.

Biography:

Giacomo Cao got his Master Degree in Chemical Engineering at the University of Cagliari in February 1986 and his PhD also in Chemical Engineering at the University of Bologna in 1990. He became Assistant Professor in 1990, Associate Professor in 1992 and Full Professor in 2001. He has been a visiting scholar at the Department of Chemical Engineering, University of Notre Dame, USA, in 1988, 1991 and 1992 and research associate at the same University in 1993. He is co-author of 3 books, 1 edited book, more than 150 papers in refereed journals, 17 papers in refereed conference proceedings, 12 patents, 18 book chapters, 126 papers in conference proceedings. He has been the co-author of 239 presentations at national and international symposia.