Search Results (698)

Large-scale high-value utilization of industrial solid waste is urgently required worldwide. Porous ceramics prepared from single-type solid waste face great limitations in balancing mechanical properties and thermal insulation performance. In this work, various types of industrial solid wastes—red mud, waste electric porcelain, and coal gangue—were fully adopted as primary raw materials, while SiC was employed as a foaming agent to prepare porous ceramics. Results show that at 3% SiC addition and 1140 °C sintering temperature, the apparent porosity of the ceramics reaches to 21.8%, with thermal conductivity of 0.08 W/(m·K). Moreover, favorable pore-size distribution and desirable crystalline phases (Mg–Fe–Al spinel and sodium calcium feldspar) are obtained under this optimal condition, accompanied by a favorable compressive strength of 2.91 MPa, making it a promising low-cost, high-performance high-temperature insulation material. Full article

The growing demand for sustainable and environmentally friendly materials has accelerated interest in the valorization of industrial wastes within the framework of the circular economy. In this study, porous wollastonite-based ceramics were successfully fabricated using cement kiln bypass dust (CKD) and waste glass cullet as low-cost and sustainable secondary raw materials. The proposed approach aims to mitigate environmental pollution, reduce landfill disposal, conserve natural resources, and promote the recycling of industrial by-products into value-added ceramic products. Different batch compositions containing varying proportions of CKD and glass cullet were prepared, compacted, and subsequently sintered under controlled conditions to induce crystallization. The crystallization behavior and phase development were characterized by X-ray diffraction (XRD), while the microstructural features were examined using scanning electron microscopy (SEM). Physical and dielectric properties, including bulk density, open porosity, dielectric constant (ε′), dielectric loss (ε″), and electrical conductivity (σ), were also evaluated. The results confirmed the successful formation of parawollastonite as the predominant crystalline phase, accompanied by a relatively homogeneous porous microstructure. The prepared ceramics exhibited high open porosity values ranging from 52.55 to 63.63% and low bulk densities between 1.050 and 1.318 g cm⁻³, making them suitable for lightweight construction and insulation applications. Dielectric measurements performed over the frequency range of 50 Hz–8 MHz revealed that both dielectric constant (ε′) and dielectric loss (ε″) decreased with increasing frequency. At 50 Hz, ε′ and ε″ ranged from 8.44–9.39 and 0.709–0.733, respectively. The electrical conductivity values (~10⁻² μS cm⁻¹) at low frequencies indicated insulating behavior, whereas poor-to-fair semiconducting characteristics were observed at higher frequencies. The incorporation of large amounts of recycled CKD and waste glass significantly reduced dependence on virgin raw materials while providing a sustainable route for waste utilization. Consequently, this work demonstrated an environmentally responsible and economically viable strategy for producing porous wollastonite-based ceramics with potential applications in both the construction and electrical sectors, thereby contributing to resource efficiency, waste valorization, carbon-emission reduction, and sustainable industrial development. Full article

Chemical analysts and archeologists are increasingly interested in organic remains that penetrate the porous structures of ceramic vessels. Fatty acids and archaeological biomarkers are chemical compounds that are particularly important for determining the contents of ceramic vessels. This study involved gas chromatography coupled with mass spectrometry (GC–MS) analysis of organic residues extracted from 56 Neolithic pottery samples found in 18 different settlements in Poland. Fatty acid ratios, including the newly proposed C15:0/C17:0 ratio (pentadecanoic acid/heptadecanoic acid) for the identification of dairy products and archaeological biomarker analysis, were used to determine the possible origin of these residues. The data obtained from the gas chromatography studies were statistically analyzed using principal component analysis (PCA), k-means clustering, and PERMANOVA to determine differences in the diet of the people inhabiting individual settlements. The obtained results allowed us to determine that the Neolithic diet was probably similar in different regions of Poland and throughout different periods of the Neolithic era. However, because of the large difference in variance between the different sample groups, we believe that research should continue and that a larger number of samples per settlement or historical period should be examined. We can conclude that all samples contained residues of mixed animal and plant origin, and the food stored in these vessels was likely subjected to thermal processing. Full article

