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Purpose: To evaluate the effect of toothbrushing on the surface roughness (Sa), roughness profile (Rv), gloss units (GU), and surface morphology of three glazed ceramics. Materials and Methods: Specimens (n = 7) were made from the following different CAD/CAM materials and evaluated: lithium disilicate-based glass ceramic (EM); zirconia-reinforced lithium silicate glass ceramic (CE); and 6 mol% yttria partially-stabilized zirconia (IN). IPS e.max CAD (EM) and InCoris (IN) specimens were sintered, and all groups were prepolished and glazed according to the manufacturer's recommendations using IPS Ivocolor Glaze Paste (Ivoclar Vivadent) or Universal Overglaze High Flu (Dentsply/Sirona). Sa, Rv, GU, and morphology were analyzed before and after brushing at 30,000, 120,000, and 180,000 cycles. The data of Sa and GU were analyzed with ANOVA two-way and post hoc Tukey tests (a = .05). Rv was analyzed with Kruskal-Wallis and Student-Newman-Keuls tests. Surface morphology was analyzed qualitatively. Results: Sa decreased significantly after 180,000 toothbrushing cycles for all materials tested. CE showed higher Rv than EM and IN, and IN showed the highest GU after 180,000 toothbrushing cycles, which promoted a polishing effect for all materials. Conclusions: Long-term toothbrushing did not jeopardize the glazed surface of all tested materials compared to lack of brushing. [ABSTRACT FROM AUTHOR]

The ionic conductivity at the grain boundaries (GBs) in oxide ceramics is typically several orders of magnitude lower than that within the grain interior. This detrimental GB effect is the main bottleneck for designing high-performance ceramic electrolytes intended for use in solid-state lithium-ion batteries, fuel cells, and electrolyzer cells. The macroscopic ionic conductivity in oxide ceramics is essentially governed by the underlying polycrystalline microstructures where GBs and grain morphology go hand in hand. This provides the possibility to enhance the ion conductivity by microstructure engineering. To this end, a thorough understanding of microstructure–property correlation is highly desirable. In this work, we investigate numerous polycrystalline microstructure samples with varying grain and grain boundary features. Their macroscopic ionic conductivities are numerically evaluated by the finite element homogenization method, whereby the GB resistance is explicitly regarded. The influence of different microstructural features on the effective ionic conductivity is systematically studied. The microstructure–property relationships are revealed. Additionally, a graph neural network-based machine learning model is constructed and trained. It can accurately predict the effective ionic conductivity for a given polycrystalline microstructure. This work provides crucial quantitative guidelines for optimizing the ionic conducting performance of oxide ceramics by tailoring microstructures. [ABSTRACT FROM AUTHOR]

Purpose: To compare the masking ability of monolithic CAD/CAM veneers placed over different resin cement shades and substrate colors. Materials and Methods: Veneers were milled from four different monolithic CAD/CAM restorative materials: feldspathic ceramic (VMII), lithium disilicate ceramic (Emax CAD), zirconiareinforced lithium silicate ceramic (VS), and high-translucency zirconia ceramic (YZ-XT). Veneers were luted on natural tooth-colored (ND1) or discolored substrates (ND3 or ND5) using two different resin cement shades (opaque white or translucent). Each CAD/CAM material, resin cement shade, and substrate combination comprised 9 sample veneers (N = 216). Color parameters were obtained using a dental spectrophotometer before and after luting. Color differences (E00) were calculated using CIEDE2000 formula and compared to perceptibility (P = .81 E00 units) and acceptability (AT = 1.77 E00 units) visual thresholds. Color variation data were statistically analyzed using Kruskal-Wallis and Mann-Whitney U tests with Bonferroni-Holm correction (a = .05). Results: The highest E00 value was obtained in the VMII group placed over a discolored substrate, followed by the Emax CAD, YZ-XT, and VS groups. The effect of material types on E00 values was significantly observed when the veneers were luted on discolored substrates using translucent resin cement (P < .05). Conclusions: Restorative material type, substrate color, and resin cement shade affect the masking ability of monolithic CAD/CAM laminate veneers. [ABSTRACT FROM AUTHOR]

The article discusses the innovative use of additive manufacturing technology for creating lithium disilicate ceramic restorations in dentistry. Traditionally, these restorations were made using analog pressing or subtractive milling techniques. The article presents a case study demonstrating the feasibility of 3D printing lithium disilicate crowns for natural teeth and implants, comparing the results with subtractive fabrication. The study highlights the potential benefits of additive manufacturing, such as improved precision and cost-effectiveness, while emphasizing the need for further research and optimization of the technology. [Extracted from the article]

It was shown in Part II of this series of articles that geopolymers synthesized with organic bases could be used as precursors to mullite and mullite + glass composites. A natural next step is to determine whether it is possible to synthesize materials outside the Al2O3·SiO2 and alkali oxide·Al2O3·SiO2 phase systems. Hence, the focus of this study was the use of geopolymer‐like processing to make preceramic bodies with magnesium, yttrium, and zinc aluminosilicate and silicate compositions. These preceramics were successfully fired into monolithic bodies of cordierite, mixed yttrium and aluminum silicates, yttrium disilicate, and willemite. The synthesis of these preceramics employed a guanidine silicate solution, a synthetic oxide powder, and in some cases metakaolin to reach the oxide composition of the ceramic. All solidified within 3 days at 20°C or 50°C, depending on the composition. For the first time, this study showed that Y2O3 and ZnO can react with silicate solutions to give some Y‐O‐Si and Zn‐O‐Si bonding analogous to Al‐O‐Si bonding in geopolymers. These results suggest that other silicate compositions may be possible, such as with the rare earth oxides, which might be valuable to process like a geopolymer rather than by traditional ceramic processing. However, the ceramics made here were generally porous due to the expansion of gases within the sample that were trapped by a viscous liquid phase during firing. [ABSTRACT FROM AUTHOR]

Mixed oxide cubic pyrochlores of the composition Bi 2 Cu 1/3 Ni 1/3 Co 1/3 (Nb/Ta) 2 O 9±δ (sp.gr. Fd-3m) were synthesized for the first time by standard ceramic technology. According to X-ray phase analysis and Rietveld analysis, the Bi 2 Cu 1/3 Ni 1/3 Co 1/3 (Nb/Ta) 2 O 9±δ samples are single-phase and have a cell parameter of 10.5416(3)/10.5341(2) Å, respectively. The chemical state of transition element cations in oxide pyrochlores was characterized by X-ray photoelectron spectroscopy (XPS). The Nb 3d and Ta 4f spectra of the synthesized pyrochlores exhibit a characteristic shift to lower energies by 0.65 eV, which indicates that the effective charge of the niobium and tantalum cations is +(5-δ). A shift of Bi 4f spectra by 0.25 eV is typical only for niobium pyrochlore. It has been shown that NEXAFS Cu 2p spectra of oxide ceramics, according to the main characteristics of the spectrum, represent a superposition of spectra from Cu(I) and Cu(II) cations. Based on the analysis of the relative intensity of the peaks in the XPS spectrum of Cu 2p for pyrochlores, the content of Cu(I,II) cations was estimated. The ratio of Cu(I) to Cu(II) cations in niobium pyrochlore is higher than in tantalum pyrochlore, with approximately two times more Cu(I) cations than Cu(II). X-ray spectroscopy studies indicates that Co and Ni cations are present in the valence state (II, III). [ABSTRACT FROM AUTHOR]

