Journal Description
Ceramics
Ceramics
is an international, peer-reviewed, open access journal of ceramics science and engineering, published quarterly online by MDPI.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, ESCI (Web of Science), and other databases.
- Journal Rank: JCR - Q1 (Materials Science, Ceramics) / CiteScore - Q2 (Materials Science (miscellaneous))
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 25.2 days after submission; acceptance to publication is undertaken in 3.5 days (median values for papers published in this journal in the first half of 2024).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
Impact Factor:
2.7 (2023);
5-Year Impact Factor:
2.1 (2023)
Latest Articles
Exploring Enhanced Structural and Dielectric Properties in Ag-Doped Sr(NiNb)0.5O3 Perovskite Ceramic for Advanced Energy Storage
Ceramics 2024, 7(3), 958-974; https://doi.org/10.3390/ceramics7030062 (registering DOI) - 10 Jul 2024
Abstract
The ceramic Sr(NiNb)0.5O3, incorporating silver doping in the A site, was synthesized using a sol–gel route and subjected to comprehensive analysis through various experimental techniques. X-ray diffraction data analysis indicates a rhombohedral crystal structure. Scanning electron microscopy (SEM) examination
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The ceramic Sr(NiNb)0.5O3, incorporating silver doping in the A site, was synthesized using a sol–gel route and subjected to comprehensive analysis through various experimental techniques. X-ray diffraction data analysis indicates a rhombohedral crystal structure. Scanning electron microscopy (SEM) examination reveals densely packed grains with minimal surface porosity. A thorough investigation of electrical properties, encompassing dielectric constant, loss tangent, electrical impedance, modulus, conductivity, etc., was conducted across a wide frequency range (103–106 Hz) and temperature range (260–340 K). This analysis provided valuable insights into structure–property relationships and conduction mechanisms. The discussion highlights the significance of interface effects, space charge polarization, and Maxwell–Wagner dielectric relaxation in achieving the material’s high dielectric constant at low frequencies and elevated temperatures. Examination of temperature dependence through Nyquist plots elucidates the contributions of grain behavior to the material’s resistive and capacitive properties. The dielectric permittivity, dissipation of energy, and electrical characteristics like impedance, modulus and conductivity are notably influenced by the frequency of the applied electric field and temperature. Overall, the material exhibits promising potential for industrial applications such as energy storage, given its intriguing properties.
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(This article belongs to the Special Issue Advances in Electronic Ceramics)
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Pretreatment of Hybrid Ceramics Using Ho: YAG, Low-Level Laser Therapy Activated Malachite Green, and Non-Thermal Plasma on Surface Roughness, Bond Strength, and Color Change, SEM and EDX Analysis
by
Fahad Alkhudhairy and Yasser F. AlFawaz
Ceramics 2024, 7(3), 944-957; https://doi.org/10.3390/ceramics7030061 - 9 Jul 2024
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The study aimed to assess the effects of different surface conditionings on hybrid ceramics (HBC). Hydrofluoric acid was combined with a silane (HFA+S), low-level laser therapy activated Malachite green (LLLT-MG), Ho: YAG laser, and non-thermal plasma (NTP) as surface conditioning methods for HBC.
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The study aimed to assess the effects of different surface conditionings on hybrid ceramics (HBC). Hydrofluoric acid was combined with a silane (HFA+S), low-level laser therapy activated Malachite green (LLLT-MG), Ho: YAG laser, and non-thermal plasma (NTP) as surface conditioning methods for HBC. Eighty-four HBC discs were prepared and divided into four groups according to surface conditioning methods. The total number of samples (n = 21) for each group was further split into two for the non-thermocycling and thermocycling subgroups. After surface treatment, all samples were examined to study the effect of color change and surface roughness. The shear bond strength (SBS) test of HBC was performed on thermo-cycled samples. Statistical analysis using ANOVA with Tukey post hoc was performed to observe any significant difference among tested groups, p > 0.05. The HFA+S and Ho: YAG surface-treated samples showed higher SBS than other surface-treated samples due to higher surface roughness. All surface conditioning methods, except NTP, induced noticeable color change, making them less suitable for aesthetical purposes in clinical settings. Overall, surface conditioning methods are critical in affecting shear bond strength through surface roughness and color change.
