Search Results (303)

This study examined the effectiveness of using biochar from the tanning industry as a silicon carrier to reduce trace element toxicity and improve plant nutrition in soil–plant systems. Silicon-enriched biochar was produced from chromium-free leather waste and applied in 21-day pot trials with cucumber. It contained 11.6 ± 2.3% SiO₂ and effectively served as a slow-release silicon carrier. Optimal plant growth and nutrient uptake were achieved with the application of 100% silicon without additional NPK fertilizers, demonstrating a strong positive correlation with essential trace elements such as copper and iron. Importantly, silicon fertilization significantly reduced the uptake of toxic metals such as Al, Cd, and Ti, underscoring the potential of silicon-enriched biochar for phytoremediation and sustainable crop production. Using silicon-enriched biochar from industrial leather waste thus provides a novel, sustainable strategy to improve soil fertility and plant health while repurposing waste. Future work should include long-term field trials and examine species-specific responses and management practices to scale up this approach for enhanced crop resilience. Full article

In this study, a series of amphiphilic polyether-modified silicone oil (PMSO) polymers with hydrophilic–lipophilic balance (HLB) values ranging from 3.5 to 5 were synthesized via hydrosilylation. These polymers are self-emulsifying and can form stable micelles in water without the need for external emulsifiers, with micelle sizes ranging from 79.9 to 161.4 nm. For the first time, such amphiphilic micelles were employed as an internally incorporated hydrophobic admixture to investigate the waterproofing and corrosion resistance of cement-based materials. The results showed that PMSO micelles with an HLB value of 4 significantly reduced the water absorption of cement mortar and improved mechanical properties by enhancing the compactness and crystallinity of the cement matrix. At a dosage of 0.5 wt% PMSO in mortar, the water absorption at 48 h was reduced by 50.27% compared with the control group, and the inner and outer contact angles of the mortar specimens reached 105° and 126°, respectively. The chloride diffusion coefficient of concrete decreased by 70.8% relative to the control group. At an appropriate dosage (0.1 wt%), the flexural strength of the mortar at 28 days increased by 12.50%, and the compressive strength increased by 14.19% compared with the control group. Low-field nuclear magnetic resonance (NMR) was used to determine the changes in the pore structure of mortar specimens before and after the addition of PMSO micelles. The experimental results showed that the addition of PMSO micelles reduced the number of harmful large pores, resulting in a denser microstructure. Finally, the corrosion resistance of concrete was evaluated via electrochemical accelerated-corrosion aging tests. The cracking time of concrete containing PMSO micelles was extended from 144 h (control group) to 240 h, demonstrating improved corrosion resistance. Full article

MoSi₂-based intermetallics are interesting materials for high-temperature applications, due to their moderate density, high melting point and significant oxidation resistance. In this paper, MoSi₂-based materials in the form of multi-layered structures were fabricated by tape casting and pressureless sintering. Composites containing up to 20 wt.% of NbSi₂ were produced, with the aim of obtaining biphasic structures with low pest oxidation at low temperature. The prepared samples were characterised with regard to phase composition, microstructure, mechanical properties and oxidation resistance. It was shown that the addition of a limited amount of NbSi₂ prevents the pest oxidation phenomenon characteristic of pure MoSi₂. Silica inclusions responsible for lowering the material toughness, were observed to disappear in the sintered silicides, thanks to the presence, during the binder burn-out, of a reducing atmosphere and to the carbonaceous residua. The phase and composition analysis also revealed the formation of small amounts of secondary phases like silicon carbide. Full article

In 2.5D/3D stacked advanced packaging, thermal conductive silicone adhesives are widely employed to achieve structural bonding and efficient heat dissipation. In this study, one thermal conductive silicone adhesive was prepared using medium viscosity vinyl silicone oil, hydrogen-containing silicone oil, and micron-sized alumina powder as the primary components. The results demonstrated that the adhesive exhibited excellent thermal and mechanical performance. Specifically, its thermal decomposition temperature exceeded 400 °C, the thermal conductivity reached over 1.80 W·m⁻¹·K⁻¹, and the thermal resistance was below 12.0 °C·cm²·W⁻¹. The shear strength exceeded 5.00 MPa. Furthermore, after exposure to an unbiased highly accelerated stress test for 384 h, 1000 thermal cycles, and thermal aging for 1000 h, the adhesive maintained stable thermal conductivity and mechanical properties. The thermal conductivity remained above 1.70 W·m⁻¹·K⁻¹, and the shear strength remained higher than 5.00 MPa. In addition, the tensile modulus was maintained below 100 MPa, and the coefficient of linear thermal expansion was less than 160 ppm·°C⁻¹. Overall, the comprehensive performance of the adhesive satisfies the reliability requirements for advanced packaging substrates and heat dissipation lid assemblies. Full article

