Search Results (56)

Simultaneously achieving high densification, excellent mechanical properties, and high thermal conductivity remains challenging for aluminum nitride–silicon carbide (AlN-SiC) composites. In this study, fine-grained AlN-SiC composite ceramics were fabricated via in situ reaction hot pressing with the addition of small amounts of silicon (Si) and carbon (C). At an optimal sintering temperature of 1800 °C, the primary phase composition consisted of AlN, SiC and residual graphite, with an average AlN grain size of 0.94 μm. The Si additive melted and wetted the AlN matrix via capillary action, thereby providing sufficient kinetic driving force for densification. Meanwhile, the C additive not only removed oxygen impurities and purified grain boundaries but also reacted in situ with liquid Si to form SiC. The uniformly dispersed SiC particles inhibited the abnormal growth of AlN grains via the grain boundary pinning effect. Consequently, the relative density, flexural strength, and Vickers hardness of the obtained AlN-SiC ceramics reached 99.08%, 365 MPa and 22.58 GPa, respectively. At room temperature, the composite exhibited a thermal conductivity of 66 W/(m·K) and a thermal diffusivity of 32.6 mm²/s. This superior thermal performance is attributed to the purified grain boundaries, uniform SiC distribution, high densification, and tightly bonded SiC/AlN interfaces, which result in weak phonon interfacial scattering. Full article

This study assessed the performance of three microfiltration (MF) membrane modules: M1 (spiral, polyvinylidene fluoride), M2 (capillary, polypropylene), and M3 (capillary, α-Alumina) in treating backwash water from utility-scale surface water (SW) and infiltration water (IW) plants, each with a capacity of approximately 100,000 m³/day. Considering 168 h (one-week) filtration cycles, the membranes were evaluated for permeate flux, turbidity removal, dissolved organic carbon (DOC) removal, and reduction in total number of microorganisms (TNM). In contrast to most previous studies that have primarily examined surface water sources under laboratory conditions, this research contributes to the literature by evaluating membrane performance using actual backwash water from both SW and IW treatment plants. The comparative assessment of three structurally and materially distinct membrane modules under identical flow-through conditions yields new insights into the trade-offs among hydraulic performance, contaminant removal, and treatment cost. Logarithmic models fitted to permeate flux data yielded determination coefficients (R²) ranging from 0.60 to 0.99, supporting the prediction of early-stage performance. No consistent trend in flux decline was observed, mainly due to fluctuations in the water bacterial load. With a median TNM removal efficiency of 97%, M1 outperformed M2 and M3 (84% and 70%, respectively) in terms of microorganism removal. The effectiveness of DOC removal generally depended on the type of backwash water; the highest efficiency was observed for M2 in the case of backwash from IW treatment and for M1 in the case of backwash from SW treatment. M2 provided the highest permeate flux rates, regardless of water type or operational limitations. The ceramic membrane (M3) exhibited the greatest variability in hydraulic performance and removal efficiency, depending on the type of backwash water. A simplified cost analysis over two filtration cycles found that treatment costs were generally higher for SW backwash, with differences reaching up to 90% between membrane-water type combinations. Although treatment costs are higher than those for raw water treatment, the increasing water scarcity makes it a potential additional source of safe water. Full article

Soil salinization represents a growing threat to agricultural productivity, particularly in arid and semi-arid regions where evaporation-driven salt accumulation forms surface crusts that inhibit further moisture transport. This study introduces a novel passive and low-cost remediation strategy consisting of vertically inserted fired-clay ceramic sheets that function as capillary wicks, enabling the simultaneous enhancement of evaporative flux and salt removal from saline-irrigated soils. Controlled laboratory experiments were conducted on soil columns irrigated with saline water (180 and 250 g/L) and equipped with one to four ceramic sheets (porosity = 0.33). Evaporation tests showed that saline soil without inserts lost 34 g of water over 120 h, compared to 47 g with one ceramic sheet and up to 68 g with four sheets. Salt extraction increased similarly, reaching 59% removal with four sheets versus 20% with a single sheet. Most extraction occurred within the first 72 h, after which performance declined due to salt crystallization within ceramic pores. These findings establish that vertically inserted fired-clay ceramics represent a viable, scalable, and low-cost technology for passive soil desalinization, with optimal operational cycles of 72–120 h recommended before periodic sheet replacement. Full article

