Search Results (2,074)

Composition design is critical for high-performance transparent LAS glass ceramics. This study investigated the effects of heat treatment temperature and CaO/La₂O₃ ratio at a fixed modifier content on crystallization behavior, network structure, microstructure, and comprehensive properties of LAS glass ceramics. Base glasses with different CaO/La₂O₃ ratios at a fixed modifier content were prepared by melt quenching and subjected to two-step nucleation–crystallization treatment at 700~900 °C. XRD and FTIR analyses revealed that β-quartz solid solution initially precipitated at 700 °C, followed by the formation of petalite and Li₂Si₂O₅ at 750~800 °C, whereas β-spodumene and wollastonite emerged at 850 °C. Increasing temperature promoted crystallization, grain growth, and densification up to 850 °C, while excessive heating resulted in grain coarsening and slight property deterioration. Increasing La₂O₃ content refined the grains and improved density, hardness, and visible light transmittance. In contrast, higher CaO content enhanced network depolymerization, ion migration, and wollastonite precipitation. The C4L6 composition exhibited the best overall performance, achieving a bending strength of approximately 160 MPa at 800 °C and the lowest thermal expansion coefficient of 3.64 × 10⁻⁶ K⁻¹ up to 300 °C, demonstrating an optimal balance among crystallization, microstructural refinement, and phase composition. Full article

The cement industry is a major source of global CO₂ emissions, driving the development of low-carbon alternatives such as geopolymers. This study examines geopolymer binders produced from ceramic brick waste (CBW) and metakaolin waste (MKW), evaluating their fresh and hardened properties as well as their performance under elevated temperatures. Five binder compositions were formulated by progressively replacing CBW with MKW (25–100 wt.%). The alkaline activator ratio (Na₂SiO₃/NaOH = 1.5) and NaOH molality (8 M) were kept constant. Fresh-state behavior was evaluated using Suttard viscometry and Vicat testing, while hardened-state performance was assessed through compressive and flexural strength, softening coefficient, and drying shrinkage. Thermal resistance was examined at 200, 400, 600, and 800 °C, supported by XRD, FT IR, and SEM analyses. The present study investigates how waste-derived aluminosilicate precursors with differing crystallinity and reactivity affect geopolymerization mechanisms and high-temperature phase evolution. MKW-rich binders were found to form highly reactive amorphous gels, resulting in superior early mechanical strength, whereas CBW-rich binders retained thermally stable crystalline phases that enhanced resistance to structural degradation at elevated temperatures. The MKW-rich formulation (F5) demonstrated the highest ambient mechanical performance, reaching 82.8 MPa after curing at 200 °C, due to intensified secondary geopolymerization. In contrast, the CBW-only binder (F1) exhibited superior thermal stability, maintaining a compressive strength of 46.4 MPa even after exposure to 800 °C. These findings establish a clear structure–property relationship between precursor mineralogy, gel chemistry, and high-temperature performance, offering valuable insights for the tailored design of waste-derived geopolymers with optimized thermal and mechanical properties. Full article

This review critically evaluates glass-ceramics derived from aluminosilicate solid wastes through the linked framework of raw-material chemistry, the processing route, microstructure, thermal performance, and environmental safety. Waste-derived CaO–Al₂O₃–SiO₂ (CAS) and CaO–MgO–Al₂O₃–SiO₂ (CMAS) systems currently provide the most developed basis for dense and porous building products, whereas evidence for other compositional systems remains less mature. Across these materials, phase assemblage, residual-glass connectivity, crystallized pore-wall integrity, and pore structure jointly govern thermal stability, heat transfer, dimensional stability, cracking behavior, and mechanical-property retention after high-temperature treatment. Bulk crystallization and powder sintering are the principal demonstrated preparation routes, although their applicability depends strongly on waste composition, glass-forming ability, and processing windows. Future studies should integrate multi-source waste design, low-energy processing, standardized thermal and mechanical characterization, long-term leaching assessment, and life-cycle analysis to establish reliable performance and environmental boundaries for practical applications. Full article

