Ceramics

10 pages, 4971 KB

Open AccessFeature PaperArticle

Fracture Strength and Behavior of Pore-Free 3 mol% Y₂O₃:ZrO₂ Ceramics

by Akio Ikesue and Yan Lin Aung

Ceramics 2026, 9(7), 64; https://doi.org/10.3390/ceramics9070064 (registering DOI) - 23 Jun 2026

Hot isostatic pressing (HIP) was employed to fabricate 3 mol% Y₂O₃-stabilized ZrO₂ ceramics with nearly pore-free microstructures. Zirconia ceramics containing residual pores (size: ~0.3 μm, <0.1%) exhibited a four-point bending strength of 1.11 GPa. In contrast, pore-free specimens [...] Read more.

Hot isostatic pressing (HIP) was employed to fabricate 3 mol% Y₂O₃-stabilized ZrO₂ ceramics with nearly pore-free microstructures. Zirconia ceramics containing residual pores (size: ~0.3 μm, <0.1%) exhibited a four-point bending strength of 1.11 GPa. In contrast, pore-free specimens achieved significantly higher strengths of 1.74 GPa for samples containing a small fraction of cubic grains and 2.29 GPa for specimens composed solely of the tetragonal phase. At the moment of fracture in the high-strength specimens, intense electrical discharges (visible sparks) were observed near the fracture origin. Post-fracture observations revealed that zirconia containing residual pores fractured into two pieces with relatively smooth fracture surfaces, whereas pore-free zirconia exhibited extensive fragmentation, producing highly irregular fracture surfaces. This behavior is likely associated with extensive rupture of Zr–O bonds within the crystal lattice during catastrophic fracture. These results demonstrate that the elimination of residual pores by HIP markedly enhances the attainable strength of zirconia ceramics and significantly alters their fracture behavior. Full article

(This article belongs to the Special Issue Advances in Ceramics, 3rd Edition)

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15 pages, 4069 KB

Open AccessArticle

Elucidating the Firing Mechanisms of Ceramics in Guizhou Province via Interfacial Electronic and Mechanical Properties

by Yun Xu and Weifu Cen

Ceramics 2026, 9(6), 63; https://doi.org/10.3390/ceramics9060063 (registering DOI) - 22 Jun 2026

Abstract

Ceramics, as a handicraft, is the crystallization of art and science. In order to study the firing process of ceramics, improve their density, mechanical properties, viscosity, and surface tension, and enhance the surface quality of the shaft, this article uses first-principles methods to [...] Read more.

Ceramics, as a handicraft, is the crystallization of art and science. In order to study the firing process of ceramics, improve their density, mechanical properties, viscosity, and surface tension, and enhance the surface quality of the shaft, this article uses first-principles methods to study the electronic properties of ceramic colorants Al₂O₃, Fe₂O₃, TiO₂, CaO, MgO, Na₂O, KO₂, and ceramic body SiO₂. Research has shown that these seven color-developing agents exhibit anisotropy and have stable crystal structures. The bandgap values of Al₂O₃, CaO, Fe₂O₃, KO₂, MgO, Na₂O, TiO₂, and ceramic SiO₂ are 6.325 eV, 3.654 eV, 0 eV, 0 eV, 4.731 eV, 1.972 eV, 2.18 eV and 6.002 eV, respectively. In Al₂O₃/SiO₂, Fe₂O₃/SiO₂, TiO₂/SiO₂, CaO/SiO₂, MgO/SiO₂, Na₂O/SiO₂, and KO₂/SiO₂ systems, due to the influence of the potential field in the SiO₂ system, the charge characteristics exhibit obvious interfacial and non-periodic characteristics. The research results revealed the charge transfer and distribution patterns at the interface between ceramic colorants and ceramic ligands, elucidating the influence mechanism of different colorants/embryo components on firing temperature, shrinkage rate, and finished product defects. This mechanism can be used to predict the advantages and disadvantages of alkali metals, iron, titanium, and aluminum components in raw materials, optimize low-temperature rapid firing formulas, suppress firing deformation, control pore defects, and improve the mechanical properties of finished products. It provides micro theoretical support for the industrialization, stabilization, and high-quality production of local ceramics in southwestern China. Full article

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19 pages, 6695 KB

Open AccessArticle

Optimizing Piezoelectric and Ferroelectric Properties in BCZT Ceramics via Nd/Mn Co-Doping and Sintering Engineering

by Wenhao He, Shaohua Su, Bijun Fang, Shuai Zhang, Xiaolong Lu and Jianning Ding

Ceramics 2026, 9(6), 62; https://doi.org/10.3390/ceramics9060062 (registering DOI) - 22 Jun 2026

Abstract

Lead-free [(Ba_0.85Ca_0.15)_1−1.5xNd_x][(Zr_0.1Ti_0.9)_0.995Mn_0.005]O₃ (x mol% Nd/Mn BCZT, x = 0.05, 0.1, 0.5, 1 mol%) ceramics were prepared by the traditional solid-state reaction method, in which the synergistic [...] Read more.

