Periodic Reporting for period 1 - EREMOZ (Effect of rare-earth doping elements on the mechanical and oxidation resistance performance of silicon carbide coated carbon fibre / zirconium carbide composites for high temperature applications)
Período documentado: 2018-04-18 hasta 2020-04-17
There is an increased demand for high temperature structural materials suitable for use at >1400°C, including heat exchangers, Generation IV nuclear reactor components (e.g. control rod sheath & fuel constituents), fusion energy (first wall materials), the receiver materials of concentrated solar power (CSP) systems, high temperature thermoelectric devices and static components in gas turbines and aero engines. Ultra-high temperature ceramics (UHTCs) exhibit especially high melting temperatures and include the diborides and carbides of zirconium and hafnium (ZrC, TaC, ZrB2, HfB2 & HfC). Unfortunately, UHTCs also suffer from poor fracture toughness, relatively poor oxidation resistance and are very difficult to process since the densification temperature required is also very high. EREMOZ addressed these challenges by using a non-conventional process route along with a combination of continuous fibre reinforcement and rare earth oxide (RE) coating / dopants. Specifically, processing was based on the energy efficient process of chemical vapour infiltration (CVI), slurry impregnation and pyrolysis (SIP) rather than more conventional sintering methods such as hot pressing / spark plasma sintering; the former allows nano sized particle composites to be produced at much lower temperatures. The poor fracture toughness is improved by the introduction of continuous carbon fibres (Cf) or pre SiC / RE coated carbon fibres, which enhance resistance to crack propagation and allows the fibre pull out mechanism. Finally, oxidation & ablation resistance can also be improved by the introduction of second phases, such as those based on silicon and/or rare earths metal oxides (yttria & ceria), which facilitate the formation of oxide scales that inhibit oxygen diffusion.
The Specific Research Objectives (SRO) of EREMOZ were: 1) processing of ultra-high temperature ceramic matrix composites (UHTCMCs), these are typically a continuous fibre reinforced with matrix of ultra-high temperature ceramic (UHTC), 2) detailed microstructural characterisation and 3) evaluation of the thermal properties via oxidation and ablation studies.
The Specific Research Objectives (SRO) of EREMOZ were: 1) processing of ultra-high temperature ceramic matrix composites (UHTCMCs), these are typically a continuous fibre reinforced with matrix of ultra-high temperature ceramic (UHTC), 2) detailed microstructural characterisation and 3) evaluation of the thermal properties via oxidation and ablation studies.
Work performed and the main results achieved from this project are many fold:
i) nano size ZrC particles were obtained using energy assisted (Radio Frequency) RFCVI,
ii) the SIP process enabled us to make ZrC composites with doping of RE metal oxides,
iii) interfacial engineering was designed by isothermal CVI deposition of SiC combined with injection of RE metal oxides and sol-gel coating of RE oxides on carbon fibre preforms.
iv) Enhanced oxidation resistance was observed with the doping of RE oxides in SiC coating as well ZrC composites.
v) Improved ablation resistance was seen with the doping of RE oxides in ZrC based UHTCMCs.
One publication titled “Selection, processing, properties and applications of ultra-high temperature ceramic matrix composites, UHTCMCs – a review”, in International Materials Reviews published and deposited in the UoB open access repository with Green open access.
Five more publications are forthcoming from EREMOZ.
i) nano size ZrC particles were obtained using energy assisted (Radio Frequency) RFCVI,
ii) the SIP process enabled us to make ZrC composites with doping of RE metal oxides,
iii) interfacial engineering was designed by isothermal CVI deposition of SiC combined with injection of RE metal oxides and sol-gel coating of RE oxides on carbon fibre preforms.
iv) Enhanced oxidation resistance was observed with the doping of RE oxides in SiC coating as well ZrC composites.
v) Improved ablation resistance was seen with the doping of RE oxides in ZrC based UHTCMCs.
One publication titled “Selection, processing, properties and applications of ultra-high temperature ceramic matrix composites, UHTCMCs – a review”, in International Materials Reviews published and deposited in the UoB open access repository with Green open access.
Five more publications are forthcoming from EREMOZ.
the Researcher who was involved in EREMOZ achieved the scientific, intellectual and practical competences. Total 4 public outreach programmes were carried out at Think Tank Museum and Staffordshire University for school kids, visitors of the museum and other citizens of UK on advanced ceramics. Research results are helpful to explore further for various structural component applications including heat exchangers, Generation IV nuclear reactor components, fusion energy, concentrated solar power (CSP) systems, high temperature thermoelectric devices and static components in gas turbines and aero engines.