Surface functionalization of metallic implants is widely explored to enhance their performance and functionality. In this study, multifunctional hydrogel coatings based on poly(vinylpyrrolidone) and polyethylene glycol were developed and functionalized with a taxifolin (TAX) inclusion complex and collagen to introduce bioactive features. TAX, a naturally occurring flavonoid with antioxidant and anti-inflammatory properties, was incorporated using β-cyclodextrin to improve its stability and enable controlled release. The coatings were applied to titanium-hydroxyapatite composites and titanium sheet substrates to evaluate their applicability across surfaces with varying morphologies, ranging from porous to relatively smooth. The ceramic phase was modified with magnesium ions to enhance its bioactivity and better mimic the composition of natural bone tissue. FTIR and SEM analyses confirmed hydrogel formation and effective surface coverage. Degradation and incubation studies in simulated physiological environments demonstrated the material’s stability, while UV–Vis analysis indicated TAX release, highlighting the system’s potential as a carrier for flavonoid-based compounds. Indirect cytotoxicity studies using MC3T3-E1 preosteoblasts indicated low cytotoxicity and a favorable biological response of collagen- and taxifolin-modified systems. The developed coatings represent a versatile platform for surface modification of titanium-based biomaterials and demonstrate potential for application across substrates with diverse surface characteristics. Further studies are required to assess their biological potential. Full article

Clay, as a sediment material, is an attractive option for the production of porous ceramics due to its low price and high abundance. Porous ceramics possess a combination of essential properties of clay-based materials, including high porosity and thermal and chemical stability, making them suitable for various industrial applications, such as filters, heat insulators, and absorbents. In this study, thermally and chemically purified clay was mixed with boric acid as a pore-forming agent. Obtained results reveal that different contents of boric acid (2 wt.% and 0.5 wt.%) and variations in synthesis conditions, including low pressing pressures up to 60 MPa and low sintering temperatures of 1150 °C and 1300 °C, optimize the production of a filter medium with good separation and mechanical properties. Further, these findings indicate that an adequate combination of boric acid content and synthesis conditions positively affects mechanical properties, including values of hardness, Young’s modulus, compressive and tensile strength of clay-based filters. The clay-based filter with 2 wt.% boric acid exhibited a larger maximum pore diameter of nearly 0.2 mm, compared to the one with 0.5 wt.% boric acid. The filtering efficiencies of both filters were tested on pharmaceutical-grade ciprofloxacin with removal efficiency above 80% for two tested concentrations (6 μM and 9 μM). Full article

Porous ceramics have garnered widespread attention in high-temperature insulation, aerospace, and other fields due to their excellent thermal stability, low density, and superior thermal insulation performance. However, traditional preparation technologies suffer from limitations such as poor pore structure controllability, unstable mechanical properties, and long production cycles. In recent years, 3D printing (additive manufacturing) technology has emerged as a disruptive approach to address these challenges, enabling precise fabrication of porous ceramics with complex structures and tailored properties. This review comprehensively summarizes the research progress on 3D-printed porous ceramics, focusing on preparation technologies, structure optimization, and performance regulation. First, the principles and drawbacks of traditional preparation methods are analyzed. Then, four mainstream 3D printing technologies (Binder Jetting, Material Extrusion, Vat Photopolymerization, and Material Jetting) for porous ceramics are elaborated on in terms of forming mechanisms, process characteristics, typical cases, and performance advantages/disadvantages. Additionally, the structure–property optimization strategies, including the design of Triply Periodic Minimal Surface structures and the application of computational modeling and simulation, are discussed to achieve the balance between thermal insulation and mechanical properties. Finally, current challenges and future development trends of 3D-printed porous ceramics are prospected. This review provides a systematic reference for the rational selection of preparation technologies, structural design, and performance optimization of porous ceramics, promoting their engineering applications in high-value fields. Full article