Lead-free [(Ba_0.85Ca_0.15)_1−1.5xNd_x][(Zr_0.1Ti_0.9)_0.995Mn_0.005]O₃ (x mol% Nd/Mn BCZT, x = 0.05, 0.1, 0.5, 1 mol%) ceramics were prepared by the traditional solid-state reaction method, in which the synergistic effects of sintering temperature and Nd/Mn co-doping on the phase structure, microstructural evolution, and electrical properties were systematically investigated. All ceramics exhibit a pure perovskite structure, with the tetragonal (P4mm) phase dominating at room temperature as confirmed by the X-ray diffraction Rietveld refinement. The sintering temperature (1475–1520 °C) is found to be the primary factor governing densification and grain growth, with the relative density peaking at 91.7% for the x = 0.5 mol% sample sintered at 1505 °C. Within this optimized processing window, increasing the Nd content induces a gradual migration of the Curie temperature (T_C) toward lower temperatures, accompanied by enhanced relaxor behavior. A highlight of this work is the strategic balance between piezoelectric activity and mechanical quality factor through a “donor–acceptor” co-doping mechanism. Specifically, for the x = 0.5 mol% ceramics, an exceptionally high mechanical quality factor (Q_m = 424.5) is achieved for samples sintered at 1490 °C, which is proposed to be associated with the temperature-modulated formation of

{M n}_{T i}^{″} - V_{O}^{• •}

defect dipoles, while a peak inverse piezoelectric coefficient

d_{33}^{*}

of 685.1 pm/V is maintained at a sintering temperature of 1520 °C. Full article

(This article belongs to the Special Issue Advances in Electronic Ceramics, 2nd Edition)

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15 pages, 4141 KB

Open AccessReview

Coupled Effects of Grinding-Induced Damage and Annealing-Assisted Recovery on Fracture Toughness and Reliability of Zirconia-Toughened Alumina Ceramics: A Review

by Wenxin Tan, Ran Fu, Yongjun Zhang and Wenjuan Liang

Ceramics 2026, 9(6), 61; https://doi.org/10.3390/ceramics9060061 - 8 Jun 2026

Abstract

Zirconia-toughened alumina (ZTA) ceramics are promising for load-bearing biomedical applications because they combine the hardness, chemical stability, wear resistance, and biocompatibility of alumina with the transformation-toughening capability of zirconia. Grinding is indispensable for achieving dimensional accuracy and surface quality, yet it inevitably introduces [...] Read more.

Zirconia-toughened alumina (ZTA) ceramics are promising for load-bearing biomedical applications because they combine the hardness, chemical stability, wear resistance, and biocompatibility of alumina with the transformation-toughening capability of zirconia. Grinding is indispensable for achieving dimensional accuracy and surface quality, yet it inevitably introduces surface and subsurface cracks, residual stresses, and a local tetragonal-to-monoclinic transformation of zirconia. These changes can degrade fracture toughness, increase reliability scatter, and reduce long-term service stability. Annealing is therefore often considered a post-grinding recovery strategy because it can relax residual stresses, blunt crack tips, and partially restore the zirconia phase state. However, the extent of recovery depends strongly on the initial damage state, ZTA microstructure, and thermal schedule. This review systematically summarizes the current understanding of grinding-induced damage and annealing-assisted recovery in ZTA ceramics, with particular emphasis on the coupled relationships among subsurface damage, residual-stress evolution, phase transformation, and fracture toughness. Particular attention is given to distinguishing direct ZTA-specific evidence from mechanistic interpretations inferred from related zirconia-containing ceramic systems, because datasets based exclusively on ZTA remain relatively limited. By integrating the existing evidence, this review proposes a coupled processing-damage-recovery framework and identifies the key knowledge gaps that must be addressed to achieve more reliable process optimization in advanced ZTA components. Full article

(This article belongs to the Special Issue Advances in Ceramics, 3rd Edition)

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16 pages, 2224 KB

Open AccessArticle

Additively Manufactured Carbon Fiber-Reinforced Siliconized Silicon Carbide Composites Using Carbon Fiber-Reinforced Poly-Ether-Ether-Ketone (PEEK) as a Precursor

by Bola Yoon, James W. Klett, Ryan M. Paul, Michael J. Lance, Hsin Wang, Kashif Nawaz and Edgar Lara-Curzio

Ceramics 2026, 9(6), 60; https://doi.org/10.3390/ceramics9060060 - 7 Jun 2026

Abstract

Herein, we report a method to additively manufacture carbon fiber-reinforced siliconized silicon carbide composites. The process involves the pyrolysis of a 3D-printed carbon fiber-reinforced poly-ether-ether-ketone (PEEK) composite to produce a porous carbon fiber-reinforced carbon matrix composite preform, which is subsequently infiltrated with molten [...] Read more.