Efficient recovery of ammonia from sludge hydrolysate (SH) remains a challenging task. This study developed a superhydrophobic capillary ceramic-membrane contactors (MCs), which, by establishing a stable gas-phase mass transfer interface, provides a reliable guarantee for ammonia recovery under high-temperature, high-pH, and high-organic-load conditions. In a controllable simulation system, the system investigated the effects of key operational parameters such as pH, flow rate, and feed ammonia concentration on ammonia mass transfer behavior, and verified the feasibility of this MCs in efficient ammonia removal. Then, this membrane contactor was applied to the actual sludge hydrolysate (SH) system, and its anti-pollution effects, wetting stability, and adaptability to fluctuating conditions under long-term continuous operation were evaluated. The results showed that after operating for 10 h, the ammonia removal in the simulation system and the actual system reached 93.6% and 90.3%, respectively. During long-term operation, the ammonia recovery reached 90.3%. Meanwhile, the organic matter in SH was completely retained, and (NH₄)₂SO₄ was not contaminated by organic matter. Throughout the entire operation process, the contact angle of the membrane remained above 129.6°. This study provides a theoretical basis and practical reference for recovering ammonia using a hydrophobic capillary ceramic-membrane contactor in SH. Full article

Nature-based solutions (NBSs), such as green roofs, are among the most effective ways to manage urban stormwater, improve building energy efficiency, and adapt to climate change. However, conventional green roofs confront several restrictions related to stormwater drainage, retention capacity, irrigation demand, and pressure on urban water networks during dry periods. This study proposes and experimentally validates a novel system applicable to green roofs and other NBS, including streetside planting systems and vegetated sports grounds. The novelty of the proposed system lies in a double-layer design, the integration of filters within soil substrate to enhance short-term stormwater retention and controlled drainage, and passive subsurface capillary irrigation with cords to improve irrigation efficiency. Infiltration tests showed that filter hydraulic conductivity strongly depends on pore size, with measured infiltration rates ranging from 0.01 mm/min (ceramic, 0.1 μm) to 20 mm/min (polypropylene, 50 μm). The results showed that filter material and pore size significantly influence infiltration behaviour and short-term storage capacity. When integrated with the soil substrate, the combined system exhibited infiltration rates of 0.8–2.0 mm/min, decreasing as hydraulic head declined. Capillary rise experiments demonstrated a maximum vertical rise of 32 cm and horizontal rise of 39 cm for polyester cords (6 mm width), confirming the feasibility of passive subsurface irrigation through stored runoff reuse without external energy. The experiments were conducted at a laboratory scale (25 × 25 cm) as a proof-of-concept validation. Finally, the study results demonstrate the feasibility of the proposed system as a multifunctional NBS solution that enhances stormwater retention while enabling passive irrigation using retained runoff. Full article

High regeneration energy demand remains a critical barrier to the large-scale deployment of ethanolamine-based (MEA-based) CO₂ capture. This study adopts an Al₂O₃ ceramic-membrane heat exchanger (CMHE) to recover both sensible and latent heat from the stripped gas. Experiments confirm that heat and mass transfer within the CMHE follow a coupled mechanism in which capillary condensation governs trans-membrane water transport, while heat conduction through the ceramic membrane dominates heat transfer, which accounts for more than 80%. Guided by this mechanism, systematic structural optimization was conducted. Alumina was identified as the optimal heat exchanger material due to its combined porosity, thermal conductivity, and corrosion resistance. Among the tested pore sizes, CMHE-4 produces the strongest capillary-condensation enhancement, yielding a heat recovery flux (q value) of up to 38.8 MJ/(m² h), which is 4.3% and 304% higher than those of the stainless steel heat exchanger and plastic heat exchanger, respectively. In addition, Length-dependent analyses reveal an inherent trade-off: shorter modules achieved higher q (e.g., 14–42% greater for 200-mm vs. 300-mm CMHE-4), whereas longer modules provide greater total recovered heat (Q). Scale-up experiments demonstrated pronounced non-linear performance amplification, with a 4 times area increase boosting q by only 1.26 times under constant pressure. The techno-economic assessment indicates a simple payback period of ~2.5 months and a significant reduction in net capture cost. Overall, this work establishes key design parameters, validates the governing transport mechanism, and provides a practical, economically grounded framework for implementing high-efficiency CMHEs in MEA-based CO₂ capture. Full article