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Open AccessArticle
2D/2D Heterojunctions of Layered TiO2 and (NH4)2V3O8 for Sunlight-Driven Methylene Blue Degradation
by
Juan Aliaga, Matías Alegria, J. Pedro Donoso, Claudio J. Magon, Igor D. A. Silva, Harold Lozano, Elies Molins, Eglantina Benavente and Guillermo González
Ceramics 2024, 7(3), 926-943; https://doi.org/10.3390/ceramics7030060 - 2 Jul 2024
Abstract
Photocatalysis based on titanium dioxide (TiO2) has become a promising method to remediate industrial and municipal effluents in an environmentally friendly manner. However, the efficiency of TiO2 is hampered by problems such as rapid electron–hole recombination and limited solar spectrum
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Photocatalysis based on titanium dioxide (TiO2) has become a promising method to remediate industrial and municipal effluents in an environmentally friendly manner. However, the efficiency of TiO2 is hampered by problems such as rapid electron–hole recombination and limited solar spectrum absorption. Furthermore, the sensitization of TiO2 through heterojunctions with other materials has gained attention. Vanadium, specifically in the form of ammonium vanadate ((NH4)2V3O8), has shown promise as a photocatalyst due to its ability to effectively absorb visible light. However, its use in photocatalysis remains limited. Herein, we present a novel synthesis method to produce lamellar (NH4)2V3O8 as a sensitizer in a supramolecular hybrid photocatalyst of TiO2–stearic acid (SA), contributing to a deeper understanding of its structural and magnetic characteristics, expanding the range of visible light absorption, and improving the efficiency of photogenerated electron–hole separation. Materials, such as TiO2–SA and (NH4)2V3O8, were synthesized and characterized. EPR studies of (NH4)2V3O8 demonstrated their orientation-dependent magnetic properties and, from measurements of the angular variation of g-values, suggest that the VO2+ complexes are in axially distorted octahedral sites. The photocatalytic results indicate that the 2D/2D heterojunction layered TiO2/vanadate at a ratio (1:0.050) removed 100% of the methylene blue, used as a model contaminant in this study. The study of the degradation mechanism of methylene blue emphasizes the role of reactive species such as hydroxyl radicals (•OH) and superoxide ions (O2•−). These species are crucial for breaking down contaminant molecules, leading to their degradation. The band alignment between ammonium vanadate ((NH4)2V3O8) and TiO2–SA, shows effective separation and charge transfer processes at their interface. Furthermore, the study confirms the chemical stability and recyclability of the TiO2–SA/(NH4)2V3O8 photocatalyst, demonstrated that it could be used for multiple photocatalytic cycles without a significant loss of activity. This stability, combined with its ability to degrade organic pollutants under solar irradiation, means that the TiO2–SA/(NH4)2V3O8 photocatalyst is a promising candidate for practical environmental remediation applications.
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(This article belongs to the Special Issue Advances in Ceramics, 2nd Edition)
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Open AccessArticle
Computational Investigation of the Influencing Parameters on the Solidification of Thermoplastic Beryllium Oxide Slurry in a Cylindrical Shell
by
Zamira Sattinova, Bakytzhan Assilbekov, Tassybek Bekenov and Gaukhar Ramazanova
Ceramics 2024, 7(3), 906-925; https://doi.org/10.3390/ceramics7030059 - 1 Jul 2024
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This article presents a computational study of the influencing parameters on the solidification of the thermoplastic beryllium oxide slurry in an annular forming cavity. The main purpose of this paper is to study the effect of cooling and casting conditions on the solidification
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This article presents a computational study of the influencing parameters on the solidification of the thermoplastic beryllium oxide slurry in an annular forming cavity. The main purpose of this paper is to study the effect of cooling and casting conditions on the solidification of the BeO suspension by considering the temperature-dependent rheological and physical properties. The results of calculations of the Bingham–Papanastasiou rheological model with experimental data in the intervals of phase transitions with different casting rates of beryllium ceramics have been validated. The use of the regularization parameter made it possible to approximate the flow of the slurry at all levels of its shear rates as highly viscous, followed by a continuous transition to a solid state. The speed of heat removal from the molding during the solidification period is determined by the speed of movement of the slurry and the temperature field on which the width of the transition region depends. The process of solidification of the slurry mass has been evaluated by changing its heat flow distribution and density along the length of the concentric channel. The obtained model calculation results make it possible to control the casting process and eventually realize a uniform structure of castings.
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Open AccessArticle
Properties of a Pressureless Sintered 2Y-TZP Material Combining High Strength and Toughness
by
Frank Kern and Bettina Osswald
Ceramics 2024, 7(3), 893-905; https://doi.org/10.3390/ceramics7030058 - 28 Jun 2024
Abstract
Yttria stabilized zirconia materials are frequently used in mechanical engineering and biomedical applications. Demanding loading conditions require materials combining a high level of strength and fracture toughness. A ready-to-press alumina doped 2 mol% yttria-stabilized zirconia powder was shaped by axial pressing and sintering
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Yttria stabilized zirconia materials are frequently used in mechanical engineering and biomedical applications. Demanding loading conditions require materials combining a high level of strength and fracture toughness. A ready-to-press alumina doped 2 mol% yttria-stabilized zirconia powder was shaped by axial pressing and sintering in air at 1250–1500 °C for 2 h. At 1350 °C the best combination of strength (1450 MPa) and toughness (7.8 MPa√m) was achieved. Materials sintered in the middle of the chosen temperature range combine full density, high transformability and small grain size. Toughness measurements by direct crack length measurements delivered unrealistically high fracture toughness values.