Herein, we report a method to additively manufacture carbon fiber-reinforced siliconized silicon carbide composites. The process involves the pyrolysis of a 3D-printed carbon fiber-reinforced poly-ether-ether-ketone (PEEK) composite to produce a porous carbon fiber-reinforced carbon matrix composite preform, which is subsequently infiltrated with molten silicon to obtain a carbon fiber-reinforced siliconized silicon carbide composite. A key aspect of the method is limiting polymer melt flow during pyrolysis of PEEK, which is achieved by thermally annealing the 3D-printed carbon fiber-reinforced PEEK preform in air at a temperature below PEEK’s melting temperature. Rheological and differential scanning calorimetry (DSC) measurements demonstrate that the thermal annealing treatment altered the melting behavior of PEEK, while NMR and FTIR measurements provided a mechanistic explanation for the structural changes responsible for the behavior. It was also found that dimensional changes during pyrolysis were anisotropic with greater shrinkage in the stacking direction of the material. Full article

(This article belongs to the Special Issue Ceramic Materials for Industrial Decarbonization)

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22 pages, 11158 KB

Open AccessArticle

Durability Assessment of Self-Compacting Sand Concrete Incorporating Windshield Glass Aggregate Under Extreme Environmental Conditions: High Temperature and Freeze–Thaw Cycling

by Zahra Beladzar, Djamila Boukhelkhal, Mohamed Guendouz, Seyed Mostafa Nouri, Ilario Biblioteca and Marco Valente

Ceramics 2026, 9(6), 59; https://doi.org/10.3390/ceramics9060059 - 1 Jun 2026

Abstract

This study evaluates the durability of Self-Compacting Sand Concrete (SCSC) incorporating Windshield Glass Aggregate (WGA) as a sustainable replacement for natural sand, utilizing Blast Furnace Slag (BFS) as a constant filler component. Eleven mixtures were investigated: a control mix and ten variants with [...] Read more.

This study evaluates the durability of Self-Compacting Sand Concrete (SCSC) incorporating Windshield Glass Aggregate (WGA) as a sustainable replacement for natural sand, utilizing Blast Furnace Slag (BFS) as a constant filler component. Eleven mixtures were investigated: a control mix and ten variants with WGA substitution levels ranging from 10% to 100% in 10% increments. The specimens were exposed to elevated temperatures of 200–800 °C and to 240 freeze–thaw cycles between −18 °C and +9 °C. Under heating, mass loss increased with temperature, but WGA-rich mixtures generally showed lower mass loss and higher residual mechanical performance than the control. At 400 °C, WGA100 reached about 96 MPa in compressive strength and 15 MPa in flexural strength, corresponding to residual values of approximately 110.34% and 166.7%, respectively. After freeze–thaw cycling, all mixtures showed limited surface deterioration and mass loss below 1%, decreasing from about 0.76% for the control mixture to about 0.05% for WGA100. The improved durability is mainly attributed to the physical effect of WGA replacement and the baseline matrix refinement associated with BFS. Full article

(This article belongs to the Special Issue Ceramics in the Circular Economy for a Sustainable World, 2nd Edition)

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19 pages, 2516 KB

Open AccessArticle

Synergistic Effects of Mg₂Si-YH₂ Composite Additives on the Microstructure and Properties of Silicon Nitride Ceramics

by Zizheng Cai, He Ma, Kun Tian, Feng Sun, Lijuan Zhou and Shuang Li

Ceramics 2026, 9(6), 58; https://doi.org/10.3390/ceramics9060058 - 29 May 2026

Abstract

Sintering additives play a decisive role in the densification behavior, mechanical properties, and thermal conductivity of silicon nitride ceramics. In this study, Mg₂Si and YH₂ were used as sintering additives for gas pressure sintering of silicon nitride based on the [...] Read more.

Sintering additives play a decisive role in the densification behavior, mechanical properties, and thermal conductivity of silicon nitride ceramics. In this study, Mg₂Si and YH₂ were used as sintering additives for gas pressure sintering of silicon nitride based on the synergistic mechanism of “silicide silicon extraction-hydride dehydrogenation”. The regulation rules of the additives on ceramic densification, mechanical properties, and thermal conductivity were systematically investigated. Two optimization strategies were proposed for the technical route of replacing traditional oxide additives with non-oxide systems. (i) Rare-earth hydride YH₂ was used to replace traditional rare-earth oxides. It reacts with SiO₂ to achieve strong deoxidation and precisely regulate the liquid phase composition. (ii) Metal silicide Mg₂Si was used to replace metal oxides. It promotes the preferred growth of β-Si₃N₄ grains, consumes oxygen in the system, and reduces lattice defects. Mg₂Si introduces Si into the liquid phase, increasing the Si/O ratio, which lowers lattice oxygen content and supports higher thermal conductivity. YH₂ consumes SiO₂ on the Si₃N₄ surface, which reduces liquid phase oxygen content and inhibits lattice oxygen incorporation, promoting a liquid phase with a high N/O ratio. Compared with traditional Y₂O₃, YH₂ increases the Y₂O₃/SiO₂ ratio in the liquid phase. It promotes grain growth, reduces SiO₂ activity, and further improves the thermal conductivity of ceramics. Silicon nitride ceramics prepared by gas pressure sintering at 1750 °C with 3 wt.% Mg₂Si and 4 wt.% YH₂ composite additives exhibit the highest thermal conductivity of 87 W/(m·K), with a Vickers hardness of 14.36 GPa and a flexural strength of 643.15 MPa. This study provides an innovative idea for the preparation of high-performance silicon nitride heat dissipation substrates. Full article