The construction sector is progressively prioritizing environmental norms owing to its substantial role in carbon emissions from clinker manufacture. Industrial waste materials are increasingly used as alternative constituents in cement-based systems, garnering interest as a sustainable strategy. Ceramic waste powder (CWP), produced in substantial quantities with enduring properties, offers a viable alternative. Nonetheless, its elevated water absorption presents issues, requiring modification procedures such as hydrophobization and the use of nanosilica to enhance performance. This study assessed CWP in both raw and modified forms (ground and hydrophobized) as a partial aggregate replacement in concrete. A silane-derived chemical was employed for hydrophobization, with varying amounts of nanosilica. Recent mortar testing encompassed setting time, flow, and density. Durability was evaluated using capillary water absorption, and flexural and compressive strengths were quantified at 2, 7, and 28 days. Mineralogical and microstructural investigations were conducted utilizing XRD and FTIR to monitor hydration phases and reaction processes. Results indicated that unmodified CWP containing up to 1% (wt) nanosilica enhanced mechanical strength; however, elevated nanosilica concentrations diminished early strength. Hydrophobized CWP samples demonstrated improved early strength with nanosilica levels up to 0.5% (wt), but strength diminished at elevated concentrations. Microstructural analysis confirmed reduced portlandite levels and increased C–S–H production, thereby validating the progress of hydration. The regulated and altered application of CWP with nanosilica can improve mechanical performance and durability while promoting ecological sustainability in cement-based systems. Full article

This study addresses water scarcity in arid regions by developing low-temperature-sintered porous ceramics for agricultural water management, utilizing coal gangue solid waste as the primary resource. Systematic single-factor experiments first identified the optimal sintering temperature (615 °C) and polystyrene content (25%) that critically balance pore formation and structural integrity. Building on this, orthogonal experiment optimization yielded an optimal formulation exhibiting exceptional comprehensive performance (coal gangue 20 g, starch 25 g, glass powder 11 g, polystyrene 27 g): 149.70% water absorption, 57.75 h water retention, 77.28% porosity, and 0.55 MPa compressive strength. The material’s graded pore structure, achieved through composite pore-formers (polystyrene/starch) and diatomaceous earth, underlies its enhanced capillary action. The pot experiment of Chinese cabbage confirmed its effect, shortened the emergence time of seedlings to <24 h, and significantly improved the emergence rate and the growth of seedlings in the early stage (7 days). This work provides a new way for the value of coal gangue in dryland agriculture and ecological restoration. Full article

Filtration of submicron particles and nanoparticles is an important problem in nano-industry and in air conditioning and ventilation systems. The presence of submicron particles comprising fungal spores, bacteria, viruses, microplastic, and tobacco-smoke tar in ambient air is a severe problem in air conditioning systems. Many nanotechnology material processes used for catalyst, solar cells, gas sensors, energy storage devices, anti-corrosion and hydrophobic surface coating, optical glasses, ceramics, nanocomposite membranes, textiles, and cosmetics production also generate various types of nanoparticles, which can retain in a conveying gas released into the atmosphere. Particles in this size range are particularly difficult to remove from the air by conventional methods, e.g., electrostatic precipitators, conventional filters, or cyclones. For these reasons, nanofibrous filters produced by electrospinning were developed to remove fine particles from the post-processing gases. The physical basis of electrospinning used for nanofilters production is an employment of electrical forces to create a tangential stress on the surface of a viscous liquid jet, usually a polymer solution, flowing out from a capillary nozzle. The paper presents results for investigation of the filtration process of metal oxide nanoparticles: TiO₂, MgO, and Al₂O₃ by electrospun nanofibrous filter. The filter was produced from polyvinylidene fluoride (PVDF). The concentration of polymer dissolved in dimethylacetamide (DMAC) and acetone mixture was 15 wt.%. The flow rate of polymer solution was 1 mL/h. The nanoparticle aerosol was produced by the atomization of a suspension of these nanoparticles in a solvent (methanol) using an aerosol generator. The experimental results presented in this paper show that nanofilters made of PVDF with surface density of 13 g/m² have a high filtration efficiency for nano- and microparticles, larger than 90%. The gas flow rate through the channel was set to 960 and 670 l/min. The novelty of this paper was the investigation of air filtration from various types of nanoparticles produced by different nanotechnology processes by nanofibrous filters and studies of the morphology of nanoparticle deposited onto the nanofibers. Full article

