Search Results (1,746)

The effect of dimensional compatibility between rGO sheets and B₄C particles plays a critical role in governing the microstructure evolution and mechanical performance of rGO–B₄C composites. In this work, rGO–B₄C composites (5 wt.% GO addition) with varied initial B₄C particle sizes were fabricated via self-assembly polymerization combined with spark plasma sintering. The influence of B₄C powder particle size on the microstructure and mechanical properties of rGO–B₄C composite ceramics was investigated, and the dimensional compatibility of B₄C powder particle size to rGO sheet size was analyzed, further verifying the toughening mechanism of rGO–B₄C composite ceramics. The study showed that the dimensional compatibility of rGO sheet size to W3.5 B₄C raw material powder particle size is the best. Through self-assembly polymerization combined with spark plasma sintering, a uniformly dispersed and interconnected network structure of rGO in W3.5 rGO–B₄C composite ceramics can be obtained. This dense microstructure with an interconnected rGO network helps rGO–B₄C composite ceramics achieve optimal mechanical properties, with the highest relative density, hardness, bending strength, and fracture toughness, which are 99.67%, 31.07 GPa, 496 MPa, and 5.45 MPa·m^1/2, respectively. Full article

Four-dimensional (4D) printing is a cutting-edge additive manufacturing technique that enables dynamic deformation of three-dimensional printed components under external stimuli. Polymer-derived ceramics (PDCs) feature excellent design flexibility, corrosion and wear resistance, but ceramic 4D printing still faces critical drawbacks including inferior deformability, low forming precision, poor slurry-photopolymerization compatibility, and single-response actuation limits. This study proposes an innovative strategy for high-resolution, programmable multi-responsive ceramic 4D printing to tackle these issues. We integrated stereolithography (SLA) with thermosetting shape memory polymers (SMPs) and Fe₃O₄/Al₂O₃ ceramic composites with magnetothermal conversion effects. The prepared composite slurries were systematically characterized, and an integrated process of stepwise curing and shape programming was constructed. Molecular dynamics simulations clarified the interfacial bonding between polymers and inorganic particles. The ceramic precursors achieve autonomous and precise shape recovery under magnetic or thermal stimulation, and the programmed geometries can be stably maintained as designed configurations. This work establishes a complete technical framework that synergistically integrates SLA-based high-precision forming, magnetothermal dual-responsive actuation, and programmable reconfigurability, enabling complex ceramic precursor structures with tunable shape memory effects. The strategy offers a viable route for smart ceramic fabrication and opens promising perspectives for applications in aerospace deployable structures and non-contact biomedical devices. Full article

Background/Objectives: Restorative system configuration may influence the surface chemistry and interfacial behavior of dental ceramic and metal–ceramic systems, but direct comparative evaluations integrating SEM, EDS, and XPS remain limited. Methods: This in vitro study compared three restorative configurations: Monolithic ZrO₂, Feldspar/ZrO₂, and Feldspar/Co-Cr. Thirty specimens were fabricated and allocated into three groups (n = 10/group). Surface and cross-sectional morphology were assessed by scanning electron microscopy, while elemental composition and interfacial transition patterns were evaluated using energy-dispersive X-ray spectroscopy, including point analysis, elemental mapping, and line-scan profiles. X-ray photoelectron spectroscopy was used to characterize material-specific surface chemical profiles. Results: Monolithic ZrO₂ showed a compact and homogeneous ceramic morphology, with a dominant Zr–O–Y chemical profile. Feldspar/ZrO₂ specimens exhibited a sharply defined ceramic–ceramic interface, with limited elemental overlap between the feldspathic veneer and zirconia core. In contrast, Feldspar/Co-Cr specimens showed a broader ceramic–metal transition zone, mainly supported by SEM–EDS evidence of Cr-, Co-, and O-related interfacial signals. XPS provided complementary surface chemical information, without definitive oxide phase identification. Conclusions: Within the limitations of this in vitro study, the analyzed restorative configurations exhibited distinct morphological, elemental, and surface chemical patterns. Feldspar/Co-Cr showed a broader ceramic–metal elemental transition than Feldspar/ZrO₂; however, the present findings should not be interpreted as evidence of superior bond strength, mechanical stability, fatigue resistance, or clinical performance. Further mechanical and aging studies are required to determine the functional significance of these interfacial differences. Full article

