Monolithics

Monolithics

Daniel (ICL) Processing and characterisation of ternary carbides and UHTCs for extreme environments; Feb 2013 – Feb 2015: This was a 25 month postdoctoral project covering two related topics. The first involved the development and characterisation of single-phase ternary carbides for accident tolerant (nuclear) fuels, ATFs, and other extreme environment applications, whilst the second focused on rare earth doped borides for improved oxidation behaviour. Partners in the project included Tokyo Institute of Technology, the Japan Aerospace Exploration Agency, the CARAT consortium (led by Westinghouse). Samples were prepared at QMUL using the SPS process. A range of ternary carbides in the Hf Al C system were fabricated and their thermal, mechanical and oxidation behaviour was characterised. Full characterisation of rare earth doped ZrB2/HfB2 has been carried out in collaboration with DSTL with a view to improving the oxidation resistance of the composites.

Zapata-Solvas (ICL) Study of oxidation kinetics, thermal and mechanical properties of ultra-high temperature ceramics; Mar 2015 – Apr 2015: A Fellow of the Spanish National Research Council (CSIC) working at the Materials Science Institute of Seville, he was an Academic Visitor at ICL funded primarily by DSTL/CASC but working within XMat. During his visits he undertook high temperature mechanical property testing and TEM studies on three compositions, viz. HfB2, HfB2 with 20 wt% SiC additions (HS20) and the latter with further additions of lanthanum (HS20La). Whilst the monolithic HfB2 showed the presence of hardening due to the generation of high dislocation densities during deformation, the latter underwent softening at elevated temperatures. Consequently, the creep resistance of HS20 and HS20La was observed to be very low compared to monolithic HfB2, especially at 2000ºC; an undesirable mechanical response for hypersonic flight applications. TEM microstructural characterization showed the formation of new phases; these have been thoroughly characterised and both their origins and effects on the mechanical behaviour determined.

Zou (UoB) Powder synthesis, green forming and densification (flashing sintering and spark plasma sintering) of UHTCs; Oct 2014 – Sep 2016): This is a 2 year project that lies at the interface between the work on UHTCMCs and monolithic ceramics. The focus is on three deliverables, viz. producing finer UHTCs powders than currently available; learning how to green form monolithic UHTCs with complex shapes for the joining research being undertaken by Ramanujam; and, working with Grasso, developing a better understanding of the densification behaviour of UHTCs in a strong electric field. Good progress is being made across all three fronts. Work is also underway on validating a model originally produced by Parthasarathy of AFRL on the oxidation of monolithic ZrB2 components but now being tested using doped powders in the HfB2 system.

Humphry-Baker & Ke Peng (ICL) Irradiation and thermal damage of WC in hard radiation environments; Sep 2014 – Aug 2016): This is a 2 year project with financial leveraging from Tokamak Energy. The project involves Co-free WC cermets provided by Sandvik and ion irradiation by Huddersfield University, the primary aim being to investigate the performance of tungsten carbide composites in hard irradiation environments. To date, new compositions have been fabricated, mechanical data obtained, irradiation by He-ions at up to 500oC undertaken and oxidation resistance has been improved via a highly successful coating method using pack cementation.