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8 pages, 631 KB

Open AccessArticle

Elastic Properties of Illite-Based Ceramics at Low Temperatures of Firing

by Štefan Csáki, Tomáš Húlan, Anton Trník and Igor Štubňa

Ceramics 2026, 9(6), 57; https://doi.org/10.3390/ceramics9060057 - 29 May 2026

Abstract

Samples made from illitic clay were investigated using thermogravimetry (TG), thermodilatometry (TD) and dynamic mechanical analysis (DMA) during heating from room temperature to 300 °C. TG revealed three steps of mass loss: (a) the release of weakly bound H₂O (with the [...] Read more.

Samples made from illitic clay were investigated using thermogravimetry (TG), thermodilatometry (TD) and dynamic mechanical analysis (DMA) during heating from room temperature to 300 °C. TG revealed three steps of mass loss: (a) the release of weakly bound H₂O (with the maximum rate at ~120 °C) from the pores, (b) a small mass loss event around 215 °C, (c) a small mass loss event near ~300 °C related to dehydration when H₂O molecules located in K-free sites of the illite interlayers are removed. TD indicated very small dimension changes for 20 °C → 300 °C. This behavior may result from two competing mechanisms, where the first one is regular thermal expansion and the second one is particle rearrangement caused by the removal of physically bound water. Young’s modulus initially decreases during heating up to approximately 70 °C. Young’s modulus subsequently increases exponentially, which may be explained by mechanisms analogous to those observed in the TD measurements. The activation energies derived from the exponential dependence E(t) are 5.66 kJ/mol for the temperature interval 130–200 °C and 10.96 kJ/mol for the 200–280 °C range. Full article

(This article belongs to the Special Issue Advances in Ceramics, 3rd Edition)

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10 pages, 4184 KB

Open AccessArticle

The Effect of Doping Modification on the Piezoelectric Properties of Ba_1−xCa_xZr_0.1Ti_0.9−ySn_y Lead-Free Piezoelectric Ceramics

by Zhiyong Yang, Shengxian Luo, An Xue, Fangfang Zeng, Yang Liao, Yang Li, Zhiyao Chu, Qibin Liu and Huaizhang Gu

Ceramics 2026, 9(6), 56; https://doi.org/10.3390/ceramics9060056 - 29 May 2026

Abstract

Lead-free piezoelectric ceramics have attracted substantial attention in environmental protection and energy storage applications due to their excellent performance. In this study, the Ba_1−xCa_xZr_0.1Ti_0.9−ySn_yO₃(BCZTS) lead-free piezoelectric ceramic system was [...] Read more.

Lead-free piezoelectric ceramics have attracted substantial attention in environmental protection and energy storage applications due to their excellent performance. In this study, the Ba_1−xCa_xZr_0.1Ti_0.9−ySn_yO₃(BCZTS) lead-free piezoelectric ceramic system was synthesized. The effects of doping ratios of Ca and Sn, as well as sintering temperature, were systematically investigated on the phase structure, microstructure, and piezoelectric properties of BCZTS ceramics. The results showed that the Ba_0.88Ca_0.12Zr_0.1Ti_0.81Sn_0.09 ceramics synthesized with a Ca doping content of x = 12 mol% and a Sn doping content of y = 9 mol % had a homogeneous phase structure with an Orthorhombic–Tetragonal (O-T) morphotropic phase boundary (MPB) and uniform grain size. At a sintering temperature of 1300 °C, the ceramics achieved optimal piezoelectric performance, with a piezoelectric coefficient d₃₃ = 319 pC/N. These lead-free piezoelectric ceramics have superior properties compared to conventional lead-based piezoelectric ceramics in the local market, providing a novel and feasible way to replace lead-based ones in civilian applications. Full article

(This article belongs to the Special Issue Advances in Electronic Ceramics, 2nd Edition)

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15 pages, 5926 KB

Open AccessArticle

Green Synthesis of AgNP-Modified TiO₂-Fe₃O₄ Magnetic Spheres for Aqueous Organic Pollutant Removal

by José Adalberto Castillo-Robles, Rubí Maria Cobos-Ramos, Jesús Emmanuel López-Zúñiga, Eddie Nahúm Armendáriz-Mireles and Enrique Rocha-Rangel

Ceramics 2026, 9(6), 55; https://doi.org/10.3390/ceramics9060055 - 29 May 2026

Abstract

This work reports the synthesis, characterization, and photocatalytic performance of multifunctional spheres based on AgNP-doped TiO₂-Fe₃O₄ embedded in an alginate–chitosan biopolymeric matrix for the removal of organic contaminants from water. The composite powders exhibited a nanocrystalline structure composed [...] Read more.

