2026-05-06T09:59:44Zhttps://riubu.ubu.es/oai/request

oai:riubu.ubu.es:10259/58182024-07-25T07:32:20Zcom_10259_9476com_10259.4_106com_10259_2604col_10259_9477

Barbarossa, Simone 9a4e3d00-5a66-4910-9ef7-2eb7a0cd72a7 500 Orrù, Roberto 46c89b08-835f-4508-9ae7-eda669401b81 500 Garroni, Sebastiano 227 500 0000-0001-7686-6589 Licheri, Roberta 2ce2400e-56e5-42b5-8aa6-a5a609a869c8 500 Cao, Giacomo abae738d-e475-41ca-93b0-a096ee03427a 500 2021-06-28T11:37:21Z 2021-06-28T11:37:21Z 2021-03 0272-8842 http://hdl.handle.net/10259/5818 10.1016/j.ceramint.2020.10.200 The introduction of 0.5–1.0 wt.% graphite to the powders prepared by Self-propagating High-temperature Synthesis (SHS) is found to be highly beneficial for the removal of oxide impurities (from 2.7-8.8 wt.% to 0.2–0.5 wt.%) during spark plasma sintering (1950°C/20 min, 20 MPa) of (Hf0.2Mo0.2Ta0.2Nb0.2Ti0.2)B2 and (Hf0.2Mo0.2Ta0.2Zr0.2Ti0.2)B2 ceramics. Concurrently, the consolidation level achieved is enhanced from about 92.5% and 88%, respectively, to values exceeding 97%. While a further increase of graphite slightly improves samples densification, final products become progressively richer of the unreacted carbon. It is assumed that graphite plays a double role during SPS, e.g. not only as a reactant during the carbothermal reduction of oxides contaminant, but also as lubricating agent for the powder particles. The latter phenomenon is likely the main responsible for the densification improvement when 3 wt.% or larger amounts of additive are used. Another positive effect is the crystallite size refinement of the high-entropy phases with the progressive abatement of oxides, to confirm that their presence promotes grain coarsening during the sintering process. ARCHIMEDES project sponsored by Regione Autonoma della Sardegna (Italy) - Fondo di Sviluppo e Coesione (FSC) 2014–2020 (Cod. RAS: RASSR88309, Cod. CUP: F76C18000980002). One of the authors (S.B.) performed his activity in the framework of the International PhD in Innovation Sciences and Technologies at the University of Cagliari, Italy. One of us (G.C.) acknowledges the results obtained in this manuscript as quite important for the “Ithermal” and “Generazione E” projects, sponsored by Sardegna Ricerche, Italy (Cod. CUP: F21I18000130006) and by the Italian Ministry of Education, University and Research, Italy (Cod. CUP: B96G18000560005) application/pdf eng Elsevier Ceramics International. 2021, V. 47, n. 5, p. 6220-6231 https://doi.org/10.1016/j.ceramint.2020.10.200 Attribution-NonCommercial-NoDerivatives 4.0 Internacional http://creativecommons.org/licenses/by-nc-nd/4.0/ info:eu-repo/semantics/openAccess High-entropy metal borides Oxide impurities Spark plasma sintering Self-propagating high-temperature synthesis X-ray diffraction Materiales Materials Ultra high temperature high-entropy borides: effect of graphite addition on oxides removal and densification behaviour info:eu-repo/semantics/article info:eu-repo/semantics/acceptedVersion Ceramics International 47 5 6220 6231 THUMBNAIL Barbarossa-ci_2021.pdf.jpg Barbarossa-ci_2021.pdf.jpg IM Thumbnail image/jpeg 4328 https://riubu.ubu.es/bitstream/10259/5818/4/Barbarossa-ci_2021.pdf.jpg 46c18f9e7b9594706a752c656beaa19f MD5 4 LICENSE license.txt license.txt text/plain; charset=utf-8 998 https://riubu.ubu.es/bitstream/10259/5818/3/license.txt aa90105e1c90a1b4fe810649aa967b7d MD5 3 CC-LICENSE license_rdf license_rdf application/rdf+xml; charset=utf-8 805 https://riubu.ubu.es/bitstream/10259/5818/2/license_rdf 4460e5956bc1d1639be9ae6146a50347 MD5 2 ORIGINAL Barbarossa-ci_2021.pdf Barbarossa-ci_2021.pdf application/pdf 2024887 https://riubu.ubu.es/bitstream/10259/5818/1/Barbarossa-ci_2021.pdf 9fcf3aabe02f09b6e6edacbd127d3552 MD5 1 10259/5818 oai:riubu.ubu.es:10259/5818 2024-07-25 09:32:20.91 Repositorio Institucional de la Universidad de Burgos bubrep@ubu.es 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