Open Ceramics最新文献

{"title":"Mechanical properties of reactive sintered high-entropy boride/carbide composite","authors":"Ines Sara Moussaoui ,&nbsp;Annamária Naughton-Duszová ,&nbsp;Monika Hrubovčáková ,&nbsp;Tamás Csanádi ,&nbsp;Marek Vojtko ,&nbsp;Mark Windisch ,&nbsp;Ondrej Petruš ,&nbsp;Péter Pinke ,&nbsp;Ján Dusza","doi":"10.1016/j.oceram.2025.100879","DOIUrl":"10.1016/j.oceram.2025.100879","url":null,"abstract":"<div><div>High-entropy equimolar (Ti-Zr-Nb-Ta-Hf)B₂ - (Ti-Zr-Nb-Ta-Hf)C dual–phase boride/carbide composite was prepared via a two-step spark plasma sintering (SPS). The aim of this research is to quantify the nano, micro, and macro-scale hardness and the indentation fracture resistance of this dual-phase composite, and to relate these properties to its microstructure and observed crack-toughening mechanisms. The composite exhibits a high relative density (∼99 %) and a homogeneous microstructure, with average grain sizes of the boride and carbide phases measuring 4.4 μm and 4.1 μm, respectively, with a negligible oxide content (HfO₂/ZrO₂ &lt; 1 wt%). The nanohardness and indentation modulus of the boride and carbide grains are 41.4 GPa and 628 GPa, as well as 39.3 GPa and 577 GPa, respectively. The nanohardness and indentation modulus at the boride/carbide grains/phase boundary are 35.7 GPa and 592 GPa, respectively. The hardness, HV1, and the indentation fracture resistance of the composite are 22.4 GPa and 4.9 MPa·m^1/2, respectively. Toughening mechanisms in the form of crack deflection, crack branching and crack bridging, are often found at the grain boundaries and during the transgranular fracture of larger boride and carbide grains, probably connected with the high-entropy effects.</div></div>","PeriodicalId":34140,"journal":{"name":"Open Ceramics","volume":"25 ","pages":"Article 100879"},"PeriodicalIF":2.8,"publicationDate":"2025-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145616791","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reactive Ultra-fast High-temperature Sintering (UHS) of alumina from boehmite","authors":"Pedro Rivero-Antúnez ,&nbsp;Zonghao Guo ,&nbsp;Richard Todd ,&nbsp;Víctor Morales-Flórez","doi":"10.1016/j.oceram.2025.100878","DOIUrl":"10.1016/j.oceram.2025.100878","url":null,"abstract":"<div><div>This work explores the consolidation of alumina via an innovative procedure: the reactive Ultra-fast High-temperature Sintering (r-UHS) from boehmite precursors. The method exploits Joule heating to achieve rapid densification without applied pressure and using extremely low-cost equipment. Crystallographic analysis reveals the phase evolution from <span><math><mi>γ</mi></math></span>-AlOOH to <span><math><mi>γ</mi></math></span>-Al<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span> at 730 <span><math><mo>°</mo></math></span>C, and to fully crystallized <span><math><mi>α</mi></math></span>-Al<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span> above 1300 <span><math><mo>°</mo></math></span>C after 30 s. Densification up to 93% relative density was achieved in just 60 s at 1800 <span><math><mo>°</mo></math></span>C, with longer dwell times showing negligible improvement. The formation of a fully sintered surface shell hinders densification, suggesting that higher densities may be achievable with optimized heating schedules. The resulting samples show competitive hardness and structural homogeneity. Unlike flash sintering, r-UHS does not require stringent electrical contact, offering a scalable and robust route for fast advanced ceramic fabrication. Its simplicity, speed, low energy demand, and minimal equipment cost highlight its viability for alumina manufacturing.</div></div>","PeriodicalId":34140,"journal":{"name":"Open Ceramics","volume":"24 ","pages":"Article 100878"},"PeriodicalIF":2.8,"publicationDate":"2025-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145519779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of Ni-Cu substitution and uneven element content on electrical properties of high entropy oxides","authors":"Daria Pankratova ,&nbsp;Khabib Yusupov ,&nbsp;Wenjuan Zhao ,&nbsp;Silvia Mauri ,&nbsp;Paolo Moras ,&nbsp;Alberto Vomiero","doi":"10.1016/j.oceram.2025.100874","DOIUrl":"10.1016/j.oceram.2025.100874","url":null,"abstract":"<div><div>High entropy oxides (HEOs) are of great interest for heat conversion due to their promising electrical and thermal properties. In this research, we aim to obtain single-phase HEO with the chemical composition Co-Cr-Fe-Mn-Ni-O, with the unequal at. % of metals, via Solid-State Reaction (SSR), and substitute Ni with Cu. The samples were sintered at 1000 °C for 20 – 35 h. For the samples with Ni, two main phases were formed: rock salt-structured Fm-3m and spinel-structured Fd-3m. As for the material with Cu, single-phase material was formed with the spinel-crystal structure Fd-3m. Obtained samples exhibit high values of the Seebeck coefficient (330 μV/K at 573 K for the sample with Ni that was synthesized for 35 h and 120 μV/K at 573 K for the sample with Cu) and electrical conductivity (4.58 S/cm at 1073 K for the single-phased sample with Cu). These results indicate that these materials can be used as highly efficient semiconductor high-entropy alloys. Further optimization of the SSR is needed to produce a single-phase material with Ni.