This work reports the synthesis, characterization, and photocatalytic performance of multifunctional spheres based on AgNP-doped TiO₂-Fe₃O₄ embedded in an alginate–chitosan biopolymeric matrix for the removal of organic contaminants from water. The composite powders exhibited a nanocrystalline structure composed of anatase TiO₂ (~20 nm) and magnetite (~25 nm), with homogeneously dispersed Ag nanoparticles, as observed by SEM. The spheres presented a mainly submicrometric particle size distribution (0.55–0.92 µm), favoring high surface area and colloidal stability. Under simulated solar irradiation, the material achieved efficient photocatalytic degradation of methylene blue, with a pseudo-first-order rate constant of 0.112 h⁻¹ and ~46% decolorization after 5 h. UV-Vis spectra showed progressive attenuation of the dye absorption band without accumulation of intermediates. Magnetic recovery tests confirmed rapid separation and reuse without performance loss. The enhanced activity is attributed to the synergistic interaction among plasmonic Ag, photocatalytic TiO₂, redox-active Fe₃O₄, and the adsorptive carbon–biopolymer matrix. The material exhibited strong antibacterial activity, achieving over 90% removal of fecal coliforms after 5 h of irradiation. Therefore, the developed AgNP-doped TiO₂-Fe₃O₄ spheres represent a sustainable, reusable, and efficient material for solar-assisted water sanitation. Full article

(This article belongs to the Special Issue Advances in Ceramics, 3rd Edition)

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Graphical abstract

16 pages, 7061 KB

Open AccessArticle

Effect of Kyzylorda Thermal Power Plant Ash and Rice Husk Ash on the Physical and Mechanical Properties of Ceramic Materials

by Saken Uderbayev, Aizhan Dilmanova, Aigerim Khamit, Gulnaz Zhakapbayeva, Akmaral Zhapakhova, Nargul Saktaganova and Koktem Yerimbetov

Ceramics 2026, 9(6), 54; https://doi.org/10.3390/ceramics9060054 - 28 May 2026

Abstract

This study investigates the development of sustainable ceramic materials using industrial and agricultural waste from the Kyzylorda region of Kazakhstan. The research focuses on the combined use of local clay, ash from the Kyzylorda thermal power plant (TPP), and rice husk ash (RHA). [...] Read more.

This study investigates the development of sustainable ceramic materials using industrial and agricultural waste from the Kyzylorda region of Kazakhstan. The research focuses on the combined use of local clay, ash from the Kyzylorda thermal power plant (TPP), and rice husk ash (RHA). Experimental investigations included the evaluation of chemical composition, linear and volumetric shrinkage, water absorption, bulk density, and compressive strength of ceramic samples fired at 950–1050 °C. Microstructural (SEM) and phase composition (XRD) analyses were performed to explain the observed behavior. The results showed that the optimal composition was 70% clay, 20% TPP ash, and 10% RHA, which demonstrated the highest compressive strength (15.45 MPa), reduced water absorption, and improved densification. The enhanced performance is attributed to partial vitrification and viscous-phase-assisted densification and the formation of crystalline phases such as mullite, cristobalite, and anorthite. The study confirms that the combined use of TPP ash and RHA enables effective recycling of local waste materials and improves the physical and mechanical properties of ceramic products. Full article

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20 pages, 3209 KB

Open AccessArticle

Sustainable Solar-Reflective Ceramic Engobes Based on Secondary Raw Materials

by Davide Casotti, Erika Iveth Cedillo-González and Cristina Siligardi

Ceramics 2026, 9(6), 53; https://doi.org/10.3390/ceramics9060053 - 26 May 2026

Abstract

The ceramic tile industry is increasingly required to reduce its environmental impact while maintaining high technological and aesthetic standards. In this context, the use of secondary raw materials (SRMs) represents a promising strategy to decrease the consumption of virgin resources and the energy [...] Read more.