The reuse of construction and demolition waste in cementitious materials supports the development of sustainable low-carbon composites and circular economy strategies. This study investigated the influence of recycled ceramic fine aggregate (RCerFA) and recycled concrete fine aggregate (RConFA) on the mechanical properties, freeze–thaw durability, pozzolanic potential, and environmental performance of cement mortars prepared with different cement types. Mortars containing 20% and 40% replacement of natural sand with recycled aggregates were evaluated through strength testing and freeze–thaw resistance assessment, while SEM analysis and pozzolanic potential were assessed on separate mortars in which 25% of the cement binder was replaced with the recycled materials, alongside carbon footprint calculations based on global warming potential (GWP), using the recycled materials directly after the crushing process without additional grinding. The results showed that mortars containing recycled concrete fine aggregate generally maintained satisfactory mechanical performance and freeze–thaw resistance, particularly at the 20% replacement level. In contrast, 40% RCerFA reduced mechanical performance and freeze–thaw resistance. Neither recycled material demonstrated confirmed pozzolanic reactivity in its unground state. Although one RConFA mixture exceeded the 75% compressive strength index criterion, this result alone was insufficient to confirm a chemical pozzolanic reaction. Environmental assessment demonstrated that cement type had a greater influence on carbon footprint than recycled aggregate incorporation. The study confirms the potential applicability of recycled fine aggregates in sustainable low-carbon cement mortars and explores their possible use as low-energy supplementary cementitious components. 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

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

Chronic oral and maxillofacial diseases are frequently associated with progressive alveolar bone loss, leading to impaired structural integrity of the jaw and increased risk of implant failure, microbial colonization, and microfracture formation. Ceramic scaffolds such as those made of hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) have attracted considerable attention because of their controlled resorption properties and the promotion of rapid new vital bone formation. The aim of this research is to enhance the performance of scaffolds composed of HA and β-TCP used for guided bone tissue regeneration in oral surgery. HA/β-TCP scaffolds were loaded with simvastatin (SIMV) and coated with multiple layers of alginate (ALG). The proposed strategy was designed to achieve a local and prolonged drug release while simultaneously improving mechanical properties. The scaffolds were characterized in terms of porosity, water absorption, in vitro degradation, in vitro bioactivity, and SIMV release. In addition, microscale mechanical properties were evaluated using Brillouin microscopy before and after the coating process. Cytocompatibility was further evaluated by using murine macrophages as an in vitro cellular model. The results demonstrated that ALG coatings significantly modulated SIMV release, promoting a delayed drug release. Moreover, ALG deposition improved the micromechanical properties of the scaffolds, conferring a dual structure analogous to those of bone tissue. These findings indicate that ALG-coated SIMV-loaded HA/β-TCP scaffolds represent a promising multifunctional platform for the medical field. Full article

Due to the superior thermal, mechanical and chemical properties of ceramics, metallized ceramics are widely used as circuit carriers and interconnect devices, wherever standard polymer-based circuit boards come to their limits. 2D metallization represents the current state of the art. The metallization of 3D-shaped ceramics cannot be achieved with standard metallization techniques, such as screen printing, but, for example, with the so-called laser-induced direct metallization (LDM). For LDM, a pulsed laser is used to locally activate the ceramic surface, followed by a selective electroless copper plating on the laser-irradiated areas. Although it has already been shown that LDM on Al₂O₃-based ceramics is possible with different laser systems, a comprehensive study on the effect of different laser parameters on ablation and activation, which includes the influences of structuring on inclined surfaces, has not been done yet. In this study, laser power, pulse repetition frequency, pulse overlap and the number of passes were varied systematically to determine the parametric sensitivity of the ablation and metallization behavior for pulsed infrared laser activation of Cr₂O₃-doped ZTA. It was found that ablation is necessary for the metallization and that the peak fluence is the governing factor for the ablation and metallization process. It was further shown that ablation can be well predicted with an accumulated fluence, which includes pulse overlap. Structuring under an inclination angle up to 60° does not result in a reduced activation or adhesion strength of the deposited copper. Injection-molded 3D ceramic substrates were successfully metallized and functionalized by applying an optimized set of laser parameters, showing that LDM enables the functionalization of complex 3D ceramic substrates and therefore opens up new possibilities for integrated ceramic circuit carriers. Full article

The main objective of this systematic review was to synthesise current knowledge on tricalcium phosphate (TCP) as a functional modifier of poly(methyl methacrylate) (PMMA)-based bone cements, relating the microstructure of PMMA/TCP composites to their mechanical, biological and functional (handling) performance. Web of Science, Scopus and PubMed were searched for 2010–2025. Studies reporting primary quantitative data on PMMA cements specifically modified with TCP were eligible. Over one hundred records were screened by two independent reviewers, yielding 15 studies appraised qualitatively and combined by narrative synthesis. The evidence links polymerisation of the PMMA matrix, calcium and phosphate ion release from TCP, apatite-layer precipitation, and cell-mediated TCP resorption coupled to bone remodelling. TCP, especially β-TCP or biphasic calcium phosphate systems, can balance mechanical stability with bioactivity: moderate β-TCP contents (of the order of 10 wt% for solid cements under quasi-static compression) preserve clinically acceptable properties while enhancing osteoconductivity, though this limit falls for porous, α-TCP-containing and fatigue-loaded formulations. Porosity, TCP amount, crystalline form and particle size are the governing microstructural variables. The evidence is limited, dominated by in vitro and short-term static tests, with heterogeneous formulations and no controlled clinical data, so benefits should be interpreted qualitatively rather than as firm quantitative relationships. The review was not registered; this research received no external funding. Full article