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(This article belongs to the Special Issue Mechanical Behavior and Reliability of Engineering Ceramics)
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Open AccessArticle
The Mechanical Properties of Geopolymers as a Function of Their Shaping and Curing Parameters
by
Camille Zoude, Elodie Prud’homme, Kévyn Johannes and Laurent Gremillard
Ceramics 2024, 7(3), 873-892; https://doi.org/10.3390/ceramics7030057 - 25 Jun 2024
Abstract
This study investigates the impact of curing conditions, porosity and shaping techniques on the mechanical properties of metakaolin-based geopolymers. Geopolymers offer versatility in shaping, including 3D printing, yet the influence of curing conditions after printing on mechanical properties remains unclear. This is assessed
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This study investigates the impact of curing conditions, porosity and shaping techniques on the mechanical properties of metakaolin-based geopolymers. Geopolymers offer versatility in shaping, including 3D printing, yet the influence of curing conditions after printing on mechanical properties remains unclear. This is assessed by measuring the bending properties of 3D-printed metakaolin-based geopolymer filaments cured under varied humidity and temperature conditions. The influences of porosity and of shaping technique are observed by comparing the compression properties of molded and 3D-printed samples of various porosity. Samples cured at low humidity exhibit unusually high mechanical properties, which decrease when moved from a dry to a humid environment. This behavior may be due to the presence of PEG within the composition and/or to residual stresses due to the too rapid evacuation of water. High humidity is therefore necessary to ensure optimal curing and stable properties. Increasing the curing temperature helps accelerate geopolymerization without significantly compromising mechanical properties. Direct ink writing offers design flexibility and suitable porosity, but the samples appear to exhibit different failure mechanisms than the molded samples. Additional studies are necessary to understand the interactions between PEG and the geopolymer as well as to better identify the fracture mechanisms within the different samples.
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(This article belongs to the Special Issue Innovative Manufacturing Processes of Silicate Materials)
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Open AccessArticle
Effect of Sodium Oxide on Structure of Lanthanum Aluminosilicate Glass
by
Assia Mabrouk, Ahmed Bachar, Yann Vaills, Aurélien Canizarès and Stuart Hampshire
Ceramics 2024, 7(3), 858-872; https://doi.org/10.3390/ceramics7030056 - 22 Jun 2024
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Rare earth (RE) aluminosilicate glasses exhibit several favorable chemical, mechanical and thermal properties. As such, they are considered to be model systems for long-half-life actinides and are candidate containment materials for long-term immobilization of radioactive wastes. The aim of the present study was
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Rare earth (RE) aluminosilicate glasses exhibit several favorable chemical, mechanical and thermal properties. As such, they are considered to be model systems for long-half-life actinides and are candidate containment materials for long-term immobilization of radioactive wastes. The aim of the present study was to investigate the effect of the substitution of sodium oxide on the glass transition temperature and structure of lanthanum aluminosilicate glasses. The primary objective was to elucidate the relationship between the substitution of Na2O for La2O3 on the Tg reduction and structural characteristics of lanthanum aluminosilicate glass, including identifying changes in the main Qn species and local environments of Si and Al. The structure of SiO2–Al2O3–La2O3–Na2O glasses has not been studied previously, and, thus, this investigation is the first to assess the structural changes occurring when La2O3 is substituted by Na2O. Three glasses were prepared with general composition (mol.%): 55SiO2–25Al2O3–20M2On (M = La or Na; n = 3 or 1). Glass G1 contains 20 mol.% La2O3; in G2, 15 mol.% of La2O3 was substituted by 15 mol.% Na2O; and Glass G3 contains 20 mol.% Na2O. The glasses were characterized by DSC to determine glass transition temperatures. As expected, as Na is substituted for La, Tg decreases substantially. Structural studies were carried out by FTIR spectroscopy, 29Si, and 27Al MAS NMR. As Na is substituted for La in these aluminosilicate glasses, the main goals that were achieved were the identification of Qn species and also changes in the local environments of Si and Al: {QnSi(mAl)} and {QnAl(mSi)}.