The ceramic tile industry is increasingly required to reduce its environmental impact while maintaining high technological and aesthetic standards. In this context, the use of secondary raw materials (SRMs) represents a promising strategy to decrease the consumption of virgin resources and the energy demand associated with conventional frit production. At the same time, solar-reflective engobes can contribute to passive cooling by limiting solar heat absorption and mitigating the urban heat island effect. In this study, white solar-reflective engobes were developed by incorporating at least 8 wt.% of SRMs, including various recycled glass streams, ceramic wastes, and yttria-stabilized zirconia residues. The results demonstrate that optimized formulations achieve high solar reflectance values (up to 0.79) while maintaining the technological and aesthetic requirements of industrial ceramic tiles. Recycled glasses act as effective fluxing agents, whereas waste zirconia enhances optical performance due to its strong light-scattering capability. The most promising formulations were validated at the industrial scale, confirming their applicability under real production conditions. Overall, the developed engobes represent a scalable alternative to traditional frit-based systems, enabling reduced resource consumption and supporting the development of energy-efficient ceramic surfaces. Full article

(This article belongs to the Special Issue Ceramics in the Circular Economy for a Sustainable World, 2nd Edition)

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20 pages, 5182 KB

Open AccessArticle

Grain Versus Grain-Boundary Contributions to Thermal Conductivity in Prospective Oxide Ceramics for Next-Generation Thermal Barrier Coatings

by Roman Aleksandrovich Shishkin

Ceramics 2026, 9(5), 52; https://doi.org/10.3390/ceramics9050052 - 21 May 2026

Abstract

Thermal barrier coatings (TBCs) require materials with intrinsically low thermal conductivity and high grain-boundary thermal resistance to maximize the temperature gradient across the top coat. In this work, the effective thermal conductivity of more than 40 prospective TBC oxides belonging to seven structural [...] Read more.

Thermal barrier coatings (TBCs) require materials with intrinsically low thermal conductivity and high grain-boundary thermal resistance to maximize the temperature gradient across the top coat. In this work, the effective thermal conductivity of more than 40 prospective TBC oxides belonging to seven structural families (YSZ/YSH, pyrochlores/fluorites A₂B₂O₇, defective fluorites A₃BO₇, fergusonite/monazite ABO₄, and perovskites ABO₃) was systematically deconvoluted into intrinsic grain thermal conductivity (k_grain) and grain-boundary (R_gb) contributions. It is shown that grain-boundary Kapitza resistance dominates heat transport in virtually all advanced oxides, contributing 60–90% to the total thermal resistance of polycrystalline samples. The lowest k_grain values (4–12 W m⁻¹ K⁻¹) are found for cerates and certain tantalates, while the highest R_gb (up to 7.2 × 10⁻⁶ m² K W⁻¹) are characteristic of high-entropy and heavily doped perovskites. Orthorhombically distorted SrCeO₃-based and high-entropy perovskites combine moderate k_grain (4.7–27.9 W m⁻¹ K⁻¹), high R_gb, and tunable thermal-expansion coefficients (10–13 × 10⁻⁶ K⁻¹), making them the most promising candidates for next-generation TBCs. These findings provide a rational basis for microstructure engineering and composition design aimed at maximizing the temperature drop across TBC layers while maintaining phase stability and CMAS resistance. Full article

(This article belongs to the Special Issue Ceramic and Glass Material Coatings)

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24 pages, 6625 KB

Open AccessArticle

The Influence of Parameters on Surface Properties and the Optimization of HVOF-Sprayed NiCr/WC-Co Coatings

by Weimin Luo and Mingder Jean

Ceramics 2026, 9(5), 51; https://doi.org/10.3390/ceramics9050051 - 17 May 2026

Abstract

This study centred on the parametric optimisation and performance prediction of NiCr/WC-Co coatings produced by high-velocity oxygen fuel (HVOF) spraying. An L18 orthogonal experimental design based on the Taguchi method and the response surface method (RSM) was adopted to examine how key process [...] Read more.

This study centred on the parametric optimisation and performance prediction of NiCr/WC-Co coatings produced by high-velocity oxygen fuel (HVOF) spraying. An L18 orthogonal experimental design based on the Taguchi method and the response surface method (RSM) was adopted to examine how key process parameters affect the microstructure, phase composition and hardness of the coatings. The results revealed that analysis of variance (ANOVA) indicated that travel speed, methane flow rate, powder feed rate, and stand-off distance were the primary parameters affecting coating hardness, collectively accounting for 76.25% of the total variance. Also, the RSM model established in this study demonstrates remarkably high predictive accuracy, with a coefficient of determination (R²) of 0.985 and an average prediction error of just 1.16%. Verification experiments were also conducted under optimal conditions. The measured hardness was 1352.7 ± 75 HV, in close agreement with the predicted value of 1365 HV. The coating, which was applied using HVOF spraying, had a dense layered structure and low porosity, and the decarburisation of the tungsten carbide was extremely minimal. In addition, interfacial bonding is improved and structural defects are reduced by the addition of a NiCr intermediate layer. It is demonstrated by the results that the Taguchi-RSM method is reliable for the optimization of HVOF spraying parameters and the prediction of coating hardness. Full article

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20 pages, 8004 KB

Open AccessReview

Advances in Zirconia Crowns: A Comprehensive Review of Strength, Aesthetics, Digital Manufacturing, and Clinical Performance

by Sohaib Fadhil Mohammed, Mohd Firdaus Yhaya, Matheel Al-Rawas and Tahir Yusuf Noorani

Ceramics 2026, 9(5), 50; https://doi.org/10.3390/ceramics9050050 - 13 May 2026

Abstract

The use of zirconia as a material in the base of modern restorative dentistry is due to its high strength, biocompatibility, and improved aesthetic performance. The aim of this review is to provide an integrated and coherent overview of the recent developments in [...] Read more.