Ceramic oxides are extensively utilized in soft magnetic composites (SMCs). However, further optimization is required to enhance their adaptability to the increasingly complex operational environments. This study investigated the applicability of a calcium–silicate–hydrate (CSH), prepared through the reaction between SiO 2 and Ca(OH) 2 , as an insulation layer in SMCs. The process began with the deposition of SiO 2 on FeSi soft magnetic powder using fluidized in situ chemical vapor deposition, followed by the introduction of Ca(OH) 2 to produce the FeSi/CSH SMCs. The mechanism behind the formation of the composite insulation layer was examined in depth. Furthermore, the effect of Ca(OH) 2 addition on the electro-magnetic characteristics of the prepared SMCs was examined. It was observed that in a relatively weakly alkaline reaction system, the interaction between SiO 2 and Ca(OH) 2 tends to form an amorphous CSH insulation layer with short-range order but without long-range order. As the contents of Ca(OH) 2 rises, so does the alkalinity, resulting in a crystalline CSH layer. However, excessive Ca(OH) 2 can cause agglomeration on the FeSi powder surface. Increasing the contents of Ca(OH) 2 from 0.5 to 2.5 wt% resulted in a reduction in both saturation magnetization and permeability of the FeSi/CSH SMCs, whereas the resistivity increased. The total core loss initially increased but decreased afterward. The FeSi/CSH SMCs prepared with 1 wt% Ca(OH) 2 exhibited the best overall magnetic properties. Under the 30 mT and 500 kHz, these SMCs stably maintained an effective permeability (μ e) of 46.15, while the total core loss (P total) was only 649.9 kW/m3. The saturation magnetization reached 183.1 emu/g, and the resistivity was 5.786 kΩ cm. These findings demonstrate that this method for constructing the insulation layer successfully produces FeSi-based SMCs with both high permeability and low total core loss. This method shows significant potential in the field of energy storage and paves the way for the development of high frequency SMCs. [Display omitted] [ABSTRACT FROM AUTHOR]

This study explores the emergence of oxidation-resistant alloys as potential replacements for traditional ceramics in Solid Oxide Fuel Cells (SOFCs), specifically Ferritic Stainless Steel (FFS). Despite its promise, FFS encounters challenges such as oxidation and corrosion. Most research on FFS interconnect damage has primarily focused on high-temperature oxidation in single atmospheres. However, in practice, the interconnect is exposed to both oxidizing and reducing atmospheres concurrently, leading to enhanced oxidation known as the dual atmosphere effect. The significance of this phenomenon is increasingly recognized by researchers and industry experts, yet understanding its implications for FFS degradation and protective measures remains a young discipline. This article provides an overview of the oxidation mechanisms of FSS under various conditions, proposed mechanisms, and potential protective strategies to address the effects of the dual atmosphere. • Describes the failure mechanisms of Ferritic Stainless Steel (FSS) interconnects. • Presents the parabolic exponential constant of FFS interconnects. • Reviews the oxidation of metal interconnectors under dual atmospheres. • Discusses prevalent coatings and application methods for FFS interconnects. [ABSTRACT FROM AUTHOR]

To resolve issues such as high sintering temperatures and relatively low relative densities and bending strengths of sintered bodies during the preparation of ceramic parts using binder jetting (BJ) additive manufacturing (AM) technology. In this study, high-performance SiO 2 -Al 2 O 3 -K 2 O (Na 2 O) ceramics were fabricated using quartz, kaolin, potassium feldspar, and sodium feldspar as raw materials through BJ technology. Initially, the sintering process of the BJ ceramics was studied by adjusting the ratio of potassium feldspar to sodium feldspar and the sintering temperature, which enhanced the relative density and bending strength of the silicate ceramics. Subsequently, using response surface methodology (RSM), the effects of print layer thickness (A), scraper speed (B), and ink volume per unit area (C) on the performance of the ceramics after sintering were investigated. Results indicated that the optimal parameters of the BJ printing process were determined using RSM: A was 250 μm, B was 3.44 mg cm−3, and C was 35 mm s−1. Under these conditions, the sintered ceramics achieved optimal relative densities, closed porosities, and flexural strengths of 89.05 %, 10.85 %, and 69.19 MPa for relative density, closed porosity, and flexural strength, respectively. [ABSTRACT FROM AUTHOR]

This study investigated the impact of various types of deflocculants with different chemical composition on ceramic slurries rheology. Organic and inorganic plasticizers were substituted for sodium silicate plasticizers in floor tile recipes, and their effects on rheology were assessed. The interactions of these materials with the silicate and ceramic slurry in terms of synergistic, antagonistic, and additive properties were then determined. In addition, the physico-mechanical properties of the ceramic bodies obtained using commercial plasticizers were investigated. Microstructural analysis using scanning electron microscopy (SEM) and mineralogical properties using x-ray diffraction (XRD) were performed. Results revealed that the addition of silicate to the slurry had a synergistic effect on rheology, reducing second viscosity to 50 s with a thixotropy ratio of 22%. Moreover, the flexural strength of the sample with 1% silicate addition increased by 13.6%, indicating positive effects on physico-mechanical properties. SEM analysis indicated the formation of a more uniform dispersion of particles with silicate addition. These findings suggest that incorporating silicate into ceramic slurries can effectively enhance both rheology and physico-mechanical properties, holding significant implications for ceramic tile and product manufacturing. [ABSTRACT FROM AUTHOR]

Gallium oxide (Ga2O3) has attracted much attention due to its promising applications in optical and electronic devices, while it is difficult to fabricate high‐quality Ga2O3 transparent ceramics because of the non‐cubic crystal structure. In this work, fully densified undoped and rare earth (RE = Tb, Dy. Er)‐doped Ga2O3 transparent ceramics were successfully fabricated by using spark plasma sintering (SPS) and co‐precipitated ceramic powders. Both the powders and ceramics showed pure monoclinic β‐ Ga2O3 crystal structure and unique orientation. After sintering by SPS for 30 min, all the ceramics reached a relative density higher than 99.21%. The total transmittance of RE‐doped Ga2O3 transparent ceramics ranges from 60% to 69% originating from the oriented and dense microstructures. The photoluminescence spectra and fluorescence lifetime of RE‐doped Ga2O3 transparent ceramics confirm characteristics of energy transfers corresponding to Tb3+, Dy3+, or Er3+ ions in the visible and NIR spectral region. This study demonstrates that oriented RE‐doped Ga2O3 transparent ceramics have great potential to be used in various optical applications. [ABSTRACT FROM AUTHOR]