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Open AccessArticle
0.98(K0.5Na0.5)NbO3–0.02(Bi0.5Na0.5)(Zr0.85Sn0.15)O3 Single Crystals Grown by the Seed-Free Solid-State Crystal Growth Method and Their Characterization
by
Eugenie Uwiragiye, Thuy Linh Pham, Jong-Sook Lee, Byoung-Wan Lee, Jae-Hyeon Ko and John G. Fisher
Ceramics 2024, 7(3), 840-857; https://doi.org/10.3390/ceramics7030055 - 21 Jun 2024
Abstract
(K0.5Na0.5)NbO3-based single crystals are of interest as high-performance lead-free piezoelectric materials, but conventional crystal growth methods have some disadvantages such as the requirement for expensive Pt crucibles and difficulty in controlling the composition of the crystals. Recently,
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(K0.5Na0.5)NbO3-based single crystals are of interest as high-performance lead-free piezoelectric materials, but conventional crystal growth methods have some disadvantages such as the requirement for expensive Pt crucibles and difficulty in controlling the composition of the crystals. Recently, (K0.5Na0.5)NbO3-based single crystals have been grown by the seed-free solid-state crystal growth method, which can avoid these problems. In the present work, 0.98(K0.5Na0.5)NbO3–0.02(Bi0.5Na0.5)(Zr0.85Sn0.15)O3 single crystals were grown by the seed-free solid-state crystal growth method. Sintering aids of 0.15 mol% Li2CO3 and 0.15 mol% Bi2O3 were added to promote single crystal growth. Pellets were sintered at 1150 °C for 15–50 h. Single crystals started to appear from 20 h. The single crystals grown for 50 h were studied in detail. Single crystal microstructure was studied by scanning electron microscopy of the as-grown surface and cross-section of the sample and revealed porosity in the crystals. Electron probe microanalysis indicated a slight reduction in K and Na content of a single crystal as compared to the nominal composition. X-ray diffraction shows that the single crystals contain mixed orthorhombic and tetragonal phases at room temperature. Raman scattering and impedance spectroscopy at different temperatures observed rhombohedral–orthorhombic, orthorhombic–tetragonal and tetragonal–cubic phase transitions. Polarization–electric field (P–E) hysteresis loops show that the single crystal is a normal ferroelectric material with a remanent polarization (Pr) of 18.5 μC/cm2 and a coercive electrical field (Ec) of 10.7 kV/cm. A single crystal presents d33 = 362 pC/N as measured by a d33 meter. Such a single crystal with a large d33 and high Curie temperature (~370 °C) can be a promising candidate for piezoelectric devices.
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(This article belongs to the Special Issue Advances in Ceramics, 2nd Edition)
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Open AccessArticle
Influence of Nanoceramic-Plated Waste Carbon Fibers on Alkali-Activated Mortar Performance
by
Matteo Sambucci, Yazeed A. Al-Noaimat, Seyed Mostafa Nouri, Mehdi Chougan, Seyed Hamidreza Ghaffar and Marco Valente
Ceramics 2024, 7(2), 821-839; https://doi.org/10.3390/ceramics7020054 - 19 Jun 2024
Abstract
Waste carbon fibers as reinforcing elements in construction materials have recently gained increasing interest from researchers, providing outstanding strength performance and a lower environmental footprint compared to virgin fibers. Combination with cement-free binders, namely alkali-activated materials, is becoming increasingly important for sustainable development
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Waste carbon fibers as reinforcing elements in construction materials have recently gained increasing interest from researchers, providing outstanding strength performance and a lower environmental footprint compared to virgin fibers. Combination with cement-free binders, namely alkali-activated materials, is becoming increasingly important for sustainable development in the construction industry. This paper presents results relating to the potential use of waste carbon fibers in alkali-activated mortars. The waste carbon fiber fraction utilized in this research is difficult to integrate as reinforcement in ceramic–cementitious matrices due to its agglomerated form and chemical inertness. For this reason, a nanoceramic coating pretreatment based on nanoclay has been implemented to attempt improvements in terms of deagglomeration, dispersibility, and compatibility with alkali-activated materials. After chemical–physical and microstructural analysis on the nanoclay-plated fibers (including X-ray diffraction, IR spectroscopy, contact angle measurements, and electron microscopy) mortars were produced with four different dosages of treated and untreated waste fibers (0.25 wt.%, 0.5 wt.%, 0.75 wt.%, and 1 wt.%). Mechanical tests and fractographic investigations were then performed. The nanoclay coating interacts compatibly with the waste carbon fibers and increases their degree of hydrophilicity to improve their deagglomeration and dispersion. Compared to the samples incorporating as-received fillers, the addition of nanoclay-coated fibers improved the strength behavior of the mortars, recording a maximum increase in flexural strength of 19% for a fiber content of 0.25 wt.%. This formulation is the only one providing an improvement in mechanical behavior compared to unreinforced mortar. Indeed, as the fibrous reinforcement content increases, the effect of the nanoclay is attenuated by mitigating the improvement in mechanical performance.