Despite the robust mechanical and chemical stability that make hollow flat-sheet ceramic membranes highly attractive for membrane bioreactors (MBRs), the fundamental relationship between their structural design, specifically pore size and structural symmetry, and biological fouling behavior remains elusive. To decouple the effects of membrane architecture on fouling mechanisms, a series of symmetric and asymmetric hollow flat-sheet alumina membranes were systematically engineered. Symmetric architectures with tunable pore sizes were fabricated by controlling aggregate particle sizes, whereas asymmetric counterparts featuring distinct separation layer thicknesses were developed via a tailored dip-coating process. Long-term operational evaluations treating municipal wastewater uncovered a counterintuitive phenomenon. Asymmetric membranes, despite yielding superior retention, experienced markedly accelerated transmembrane pressure evolution and severe cake layer fouling compared to the symmetric supports. Resistance-in-series analysis coupled with classical filtration models demonstrated that thicker separation layers and larger pore sizes were associated with shifts in the dominant fouling mechanism toward rapid and dense cake layer formation, which significantly exacerbated irreversible biological fouling. Furthermore, advanced spectroscopic and high-throughput sequencing techniques revealed that structurally complex asymmetric layers were associated with shifts in extracellular polymeric substances and specific fouling-associated bacterial phyla at the membrane interface. Ultimately, these findings underscore the necessity of architectural optimization to mitigate biofouling and prolong the operational lifespan of ceramic membranes, highlighting the sustainable advantages of symmetric structures. Full article

Lithium aluminosilicate (LAS) ultra-low-expansion glass ceramics are core materials for precision optical systems, whose quality and dimensional stability are critically constrained by the uniformity of the coefficient of thermal expansion (CTE). This work proposes a nondestructive ultrasonic immersion pulse reflection (UIPR) method for rapid and low-cost characterization of the CTE in LAS glass ceramics. Key parameters of the ultrasonic measurement system are optimized via finite element method (FEM) simulations and experimental validation. Employing the correlation method, the ultrasonic longitudinal wave velocity is measured in LAS glass ceramic samples with distinctly different CTE values. The proposed method achieves an ultrasonic longitudinal wave velocity measurement uncertainty of 0.49 m/s, contributing 4.78 ppb/°C to the overall uncertainty of ultrasonic CTE determination. Within the investigated sample set, a negative relationship is observed between ultrasonic longitudinal wave velocity and the mean CTE (0–50 °C). The linear fit yields a slope of −9.75736 (ppb/°C)/(m/s), with a Pearson correlation coefficient of −0.84303. Featuring noncontact and nondestructive capabilities, this method lays a solid methodological foundation for CTE evaluation and efficient iterative optimization of material fabrication processes. Meanwhile, it shows great potential for rapid full-aperture characterization of CTE uniformity in large-size LAS glass ceramics. Full article

In the present work, a series of single-source precursors were prepared via a one-pot synthesis strategy using transition metal chlorides, acetylacetone, and hydroquinone as raw materials. The molecular structure, cross-linking behavior, and polymer-to-ceramic transformation of the obtained precursors were systematically investigated by Fourier-transform infrared spectroscopy and thermogravimetric analysis. The phase composition, phase-transformation temperature, and grain size of the resulting ceramics were characterized by X-ray diffraction combined with Rietveld refinement. The resulting precursors exhibit good solubility in common organic solvents (e.g., ethanol, propanol, and acetone), rendering them suitable for fabricating ultra-high temperature ceramic matrix composites through polymer infiltration and the pyrolysis method. At 1400 °C, the ceramic yields of the TaC, HfC, ZrC, NbC, and TiC precursors were 62.45%, 57.53%, 48.55%, 45.53%, and 30.32%, respectively. After heat treatment at their respective phase-transformation temperatures, the resulting ceramics exhibited grain sizes of carbides in the range of approximately 80–100 nm. The mechanism governing the different phase-transformation temperatures (T) of the derived ceramics, which follow the order T_NbC < T_TaC < T_TiC < T_HfC < T_ZrC, was elucidated through combined thermodynamic and kinetic analyses. This synthesis strategy was extended to the family of ultra-high temperature refractory metal carbides with melting points exceeding 3000 °C, demonstrating promising application potential for ultra-high temperature ceramic matrix composites. Full article