This study investigates the relationship between viscosity and manufacturability of two-component silicones in extrusion-based additive manufacturing. A methodology is proposed to adapt commercially available, low-viscosity general-purpose silicones for direct 3D printing using the material extrusion system provided by Lynxter S300X. EcoFlex™ 00-50 silicone was modified through controlled additions of a thixotropic agent (THI-VEX), producing formulations with progressively increased viscosity. After a preliminary qualitative viscosity assessment, formulations were printed using identical process parameters and evaluated through a set of dedicated geometric benchmark specimens targeting critical failure modes, including unsupported thin walls, overhangs, gaps, and slender structures. Print outcomes were assessed via multi-rater visual inspection with inter-rater reliability analysis to ensure consistency. Results reveal a strong correlation between thixotropy and geometric fidelity, identifying the formulation containing 4.0 wt% THI-VEX as optimal under the tested conditions. The study provides practical design and process guidelines for silicone additive manufacturing and highlights the importance of integrated material–process optimization for reliable fabrication of soft, highly deformable materials. Full article

In this study, by using four different silicon sources obtained from Konya, Turkey, and its surroundings and employing the sol–gel method, we aim to synthesize silica-based aerogel, characterize it, and improve the use of the innovative building material as a thermal insulator in architectural applications. In this direction, silica aerogel production was carried out using four different starting materials (commercial casting sand, waste casting sand, radiolarite, and quartz) and five different pH values (2–4–6–8–9) by the sol–gel method. The produced silica aerogels were subjected to a surface modification process with Trimethylchlorosilane (TMCS), a modification chemical, and then superhydrophobic silica aerogel powder was obtained. In terms of characterization of the obtained final silica aerogels, XRF, XRD, ICP-OES, density study, FT-IR, BET, FESEM, and contact angle studies were performed. In terms of application of the architectural building material, plasterboard experimental samples were produced using low reinforcement rates (0 wt%, 0.5 wt%, 1 wt%, 2 wt%, and 5 wt%) of silica aerogel. To determine the mechanical and physical properties of the produced silica-aerogel-reinforced plasterboard samples, three-point bend (flexural) strength, compressive strength, thermal conductivity, and water absorption tests were applied. After surface modification, the lowest density value was 0.340 g/cm³, the highest surface area was 311.161 m²/g, and the lowest thermal conductivity coefficient was 0.29 W/mK in silica aerogel material containing radiolarite. In addition to high reinforcement contents in the literature, when it comes to silica aerogel low-reinforcement material and mechanical properties, it can be stated that increasing reinforcement contents negatively affects the mechanical behavior of the material after a certain value. Full article

This study aimed to investigate the effect of time and different disinfecting agents on nanocomposite filler composed of natural clay nanoparticles (modified and non-modified) added to maxillofacial silicone elastomers and readymade pigment additives. A total of 360 disk-shaped samples were divided into nine pigment-based groups, each with four subgroups (n = 10) exposed to different disinfectants: distilled water, 1% sodium hypochlorite (NaOCl), 2% chlorhexidine (CHX), and effervescent tablets. Color changes (ΔE) were measured before and after disinfection using a colorimeter. The ΔE values were assessed against perceptibility (ΔE = 1.1) and acceptability (ΔE = 3) thresholds. Nanoclay additives were also characterized using FTIR, XRD and EDX. Statistical analysis, including ANOVA and post hoc HSD tests, revealed that while all samples exhibited some color change, most remained below the acceptability threshold. Colorless silicone showed minimal, non-significant change according to perceptibility threshold (ΔE = 1.1). Blue pigments displayed significant change only with effervescent tablets. Red and mixed pigments showed perceptible changes with NaOCl, CHX, and effervescent tablets. However, nanoclay-containing specimens showed no significant perceptible alterations. Overall, despite minor perceptible changes in some pigments, all disinfecting agents tested resulted in color differences below the acceptability threshold, indicating their safe use for disinfecting maxillofacial silicone materials without compromising esthetics. Nevertheless, nanoclays are more reliable agents for the pigmentation of maxillofacial silicone as they show non-significant chromatic alteration. Full article