Oxide ceramic nanofibers are widely used in aerospace and civil facilities due to their superior thermal stability and fire resistance. Currently, electrospinning, one of the important methods for preparing oxide ceramic nanofibers, must rely on adding organic polymers to impart spinnability to inorganic sols. However, these organic polymers will inevitably leave hole flaws in the ceramic nanofibers due to thermal decomposition during the subsequent ceramization process, seriously damaging their mechanical properties. Here, a direct electrospinning strategy for inorganic sol through hydrolyzation–polycondensation rate modulation is proposed, which gets rid of the dependence of spinnability of inorganic sol on organic polymer. Taking silica nanofibers as an example, it exhibits excellent flexibility and mechanical strength (tensile stress up to 1.4 MPa), as well as thermal insulation properties (thermal conductivity as low as 0.0551 W m−1 K−1 at 300 °C). This work provides new insights into developing other high–performance oxide ceramic materials. [ABSTRACT FROM AUTHOR]

Rare earth doped SrTiO 3 is one of the most promising oxide materials meeting the safety and stability requirements for potential applications in thermoelectric converters. This work aims to assess the feasibility of engineering SrTiO 3 -based materials to improve their thermoelectric performance. A comparative analysis of the thermoelectric properties of Sr 0.925 Dy 0.075 TiO 3 ceramic samples obtained from preliminarily mechanically activated Sr 0.925 Dy 0.075 TiO 3 nano-powder by two methods – solid-state reaction synthesis and spark plasma sintering – was carried out. Significant differences in the morphology of the samples lead to significant differences in the temperature dependences of electrical resistivity and the Seebeck coefficient. Ceramics obtained by solid-state reaction synthesis exhibit lower porosity and lower electrical resistivity. The thermoelectric power factor of such ceramics is 2–3 times higher than that of samples obtained by spark plasma sintering. The obtained value of thermoelectric figure of merit ZT = 0.41 at T = 673 K for Sr 0.925 Dy 0.075 TiO 3 is the highest value among n-type oxide thermoelectric ceramics at a given temperature and maintains a tendency to increase with increasing temperature. [ABSTRACT FROM AUTHOR]

High-entropy oxides (HEOs) have attracted extensive research interest due to their unique structural features, customizable elemental compositions, and tunable functional properties. Nevertheless, the complexity, low efficiency, and high cost of the existing HEO synthesis methods place limitations on them. In this study, Laser directed energy deposition (LDED) was employed to synthesize (Mg, Co, Ni, Cu, Zn)O oxides. Additionally, the novelty of applying the LDED process to multicationic systems was emphasized. The comparison between specimens fabricated from mixed powder via LDED(MP) and those fabricated from pre-sintered powder via LDED(SP) encompasses macroscopic morphology, microstructure, and performance. The results showed that SP significantly enhanced the density from 86.44 % to 96.70 % compared to MP. The macro-segregation of Cu and Cu 2 O in the phase composition was observed in MP and SP. High-temperature pre-sintering promoted the solid solution formation of Co and Ni during LDED, leading to more severe micro-segregation of Co and Ni. When employed as anodes in lithium-ion batteries, MP and SP have outstanding long-term cycle stability, according to electrochemical performance studies. At a current density of 100 mAg−1, these specimens maintained a capacity retention rate of 100 % even after 200 cycles. The initial discharge capacities of MP and SP were respectively 477.73 mAh g−1 and 373.86 mAh g−1. This study is expected to present a novel approach for the rapid synthesis of (Mg, Co, Ni, Cu, Zn)O oxide ceramics. [ABSTRACT FROM AUTHOR]

The sliding contact between a metal or semiconductor with another semiconductor can lead to a new charge generation mechanism known as the tribovoltaic effect. This effect has several advantage over the more common triboelectric effect, such as a higher rate of charge transfer and the ability to produce a direct current (DC) output directly via the junction interface. During operation, the junction interface produces a built-in electric field. In this study, we investigate the tribovoltaic effect on sliding between copper and unpoled lead zirconate titanate (PZT) ceramic. It was found that the contact between the metal and semiconducting oxide ceramic leads to the Schottky junction effect, which can effectively drive frictionally excited charges to an external load. By increasing the applied stress to PZT, we observed different current-voltage characteristic curves. The proposed electronic band behavior determines the electrical output direction in the tribovoltaic nanogenerator (TVNG). This direction depends on the built-in electric fields formed at the junction. The performance of the TVNG was tested in both series and parallel connections, observing clearly improved electrical outputs for both. The proposed TVNG can efficiently power small electronic devices, such as LEDs, and charge capacitors in a short period of time. This work expands the understanding of unconventional transport mechanisms through the Schottky contact of PZT and metal, and provides fundamental knowledge for the future development of tribovoltaic devices. [ABSTRACT FROM AUTHOR]

High entropy oxides with interesting physical properties can be obtained by the design of A-site cations. Herein, a series of medium entropy and high entropy perovskite ceramics (Ba 0.25 Sr 0.25 Ca 0.25 Bi 0.25)TiO 3 , (Ba 0.2 Sr 0.2 Ca 0.2 Bi 0.2 La 0.2)TiO 3 , (Ba 0.2 Sr 0.2 Ca 0.2 Bi 0.2 Na 0.2)TiO 3 and (Ba 0.2 Sr 0.2 Ca 0.2 La 0.2 Na 0.2)TiO 3 were synthesized by the solid-state method, which selected various valence elements to achieve a single-phase structure and increase the lattice distortion. The microstructure indicated that the high-entropy ceramics exhibited the same macroscopic single perovskite while the local configuration is different. Mesoscopic results show that high entropy can adjust the polarization and relaxation of ferroelectrics, so as to optimize the energy storage performance. Meanwhile, the results manifest that grain boundaries, oxygen defects and relaxation can be changed by entropy configuration. Our work proves that the properties of high entropy ferroelectric materials can be regulated by different valence states of the elements in high entropy and explores the relevant mechanism, which provides a possible opportunity for the design and application of high-entropy dielectric materials with excellent properties. [ABSTRACT FROM AUTHOR]

This study investigates the dislocation density in ceramics processed by severe plastic deformation at room and elevated temperatures via high-pressure torsion (HPT) for various numbers of turns and shear strains. Ceramics, characterized by ionic or covalent bonding, typically exhibit brittleness due to limited dislocation activity. However, HPT enables significant microstructural transformations in ceramics including dislocation nucleation and accumulation. Despite recent advances in the visualization of such dislocations by transmission electron microscopy (TEM), there is a lack of comprehensive reports on the quantification of dislocation density in severely deformed ceramics. This paper addresses this gap by employing X-ray diffraction (XRD) analysis to quantify dislocation density and crystallite size in a few oxide ceramics. Results demonstrate that HPT induces exceptionally high dislocation densities comparable to theoretical upper limits of dislocation density in ceramics, on the order of 1015 to 1016 m−2, with crystallite sizes reduced to the nanometer scale. These findings significantly enhance the understanding of dislocation behavior in ceramics and suggest a potential approach for tuning the mechanical and functional properties of these materials by dislocations. [ABSTRACT FROM AUTHOR]