Despite extensive research on iron-based metal matrix composites (Fe-based MMCs), an integrated assessment linking fabrication methods, reinforcement architectures, interface engineering, and strengthening mechanisms remains limited. This review summarizes recent advances in Fe-based MMCs, with emphasis on the relationships among processing routes, microstructural evolution, reinforcement characteristics, and mechanical performance. Powder metallurgy, casting, and additive manufacturing are critically compared in terms of their processing characteristics, advantages, limitations, and suitability for iron-based systems. The effects of reinforcement size, morphology, distribution, and volume fraction on composite performance are discussed. Particular attention is given to interface engineering strategies and architectured core–shell reinforcements produced through in situ reactions and solid-state diffusion, infiltration, laser cladding, sol–gel coating combined with additive manufacturing, electrochemical synthesis, and high-energy ball milling. Recent studies indicate that core–shell architectures can offer enhanced control of reinforcement–matrix interactions by combining hard ceramic or carbide phases with more ductile metallic components. Rod-like Me@MeC/Fe (Me = Ta, Nb, W) architectures and dispersed core–shell particles show promising combinations of strength, toughness, and wear resistance, although their performance depends strongly on shell architecture, interface characteristics, and processing conditions. Remaining challenges include reproducible and scalable fabrication, shell architecture control, interface stability, and long-term performance. Further progress may benefit from advanced reinforcement design, additive manufacturing, modelling, and AI-assisted optimization of high-performance Fe-based MMCs. Full article

Alumina (Al₂O₃) ceramic sealing rings have attracted considerable attention in power battery packaging applications due to their excellent chemical stability, electrical insulation, and mechanical properties. In this study, 95% Al₂O₃ ceramics were fabricated using a CaO–SiO₂–TiO₂–ZrO₂ quaternary sintering aid system, and the effects of the TiO₂/ZrO₂ ratio on densification behavior, microstructural evolution, mechanical properties, and Mo–Mn metallization bonding performance were systematically investigated. As the TiO₂/ZrO₂ ratio decreases, the grain size first increases and then decreases, which is attributed to the pinning effect of the Al₂TiO₅ phase formed by excessive TiO₂ at grain boundaries that inhibits grain growth, whereas an appropriate TiO₂/ZrO₂ ratio promotes grain growth. After sintering at 1600 °C and 1625 °C, the density first increases and then decreases with decreasing TiO₂/ZrO₂ ratio; at 1650 °C, accelerated grain boundary migration engulfs residual pores into grain interiors, reversing the density trend. The flexural strength exhibits a rise–and–fall pattern with decreasing TiO₂/ZrO₂ ratio at all sintering temperatures, governed by the synergistic interplay among densification, grain size, and grain boundary characteristics. The metallization tensile strength first decreases and then increases with decreasing TiO₂/ZrO₂ ratio for ceramics sintered at 1600 °C and 1625 °C, but shows the opposite trend for those sintered at 1650 °C, governed by the glass–phase diffusion capability and surface roughness, respectively. The Al–2–2 sample (TiO₂/ZrO₂ = 1/1) sintered at 1650 °C exhibits the optimal overall performance, achieving a flexural strength of 351 ± 46 MPa and a metallization tensile strength of 153 ± 2 MPa. Full article

Three-dimensionally (3D)-printed alpha-tricalcium phosphate (α-TCP) scaffolds, fabricated through a low-temperature hydrothermal dissolution-precipitation process, replicate the structural and compositional features of native bone. Reinforcing hydrothermally processed α-TCP with poly(lactic-co-glycolic acid) (PLGA) as a binder has previously been shown to confer distinct mechanical advantages, supporting its potential as a viable material for bone regenerative scaffolds. Although the hydrothermal processing of α-TCP scaffolds and PLGA-based mechanical reinforcement have each been characterized individually in earlier studies, this work represents the first pre-clinical in vivo assessment of osseoconduction and biocompatibility of 3D-printed, PLGA-reinforced, self-hardening calcium phosphate scaffolds in a large translational animal model. A ceramic ink suitable for extrusion was prepared by combining a 30 wt/vol% poloxamer 407 solution with α-TCP powder at a 0.45 wt/wt ratio (CTRL). A second extrudable ink, consisting of an α-TCP ceramic suspension incorporating a 35 wt/wt% PLGA binder, was formulated at a 0.5 wt/wt ratio (EXP). Cylindrical scaffolds (6 mm × 6 mm) were fabricated at room temperature using a custom-built Direct Ink Write 3D printer, then hydrothermally treated via submersion in water and thermal consolidation at 121 °C. Osteotomies were created in the ilium of adult sheep, with two cylindrical defects (7 mm × 6 mm) per animal, each receiving either a CTRL or EXP scaffold. Animals were euthanized at 3 and 12 weeks post-surgery (n = 6 animals per time point), and samples were collected en bloc for analysis. For both scaffold formulations, hard tissue formed by 12 weeks displayed high cellularity and active vascularization, consistent with early woven bone formation. Quantitative analysis revealed no significant between-group differences in bone formation at either time point (p > 0.05). These findings indicate that 3D-printed, PLGA-reinforced, self-hardening α-TCP scaffolds are osseoconductive and biocompatible, supporting their potential use in orthopedic and craniomaxillofacial bone defect repair. Full article