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(This article belongs to the Special Issue Research Progress in Ceramic Coatings)
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Open AccessArticle
Mullite 3D Printed Humidity Sensors
by
Yurii Milovanov, Arianna Bertero, Bartolomeo Coppola, Paola Palmero and Jean-Marc Tulliani
Ceramics 2024, 7(2), 807-820; https://doi.org/10.3390/ceramics7020053 - 10 Jun 2024
Abstract
Mullite substrates with two different porosities were 3D printed, and tested as humidity sensors. To evaluate the effects of porosity on humidity sensitivity, the samples were sintered at 1400 °C (Sensor 1) and 1450 °C (Sensor 2). The sensors were tested in a
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Mullite substrates with two different porosities were 3D printed, and tested as humidity sensors. To evaluate the effects of porosity on humidity sensitivity, the samples were sintered at 1400 °C (Sensor 1) and 1450 °C (Sensor 2). The sensors were tested in a range from 0% to 85% relative humidity (RH) at room temperature. When exposed to water vapor at room temperature, the impedance value dropped down from 155 MΩ under dry air to 480 kΩ under 85 RH% for Sensor 1 and from 115 MΩ under dry air to 410 kΩ for Sensor 2. In addition, response time and recovery time were below 2 min, whatever the firing temperature, when RH changed from 0% to 74%. Finally, tests carried out involving ammonia, methane, carbon dioxide and nitrogenous oxide, as well as ethanol and acetone, showed no interference.
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(This article belongs to the Special Issue Innovative Manufacturing Processes of Silicate Materials)
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Open AccessArticle
Fabrication of Dicarboxylic-Acid- and Silica-Substituted Octacalcium Phosphate Blocks with Stronger Mechanical Strength
by
Yuki Sugiura, Yasuko Saito, Etsuko Yamada and Masanori Horie
Ceramics 2024, 7(2), 796-806; https://doi.org/10.3390/ceramics7020052 - 7 Jun 2024
Abstract
Octacalcium phosphate (OCP) is an attractive base material to combine into components developed for medical purposes, especially those used in bone replacement procedures, not only because of its excellent biocompatibility but also because of its ability to intercalate with multiple types of molecular
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Octacalcium phosphate (OCP) is an attractive base material to combine into components developed for medical purposes, especially those used in bone replacement procedures, not only because of its excellent biocompatibility but also because of its ability to intercalate with multiple types of molecular layers such as silica, dicarboxylic acid, and various cations. On the other hand, there are no examples of simultaneous substituting for several different compounds on OCPs. Therefore, in this study, the physical and mechanical strength (DTS: diametral tensile strength) of OCPs substituted with both silica and dicarboxylic acids (thiomalate: SH-malate) were evaluated. By optimizing the amount of SH-malate, we were able to prepare a block consisting of OCPs with both silica and SH-malate supported in the interlayer. The composition of the OCP-based compound comprising this block was Ca8Na1.07H6.33(PO4)4.44(SiO4)1.32(SH-malate)2.40·nH2O. Interestingly, the low mechanical strength, a drawback of silica-substituted OCP blocks, could be improved by dicarboxylic acid substituting. The dicarboxylic acid addition increased the mechanical strength of silica-substituted OCP blocks, and the acid successfully incorporated into the interlayer, even with the presence of silica. These results are expected to advance the creation of better silica-substituted OCPs and improved bone replacement materials.
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(This article belongs to the Special Issue Innovative Manufacturing Processes of Silicate Materials)
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Open AccessArticle
CaCO3-Infused Carbon Fiber Aerogels: Synthesis and Characterization
by
Cristina Mosoarca, Iosif Hulka, Pavel Șchiopu, Florina S. Rus and Radu Bănică
Ceramics 2024, 7(2), 777-795; https://doi.org/10.3390/ceramics7020051 - 6 Jun 2024
Abstract
Carbon aerogels represent a distinctive category of high surface area materials derived from sol-gel chemistry. Functionalizing these aerogels has led to the development of composite aerogels with the potential for a wider range of applications. In this study, the technique of lyophilization was
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Carbon aerogels represent a distinctive category of high surface area materials derived from sol-gel chemistry. Functionalizing these aerogels has led to the development of composite aerogels with the potential for a wider range of applications. In this study, the technique of lyophilization was employed to fabricate aerogel composites consisting of inorganic salts and cellulosic fibers. Cellulose carbonization can occur through chemical dehydration by heat treatment in an inert atmosphere. X-ray diffraction analysis spectra and scanning electron microscopy images indicate that the formed polymeric composites contain partially carbonized cellulose fibers, amorphous carbon, and calcium carbonates. CaCO3 primarily forms through the reaction of CaCl2, which moistens cellulose or amorphous carbon fibers with CO2 in ammonia fumes. The water loss in 3D structures was analyzed using thermogravimetric analysis, Fourier Transform Infrared Spectroscopy, and ultraviolet-visible-near-infrared spectroscopy. Depending on the synthesis method, 3D structures can be created from partially or completely dehydrated cellulose fibers. The aerogels were examined for their ability to support the growth of bacterial biofilm and then adorned with metal silver and AgCl to produce bactericidal products. Due to their open pores and CaCO3 content, these aerogels can serve as durable and environmentally friendly thermal insulators with bactericidal properties, as well as a medium for absorbing acidic gases.