</div></div>","PeriodicalId":34140,"journal":{"name":"Open Ceramics","volume":"24 ","pages":"Article 100874"},"PeriodicalIF":2.8,"publicationDate":"2025-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145568707","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Advanced shaping of diverse ceramic materials via dental CNC technology: A sustainable strategy for high-precision machining of green and brown bodies","authors":"Dagmara Uhl ,&nbsp;Tamanna Thakur ,&nbsp;Oskar Waldemar Ausobsky ,&nbsp;Natalia Kovalska ,&nbsp;Luc Conti ,&nbsp;Mahmoud Hadad ,&nbsp;Dariusz Kata ,&nbsp;Gurdial Blugan","doi":"10.1016/j.oceram.2025.100877","DOIUrl":"10.1016/j.oceram.2025.100877","url":null,"abstract":"<div><div>This study presents a comprehensive investigation into the development of machinable brown ceramic bodies with compact five-axis CNC machining systems. Green body disc formation, pre-sintering protocols, and machining parameters were systematically refined to achieve enhanced dimensional precision and surface quality. The coordinated design improvement of powder dosing, packing density, pressing pressure, and pre-sintering temperature produced ceramic blanks with mechanical properties well-suited for stable and accurate machining. By lowering pre-sintering temperatures, the brittleness of brown bodies was reduced, enabling smoother cutting, minimized tool wear, and improved structures. Using this approach, complex geometries with sub-millimeter wall thicknesses (300–350 μm) were successfully machined with high accuracy. Sintered TZ-3YSB-E and ZTA ceramics demonstrated flexural strengths of 837 MPa and 483 MPa, respectively, alongside excellent thermal conductivity and machinability. The findings support the development of robust, efficient machining strategies for next-generation ceramic components with complex geometries.</div></div>","PeriodicalId":34140,"journal":{"name":"Open Ceramics","volume":"24 ","pages":"Article 100877"},"PeriodicalIF":2.8,"publicationDate":"2025-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145466628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Properties of alumina 10 vol% zirconia composites — The role of alumina starting powders","authors":"Simon Keller,&nbsp;Bettina Osswald,&nbsp;Frank Kern","doi":"10.1016/j.oceram.2025.100875","DOIUrl":"10.1016/j.oceram.2025.100875","url":null,"abstract":"<div><div>Due to their high strength, hardness and abrasion resistance alumina zirconia composites (ZTA) are well established materials for mechanical engineering and biomedical applications. While the basic material concept is simple, the effects of changes in raw materials are insufficiently investigated. In this study five different submicron alumina powders are combined with 10 vol% of an unstabilized zirconia powder. Samples are consolidated by hot pressing at 1475–1600°C and investigated with respect to microstructure, mechanical properties and phase composition. Adaptation of sintering parameter allows to manufacture ZTA of acceptable quality from all starting powders. Alumina powders of higher purity help to retain a well dispersed and stable microstructure at higher sintering temperatures while in ZTA from alumina powders of lower purity segregation and grain growth is observed at high sintering temperature.</div></div>","PeriodicalId":34140,"journal":{"name":"Open Ceramics","volume":"24 ","pages":"Article 100875"},"PeriodicalIF":2.8,"publicationDate":"2025-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145466629","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bayesian experimental design for the synthesis of doped-ye'elimite","authors":"Yassine El Khessaimi ,&nbsp;Maria Zapata ,&nbsp;Youssef El Hafiane ,&nbsp;Koichiro Fukuda ,&nbsp;Agnès Smith","doi":"10.1016/j.oceram.2025.100876","DOIUrl":"10.1016/j.oceram.2025.100876","url":null,"abstract":"<div><div>This study focuses on ye'elimite, a versatile mineral compound of low carbon sulfo-aluminate cements. While stoichiometric ye'elimite typically exhibits orthorhombic symmetry, the introduction of foreign ions, especially iron, stabilizes a pseudocubic symmetry. This research advances the field by synthesizing highly pure cubic ye'elimite doped with iron and sodium, a unique combination not extensively explored. The study integrates Bayesian optimization to systematically enhance the purity of doped ye'elimite. The results demonstrate an impressive 83 wt.