Porous ceramics have shown great application potential in aerospace, electronics, and lithium-ion battery thermal management due to their low density, high specific strength, and excellent thermal insulation. Material Jetting (MJ), a high-precision 3D printing technology, enables the fabrication of porous ceramics with tailored pore structures, but the synergistic effects of pore structure parameters (configuration, porosity, and number of periods) on their thermal insulation performance remain insufficiently explored. This study systematically investigates the thermal insulation behavior of zirconia porous ceramics fabricated by MJ through experimental tests and numerical simulations. Three typical lattice configurations (Octet, Schwarz, and Gyroid) were selected, and samples with varying porosities (40%, 50%, 60%) and numbers of periods (1, 2, 3) were prepared. The results indicate that the Octet configuration (60% porosity, 3 periods) exhibits the optimal thermal insulation performance, with a minimum cold-end temperature of 58.5 °C (experiment) and 59.21 °C (simulation), attributed to its strut-based structure that forms a more tortuous heat conduction path. For the Gyroid configuration, thermal insulation performance improves with increasing porosity (reducing solid conduction dominance under non-forced convection) and decreases with decreasing number of periods (due to inhomogeneous pore distribution extending heat transfer paths). Notably, the trend of porosity affecting thermal insulation is opposite to that of compressive performance. Numerical simulation results are consistent with experimental data in both values and trends, verifying the reliability of the model. This work clarifies the key factors regulating the thermal insulation of MJ-fabricated porous ceramics and provides practical structural design guidelines for applications such as lithium-ion battery thermal runaway management. Full article

This research reports on the properties of oxide-ceramic coatings produced by plasma electrolytic oxidation in novel electrolyte solutions for implantology applications. A series of bioactive calcium-phosphate coatings was synthesized on medical-grade Ti-13Zr-13Nb alloy using the plasma electrolytic oxidation (PEO) method. Novel electrolytes enriched with calcium and phosphorus were developed, enabling the formation of coatings with tailored physicochemical and structural characteristics. A correlation was established between the electrolyte composition and the phase composition, thickness, morphology, porosity, and microhardness of the resulting coatings. The optimum coatings exhibited a Ca/P ratio close to that of natural human bone tissue, homogeneity, a well-developed porous surface topography, and controlled resorption behavior. For the first time, a mechanism of calcium-phosphate coating resorption in a biologically active environment has been proposed. It involves partial dissolution, the formation of apatite-like surface structures, and the subsequent controlled release of Ca and P ions. In vitro testing in simulated body fluid indicated the potential bioactivity of the synthesized coatings. The proposed calcium-phosphate coatings may be considered promising candidates for future implant surface modification. The results obtained are significant for the development of advanced orthopedic and dental implants, including those fabricated using additive manufacturing technologies. Full article

The present study addresses the fabrication of porous gyroid architectures by additive manufacturing from preceramic polymer feedstocks. Photocurable emulsions were engineered by combining a silicone powder with acrylate monomers and dispersing an emulsified secondary phase of calcium nitrate. The formulations showed light-curing behaviour compatible with digital light processing vat photopolymerization (DLP-VPP), enabling high-fidelity replication of triply periodic minimal surface (TPMS) gyroids (designed porosity: 85 vol.%). After pyrolysis in nitrogen at 700 °C, the lattices converted into CaO–SiO₂-derived amorphous matrices embedding an in situ turbostratic/pyrolytic carbon fraction, as suggested by the photothermal response and preliminary impedance behaviour, although the latter was measured in liquid electrolyte and therefore does not isolate electronic transport. To improve robustness during polymer-to-ceramic conversion, pharmaceutical borosilicate waste glass (BASG) was added as a passive filler (30–70 wt.%). The waste-glass phase acts as a passive filler that improves processing robustness and can mitigate shrinkage-induced damage during pyrolysis, while remaining electrically insulating (dielectric) and therefore not directly contributing to electronic conduction. The resulting structures combine high surface-to-volume ratio, controlled open porosity, and structural integrity with electrochemical responsiveness under the adopted test conditions, making them promising architected platforms for electrochemical components where interconnected porosity is advantageous. Full article