The work illustrates a solid-state reaction technique to synthesize the strontium-doped zinc oxide ceramics (Zn1-xSrxO) at varying dopant concentrations (x = 0–0.03). The phase of the synthesized sample was investigated using X-ray diffraction (XRD) and its structural parameters were analyzed using Rietveld refinement. The elemental composition and morphology of the synthesized samples were evaluated using Energy-Dispersive X-ray Spectroscopy (EDX) and Field Emission Scanning electron microscopy (FESEM). The optical behavior was evaluated using UV–Vis diffuse reflectance spectra (UV–Vis DRS). The negative temperature coefficient of resistance (NTCR) behavior was examined through impedance spectroscopy. The synthesized samples showed a single-phase hexagonal wurtzite structure up to x = 0.03, which indicates that the Sr2+ ion is substituted in the ZnO lattice. Significant changes in the morphology were observed in the FESEM micrograph of Sr-doped ZnO ceramic samples. EDX analysis confirms the presence of Sr dopant in the ZnO lattice. The band gap (Eg) of ZnO was found to be decreased with Sr doping. The synthesized sample shows that resistance decreases as temperature rises, as obtained from impedance measurement, confirming the NTCR nature. A temperature-dependent electrical relaxation phenomenon at high temperature was observed. A parallel RC circuit has been observed for both ZnO and Sr-doped samples. [ABSTRACT FROM AUTHOR]

The article presents the concept of using 3D printing technology in ceramic foundry filter manufacturing. They are a crucial component for obtaining an acceptable quality of nickel superalloys by carrying out the process using the precision casting method. Commonly used filters of this type have a number of disadvantages. They are characterized by irregularity of the filtering structure, high brittleness, lack of resistance to mechanical shocks, and impacts of a stream of liquid metal. All these factors create a risk of introducing the material from the damaged filter into the casting mold, which translates into contamination of the casting alloy, and thus the occurrence of casting defects such as nonmetallic inclusions. The hope for a change in this state of affairs is the use of additive manufacturing technology in their production, which by assumption will allow to obtain a product with a repeatable shape, high mechanical resistance, and a specially designed structure regulating the flow of liquid metal into the mold during casting. The suitability of robocasting and binder jetting technology for producing filtration structures was initially assessed. The results have presented the selection of ceramic powder, as well as the development of the composition of the ceramic paste. The parameters of paste preparation and 3D printing individual processes were described. Moreover, the representative microstructures and basic mechanical properties of samples obtained by both of the compared technologies were presented. Furthermore, the final effect of prototype casting filters with a repeatable shape, manufactured with the use of both technologies, was presented, which were transferred for further technological research in a foundry producing critical aircraft engine parts. The possibilities of using each technology in various applications were also discussed. [ABSTRACT FROM AUTHOR]

In the current work, a simple mechanochemical route has been employed to preparatively access three spinel‐type compositionally complex ceramics, i. e., (Co, Fe, Mn)3O4, (Co, Fe, Mn, Ni)3O4, and (Co, Cr, Fe, Mn, Ni)3O4. Hydrated nitrate salts of the respective transition metal elements were mechanically ground with ammonium hydrogen carbonate. The resulting paste‐like mixture of metal hydroxides, oxyhydroxides, and carbonates was rinsed with water to remove the byproduct (NH4NO3) and converted into the respective single‐phase spinel‐type oxides via calcination. In situ X‐ray diffraction (XRD) revealed the formation of the spinel‐type structure (Fd3‾ ${\bar{3}}$ m) already at temperatures as low as 150 °C. Typically, the calcination of the precursors at temperatures beyond 500 °C led to the formation of well‐crystallized, single‐phase spinel‐type oxides with nearly equimolar composition and highly homogeneous distribution of the transition metals within the structure. The mechanochemical synthesis route in the present study is considered to be an easy, straightforward, and scalable access to compositionally complex oxides. [ABSTRACT FROM AUTHOR]

In the current work, a simple mechanochemical route has been employed to preparatively access three spinel‐type compositionally complex ceramics, i. e., (Co, Fe, Mn)3O4, (Co, Fe, Mn, Ni)3O4, and (Co, Cr, Fe, Mn, Ni)3O4. Hydrated nitrate salts of the respective transition metal elements were mechanically ground with ammonium hydrogen carbonate. The resulting paste‐like mixture of metal hydroxides, oxyhydroxides, and carbonates was rinsed with water to remove the byproduct (NH4NO3) and converted into the respective single‐phase spinel‐type oxides via calcination. In situ X‐ray diffraction (XRD) revealed the formation of the spinel‐type structure (Fd3‾ ${\bar{3}}$ m) already at temperatures as low as 150 °C. Typically, the calcination of the precursors at temperatures beyond 500 °C led to the formation of well‐crystallized, single‐phase spinel‐type oxides with nearly equimolar composition and highly homogeneous distribution of the transition metals within the structure. The mechanochemical synthesis route in the present study is considered to be an easy, straightforward, and scalable access to compositionally complex oxides. [ABSTRACT FROM AUTHOR]

Yangshao culture, as the most important Neolithic culture in China, is famous for its finely decorated pottery. In this work, Yangshao potteries excavated in Shanxi province, one of the core distribution areas, were studied by micro‐Raman spectroscopy combined with optical microscopy, X‐ray fluorescence, and scanning electron microscopy equipped with energy‐dispersive X‐ray spectroscopy. The color of the red decor is derived from hematite and maghemite. The black decorations on the surface are more complex, which could be divided into two types according to the Mn/Fe ratios and crystalline types: (1) low MnO2/Fe2O3 ratio and jacobsite and magnetite and (2) high MnO2/Fe2O3 ratio and hausmannite. The former color is obviously brighter than the latter. This study also demonstrates the potential of micro‐Raman microscopy in analyzing the nature of colorant crystals in Yangshao painted potteries and, therefore, better deciphering the technical details involved in the potteries of Yangshao culture. [ABSTRACT FROM AUTHOR]