The use of zirconia as a material in the base of modern restorative dentistry is due to its high strength, biocompatibility, and improved aesthetic performance. The aim of this review is to provide an integrated and coherent overview of the recent developments in zirconia crowns by focusing on the development of materials, microstructure, digital fabrication processes, optical capabilities, and clinical performance. A survey of literature in the form of a narrative literature review was conducted in the most significant databases, such as PubMed, Scopus, Web of Science, and Google Scholar, including publications published since 2000, with a focus on systematic reviews, meta-analyses, clinical studies, and materials science studies. The results show that zirconia materials have developed beyond traditional 3Y-TZP systems, characterized by high strength and fracture toughness to high-translucency and multilayer zirconia (4Y 6Y-PSZ) systems, which provide better aesthetics at the cost of lower mechanical reliability. The implementation of CAD/CAM technologies has enhanced the accuracy of fabrication, marginal fit and reproducibility and the development of sintering, surface modification and bonding protocols has enhanced clinical performance. Recent clinical results have shown high survival rates (around 85–95 percent over 5–10 years), and the results depend on the design of the restoration, the zirconia generation, and the functional loading circumstances. Despite these developments, there are still concerns about the durability of bonding, trade-offs between translucency and strength, and long-term performance of high-translucency zirconia. The development of new technologies, such as additive manufacturing, design-aided artificial intelligence, and bioactive surface modification, is a promising avenue toward improving clinical reliability and performance. Full article

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11 pages, 2109 KB

Open AccessFeature PaperArticle

Synthesis of Fully Dense Monoclinic Zirconia Ceramics via Ternary Sintering Aids

by Akio Ikesue and Yan Lin Aung

Ceramics 2026, 9(5), 49; https://doi.org/10.3390/ceramics9050049 - 12 May 2026

Abstract

Fully dense monoclinic zirconia ceramics were successfully fabricated by pressureless sintering and/or HIP. Although monoclinic zirconia exhibits unique physicochemical properties, fabrication of fully dense polycrystalline bodies has remained challenging due to catastrophic volume expansion during the tetragonal-to-monoclinic transformation. By introducing a synergistic ternary [...] Read more.

Fully dense monoclinic zirconia ceramics were successfully fabricated by pressureless sintering and/or HIP. Although monoclinic zirconia exhibits unique physicochemical properties, fabrication of fully dense polycrystalline bodies has remained challenging due to catastrophic volume expansion during the tetragonal-to-monoclinic transformation. By introducing a synergistic ternary (Ga₂O₃-ZnO-TiO₂) sintering aid, a relative density exceeding 99.6% with an average grain size of 0.5–2 µm was achieved by sintering under an oxygen atmosphere at 1070 °C for 3–100 h, well below the phase-transition temperature. X-ray diffractometry confirmed a single-phase monoclinic structure. Subsequent hot isostatic pressing at 1080 °C and 180 MPa for 2 h eliminated residual porosity, yielding a 4-point bending strength of 328 MPa, a fracture toughness of 2.7 MPa·m^0.5, and a Vickers hardness HV₁ of 805. This monoclinic zirconia ceramic exhibited ~30% total transmittance, while in-line transmittance remained below 0.1% due to intrinsic birefringence of the monoclinic lattice. These results established a low-temperature route for densifying phase-sensitive ceramics while achieving long-term stability. Full article

(This article belongs to the Special Issue Advances in Ceramics, 3rd Edition)

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18 pages, 5867 KB

Open AccessArticle

Phase and Microstructure Modifications in Monoclinic Zirconia: Synergistic Effects of Extended Ball Milling and Annealing

by Mahesh Kumar Munchikana, Shivakumar Jagadish Shetty, Anbukkarasi Rajendran, Gurumurthy Sangam Chandrashekar, Manjunath Shetty, Tarun Sharda and Raghavendra Karkala Gururaj

Ceramics 2026, 9(5), 48; https://doi.org/10.3390/ceramics9050048 - 30 Apr 2026

Abstract

The structural response of ceramics to extreme deformation is of significant scientific and technological relevance since such conditions are commonly encountered during both processing and service. In this study, monoclinic zirconia was subjected to high-energy ball milling for extended durations of 80 h [...] Read more.