Polymer-derived ceramics (PDCs) technology has been established for over five decades as a versatile route for the fabrication of advanced bioceramic materials. However, conventional processing routes for bioceramics, such as melt-quenching and sol–gel methods, still present significant limitations, including high processing temperatures, limited compositional flexibility, long processing times, and difficulties in fabricating complex and highly porous structures required for biomedical applications. In this context, increasing attention has been devoted to polymer-derived ceramics as an alternative approach for the fabrication of bioceramic materials. In this approach, preceramic polymers are converted into ceramic phases through thermal treatment in air or inert atmosphere (e.g., nitrogen), enabling low-temperature processing, high compositional flexibility, and precise control over phase evolution and microstructure. These features make the polymer-derived Ceramic route particularly attractive for the fabrication of complex and functional bioceramic architectures. This review provides an overview of the polymeric precursors employed for the synthesis of Polymer Derived Ceramic-based bioceramics, with particular emphasis on inorganic polymers, typically characterized by a siloxanic backbone, and the mechanisms governing their ceramization behavior. Special attention is given to emerging trends, including the integration of polymer-derived ceramics with additive manufacturing techniques and the development of functional systems for biomedical applications. Full article

To address the severe wear and galvanic corrosion of TC4/Mg three-dimensional interpenetrating composites caused by the potential difference and hardness disparity between the two phases, this work proposes a hybrid surface modification strategy combining plasma electrolytic oxidation (PEO) with a self-assembled monolayer (SAM) doped with multi-walled carbon nanotubes (MWCNTs). A PEO ceramic coating was first grown in situ on the composite surface, followed by sealing modification using MWCNTs-containing SAM. The microstructure, phase composition, tribological behavior and potentiodynamic polarization curves of the coatings were systematically evaluated. The results show that the PEO coating is mainly composed of Mg₂SiO₄, MgO, MgF₂ and TiO₂, exhibiting a typical porous structure. After the MWCNTs-doped SAM composite modification, the nano-fillers and the molecular layer synergistically seal the micropores and cracks, and the surface transforms into a continuous and dense layered morphology. Wear tests reveal that the composite coating reduces the friction coefficient to 0.195 and decreases the wear volume by 93.53% compared with the bare composite. The “micro-roller bearing” effect and debris adsorption of MWCNTs significantly improve the wear resistance, and the dominant wear mechanism changes from abrasive wear to three-body wear. Electrochemical measurements show that the corrosion current density of the composite coating decreases from 2 × 10⁻⁴ A·cm⁻² (bare composite) to 1.401 × 10⁻⁹ A·cm⁻², i.e., a reduction by five orders of magnitude, with a protection efficiency of 99.99%. This is attributed to the physical barrier effect of the PEO coating and the synergistic sealing of defects, as well as the blocking of electron transfer by MWCNTs/SAM. The multi-level protection system of “PEO + MWCNTs + SAM” constructed in this work achieves a synergistic improvement in both wear resistance and corrosion resistance of the TC4/Mg two-phase interpenetrating composite, and holds promise for further investigation as an osseointegration implant material. Full article

Ceramic thermal protective coatings during long-term service in high-temperature environments are prone to micropore shrinkage, grain coarsening, and porous structure collapse, leading to severe densification. This consequently degrades the durability and reliability of the ceramic coatings. This paper elucidates the sintering densification mechanism of ceramic coatings, analyzes innovations in material systems and multidimensional structural design strategies, and summarizes the state-of-the-art research progress on anti-sintering densification of ceramic coatings. The limitations of conventional techniques that inhibit high-temperature sintering densification via “passive pore retention” are highlighted. A novel strategy based on phase transformation-induced pore formation for achieving “active in situ pore generation” is explored. On this basis, future research directions for enhancing the anti-sintering densification performance of ceramic thermal protective coatings are proposed. Full article