To investigate the potential of rare earth oxide structural ceramics for high-temperature insulation applications, we introduced aerogel structures into Yb 2 SiO 5 ceramics. In this study, the pure Yb 2 SiO 5 ceramic aerogels were successfully prepared by calcination using formamide as a gelling agent, the sol-gel method, and the CO 2 supercritical drying method. The results indicate that the Yb 2 SiO 5 ceramic aerogel exhibits exceptional structural and phase stability at a temperature of 1400 °C. In addition, we have developed Yb 2 SiO 5 ceramic aerogel composites reinforced with aluminosilicate fiber cotton, which exhibit low density (228.77 kg m−3) and low thermal conductivity (0.038 W m−1 K−1 at 25 °C, 0.102 W m−1 K−1 at 1000 °C). The back temperature of the 10 mm thick composites is only 285 °C after exposure to a butane blowtorch flame at 1300 °C for 600 s. This demonstrates its excellent high-temperature insulation performance. This work can provide a basis for further design and preparation of oxide ceramic high-temperature thermal protection materials with controllable morphology and properties. [ABSTRACT FROM AUTHOR]

The objective of bone tissue engineering is to develop materials and techniques that can repair large segmental bone defects by locally adding bioactive materials in precise configurations. This field has advanced significantly since the introduction of scaffold materials, requiring breakthroughs in materials science, biomechanics, biomedical engineering, and regenerative medicine. 3D printing technology, due to its precision and customization capabilities, has gained prominence in creating personalized scaffolds that enhance bone healing and modulate immune responses. The review delves into the mechanisms of bone injury healing, highlighting the crucial role of the immune system and macrophage polarization in the healing process. It covers various 3D printing techniques, including extrusion-based 3D printing (EP), fused deposition modeling (FDM), and light curing 3d printing, discussing their suitability for fabricating complex scaffold structures. The materials discussed include calcium phosphate ceramics, silicate ceramics, and ceramic/polymer and ceramic/metal composites. Key factors influencing the immune regulatory functions of these scaffolds, such as surface nano-structures, pore size and porosity, surface charge, and the release of metal ions, are examined. Despite significant advancements, challenges remain in clinical applications, including issues with raw materials, high-temperature shrinkage, printing precision, structural stability, and immune regulation. Future research directions involve improving material selection, optimizing scaffold design, and leveraging advanced 3D printing technologies to enhance the biocompatibility, bioactivity, and mechanical properties of bioceramic scaffolds. This review provides a comprehensive understanding of current progress and future prospects in the field of 3D printed bioceramic scaffolds for bone tissue repair and immune regulation. [ABSTRACT FROM AUTHOR]

How to refine the grain has been a difficult problem in the preparation of high-performance ceramic targets. In this work, the doping-induced grain refinement strategy was proposed, indium zinc oxide doped with different concentrations of Pr (Pr-doped IZO, PrIZO) targets were obtained by optimizing the sintering time and holding temperature. Effects of Pr doping content on the density, phase microevolution, grain size and resistivity during the densification process as well as the kinetics of the grain growth and the mechanism of grain refinement of PrIZO targets were investigated in detail. The results demonstrated that PrIZO targets with the atomic ratios of Pr:In:Zn = 0.01-0.03:1:1 all exhibited the excellent performance with high densification (>99.10 %) and mere average grain size (<3.0 μm) at low sintering temperature of 1350 °C. Additionally, XRD and EDS analysis indicated that PrIZO targets were composed of In 2 O 3 and Zn 3 In 2 O 6 with slight PrInO 3 , which formed by the limited solid solubility of Pr element. Combined with theoretical calculations, it inferred that the mechanism of grain refinement was attributed to the solute transformation and fine PrInO 3 distributed at the grain boundaries of In 2 O 3 phases, which produced the drag effect of grain boundary migration, then hindering the further growth of grains. [ABSTRACT FROM AUTHOR]

Aluminium (Al) and Al-based alloys known as lightweight, good corrosion resistance, and low-cost materials are found used for a range of engineering applications including those in automobile, aircraft, power systems, marine, defence, and among others. Although, notwithstanding these intrinsic features of Al and its alloys, their wide application is constrained due to certain properties, for example, dendrite separation, intense wear rate over a period, and mechanical degradation under severe impact and harsh environment. Nonetheless, as studies established that nanocomposites depict a promising solution to overcome the limitations of Al, Al-based alloy and their micro composites. The current review aims to discuss the influence of nanoceramic fillers on the mechanical and tribological characteristics of Al and Al alloy-based composites prepared via melting and powder metallurgy routes. With the available literature, the mechanical and wear resistance properties of Al and Al alloys matrix were observed to be improved by different nanoceramic fillers addition. Though, their mechanical behaviour at a certain point undergoes degradation due to particles agglomeration and porosity. Again, issues like brittleness reportedly affect the superior properties' improvement of Al-based nanocomposites. Thus, as particles agglomeration, porosity, and brittleness are the main drawbacks associated with the development and characterization of Al-based nanocomposites, the authors concluded the study with challenges and recommendations for future improvement. Hence, the study will pave the way for future research opportunities and sustainable development of Al nanocomposites. [ABSTRACT FROM AUTHOR]

Oxide ceramic matrix composites (Ox‐CMCs) are composed of porous matrices reinforced by dense fibers to achieve high damage tolerance. It is generally assumed that their mechanical properties are fiber dominant. However, fiber strength can also be influenced by the surrounding matrix as it can affect fiber grain growth. Fiber–matrix interactions are studied in this work regarding fiber microstructural evolution and composite strength. Minicomposites containing Nextel 610 fibers and different matrix compositions (alumina, alumina–zirconia, and mullite–alumina) are evaluated after sintering and after additional heat treatment at 1200°C for 100 h. Fiber grain growth during sintering is faster in alumina matrix and slower in mullite–alumina matrix. Scanning transmission electron microscope–energy‐dispersive X‐ray spectroscopy (STEM–EDX) measurements show that Si diffuses between fiber and matrix grain boundaries. This outward or inward diffusion of SiO2 leads to the respectively different grain growth kinetics. Grain growth inhibition in alumina–zirconia matrix is only observed after the longer heat treatment, suggesting that ZrO2 diffusion is slower than SiO2. The resultant composite strength depends not only on fiber properties, but also on matrix densification. Minicomposite with alumina–zirconia matrix showed higher strength, while mullite–alumina composites showed higher thermal stability. In summary, the properties of Ox‐CMCs can be tailored by adjusting the matrix composition with the used fibers. [ABSTRACT FROM AUTHOR]