Converter slag and copper slag represent promising sources for ceramic materials, but their high total iron content leads to waste of iron resources and inferior ceramic performance. To address this issue, we propose a two-step utilization method for converter slag and copper slag, including iron extraction synergistic oxidation and ceramic fabrication for tailings. In this study, the effects of tailings content, sintering temperature, and sintering aid addition on the phase composition, microstructure, physico-mechanical properties, and leaching characteristics of the novel pyroxene-based ceramics were investigated. The results reveal that the ceramics containing 50 wt% tailings present a single pyroxene phase with uniformly dispersed fine closed pores. At a sintering temperature of 1190 °C, the optimized ceramic achieves a water absorption of 0.33% and a flexural strength of 80.5 MPa. Elevating the sintering temperature facilitates the grain growth of pyroxene crystals and the formation of a liquid phase. The addition of sintering aid effectively lowers the sintering temperature and improves the densification degree of ceramic matrices. In addition, the leaching toxicity of the prepared ceramics is well below the standard regulatory limits. This study provides a novel approach for the high-value recycling of tailings. Full article

Despite the success of using Al₂O₃ as a secondary phase in Ce:LuAG phosphor ceramics (PCs), there is still room for improvement in the compositional design of biphasic PCs, as well as in their luminescent and thermal performance. In this study, nanopowders with 40 wt.% Al₂O₃-0.4at.% Ce:LuAG stoichiometry were synthesized via a co-precipitation approach. Subsequently, a series of compositionally uniform PCs was successfully fabricated by adjusting the vacuum sintering temperature and dwelling time. The grain size distributions of the Al₂O₃ and LuAG phases, as well as the evolution of porosity and pore size, were systematically analyzed and correlated with the sintering conditions. The addition of Al₂O₃ has been demonstrated to enhance the thermal properties of ceramics. The thermal conductivity of the “1750 °C × 10 h” sample was 15.6 W·m⁻¹·K⁻¹ at room temperature. Concurrently, it exhibited excellent thermal quenching behavior, retaining 96% of its luminescence intensity upon heating to 450 K. Its fluorescence lifetime was determined to be 21.06 ns. Under 450 nm laser excitation, the optimized PC attained a luminous efficacy of 286 lm·W⁻¹ at 1 W·mm⁻². In addition, the luminous flux increased continuously with laser power from 1 to 20 W·mm⁻² without any sign of saturation, reaching a maximum of 2500 lm. The findings indicate that biphasic 40 wt.% Al₂O₃-0.4at.% Ce:LuAG PCs have potential as high-flux, green-color converters for next-generation high-power laser lighting. Furthermore, a laser illumination prototype device incorporating 40 wt.% Al₂O₃-0.4at.% Ce:LuAG ceramic samples and a 10 W blue laser was constructed. This device emits white light with an illumination range exceeding 500 m, thereby demonstrating its potential applications in laser-driven lighting. Full article

By introducing BaTiO₃ into conventional hydroxyapatite (HA) bioactive ceramic coatings, a novel HA/BaTiO₃ piezoelectric-hydrophilic bioactive ceramic coating was developed. In this research, four groups of composite coatings with BaTiO₃ contents of 0, 10, 20, and 30 wt.% were comparatively fabricated and investigated, which in situ constructs a bioelectric microenvironment on the titanium surface. This strategy achieves the effective integration of electrical stimulation with bioactive ceramic coatings, resulting in a piezoelectric-hydrophilic bioactive ceramic layer that mimics biomineralization-driven osteogenesis. Experimental results demonstrate that, through laser cladding, BaTiO₃ particles can be embedded within the piezoelectric-hydrophilic bioactive ceramic coating, endowing the coating with mechano-electrical conversion functionality. Microdomain piezoelectric responses were successfully generated on the coating surface, and based on the maximum local piezoelectric response, the optimal BaTiO₃ content was determined to be 20 wt.%, yielding a microdomain piezoelectric coefficient of 712.6 pm/V. Furthermore, the piezoelectric-hydrophilic bioactive ceramic coating exhibits excellent bioactivity. Electrostatic interactions between piezoelectric charges and inorganic ions in physiological fluids facilitate the adsorption of calcium and phosphorus salts onto the coating surface, thereby enhancing surface hydrophilicity. This promotes the infiltration of inorganic ions and water molecules at the material interface, which in turn strengthens bioactivity, accelerates bone integration, and expedites the establishment of a robust osseointegration interface between joint prostheses and host bone. Full article

