Multifunctional High Entropy Carbide and Boride (HECARBO) Ceramic Composites: Compositional Space, Novel Synthesis, and Property Tailoring
Lead Research Organisation:
UNIVERSITY OF EXETER
Department Name: Engineering
Abstract
High Entropy Ceramics (HECs) are a new class of materials consisting of more than five components stablised by their high configurational entropy. They are attracting a great deal of attention from the ceramics research community and industry. They were developed following some inspiration from the field of metallurgy, in which the useful compositional space for the exploration of new alloys was drastically increased upon the discovery of High Entropy Alloys (HEAs). In these materials some combination of multiple elements can produce single phase materials, rather than multiple phases by their increased configurational energy. Among HECs, high entropy transition metal carbides (HETMCs) and borides (HETMBs) are the subject of investigation because of their superior properties such as ultra-high melting point and hardness, excellent corrosion resistance, and relatively low density.
The goal of this project is to develop novel synthesis methods, and understand and optimise the physical properties, of HECs. To do this we will focus on Group IV and V transition metal carbides and borides with respectively simple rock salt and hexagonal structures as model systems. These materials have the potential to lead to new materials with novel properties that could find commercial applications under the most extreme conditions.
In the first part of the work, first principles calculations (DFT) will be used to assist in developing a deep fundamental scientific understanding of HECs, and this will then be used to guide the development of new HEC compositions with unique and industrially-applicable combinations of functional and mechanical properties.
In the second part, a novel "microwave and molten salt co-assisted carbo-/borocarbo-thermal reduction" technique will be developed to make pure 1-D/2-D HETMC/HRTMB phase with a high aspect ratio, pure spherical HETMC/HETMB particles, or a mixture consisting of both forms of particles in various ratios (compositional design guided by the above DFT calculations/modelling). The process will use relatively inexpensive metal oxides, B2O3/B4C, and carbon precursors, processed at much lower temperatures (reduction by 300-600oC) and in shorter times (could be reduced to 20min) compared to using traditional processing routes.
In the third part, in-situ formed powder mixtures or mixtures formed by combining the first two forms of presynthesised powders in appropriate ratios will be sintered using SPS or flash-SPS sintering to prepare self-reinforced HE carbides/borides composites that can be used under the most extreme engineering conditions, for example applications in, armour, aerospace, refractories, cutting tools, hypersonic vehicles, catalysis, and nuclear reactors.
This work, if successful, would not only have significant academic significance, but also great industrial impact, benefiting a number of important communities/sectors.
The goal of this project is to develop novel synthesis methods, and understand and optimise the physical properties, of HECs. To do this we will focus on Group IV and V transition metal carbides and borides with respectively simple rock salt and hexagonal structures as model systems. These materials have the potential to lead to new materials with novel properties that could find commercial applications under the most extreme conditions.
In the first part of the work, first principles calculations (DFT) will be used to assist in developing a deep fundamental scientific understanding of HECs, and this will then be used to guide the development of new HEC compositions with unique and industrially-applicable combinations of functional and mechanical properties.
In the second part, a novel "microwave and molten salt co-assisted carbo-/borocarbo-thermal reduction" technique will be developed to make pure 1-D/2-D HETMC/HRTMB phase with a high aspect ratio, pure spherical HETMC/HETMB particles, or a mixture consisting of both forms of particles in various ratios (compositional design guided by the above DFT calculations/modelling). The process will use relatively inexpensive metal oxides, B2O3/B4C, and carbon precursors, processed at much lower temperatures (reduction by 300-600oC) and in shorter times (could be reduced to 20min) compared to using traditional processing routes.
In the third part, in-situ formed powder mixtures or mixtures formed by combining the first two forms of presynthesised powders in appropriate ratios will be sintered using SPS or flash-SPS sintering to prepare self-reinforced HE carbides/borides composites that can be used under the most extreme engineering conditions, for example applications in, armour, aerospace, refractories, cutting tools, hypersonic vehicles, catalysis, and nuclear reactors.
This work, if successful, would not only have significant academic significance, but also great industrial impact, benefiting a number of important communities/sectors.
People |
ORCID iD |
| Shaowei Zhang (Principal Investigator) |