WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7150

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Author: search.filters.author.De Bona, Emanuele

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  • Article
    Citation - WoS: 2
    Citation - Scopus: 1
    Pressureless Synthesis and Consolidation of the Entropy-Stabilized (hf<sub>0.25</Sub>zr<sub>0.25< Composite by Ultra-Fast High-Temperature Sintering (uhs)
    (Elsevier Sci Ltd, 2025) Karacasulu, Levent; De Bona, Emanuele; Karacasulu, Levent; Biesuz, Mattia; Sglavo, Vincenzo M.; Akhtar, Farid; 01.01. Units Affiliated to the Rectorate; 01. Izmir Institute of Technology
    Entropy-stabilized Ultra High-Temperature Ceramics (UHTC) offer a groundbreaking solution to the challenges of extreme environments, showcasing enhanced mechanical properties, thermal stability, and resistance to oxidation at high temperatures. The consolidation of UHTC by ultra-fast high-temperature sintering (UHS) significantly reduces processing times and temperature and can produce dense high-performance ceramics with superior mechanical properties. This study reports the pressureless synthesis and consolidation of the entropy-stabilized (Hf0.25Zr0.25Ti0.25V0.25)B-2-B4C composite through UHS within 1 minute, starting from transition metal diboride powders. B4C acts as an effective sintering aid, promoting the densification of the system and the formation of a nearly single-phase hexagonal diboride with a diboride-eutectic phase. Furthermore, a secondary minor hexagonal phase rich in V and Zr is formed close to the eutectic regions. Sintering currents of 40 A were necessary to reach densities higher than 90 % under pressureless conditions, achieving nano hardness higher than 27.3 GPa, comparable with high-entropy diborides produced by Spark Plasma Sintering. The study highlights the entropy-stabilized phase formation, diffusion, densification, and grain growth mechanisms involved during UHS. The work contributes to the understanding of entropy-stabilized ceramics produced by UHS as a faster and less energy-consuming process than conventional sintering methods.
  • Article
    Citation - WoS: 5
    Citation - Scopus: 5
    Ultrafast High-Temperature Sintering of Yttria-Stabilized Zirconia in Reactive N<sub>2</Sub> Atmosphere
    (Elsevier Sci Ltd, 2025) Karacasulu, Levent; Ahmetoğlu, Çekdar Vakıf; De Bona, Emanuele; Cassetta, Michele; Vakifahmetoglu, Cekdar; Sglavo, Vincenzo M.; Biesuz, Mattia; 03.09. Department of Materials Science and Engineering; 01.01. Units Affiliated to the Rectorate; 01. Izmir Institute of Technology; 03. Faculty of Engineering
    So far, ultrafast high-temperature sintering (UHS) has always been carried out in an inert environment. In the present work, we investigated UHS of 3YSZ in nitrogen and argon atmosphere showing that "the atmosphere matters". Highly densified samples can be obtained in both environments but densification and grain growth are significantly retarded in N-2. Moreover, the phase evolution is strongly atmosphere-dependent with the samples treated in Ar remaining tetragonal and those treated under N-2 progressively reducing their tetragonality, eventually converting into cubic zirconia and rock salt oxynitride. The results can be explained by the incorporation of nitrogen within the ZrO2 lattice. Electrochemical impedance spectroscopy demonstrates that while the ionic bulk conductivity are marginally influenced by the sintering atmosphere, the grain boundaries' capacitive behavior strongly changes. After UHS under 30 A, excellent ionic conductors were obtained without substantial grain boundary-blocking effects.