Emerging composite materials are expanding the potential of additive manufacturing and enabling applications previously restricted by traditional manufacturing methods through their multi-phase nature and complex internal geometry. Additionally, these materials can be pyrolyzed to create dense metal, ceramic, and glass parts with geometries typically not achievable by traditional processes. Additive manufacturing of borosilicate glass composites can enable new applications in nuclear engineering, astronomy, and bone regrowth therapy. To elucidate the process–parameter relationship of borosilicate–polylactic acid (PLA) composites, mechanical test specimens were fabricated by fused-filament fabrication and compared with a pure PLA baseline. Optical and scanning electron microscopy were conducted to observe the specimen microstructure before and after testing. From the stress–strain curves, the highest compressive yield strength for the composite was 28.22 MPa, and the highest compressive yield strength for PLA was 49.30 MPa. Print orientation was found to benefit the composite material but have a detrimental effect on the pure matrix material. Borosilicate–PLA with 100% infill, 1 shell wall, and layer lines parallel to compression axis had an elastic modulus of 2.66 GPa. Microscopy revealed that lower-modulus composite specimens had the particulates re-distributed within the matrix. Tensile testing was done according to a polymer testing standard, which caused difficulties obtaining consistent fracture within the gauge length. Full article

Background: The integration of additive manufacturing (AM) into digital dentistry has extended 3D printing beyond auxiliary applications toward the fabrication of definitive restorations, yet the evidence remains dispersed across diverse materials and technologies. This scoping review aimed to map the available evidence on 3D-printed resin- and ceramic-based materials for definitive tooth-supported restorations, including crowns, fixed dental prostheses, endocrowns, veneers, overlays, and onlays. Methods: The review followed the JBI framework and reported according to PRISMA-ScR. MEDLINE, Embase, and Scopus were searched from inception to April 2026. Two reviewers screened records independently against predefined eligibility criteria, and data were extracted using a piloted charting form capturing study design, materials, additive manufacturing technology, restoration type, and evaluated outcomes. Given the anticipated heterogeneity, extracted data were synthesised descriptively and mapped narratively rather than pooled statistically; 111 studies met the inclusion criteria. Results: The evidence was predominantly in vitro (105 studies), with only six clinical studies, including one randomised controlled trial. Research concentrated on single crowns, zirconia and ceramic-filled/methacrylate-based resins, and vat-photopolymerization technologies. Additively manufactured restorations were frequently reported as comparable to milled controls in dimensional accuracy, marginal and internal fit, and fracture resistance, with values generally falling within the clinically accepted thresholds defined by the primary studies; reported outcomes were most consistent for printed zirconia, whereas printed resins were more often limited by lower strength and colour instability. Outcomes were strongly influenced by processing parameters, underscoring the need for workflow standardisation. Conclusions: The current evidence supports the technical feasibility of 3D-printed definitive restorations more strongly than their long-term clinical durability, highlighting a need for long-term clinical trials. Full article

Biodegradation of fused filament fabrication (FFF)-printed poly(lactic acid)/polyhydroxybutyrate (PLA/PHB) structures is governed by complex interactions between material composition, structural design, and degradation environment. Although these factors have been extensively investigated, they are typically evaluated independently, limiting a comprehensive understanding of their combined influence on degradation behaviour. This study synthesizes experimental evidence from a series of complementary studies on FFF-printed PLA/PHB systems to develop a transport-driven conceptual framework for interpreting biodegradation mechanisms. The integrated findings show that structural porosity increases fluid uptake (approximately 10% in dense structures versus 20% in porous structures) and promotes greater mass loss (25–40% after 45 days), while material modifications, including plasticizers and ceramic additives, influence local pH evolution and mechanical stability during degradation. The degradation response was also strongly dependent on the surrounding medium, with PBS maintaining relatively stable pH, saline and Hank’s solutions promoting acidification, and urea-based media leading to alkalization. Collectively, these observations indicate that fluid absorption and diffusion consistently mediate the interactions between material composition, scaffold architecture, and degradation environment, thereby governing the progression of biodegradation. Based on these experimentally supported relationships, a transport-driven conceptual framework is proposed to provide a unified qualitative interpretation of biodegradation in FFF-printed PLA/PHB structures. Rather than presenting new experimental data, this work offers an integrative perspective that may facilitate the interpretation of degradation behaviour, support the rational design of biodegradable scaffolds, and provide a foundation for future quantitative and predictive models. Full article