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Copyright of Quintessenz der Zahntechnik is the property of Quintessenz Verlags GmbH and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Two clinical cases involving the fracture of a natural tooth and one of a ceramic crown are presented and discussed based on fractography principles. In the first case, a patient reported intense pain in a sound third molar where a longitudinal fracture was identified, and the tooth was extracted. In the second case, a posterior rehabilitation using a lithium silicate ceramic crown was carried out, and the patient returned after 1 year with a fractured piece of the crown. Both were analyzed under microscopy to identify the origins of fractures and their causes. The fractures were critically analyzed so that relevant information could be generated from the laboratory to the clinic. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the performance of fully crystallized zirconia-reinforced lithium silicate (Celtra Duo, ZLS-CD), partially crystallized zirconia-reinforced lithium silicate (Vita Suprinity, ZLS-VS), and partially sintered lithium disilicate-based (IPS e.max CAD, LD) glass-ceramics submitted to polishing, glazing, or no surface treatment after aging. Material and Methods: Samples of each glass-ceramic material were subjected to polishing with rubber cups (POL), glazing (GL), or no treatment (control: unpolished) and afterward aged with 18,000 thermal cycles (5°C to 55°C). The average roughness, 2D and 3D morphology, contact angle, multispecies biofilm formation (Streptococcus mutans and Candida albicans), and mechanical strength were evaluated with atomic force microscopy (AFM, n = 5), sessile-drop goniometry (n = 5), spectrophotometry (n = 5), and the flexural strength test (n = 10), respectively. Data were analyzed using two-way ANOVA and Tukey test (a = 5%). Results: POL produced lower surface roughness than GL, and ZLS-CD presented higher roughness than LD (P < .05). Surfaces without polishing displayed higher roughness than the POL group (P < .001), greater contact angle (P < .001), and significant morphologic changes, regardless of the glassceramic material. Irrespective of the treatment, the contact angle was higher in the ZLS-CD group, and regardless of the material, there was higher biofilm formation and lower flexural strength of the unpolished compared to the POL or GL ceramics. Conclusions: POL promoted lower roughness and minor morphologic surface alterations, but biofilm formation and flexural strength were similar to the GL group. In general, ZLSCD and ZLS-VS showed more similar behavior than LD, which makes ZLS glass-ceramic a good option for indirect restorations. [ABSTRACT FROM AUTHOR]

Compared to Li+ and Na+ ion‐conducting sulfides with conductivities of ≈10⁻2 S cm⁻1 at room temperature, oxide ceramics typically exhibit conductivities an order of magnitude lower, rendering them less attractive as electrolytes for all‐solid‐state batteries (ASSBs). This study presents NASICON‐based electrolyte, achieving a remarkable conductivity of 6.0 × 10⁻3 S cm⁻1 at room temperature, rivaling that of sulfide‐based electrolytes. This is accomplished by optimizing the composition in the range Na3+x+yZr2−yAlySi2+xP1−xO12 (0.10 ≤ x ≤ 0.50, 0 ≤ y ≤ 0.1). Despite the issue of reduced sinterability with increasing Si/P ratio due to the formation of a viscous SiO2‐rich grain boundary interphase, the addition of Al2O3 effectively reduces the viscosity and improves the sinterability. In other words, a strategy of engineering the liquid phase that is in situ generated from the host phase is viable. The enhanced conductivity is attributed not only to the lowered grain boundary resistivity but also to lattice expansion from modified Na occupations in the crystal structure. Furthermore, this material demonstrates a wide electrochemical window, suppressed partial electronic conductivity, low polarization voltage in direct contact with a Na anode, and charge‐discharge cycles with minimal polarization when directly interfaced with a NASICON‐type cathode, repositioning it as a promising electrolyte for ceramic ASSBs. [ABSTRACT FROM AUTHOR]

The compositional diversity of vitrified silicate ceramics has been quantified through multivariate statistical analysis and by means of specific chemical parameters of bodies. Distinct compositional spaces can be drawn for porcelains, porcelain stoneware, red stoneware, and silicate glass-ceramics. Porcelain and vitreous china bodies are strongly peraluminous with commonly a potassic character. A sharp boundary at ∼79 % alumosity separates them from porcelain stoneware bodies, which are peraluminous with a predominantly sodic character. The comparison of glazed versus unglazed porcelain stoneware revealed essential differences in iron content, but a deeper analysis is needed at the manufacturing district scale. Glass-ceramic bodies are peralkaline and low in silica. Red stoneware is characterized by Fe 2 O 3 content about 3–9 wt% and variable Na/K and alkali-to-alkali-earths ratios. The compositional gap between red stoneware and porcelain stoneware bodies (1.5 % < Fe 2 O 3 < 3 %), still unexploited by industry, is crucial to enable many resource efficiency and waste recycling actions. The formulation of waste-based silicate ceramics usually implies a shift of the chemical composition towards higher Fe 2 O 3 /Al 2 O 3 ratio and lower alkali-to-alkali earth ratio. This can lead to batches that fall outside the compositional space of porcelain or porcelain stoneware, opening to technological behaviour and technical performance that require further research. [ABSTRACT FROM AUTHOR]

To create thermal barrier coatings (TBCs) with superior thermal characteristics and high-temperature stability, understanding the microscopic process of heat transfer in high-entropy solid solutions is crucial. In this study, novel (Zr 0.2(1-x) Ce 0.2(1-x) Pr 0.2(1-x) Y 0.2(1-x) Ho 0.2(1-x) Mg x)O 2-δ single-phase high-entropy fluorite-structured oxides with varying Mg elemental contents were successfully synthesized at 1600 °C. Given the unique ionic radius and valence nature of Mg2+, the effects of varying the Mg doping amount on the thermophysical properties and microstructures were explored. Furthermore, the mechanism influencing high-temperature thermal conductivity was studied at the microscopic scale using first-principles calculations to clarify the nature of the thermal conductivity behavior. On one hand, an increase in oxygen vacancies leads to an enhancement of the lattice distortion degree and phonon scattering level. On the other hand, divalent Mg2+ activates the lattice via unequal substitutions, thereby reducing the thermal conductivity. The experimental and simulation results revealed that as Mg doping increases, the content of oxygen vacancies significantly increases, the degree of lattice distortion increases, phonon scattering is enhanced (19.54–21.37 THz), high-temperature thermal conductivity progressively decreases (1.91-1.20 w·m−1·K−1), and the coefficient of thermal expansion progressively increases (11.70 × 10−6-12.31 × 10−6 K−1). These results offer a novel approach for designing doped high-entropy strategies that can satisfy the performance requirements of TBCs. [ABSTRACT FROM AUTHOR]

Microstructures and thermoelectric properties of porous Ca 3 Co 4 O 9 ceramics were investigated, which were prepared by tert-butanol alcohol (TBA)-based freeze casting method. The honeycomb-like porous Ca 3 Co 4 O 9 ceramic presented an average pore diameter of 2.5 μm and the porosity of 65 %. The excellent low total thermal conductivity of 0.354 W (m K)−1 was obtained along the parallel channel direction, which was attributed to the oriented pores and isolated pores dispersed in ceramics matrix. The compositing thermal conductivity behavior of porous Ca 3 Co 4 O 9 ceramics was jointly regulated by the parallel and Maxwell-Eucken (ME-1) models. The ZT value reached 0.37 at 1073 K. This work provides an effective strategy to improve thermoelectric properties of oxides thermoelectric ceramics, which can complete the decoupling of electrical and thermal properties. [ABSTRACT FROM AUTHOR]