The three-phase region of Mo₃Si-Mo₅Si₃-Mo₅SiB₂(MoSiB) exhibits excellent high-temperature oxidation resistance and is considered a highly promising high-temperature structural material. However, the presence of porous structures significantly increases the surface area exposed to oxidation. Metallic porous materials often suffer from inadequate corrosion resistance and insufficient high-temperature oxidation resistance, whereas ceramic porous materials are plagued by high brittleness. Intermetallic compounds offer a combination of the advantages of both metals and ceramics. Nevertheless, the high-temperature oxidation behavior of porous MoSiB has not yet been systematically elucidated. The study systematically investigates the effect of pore structure on the high-temperature oxidation behavior of porous MoSiB at 1000 °C and 1300 °C, with a focus on oxidation kinetics, phase evolution, surface and cross-sectional morphology and underlying oxidation mechanisms. The effects of porosity and temperature on the oxidation process are also analyzed. The results indicate that at 1000 °C, the material exhibits uniform oxidation, with lower porosity contributing to better oxidation resistance. At 1300 °C, oxidation is limited to the surface layer, where low-viscosity SiO₂(B) rapidly seals the pores to form a dense protective layer. This research reveals the high-temperature oxidation mechanism and phase evolution of porous MoSiB, providing a theoretical foundation for its application in high-temperature structural fields. Full article

Porous Ti₂AlC, a member of the MAX phase family of nanolaminated ternary carbides and nitrides, has attracted increasing attention due to its unique combination of metallic and ceramic properties. This review summarizes recent advances in the fabrication, structure–property relationships, and applications of porous Ti₂AlC. Various processing routes, including incomplete sintering, sacrificial templating, replica techniques, gel casting, extrusion, and direct ink writing, are compared in terms of achievable porosity, pore morphology, and structural control. Particular emphasis is placed on the role of porosity in tailoring mechanical performance, thermal conductivity, and high-temperature oxidation resistance, based on available literature data. Recent progress in applications of porous Ti₂AlC and related MAX phases is also discussed, including their use in filtration, membrane supports, heat exchangers, electrochemical systems for hydrogen evolution, and as preforms for lightweight interpenetrating metal/MAX phase composites. Finally, current challenges and future research directions are identified, highlighting the need for improved control of porosity and a deeper understanding of structure–property relationships. Full article

This article presents preliminary research on the development of a cast iron–ceramic composite for modern braking systems, such as brake discs. The composite matrix is gray cast iron with flake graphite (EN-GJL-150). The reinforcing phase is a porous ceramic composed of SiC and Al₂O₃ particles introduced separately (10% each) and together (70% SiC + 30% Al₂O₃). These particles were applied as a suspension onto polyurethane foam, yielding a ceramic structure with a pore density of up to 10 ppi. The resulting insert was placed in a mold cavity, and cast iron was poured into it. The resulting samples were treated as brake disc material, with a pad made of the commercial friction material P50094 serving as the countersample. Tribological tests showed that the lowest sample wear (average 2.23 mg/5000 m) was achieved for the composite reinforced with SiC + Al₂O₃ particles. This is probably due to the synergy between the antifriction properties of these particles and the lower friction coefficient (µ = 0.180–0.22). Similar mass loss values and the smallest difference between the tested samples were observed for composites with SiC particles (3.01 mg/5000 m) and Al₂O₃ (3.30 mg/5000 m). The second part consisted of microstructural studies. Microstructural analysis of the EN-GJL-150 + SiC + Al₂O₃ composite revealed a previously unobserved nucleation phenomenon at the cast iron–ceramic interface. This confirmed the general assumptions of Riposan’s theory regarding the involvement of oxide microinclusions and complex manganese sulfides of the (Mn, X)S type in the nucleation and crystallization of graphite precipitates. It was also found that, in the case of “in situ” GJL-150 + SiC + Al₂O₃ composites, this theory should account for the beneficial role of ceramic particles in promoting the uniform distribution of type A graphite flakes, which nucleate on their surfaces in the transition zone. Thus, the nucleating role of oxide microinclusions (the first stage of Riposan’s theory) could be taken over by SiC and Al₂O₃ particles, constituting a substrate for the heterogeneous nucleation of (Mn, X)S sulfides. Full article