Moisture transport in building materials significantly influences their durability, mechanical integrity, and thermal performance. This study presents an experimental investigation of moisture permeability in a range of traditional and modern wall elements, including autoclaved aerated concrete (ACC), ceramic blocks, silicate blocks, perlite concrete blocks, and concrete units. Both vapor diffusion and capillary transport mechanisms were analyzed under controlled climatic conditions using gravimetric and hygrometric methods. Among the tested materials, autoclaved aerated concrete (AAC) was selected for detailed numerical modeling because of its high porosity, strong capillarity, and widespread use in modern construction, which make it especially vulnerable to moisture-related degradation. Based on the experimental findings, a digital twin was developed to simulate hygrothermal behavior of walls made of ACC under various environmental conditions. The model incorporates advanced moisture transport equations, capturing diffusion and capillary effects while considering real-world variables, such as relative humidity, temperature fluctuations, and wetting–drying cycles. Calibration demonstrated strong agreement with experimental data, enabling reliable predictions of moisture behavior over extended exposure scenarios. This integrated approach provides a robust engineering tool for assessing the long-term material performance of AAC, predicting degradation risks, and optimizing material selection in humid climates. The study illustrates how coupling experimental data with digital modeling can enhance the design of moisture-resistant and durable building envelopes. Full article

This study demonstrates the successful fabrication of high-performance reaction-bonded silicon carbide (RBSC) ceramics through an optimized liquid silicon infiltration (LSI) process employing multi-modal SiC particle gradation and nano-carbon black (0.6 µm) additives. By engineering porous preforms with hierarchical SiC distributions and tailored carbon sources, the resulting ceramics achieved a compressive strength of 2393 MPa and a flexural strength of 380 MPa, surpassing conventional RBSC systems. Microstructural analyses revealed homogeneous β-SiC formation and crack deflection mechanisms as key contributors to mechanical enhancement. Ultrafine SiC particles (0.5–2 µm) refined pore architectures and mediated capillary dynamics during infiltration, enabling nanoscale dispersion of residual silicon phases and minimizing interfacial defects. Compared to coarse-grained counterparts, the ultrafine SiC system exhibited a 23% increase in compressive strength, attributed to reduced sintering defects and enhanced load transfer efficiency. This work establishes a scalable strategy for designing RBSC ceramics for extreme mechanical environments, bridging material innovation with applications in high-stress structural components. Full article

This study presents a preliminary evaluation of candidate wick material and working fluid for a flat-loop heat pipe (F-LHP) designed to operate within the temperature range of 500–700 K. The selection process considered key thermal and physical parameters, including thermal conductivity, chemical compatibility between wick and fluid, capillary pressure generation, pressure drop across the wick structure, and structural integrity at elevated temperatures. A range of metallic and ceramic wick materials, along with suitable high-temperature working fluids, were reviewed and compared based on performance metrics and practical availability. Special attention was given to oxidation and corrosion resistance, capillary performance, and thermal stability under elevated-temperature conditions. Nine different porous wicks with distinct materials and microstructures—differing in pore size, porosity, and permeability—were analyzed in combination with seven different working fluids. The analysis focused on determining which combinations generated the highest capillary pressure and which exhibited the lowest flow resistance due to external flow, thereby enhancing the LHP’s performance. Based on these results, the study identifies the most effective wick–fluid pairings for F-LHP applications, offering an optimal balance of thermal performance and long-term reliability. These findings provide a foundation for further experimental validation and the development of prototypes. Full article

