Flash Sintering of SiC, Boron Carbide and Boron Carbide/SiC composites

Context and impact. Flash sintering of ceramics was first reported by Cologna et al. in 2010. The novel aspect compared with traditional sintering, in which a powder compact is heated in a furnace, is the additional application of an electric field to the sample whilst heating. The main features are that (i) sintering is very rapid compared with conventional sintering (a few seconds cf. several hours - an acceleration of about 3 orders of magnitude) and (ii) sintering takes place at furnace temperatures several hundred Celsius lower than those used in conventional sintering (although the temperature of the specimen itself is closer to conventional sintering temperatures because of Joule heating). The impact of reduced cost through faster turnaround, lower energy consumption (less heating) and cheaper capital equipment (lower furnace temperature) is immediately apparent. The reduction in energy consumption also makes the processing more environmentally friendly and it may also be the case that new geometries and structures, and new microstructures giving improved properties can be manufactured. The chief novelty here is to apply the techniques to non-oxides, which need much higher processing temperatures than the oxides on which most work has been done to date. The above impacts concerning cost and environmental impact are expected to be amplified in such materials.

Aims and Objectives.
1. To extend the range of non-oxide ceramics to which flash sintering can be applied beyond SiC to Boron Carbide and Boron Carbide/SiC composites.
2. Develop new methods of harnessing the flash sintering phenomenon for the production of a wider range of geometries of non-oxide ceramic components by using novel electrode systems.
3. To investigate and understand the fundamental mechanisms involved in flash sintering of non-oxides, including the electrical response and the reasons for the rapid densification observed.
4. To measure the properties of the materials produced and to establish the potential advantages of flash sintering for non-oxide ceramics in terms of improvements in performance and reductions in cost and energy usage.

Novelty of approach. Almost all published research on flash sintering to date has been on oxide ceramics. Published work on SiC has been of a very preliminary nature. There is even less in the literature on Boron Carbide. The primary novelty will therefore be to put flash sintering of these materials on a firmer footing in terms of the processing and sintering methods, mechanistic understanding and characterisation. The current project follows on from a current EPSRC CASE project with Dstl in which basic equipment and methods for the challenging task of flash sintering non-oxides with specimen temperatures of over 2000 Celsius has been set up. Almost all of the information on processing, microstructure and properties of flash sintered non-oxides to come out of the project will be novel.

Alignment to EPSRC's strategies and research areas. The project aligns most closely with the Manufacturing the Future theme of the EPSRC portfolio. However, it also has strong links with the Energy, Living with Environmental Change, and Engineering themes.

Companies and collaborations. There are no formal collaborations within this project . However, related work has been supported by Dstl and Morgan Advanced Ceramics and it is intended to maintain these collaborations informally throughout this project. In addition, dialogue and collaboration concerning possible routes to commercial exploitation of flash sintering have been maintained with the SME Lucideon for a number of years and these will also be continued with a view to technological transfer of the outputs from the present project.