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(This article belongs to the Special Issue Advances in Ceramics, 2nd Edition)
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Open AccessArticle
Investigation of Variability of Flaw Strength Distributions on Brittle SiC Ceramic
by
Jacques Lamon
Ceramics 2024, 7(2), 759-776; https://doi.org/10.3390/ceramics7020050 - 4 Jun 2024
Abstract
The present paper investigates flaw strength distributions established using various flexural tests on batches of SiC bar test specimens, namely four-point bending as well as three-point bending tests with different span lengths. Flaw strength is provided by the elemental stress operating on the
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The present paper investigates flaw strength distributions established using various flexural tests on batches of SiC bar test specimens, namely four-point bending as well as three-point bending tests with different span lengths. Flaw strength is provided by the elemental stress operating on the critical flaw at the fracture of a test specimen. Fracture-inducing flaws and their locations are identified using fractography. A single population of pores was found to dominate the fracture. The construction of diagrams of p-quantile vs. elemental strengths was aimed at assessing the Gaussian nature of flaw strengths. Then, empirical cumulative distributions of strengths were constructed using the normal distribution function. The Weibull distributions of strengths are then compared to the normal reference distributions. The parameters of the Weibull cumulative probability distributions are estimated using maximum likelihood and moment methods. The cumulative distributions of flexural strengths for the different bending tests are predicted from the flaw strength density function using the elemental strength model, and from the cumulative distribution of flexural strength using the Weibull function. Flaw strength distributions that include the weaker flaws that are potentially present in larger test pieces are extrapolated using the p-quantile diagrams. Implications are discussed regarding the pertinence of an intrinsically representative flaw strength distribution, considering failure predictions. Finally, the influence of the characteristics of fracture-inducing flaw populations expressed in terms of flaw strength interval, size, dispersion, heterogeneity, and reproducibility with volume change is examined.
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(This article belongs to the Special Issue Advances in Ceramics, 2nd Edition)
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Open AccessArticle
Improving the Transparency of a MgAl2O4 Spinel Damaged by Sandblasting through a SiO2-ZrO2 Coating
by
Akram Zegadi, Abdelwahhab Ayadi, Ikram Khellaf, Mohamed Hamidouche, Gilbert Fantozzi, Alicia Durán and Yolanda Castro
Ceramics 2024, 7(2), 743-758; https://doi.org/10.3390/ceramics7020049 - 28 May 2024
Abstract
Transparent materials in contact with harmful environments such as sandstorms are exposed to surface damage. Transparent MgAl2O4 spinel used as protective window, lens or laser exit port, among others, is one of the materials affected by natural aggressions. The impact
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Transparent materials in contact with harmful environments such as sandstorms are exposed to surface damage. Transparent MgAl2O4 spinel used as protective window, lens or laser exit port, among others, is one of the materials affected by natural aggressions. The impact of sand particles can cause significant defects on the exposed surface, thus affecting its optical and mechanical behavior. The aim of this work is to improve the surface state of a spinel damaged surface by the deposition of a thin layer of SiO2-ZrO2. For this purpose, spinel samples obtained from different commercial powders sintered by Spark Plasma Sintering were sandblasted and further coated with a SiO2-ZrO2 thin layer. The coating was successfully synthesized by the sol/gel method, deposited on the sandblasted samples and then treated at 900 °C, reaching a final thickness of 250 nm. The results indicated that sandblasting significantly affects the surface of the spinel samples as well as the optical transmission, confirmed by UV-visible spectroscopy and profilometry tests. However, the deposition of a SiO2-ZrO2 coating modifies the UV-visible response. Thus, the optical transmission of the S25CRX12 sample presents the best transmission values of 81%, followed by the S25CRX14 sample then the S30CR sample at 550 nm wavelength. An important difference was observed between sandblasted samples and coated samples at low and high wavelengths. At low wavelengths (around 200 nm), sandblasting tends to improve significantly the transmission of spinel samples, which exhibit a low transmission in the pristine state. This phenomenon can be attributed to the healing of small superficial defects responsible for the degradation of transmission such as pores or flaws. When the initial transmission at 200 nm is high, the sandblasting worsens the transmission. Sandblasting reduces slightly the transmission values for long wavelengths due to the formation of large superficial defects like chipping by creation and propagation of lateral cracks. The coating of the sandblasted samples exhibits some healing of defects induced by sandblasting. The deposition of the SiO2-ZrO2 layer induces a clear increase in the optical transmission values, sometimes exceeding the initial values of the transmission in the pristine state.