Reducing ordinary Portland cement (OPC) content through waste-derived binders can improve the resource efficiency of mortar and concrete. This study explores the effect of single and combined replacement of ordinary Portland cement (OPC) with ceramic waste powder (CWP) and calcium carbide residue (CCR), with the original contribution being the systematic mixture-design evaluation of a ternary OPC–CWP–CCR binder using mixture design and an integrated assessment of mechanical and durability-related performance. Ten mixes with varying mixture proportions were designed using the mixture design of experiments (DoE). Fresh and hardened properties were evaluated, including flowability, compressive strength, bulk resistivity, and water absorption tests up to 56 days, while chemical durability was assessed by exposure to 5% sulfuric acid. OPC replacement with CCR and CWP reduced early-age strength due to dilution; however, CWP-dominant blends exhibited late-age strength gain. The mixture containing 26.7% CWP and 6.7% CCR reached 44.7 MPa at 90 days and 406.7 Ω·m at 56 days and exhibited the lowest relative strength loss after sulfuric acid exposure (12.8%, versus 16.0% for the control). High CCR contents adversely affected workability, water absorption, strength, and acid resistance. CWP-dominant blends provided the best overall balance of performance and OPC reduction. Full article

Polymer nanocomposites have attracted considerable attention owing to their ability to achieve substantial improvements in mechanical, thermal, electrical, barrier, and multifunctional properties through the incorporation of low concentrations of nanoscale fillers. This review provides a comprehensive analysis of recent advances in polymer nanocomposites, focusing on the relationships between nanofiller characteristics, processing strategies, interfacial interactions, and the resulting material performance. Different classes of nanofillers, including carbon-based, ceramic, metallic, polymeric, and hybrid nanostructures, are systematically compared with respect to their morphology, surface chemistry, of processing routes, including melt blending, solution processing, in situ polymerization, and surface functionalization, on nanoparticle dispersion and polymer–nanofiller interfacial adhesion is critically discussed. The review further evaluates how these factors govern the mechanical, thermal, electrical, dielectric, and barrier properties of polymer nanocomposites and summarizes their applications in aerospace, automotive engineering, electronics, biomedical devices, energy systems, construction, and advanced packaging. Current technological challenges, including nanoparticle aggregation, long-term stability, process scalability, environmental impact, and nanomaterial safety, are also examined. Finally, emerging research directions, including hybrid nanofillers, sustainable polymer systems, digital materials design, and machine-learning-assisted optimization of polymer nanocomposites, are highlighted. This review provides an integrated perspective on the design and processing of high-performance polymer nanocomposites and identifies key opportunities for future research and industrial implementation. Full article

Perhydropolysilazane (PHPS) has attracted considerable attention as a versatile precursor for solution-processed silicon-based materials because of its carbon-free backbone, high chemical reactivity, and compatibility with low-temperature processing. This review provides a comprehensive overview of the synthesis of PHPS, its conversion routes and mechanisms, the structure–property relationships of PHPS-derived materials, and their current and emerging applications. The literature demonstrates that PHPS conversion is governed by coupled hydrolysis, oxidation, nitridation, dehydrogenation, photochemical activation, and reactive-species-mediated processes, resulting in compositionally and structurally diverse silicon-based networks, including SiO_x-rich, SiO_xNᵧ, and SiN_x materials. The resulting optical, mechanical, surface, and barrier properties are determined by network structure, residual bonding environments, compositional gradients, and interfacial characteristics rather than by the nominal conversion method alone. Recent advances further demonstrate the potential of PHPS-derived materials for barrier coatings, dielectric and interfacial layers, protective coatings, semiconductor processing, and high-temperature ceramic applications. Overall, PHPS should be regarded not merely as a silica precursor but as a tunable preceramic platform for engineering diverse silicon-based networks. Future progress will depend on predictive control of conversion processes, standardized evaluation protocols, sustainable solution-based manufacturing, and comprehensive device-level validation to facilitate practical implementation. Full article