In this research, the accumulative roll bonding (ARB) technique was employed as a severe plastic deformation method to manufacture a unique bi-metal Pb/W composite reinforced by Co 3 O 4 ceramic oxide. For this purpose, composites with different amounts of reinforcement particles (0.25, 0.5, 1, 1.5, and 2 wt%) were successfully produced using the ARB process (up to 10 cycles). Also, the mechanical properties were evaluated using microhardness, tensile, and shear punch tests. For microstructural investigations, the X-ray diffraction method (XRD), transmission electron microscopy (TEM), and fractography analysis by scanning electron microscopy (SEM) were employed. The Pb-0.5%W/Co 3 O 4 following 10 ARB cycles exhibited optimal mechanical and microstructural properties. For this composite, the tensile strength showed a markable increase of 2.17 times, yield strength by 4.7 times, shear strength by 3.6 times, and hardness by 4.2 times compared to the pure Pb sample subjected to the same ARB cycles. However, the strain was reduced by 3.85 times. These enhanced properties are also followed by increased stiffness and improved anode dimensional stability, creep resistance, and operational lifespan. [Display omitted] [ABSTRACT FROM AUTHOR]

In this work, the Dy 2 O 3 -Al 2 O 3 -SiO 2 (DASN) and Dy 2 O 3 -Al 2 O 3 -SiO 2 -TiO 2 (DAST) glass fillers were used for joining alumina ceramic. During the cooling process of the alumina/DASN/alumina joints, Dy 2 Si 2 O 7 and Al 2 O 3 were precipitated simultaneously and gradually grown. As a result, voids were formed due to the poor flowability of the glass ceramic filler and the large density difference between the glass filler and Dy 2 Si 2 O 7 crystals. On the contrary, the addition of TiO 2 altered the sequence of the crystalline phase precipitation during the cooling process. During cooling from the joining temperature (1450 °C) to 1100 °C, only Dy 2 Si 2 O 7 was formed in the brazing seam. Simultaneously, the flowing glass phase was able to fill the spaces caused by the density differences. When the growth of Dy 2 Si 2 O 7 phase ceased, the Al 2 O 3 phase began to precipitate. Therefore, the voids caused by density differences can be eliminated in the alumina/DAST/alumina joints with high crystallinity. The optimal flexural strength of alumina/DAST/alumina joints tested at room temperature and 1000 °C reached 350 MPa and 158 MPa, respectively. [ABSTRACT FROM AUTHOR]

In this paper, the evolution of the microstructure for the zinc silicate ceramics with different Zn/Si ratios was revealed, and the factors influencing their dielectric properties were discussed. Our results demonstrate that Zn volatilization plays an important role on the defect structure of the samples. Low relative density, high conductivity loss caused by volatilization, and the presence of ZnO phase collectively result in low quality factor (Qf) of Zn 2.0 SiO 4.0. By using the powder embedded sintering method, the loss could be reduced owing to the suppression of volatilization. As the Zn/Si ratio decreases, the ZnO disappears, while the Si-rich phase emerges and increases. The formation of a liquid phase results in a dense microstructure of the non-stoichiometric samples. Moreover, these samples exhibit a minor degree of Zn loss, probably because the presence of liquid phase constraints the volatilization during sintering. The samples with x = 1.8 display desirable properties, including a relative dielectric constant (ε r) of 6.5, a Qf of 100,800 GHz, and a temperature coefficient of resonant frequency (τ f) of −21.3 ppm/°C, due to their high degree of densification, slight zinc loss, and the elimination of the ZnO phase. [ABSTRACT FROM AUTHOR]

[Display omitted] Piezocatalysis has emerged as a sustainable alternative for hydrogen peroxide production. However, the current development of efficient piezocatalysts is predominantly focusing on those conventional piezoelectric ceramic oxides with high permittivity and limited catalytic activities. Therefore, innovative approaches to develop novel piezocatalysts in particular from these outstanding paraelectric semiconductors are highly required. In this work, by employing a feasible doping strategy, robust piezoelectric property is created on the Ba 2 Nb 2-x Fe x O 6-δ double perovskite oxides, typically characterized by a stable paraelectric cubic structure. Optimum Fe doping not only intensifies the double perovskite phase but also inspires a phase transition from a centrosymmetric cubic to a piezoelectric tetragonal phase, thereby achieving desirable piezoelectricity and enabling a series of favorable physical properties including redox activity, active sites of anion defects, reduced bandgap, and increased free charge density. All these are important factors to enhance piezocatalytic activity. As a result, Ba 2 NbFeO 6-δ achieved by the optimum Fe doping demonstrated exceptional piezocatalytic H 2 O 2 yield of 512 and 690 µmol g-1 h−1 under atmosphere and oxygen-purging conditions, respectively, without the presence of any sacrificial agents. Mechanistic investigations reveal that both water oxidation and oxygen reduction involve in the H 2 O 2 production, wherein piezopotential plays a critical role not only in facilitating the charge carrier separation and transportation but also in modulating the band structure to enhance the catalyst redox capacity. This study offers a feasible and universal strategy for the design of novel piezocatalysts, expanding the windows for catalyst selection for piezocatalysis. [ABSTRACT FROM AUTHOR]

Oxide ceramic electrolytes (OCEs) have great potential for solid-state lithium metal (Li0) battery applications because, in theory, their high elastic modulus provides better resistance to Li0 dendrite growth. However, in practice, OCEs can hardly survive critical current densities higher than 1 mA/cm2. Key issues that contribute to the breakdown of OCEs include Li0 penetration promoted by grain boundaries (GBs), uncontrolled side reactions at electrode-OCE interfaces, and, equally importantly, defects evolution (e.g., void growth and crack propagation) that leads to local current concentration and mechanical failure inside and on OCEs. Here, taking advantage of a dynamically crosslinked aprotic polymer with non-covalent –CH3⋯CF3 bonds, we developed a plastic ceramic electrolyte (PCE) by hybridizing the polymer framework with ionically conductive ceramics. Using in-situ synchrotron X-ray technique and Cryogenic transmission electron microscopy (Cryo-TEM), we uncover that the PCE exhibits self-healing/repairing capability through a two-step dynamic defects removal mechanism. This significantly suppresses the generation of hotspots for Li0 penetration and chemomechanical degradations, resulting in durability beyond 2000 hours in Li0-Li0 cells at 1 mA/cm2. Furthermore, by introducing a polyacrylate buffer layer between PCE and Li0-anode, long cycle life >3600 cycles was achieved when paired with a 4.2 V zero-strain cathode, all under near-zero stack pressure. Self-healing is an appealing property for solid-state battery electrolytes to combat Li metal dendrites that pierce through the solid electrolyte. Here, authors report a self-healing electrolyte and observe its self-repairing kinetics in real-time using advanced microscopy. [ABSTRACT FROM AUTHOR]