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(This article belongs to the Special Issue Transparent Ceramics—a Theme Issue in Honor of Dr. Adrian Goldstein)
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Open AccessCommunication
Microwave-Assisted Hydrothermal Synthesis of Hydroxyapatite Flakes as Substrates for Titanium Dioxide Film Deposition
by
Néstor Méndez-Lozano, Eduardo E. Pérez-Ramírez and Miguel de la Luz-Asunción
Ceramics 2024, 7(2), 735-742; https://doi.org/10.3390/ceramics7020048 - 28 May 2024
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This article describes the synthesis of hydroxyapatite (HAp) flakes through a microwave-assisted hydrothermal method. These flakes suggest possible applications as a substrate for depositing titanium dioxide (TiO2) films using chemical vapor deposition with metal–organic precursors (MOCVD). The results reveal the formation
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This article describes the synthesis of hydroxyapatite (HAp) flakes through a microwave-assisted hydrothermal method. These flakes suggest possible applications as a substrate for depositing titanium dioxide (TiO2) films using chemical vapor deposition with metal–organic precursors (MOCVD). The results reveal the formation of crystalline hydroxyapatite characterized by a uniform morphology. Additionally, we demonstrated the successful deposition of TiO2 coatings on the hydroxyapatite flakes, resulting in a distinctive faceted prism morphology. Our findings affirm the effective synthesis of the HAp/TiO2 composite material. To further explore the material’s practical applications, we recommend assessing the photocatalytic activity of these composite membranes in future research.
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Open AccessReview
Lead-Free NaNbO3-Based Ceramics for Electrostatic Energy Storage Capacitors
by
Sairatun Nesa Soheli, Zhilun Lu, Dongyang Sun and Islam Shyha
Ceramics 2024, 7(2), 712-734; https://doi.org/10.3390/ceramics7020047 - 23 May 2024
Abstract
The burgeoning significance of antiferroelectric (AFE) materials, particularly as viable candidates for electrostatic energy storage capacitors in power electronics, has sparked substantial interest. Among these, lead-free sodium niobate ( ) AFE materials are emerging as eco-friendly and
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The burgeoning significance of antiferroelectric (AFE) materials, particularly as viable candidates for electrostatic energy storage capacitors in power electronics, has sparked substantial interest. Among these, lead-free sodium niobate ( ) AFE materials are emerging as eco-friendly and promising alternatives to lead-based materials, which pose risks to human health and the environment, attributed to their superior recoverable energy density and dielectric breakdown strength. This review offers an insightful overview of the fundamental principles underlying antiferroelectricity and the applications of AFE materials. It underscores the recent advancements in lead-free -based materials, focusing on their crystal structures, phase transitions, and innovative strategies devised to tailor their electrostatic energy storage performance. Finally, this review delineates the prevailing challenges and envisages future directions in the realm of -based electrostatic energy storage capacitors, with the goal of fostering further advancements in this pivotal field.
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(This article belongs to the Special Issue Advances in Electronic Ceramics)
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Open AccessArticle
Origin of Temperature Coefficient of Resonance Frequency in Rutile Ti1−xZrxO2 Microwave Ceramics
by
Izaz Khan, Aneela Khan, Raz Muhammad, Minmin Mao, Dandan Han, Kaixin Song, Wen Lei and Dawei Wang
Ceramics 2024, 7(2), 698-711; https://doi.org/10.3390/ceramics7020046 - 23 May 2024
Abstract
In this study, we report the effect of Zr4+ doping on the optical energy gap and microwave dielectric properties of rutile TiO2. Rietveld analysis explicitly confirmed that Zr4+ occupies the octahedral site, forming a single-phase tetragonal structure below the
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In this study, we report the effect of Zr4+ doping on the optical energy gap and microwave dielectric properties of rutile TiO2. Rietveld analysis explicitly confirmed that Zr4+ occupies the octahedral site, forming a single-phase tetragonal structure below the solubility limit (x < 0.10). Notably, at x = 0.025, a significant enhancement in Q × fo was observed. This enhancement was attributed to the reduction in dielectric loss, associated with a decrease in oxygen vacancies and a lower concentration of Ti3+ paramagnetic centers. This conclusion was supported by Raman and electron paramagnetic resonance spectroscopy, respectively. The origin of high τf in rutile Ti1−xZrxO2 is explained on the basis of the octahedral distortion/tetragonality ratio, covalency, and bond strength.