Transparent glazing systems are increasingly required to provide simultaneous control over light transmission, solar heat gain, thermal losses, surface contamination, and environmental durability, creating new challenges for the development of multifunctional coating technologies. This review critically examines advanced optical and self-cleaning coatings developed for transparent glass and polymeric substrates, with particular emphasis on the relationships between materials chemistry, surface/interface chemistry, microstructure, and functional performance. Dielectric multilayers, metal oxides, ceramic coatings, sol-gel-derived hybrid systems, and emerging chromogenic materials are discussed in terms of their chemical compositions, structural characteristics, and mechanisms governing optical, thermal, and surface properties. Particular attention is given to structure–property relationships associated with photosynthetically active radiation (PAR) transmission, near-infrared (NIR) management, thermal emissivity, solar modulation, wettability, and self-cleaning behavior, together with their implications for energy-efficient transparent glazing and greenhouse environments. The influence of coating architecture, porosity, surface roughness, interfacial interactions, and deposition conditions on functional performance and long-term stability is critically evaluated. The advantages and limitations of representative deposition strategies are further compared, considering scalability, process compatibility, substrate sensitivity, and application to heat-sensitive polymeric films. Environmental degradation mechanisms induced by ultraviolet irradiation, moisture, thermal cycling, and mechanical stresses are analyzed to identify the key factors governing coating durability and sustainability. Finally, current knowledge gaps and emerging research directions are identified, highlighting the need for rational materials design, multifunctional integration, scalable fabrication, and improved structure-property-durability correlations for next-generation transparent glazing and greenhouse applications. Full article

This study aimed to develop polymer matrix nanocomposites reinforced with Al₂O₃ nanoparticles to enhance the mechanical properties of PMMA. The composite was fabricated via friction stir processing (FSP) to ensure the homogenous dispersion of Al₂O₃ nanoparticles in the polymer. A grid of 5 holes in a 7 × 7 mm² area was made in which the hole diameter was varied from 1.77 mm to 2.28 mm to obtain different volume fractions of reinforcement ranging from 15% to 25%. The holes were made with a depth of 3 mm in a 4 mm-thick PMMA sheets. After packing the Al₂O₃ powder in the holes, a 2 mm-thick PMMA sheet was used as a cover to prevent the sputtering of nanoparticles. A number of FSP parameters were examined. The tool rotation rates ranged from 800 to 1200 rpm, traverse speeds of 25 and 50 mm/min, and tool tilts of 1 and 2° were used. A soft paraffin (Vaseline) layer was used on the top surface to prevent severe shoulder friction with the PMMA plate, which caused severe wear and thinning on the surface. For the developed PMMA/Al₂O₃ nanocomposites, the surface quality, SEM microstructure, impact energy, and transverse hardness were investigated. Good surface quality and dispersion of nanoparticles were attained by employing adequate processing conditions. The experimental results indicated that as the nanoparticle percentage increased, impact energy, hardness, and tensile strength increased, reaching 2 kJ/m², 14.7 HV, and 52.1 MPa at a nanoparticle concentration of 25%. This means that the polymer ceramic composite’s toughness, hardness, and tensile strength are higher than those of unprocessed PMMA by 66%, 33%, and 23%, respectively. Full article

Boron carbide (B₄C) ceramics suffer from poor sinterability and inherent brittleness, which severely limit their engineering applications. In this work, B₄C–graphene nanoplatelet (GNP) composites were fabricated by hot pressing using heterogeneously co-precipitated powder mixtures, with cetyltrimethyl ammonium bromide (CTAB) as a surfactant for achieving uniform dispersion of GNPs within the B₄C matrix. The formation mechanisms of B₄C–GNP hybrids were systematically elucidated. The results show that CTAB endows GNPs with positive charges, enabling electrostatic co-precipitation with negatively charged B₄C particles to construct layered hybrid architectures. The GNP content has a significant modulation effect on the microstructure and mechanical properties of B₄C composites. A maximum relative density of 99.65%, Vickers hardness of 33.5 GPa, and flexural strength of 488 MPa were obtained at 1 wt% GNPs, while the fracture toughness reached a peak value of 4.89 MPa·m^1/2 at 2 wt% GNPs, representing a 63.5% improvement over monolithic B₄C. The enhanced fracture toughness is attributed to multiple toughening mechanisms, including crack deflection, crack bridging, GNP pull-out, step-like fracture, and zigzag crack propagation. This study provides a feasible strategy for preparing uniformly dispersed ceramic–graphene composites with balanced mechanical properties. Full article