The structural response of ceramics to extreme deformation is of significant scientific and technological relevance since such conditions are commonly encountered during both processing and service. In this study, monoclinic zirconia was subjected to high-energy ball milling for extended durations of 80 h and 120 h, followed by annealing at 1000 °C. X-ray diffraction revealed a progressive increase in the tetragonal phase content with milling duration, while subsequent annealing promoted its consolidation alongside the principal monoclinic phase, resulting in a stable biphasic structure. The phase evolution is also evaluated through a Raman spectroscopy analysis and correlated with the morphology, mechanical properties, and surface area analyses. Scanning electron microscopy confirmed the preservation of nanoscale features in the milled and annealed specimens, in contrast to the unmilled sample, which exhibited pronounced grain coarsening. The combined presence of nanostructural stability and biphasic phase constitution underscores the efficacy of high-energy ball milling, in conjunction with thermal treatment, as an effective strategy to tailor the microstructure and phase stability of zirconia ceramics for advanced engineering applications. Full article

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23 pages, 4179 KB

Open AccessArticle

Multiphysics Modeling of Hot-Wall CVD Deposition of W–C–B Coatings for Process Optimization

by Andrey V. Poligenko, Evgeny A. Ruban, Kirill M. Osipov, Andrey A. Shaporenkov and Vladimir V. Dushik

Ceramics 2026, 9(5), 47; https://doi.org/10.3390/ceramics9050047 - 26 Apr 2026

Abstract

In this study, a multiphysics finite-element model was developed for the deposition of W–C–B coatings in a hot-wall tubular CVD reactor from a gas mixture of tungsten hexafluoride (WF₆), hydrogen (H₂), and trimethylamine borane ((CH₃)₃N:BH [...] Read more.

In this study, a multiphysics finite-element model was developed for the deposition of W–C–B coatings in a hot-wall tubular CVD reactor from a gas mixture of tungsten hexafluoride (WF₆), hydrogen (H₂), and trimethylamine borane ((CH₃)₃N:BH₃) at 550 °C and 5 Torr. The aim of this work is to deepen the understanding of reactant transport mechanisms and to optimize the process parameters for obtaining targeted tungsten carbide or boride phases. The simulations were performed in COMSOL Multiphysics (ver. 6.1) using a 2D axisymmetric formulation that couples laminar flow, heat transfer, and multicomponent diffusion, accounting for heterogeneous chemical reactions at the reactor walls. The obtained spatial distributions of reactant concentrations demonstrate precursor depletion along the reactor length. A comparison of the calculated B/W and C/W stoichiometric ratios for 13 operating conditions with experimental data confirms a transition from W and W–B phases at low trimethylamine borane (TMAB) flow rates to tungsten carbide-based coatings at higher flow rates. Furthermore, a parametric sweep was utilized to determine the optimal parameter range for the synthesis of tungsten borides. Full article

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14 pages, 2036 KB

Open AccessArticle

Temperature-Driven Transition from Knudsen Diffusion to Viscous Flow in a Macroporous Ceramic Membrane

by Mohammod Hafizur Rahman

Ceramics 2026, 9(5), 46; https://doi.org/10.3390/ceramics9050046 - 25 Apr 2026

Abstract

Ceramic membranes show potential for high-temperature CO₂ extraction from flue gas; nevertheless, their performance under simultaneous heat and pressure stress is not well comprehended. This research addresses the temperature-dependent CO₂/N₂ separation characteristics of a commercial ceramic membrane (pore size [...] Read more.

Ceramic membranes show potential for high-temperature CO₂ extraction from flue gas; nevertheless, their performance under simultaneous heat and pressure stress is not well comprehended. This research addresses the temperature-dependent CO₂/N₂ separation characteristics of a commercial ceramic membrane (pore size ~0.1–1 µm) utilizing simulated flue gas (11.8% CO₂, 74.2% N₂, 2.5% O₂, remainder CH₄) at temperatures ranging from 60 to 140 °C and pressures between 4 and 6 bar. Calibrated GC-TCD was used to quantify permeate compositions across multiple operating valve openings. With a CO₂/N₂ selectivity (α) of 0.75 at 4 bars, the maximum CO₂ enrichment peaked at 80 °C (10.8 mol%), getting close to the Knudsen diffusion limit (0.80). Selectivity decreased dramatically beyond 100 °C—α = 0.61 (100 °C), 0.45 (140 °C)—and CO₂ dropped to 5.8% at 4 bar and 2.2% at 6 bars. Viscous flow dominance was shown by the strong pressure amplification—α decreased by more than 60% from 4 to 6 bar at all temperatures. These findings emphasize the possibility of performance collapse in hot, pressured flue streams and identify the limited operating window under which Knudsen-controlled transport can be maintained. The study provides quantitative evidence of a transition in transport regime under mixed flue-gas conditions. Full article

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