% phase purity achieved with optimal fractions of Ca_3.6Na_0.4Al_5.65Fe_0.35SO₁₆ after only 16 experimental iterations, highlighting the effectiveness of Bayesian optimization in streamlining the synthesis process of highly pure materials with reduced experiments.</div></div>","PeriodicalId":34140,"journal":{"name":"Open Ceramics","volume":"24 ","pages":"Article 100876"},"PeriodicalIF":2.8,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145519780","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Crystallographic, morphological, magnetic and optical properties of nano cobalt ferrite synthesized by hydrothermal method over different synthesis temperature","authors":"Afia Yasmin ,&nbsp;Bristy Biswas ,&nbsp;Md. Lutfor Rahman ,&nbsp;Juliya Khanam ,&nbsp;Rabeya jahan Rakhi ,&nbsp;Mahmuda Hakim ,&nbsp;Md. Sahadat Hossain ,&nbsp;Firoz Ahmed ,&nbsp;Israt Jahan Lithi ,&nbsp;Nahid Sharmin ,&nbsp;Md. Farid Ahmed","doi":"10.1016/j.oceram.2025.100873","DOIUrl":"10.1016/j.oceram.2025.100873","url":null,"abstract":"<div><div>CoFe₂O₄ was synthesized at 150 °C, 180 °C, and 210 °C temperatures using hydrothermal method to find the effect on its structural, magnetic, electric, and optical properties. The saturation magnetization, coercivity and magnetic anisotropy was found using Vibrating Sample Magnetometer (VSM), ranging from 50.36 to 53.66 emu/g. XRD (X-ray Diffraction Analysis) and SEM (Scanning Electron Microscopy), FTIR (Fourier Transform Infrared Spectroscopy) was used for structural analysis verifying the spinel ferrite structure with a single phase. The crystalline size and lattice strain was found using Size-Strain Plot (SSP) and Debye-Scherrer (D-S) method which proved that as the synthesis temperature increased, the crystallite size also increased. The crystalline size ranges from 39.40 to 82.24 nm as observed by XRD. SEM analysis found the crystal size range to be from 9 to 12 nm. It was found that the optimum temperature to synthesize cobalt ferrite nanoparticles are at 180 °C for sample H2 with a crystal size of 82.24 nm and band gap energy of 2.60 eV. The M_s value was determined to be 50.36 emu/g for H2 sample with R_s value of 0.31.</div></div>","PeriodicalId":34140,"journal":{"name":"Open Ceramics","volume":"24 ","pages":"Article 100873"},"PeriodicalIF":2.8,"publicationDate":"2025-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145466630","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Determination of the efficiency of using multilayer CrN/MoN ceramic coatings for protection against hydrogen absorption and exposure to aggressive environments","authors":"Ye.A. Kenzhin ,&nbsp;D.I. Shlimas ,&nbsp;A.M. Zikirina ,&nbsp;A.L. Kozlovskiy","doi":"10.1016/j.oceram.2025.100872","DOIUrl":"10.1016/j.oceram.2025.100872","url":null,"abstract":"<div><div>The main objective of this study is to determine the prospects for using multilayer CrN/MoN ceramic coatings as protective sacrificial coatings providing increased resistance of steels to the complex destructive effects of hydrogen and aggressive environments due to the synergistic effect of alternating nitride layers and the formation of a dense, defect-resistant structure with highly effective diffusion barriers that restrain the diffusion of atomic hydrogen deep into the materials. The influence of hydrogenation processes on the wear and corrosion of the coating surface was determined using the scanning electron microscopy method, which was used to visualize surface defects formed as a result of external influences. Based on the data obtained, an analysis of the resistance of the coatings to degradation was conducted, and the role of the coatings in restraining destruction to wear and corrosion processes was determined. Moreover, it was found that increasing the number of layers from 4 to 20 inhibits degradation of strength properties by more than 2.2 times. Such changes in coating hardness and wear resistance are due to the barrier effect associated with the increased number of layers in the coating, which inhibits hydrogen diffusion into the coating. Tests of the resistance of samples after hydrogenation to an aggressive environment showed that the decrease in resistance to aggressive environments for coatings subjected to hydrogenation is most pronounced for samples subjected to hydrogenation for 100 h. In this case, the reduction in wear resistance (friction coefficient) is more than 1.5 to 2 times for coating samples subjected to hydrogenation compared to the original samples. According to an assessment of changes in the adhesive strength of coating samples after exposure to an aggressive environment, it was found that in the case of the original samples (not subjected to