Piezoelectric nanogenerators (PENGs), the current pathway to sustainable energy harvesting, are mostly comprised of bulk oxide ceramics which are toxic, rigid, and costly to synthesize. A suitable alternative to them is flexible polar polymers like polyvinylidene fluoride (PVDF), but stabilizing its polar phase is also a daunting task. all these aforementioned issues by employing a biocompatible have been solved, above‐room‐temperature (Tc > 390 K) ferroelectric discrete molecular complex [Cu(L‐His)(bpy)]ClO4.1.5H2O (Cu‐FE) which is not only suitable for piezoelectric energy harvesting due to its large values of piezoelectric co‐efficient (d33 = 17 pm V−1) but also is capable of imparting polar β‐phase in PVDF via hydrogen bonding interactions under mild condition (60 °C). Among the PENG devices prepared with the composite films of PVDF and various weight % (w/V) compositions of Cu‐FE, the highest output voltage of 8 V (peak to peak) has been obtained, a power density of 4 µW cm−2, and an output current of 3 µA from the 1 wt.% composite film. The fabricated PENG device also exhibits swift capacitor charging in 40 s, and acts as an excellent pressure sensor, with exceptional sensitivity to low pressures (7 kPa), giving an output of 0.4 V. [ABSTRACT FROM AUTHOR]

Surface modification of separators with inorganic oxide ceramics such as SiOx, Al2O3, and TiO2 has emerged as a promising strategy to suppress lithium dendrite growth in lithium metal batteries, thereby enhancing safety and extending battery life. However, the binder‐dependent nature of these modifications often leads to increased separator thickness and a heightened risk of detachment during lithium plating, ultimately compromising both battery performance and energy density. In this study, a conformal, ultrathin (≈20 nm) SiOx coating with strong covalent bonding is grown on a porous separator through a liquid polymer‐derived method. Compared to the pristine polyethylene (PE) separators, this SiOx‐co‐PE separator exhibits significantly improved electrolyte wettability, mechanical strength, and thermal stability without any increase in thickness, leading to vastly enhanced cycling stability and dendrite resistance in cells with Li metal anodes. In a practical demonstration, a 402.9 Wh·kg−1 Li‐S pouch cell, with a high sulfur loading of 9 mg cm−2 and a low E/S ratio of 3.3 µL mg−1, is assembled with the SiOx‐co‐PE separator, achieving stable cycling over 70 cycles at 25 °C. [ABSTRACT FROM AUTHOR]

This study systematically investigates the influence of preparation temperature on microstructure and generation mechanism of Si–Y–B-Yb ceramics as anti-corrosion matrix. Main phases of Si–Y–B-Yb ceramics are Y/YbB 4 , YSi 2 , and Si, where Y/YbB 4 is derived from the reaction between YSi 2 and YbB 6. With increase in preparation temperature, open porosity of Si–Y–B-Yb ceramics gradually decreases, reaching 0.24 % at 1350 °C, and internal phases transform from a dispersed distribution to clearly defined boundary state. Based on this, high-temperature water-oxygen corrosion behavior of Si–Y–B-Yb ceramics is characterized in 50 vol% H 2 O+50 vol% O 2 environment at 1250 °C for 100 h. In this corrosive environment, silicate phase appears on the surface of Si–Y–B-Yb ceramics. With prolonged corrosion time, silicate phase gradually forms more complete protective layer, hindering further corrosion by water-oxygen environment. These results demonstrate the feasibility of proposed Si–Y–B-Yb materials for corrosion protection. [ABSTRACT FROM AUTHOR]

Industrial boilers operate in extreme environments and are prone to degradation caused by high temperature oxidation, corrosion, and erosion. Protective coatings provide boiler components with protection to prolong their operation lifetime. Thus, a glass-ceramic coating has been developed using a slurry spray technique on carbon steel AS/NZS 3678 substrates. Microstructure, mechanical characteristics, and high temperature performance of the coating were investigated. The coating composed of chemically inert oxide ceramics dispersed in a glassy silicate binder matrix. The adhesion strength of the coating was 10.79 ± 0.86 MPa. Coating mass loss after abrasion test was 0.013 % of the tested specimen. The coating withstood at least 75 air quenched thermal shock cycles from 800 °C to the room temperature without any visible spallation and cracks. The coating mostly remained undamaged after cyclic oxidation at 800 °C for 10 cycles. However, minor iron oxide formation was observed, specifically, in relatively thin sections of the coating. The oxidation resistance of the boiler steel has been improved with the developed coating. The linear oxidation rate constant of the boiler steel has been statistically reduced from 6.90 × 10−4 mg cm−2 s−1 to 1.95 × 10−4 mg cm−2 s−1 for coated steel (p = 0.007). The developed slurry spray glass-ceramic coating is a potential candidate for boiler environments. [ABSTRACT FROM AUTHOR]

Inorganic oxide ceramics are essential for microwave applications due to their stable structure and exceptional performance. LiZnMgGaTi 2 O 8 ceramics were prepared using the solid-phase method. XRD and TEM confirmed that the ceramics possess spinel structures. The ceramics had a maximum relative density of 94.57 % and a Vickers hardness of 8.58 GPa when sintered at 1220 °C. The ionic polarizability of Ti4+ in the ceramics exceeds the Shannon value, leading to a 20.3 % deviation between ε th and ε r. The activation energy of the impedance spectrum fitting is 1.302 eV, indicating a low concentration of oxygen vacancies in the ceramic. Hence, the Q × f value of the ceramics is primarily influenced by relative density. The optimal microwave dielectric properties of LiZnMgGaTi 2 O 8 ceramics are ε r = 15.68, Q × f = 66,620 GHz, and τ f = −30.9 ppm/°C. The test curves of ε r and dielectric loss remain nearly parallel to the x-axis from −80 °C to 80 °C, demonstrating the excellent stability of LiZnMgGaTi 2 O 8 ceramics. [ABSTRACT FROM AUTHOR]

This work investigates the material extrusion‐based additive manufacturing (AM) process chain of a pure alumina‐based oxide ceramic matrix composite, starting from material selection, large‐scale compounding to pellets, the AM process itself, debinding and sintering as well as microstructural and mechanical characterization. The compounded pellets have a volume share of 50% binder (polyvinyl butyral [PVB], polyethylene glycol [PEG], and stearic acid) and 50% alumina (Al2O3, alumina powder, and Nextel 610 alumina fibers) with an aimed fiber volume share of 40% after sintering. The material is compounded on an industrial scale with approximately 10 kg/h and the material extrusion‐based AM process reaches speeds of up to 1000 mm/s. A variation of the feed rate leads to a significant increase in surface roughness and an increase in mass of 30%, in thickness of 12% and in width of 25%. The flexural behavior in the four‐point‐bending test can be described by a fast first peak and reaching higher flexural strength after the first crack subsequent with averages of 23.8 ± 3.6 MPa below.1% elongation. The fracture surfaces show the expected failure mechanisms like pull‐out and crack deflection. The resulting fiber length in the printed samples is 140 µm in average. [ABSTRACT FROM AUTHOR]