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(This article belongs to the Special Issue Advances in Electronic Ceramics)
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Open AccessArticle
Effect of Acid Surface Treatments on the Shear Bond Strength of Metal Bracket to Zirconia Ceramics
by
Punchanit Wongrachit, Bancha Samruajbenjakun, Boonlert Kukiattrakoon, Tanapat Jearanai, Supontep Teerakanok and Pannapat Chanmanee
Ceramics 2024, 7(2), 689-697; https://doi.org/10.3390/ceramics7020045 - 14 May 2024
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The surface treatment of zirconia prior to bonding remains controversial and unclear. This study aimed to compare the shear bond strength (SBS) of metal brackets to zirconia under surface treatments with either 4% HF or 37% PA in both immediate loading (IML) and
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The surface treatment of zirconia prior to bonding remains controversial and unclear. This study aimed to compare the shear bond strength (SBS) of metal brackets to zirconia under surface treatments with either 4% HF or 37% PA in both immediate loading (IML) and artificial aging by thermocycling (TMC). Methods: Eighty-four zirconia were randomly assigned to six groups based on the surface treatment and artificial aging by TMC: (1) No surface treatment (NT); (2) NT + TMC; (3) HF (4% HF for 2 min); (4) HF + TMC; (5) PA (37% PA for 2 min); and (6) PA + TMC. After bracket bonding, only the TMC groups were thermocycled for 5000 cycles. The SBS and adhesive remnant index (ARI) of all groups were analyzed (p < 0.01). Results: TMC significantly lowered the SBS more than the IML in all acid surface treatment groups (p < 0.01). The ARI score after TMC was significantly higher than the IML in all acid surface treatment groups (p < 0.001). No significant differences in the SBS values or ARI scores were observed among the surface treatments (p > 0.01). Conclusions: Two-minute simple etching methods, using either 4% HF or 37% PA, showed an insufficient SBS of metal orthodontic brackets to zirconia after TMC.
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Open AccessArticle
Nanosized Tungsten Powder Synthesized Using the Nitridation–Decomposition Method
by
Qing-Yin He, Ben-Li Zhao and Shi-Kuan Sun
Ceramics 2024, 7(2), 680-688; https://doi.org/10.3390/ceramics7020044 - 11 May 2024
Abstract
A facile, one-step nitridation–decomposition method was developed for the synthesis of nanosized tungsten powder with a high surface area. This approach involved the nitridation of WO3 in NH3 to form mesoporous tungsten nitride (W2N), followed by in situ decomposition
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A facile, one-step nitridation–decomposition method was developed for the synthesis of nanosized tungsten powder with a high surface area. This approach involved the nitridation of WO3 in NH3 to form mesoporous tungsten nitride (W2N), followed by in situ decomposition of W2N to directly yield single-phase W particles. The phase and morphology evolution during the synthesis were systematically investigated and compared with the carbothermal reduction of WO3. It was revealed that powdered tungsten product with single-phase particles was obtained after nitridation at 800 °C combined with in situ decomposition at 1000 °C, displaying an average particle size of 15 nm and a large specific surface area of 6.52 m2/g. Furthermore, the proposed method avoided the limitations associated with intermediate phase formation and coarsening observed in carbothermal reduction, which resulted in the growth of W particles up to ~4.4 μm in size. This work demonstrates the potential of the nitridation–decomposition approach for the scalable and efficient synthesis of high-quality, fine-grained tungsten powder.
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(This article belongs to the Special Issue Advances in Electronic Ceramics)
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Open AccessReview
Ceramic Matrix Composites: Classifications, Manufacturing, Properties, and Applications
by
Shriya Shrivastava, Dipen Kumar Rajak, Tilak Joshi, Dwesh K. Singh and D. P. Mondal
Ceramics 2024, 7(2), 652-679; https://doi.org/10.3390/ceramics7020043 - 10 May 2024
Abstract
Ceramic matrix composites (CMCs) are a significant advancement in materials science and engineering because they combine the remarkable characteristics of ceramics with the strength and toughness of fibers. With their unique properties, which offer better performance and endurance in severe settings, these advanced
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Ceramic matrix composites (CMCs) are a significant advancement in materials science and engineering because they combine the remarkable characteristics of ceramics with the strength and toughness of fibers. With their unique properties, which offer better performance and endurance in severe settings, these advanced composites have attracted significant attention in various industries. At the same time, lightweight ceramic matrix composites (LCMCs) provide an appealing alternative for a wide range of industries that require materials with excellent qualities such as high-temperature stability, low density, corrosion resistance, and excellent mechanical performance. CMC uses will expand as production techniques and material research improve, revolutionizing aerospace, automotive, and other industries. The effectiveness of CMCs primarily relies on the composition of their constituent elements and the methods employed in their manufacturing. Therefore, it is crucial to explore the functional properties of various global ceramic matrix reinforcements, their classifications, and the manufacturing techniques used in CMC fabrication. This study aims to overview a diverse range of CMCs reinforced with primary fibers, including their classifications, manufacturing techniques, functional properties, significant applications, and global market size.
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(This article belongs to the Special Issue Advances in Ceramics, 2nd Edition)
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