hydrogenation), an increase in the number of layers from 4 to 20 leads to a decrease in surface delamination from 1.51% to 0.95%. Moreover, for samples subjected to hydrogenation for 100 h, in the case of 4-layer coatings, the change in adhesion strength is more than 11.4%, and in the case of 20-layer coatings, the decrease in adhesion strength is approximately 6.9%, which is more than 1.5 times lower. The novelty of the study lies in determining the role of variation in the number of layers on resistance to degradation processes caused by hydrogenation and subsequent exposure to an aggressive environment, as well as determining the mechanisms of restraint due to variation in the number of layers and the barrier effects they create, which slow down the degradation processes of mechanical and strength properties.</div></div>","PeriodicalId":34140,"journal":{"name":"Open Ceramics","volume":"24 ","pages":"Article 100872"},"PeriodicalIF":2.8,"publicationDate":"2025-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145466631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermodynamic stability of doped ceria for solar reactors: Sublimation and surface segregation","authors":"K.T. Streckel ,&nbsp;L. Koch ,&nbsp;M. Müller ,&nbsp;M. Schmitkamp ,&nbsp;D. Sebold ,&nbsp;S. Baumann ,&nbsp;A. Nijmeijer ,&nbsp;W.A. Meulenberg ,&nbsp;N. Knoblauch","doi":"10.1016/j.oceram.2025.100871","DOIUrl":"10.1016/j.oceram.2025.100871","url":null,"abstract":"<div><div>The stability of ceria‑based redox oxides under high‑temperature solar‑thermal operation is crucial for fuel‑producing reactors. This study demonstrates that the gas pressure governs CeO₂ sublimation from Gd_0.1Ce_0.9O_1.95 (GDC-10) under solar thermochemical conditions. Annealing GDC-10 at 1400 °C in vacuum (≈10^-4 bar) produces a porous, sponge like surface layer enriched in Gd, confirming selective CeO₂ sublimation; identical treatments in argon at the same temperature and duration do not generate comparable porosity. Time resolved electron microscopy reveal a diffusion controlled, linear growth of the cerium depleted zone, while dilatometry records irreversible chemical expansion, indicating structural damage. Co-doping with 5 mol % Zr (Ce_0.9Gd_0.05Zr_0.05O_1.975) reduces CeO₂ loss and yields a saturated surface. Knudsen effusion mass spectrometry shows reduced CeO₂ volatility for the co-doped material after aging, linking thermodynamic stability to improved microstructural integrity. These results establish Zr co-doping as a potential strategy to stabilize GDC type redox oxides for durable solar thermochemical fuel production.</div></div>","PeriodicalId":34140,"journal":{"name":"Open Ceramics","volume":"24 ","pages":"Article 100871"},"PeriodicalIF":2.8,"publicationDate":"2025-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145519781","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Low-cost and sustainable hydroxyapatite synthesis using technical-grade phosphoric acid for environmental applications: Structural and morphological insights","authors":"Anass Hatim ,&nbsp;Driss Khaddoudi ,&nbsp;Fatima Abida ,&nbsp;Hicham Ait Ali Ouydir ,&nbsp;Sanaa Kouzbour ,&nbsp;Mahfoud Agunaou ,&nbsp;Youssef El Hafiane ,&nbsp;Abdelkrim Abourriche ,&nbsp;Abdelaziz Benhammou ,&nbsp;Zineb Hatim ,&nbsp;Younes Abouliatim","doi":"10.1016/j.oceram.2025.100870","DOIUrl":"10.1016/j.oceram.2025.100870","url":null,"abstract":"<div><div>Hydroxyapatite is a versatile material with strong potential for environmental remediation, yet its large-scale use is limited by the cost and purity requirements of conventional precursors. This study introduces a low-cost and sustainable synthesis route for hydroxyapatite using technical-grade phosphoric acid, highlighting the beneficial role of industrial impurities in tuning its structural, optical, and adsorption properties, thus promoting its broader use in environmental applications. Hydroxyapatite powders were synthesized from calcium hydroxide and technical-grade phosphoric acid (Ca/P = 1.67) at 25 °C in aqueous medium, then dried and calcined (500–1100 °C). Structural, chemical, and optical analyses revealed single-phase nano-hydroxyapatite (12.6–57.3 nm) with high surface area (176.95 m²·g^-1) and strong wettability. The optical band gap decreased from 4.5 ± 0.4 eV to 3.2 ± 0.4 eV after calcination, indicating defect-induced electronic modification. The poorly crystallized hydroxyapatite exhibited excellent Cd²⁺ and Pb²⁺ adsorption (99 % and 97 % removal in 100 min) but limited bisphenol A elimination (2.73 % in 180 min).</div></div>","PeriodicalId":34140,"journal":{"name":"Open Ceramics","volume":"24 ","pages":"Article 100870"},"PeriodicalIF":2.8,"publicationDate":"2025-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145466698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}