The physicochemical and adsorption properties of granular sorbents based on natural bentonite and modified sorbents based on it have been studied. It was found that modification of natural bentonite with iron (III) polyhydroxocations (mod. 1_Fe_5 GA) and aluminum (III) (mod. 1_Al_5 GA) by the “co-precipitation” method leads to a change in their chemical composition, structure, and sorption properties. It is shown that modified sorbents based on natural bentonite are finely porous (nanostructured) objects with a predominance of pores measuring 1.5–8.0 nm, with a specific surface area of 55–65 m²/g. Modification of bentonite with iron (III) and aluminum compounds by the “co-precipitation” method also leads to an increase in the sorption capacity of the obtained sorbents with respect to bichromate and arsenate anions and nickel cations by 5-10 times compared with natural bentonite. The obtained sorption isotherms were classified as Langmuir type isotherms. Kinetic analysis showed that at the initial stage the sorption process is controlled by an external diffusion factor, i.e. refers to the diffusion of sorbent from solution into a liquid film on the surface of the sorbent. Then the sorption process begins to proceed in a mixed diffusion mode, when it limits both the external diffusion factor and the internal diffusion factor (the diffusion of the sorbent to the active centers through the system of pores and capillaries). To determine the contribution of the chemical stage to the rate of adsorption of bichromate and arsenate anions and nickel(II) cations with the studied granular sorbents, kinetic curves were processed using the equations of chemical kinetics (pseudo-second-order model). As a result, it was found that the adsorption of the studied anions by modified sorbents based on natural bentonite is best described by a pseudo-second-order kinetic model. It is shown that the use of natural bentonite for the development of technology for the production of granular sorbents based on it has an undeniable advantage, firstly, in terms of its chemical and structural properties, it is easily and effectively modified, and secondly, having astringent properties, granules are easily made on its basis, which turn into ceramics during high-temperature firing. The result is a granular sorbent with high physical and mechanical properties. Since bentonite is an environmentally friendly product, the technology of recycling spent sorbents is also greatly simplified. Full article

This study aims to evaluate the potential of machine learning algorithms (Random Forest and Support Vector Machine) in predicting the open porosity of a general-use industrial mortar applied to different substrates based on the characteristics of both the mortar and substrates. This study’s novelty lies in predicting the mortar’s porosity considering the substrate’s influence on which this mortar is applied. For this purpose, an experimental database comprising 1592 datapoints of industrial mortar applied to five different substrates (hollowed ceramic brick, solid ceramic brick, concrete block, concrete slab, and lightweight concrete block) was generated using an experimental program. The samples were characterized by bulk density, open porosity, capillary water absorption coefficient, drying index, and compressive strength. This database was then used to train and test the machine learning algorithms to predict the open porosity of the mortar. The results indicate that it is possible to predict the open porosity of mortar with good prediction accuracy, and that both Random Forest (RF) and Support Vector Machine (SVM) algorithms (RF = 0.880; SVM = 0.896) are suitable for this task. Regarding the main characteristics that influence the open porosity of the mortar, the bulk density and open porosity of the substrate are significant factors. Furthermore, this study employs a straightforward methodology with a machine learning no-code platform, enhancing the replicability of its findings for future research and practical implementations. Full article

This article describes a module and method for measuring the surface tension of liquid solders implemented on a measuring device as part of an integrated platform for automatic measurement of brazebility parameters at high temperatures. A concept for constructing a test stand is presented, with a description of the individual functional blocks. The developed stand allows for testing of the solder’s surface tension. The surface tension is one of the parameters that describe the thermodynamics of interfacial reactions and the structure of newly created joints. Determining the physicochemical interactions between liquid and solid substances is crucial for various industrial processes in fields such as metallurgy, electronics, and aviation, mainly where soldering and brazing technologies are employed. A series of bubble experiments in solder for a ceramic capillary is carried out to verify the proposed method using the developed system. One of these experiments is described in this article. Full article