In metal cutting industries, optimizing the thermal conductivity and viscosity of vegetable oil-based cutting fluids is critical for ensuring efficient heat dissipation, effective lubrication, and sustainability, directly influencing tool life and machining performance. This study presents a comprehensive experimental analysis employing statistical methods, particularly Taguchi’s Design of Experiments, to evaluate the thermal conductivity and viscosity of Pongamia pinnata, sunflower, and coconut oil incorporated with Silicon Dioxide (SiO₂), Hexagonal Boron Nitride (hBN), and Cupric Oxide (CuO) nanoparticles across different emulsion ratios and nanoparticle volume fractions. The results revealed that Pongamia pinnata oil containing 0.5 (Vol.%) SiO₂ nanoparticles at an emulsion ratio of 1:7 achieved the maximum thermal conductivity, measured at 0.637 W/mK. Additionally, the results revealed that Pongamia pinnata oil at an emulsion ratio of 1:13 exhibited the highest viscosity of 1.33 mPa·S, confirming that both the type of cutting oil and the emulsion ratio are the primary factors influencing viscosity. Further, the ANOVA analysis for thermal conductivity and viscosity highlights that the type of cutting fluid is the dominant factor, accounting for 90.58% of the total variance in thermal conductivity and 70.47% in viscosity, each with a highly significant p-value of 0.00, underscoring its decisive impact on the stability of both properties. Overall, this research offers important guidance for the selection and formulation of vegetable oil-based emulsions with nanoparticle additives. The results support the development of advanced nano lubricants with enhanced performance, catering to the increasing requirements of diverse industrial applications. Full article

Hypoeutectic aluminum–silicon casting alloys in their unmodified state have a coarse-grained eutectic (α + β), which results in poor mechanical properties and brittleness. Microstructure refinement and improved mechanical properties are possible, among other things, by introducing various elements and chemical compounds. The literature presents numerous studies on the modification of hypoeutectic silumins, but there are no results confirming the effectiveness of the interaction of a master alloy containing titanium and boron with its main component, which may be aluminum, aluminum with silicon, or aluminum with silicon and magnesium. This paper presents the results of microstructure refinement using titanium or boron introduced into the Al, AlSi7, and AlSi7Mg master alloys. The introduction of titanium and boron into the aluminum-based master alloy resulted in microstructure refinement and improved mechanical properties. The results indicate that the most favorable results were obtained when titanium and boron were introduced into the AlSi7 master alloy. The addition of magnesium to the master alloy AlSi7 resulted in less effective microstructure refinement of the AlSi9 silumin, which resulted in lower mechanical properties than those obtained for the master alloy without Mg. Full article

7xxx series aluminum alloys are critical structural materials in aerospace applications, but their susceptibility to hydrogen embrittlement (HE) poses significant challenges to service safety and durability. The effects of Si, Er, and Zr microalloying, combined with optimized heat treatments on the HE resistance of Al–Zn–Mg–Cu alloys, were systematically investigated using transmission electron microscopy (TEM), scanning electron microscopy (SEM), and mechanical testing. Three alloys—1# (AlZnMgCuZr), 2# (AlZnMgCuErZr), and 3# (AlZnMgCuSiErZr)—were subjected to single-stage or two-stage homogenization, followed by solution treatments at 470 °C/2 h and 540 °C/1 h, and peak aging at 125 °C. The hydrogen charging experiment was conducted by first applying a modified acrylic resin coating to protect the gripping sections of the specimen, followed by a tensile test. Results demonstrate that alloy 3# with Si addition exhibited the lowest RA_loss, followed by the 2# alloy, which effectively improved the alloys’ hydrogen embrittlement behavior. Compared with the solution in 470 °C/2 h, the 540 °C/1 h solution treatment enabled complete dissolution of Mg₂Si phases, promoting homogeneous precipitation and peak hardness comparable to alloy 2#. Two-stage homogenization significantly enhanced the number density and refinement of L₁₂-structured Al₃(Er,Zr) nanoprecipitates. Silicon further accelerated the precipitation kinetics, leading to more Al₃(Er,Zr) nanoprecipitates, finely dispersed T′/η′ phases, and lath-shaped GPB-II zones. The GPB-II zones effectively trapped hydrogen, thereby improving HE resistance. This work provides a viable strategy for enhancing the reliability of high-strength aluminum alloys in hydrogen-containing environments. Full article

Investment casting of aluminum alloys is widely used in the aeronautical and automotive sectors for manufacturing complex components. However, conventional alloys lack sufficient mechanical strength and high-temperature resistance, prompting the need for enhanced materials. This study investigated the addition of submicron TiC particles, introduced via stir casting process, to an AlSi7Mg0.3 alloy for investment casting. Chemical analysis confirmed the incorporation of up to 0.1 wt.% TiC, but no significant improvement in tensile properties was observed. High Resolution Scanning Electron Microscopy (HRSEM) and Transmission Electron Microscopy (TEM) revealed a complex microstructure with few TiC particles and needle-shaped intermetallic phases containing titanium, iron, silicon, or aluminum. The high mold temperature (700 °C) and slow solidification rate likely caused partial TiC dissolution and intermetallic precipitation, which may have offset strengthening mechanisms like the Hall–Petch effect. Notably, the partial dissolution of TiC particles in investment casting has not been previously reported in similar alloys. These findings highlight the challenges of using particle-reinforced alloys in this process and emphasize the need for further research into process–microstructure relationships. Full article

Background/Objectives: This in vitro study examined the potential enhancement in resistance to accelerated aging in room-temperature vulcanized (RTV) maxillofacial silicone, intrinsically pigmented in two skin tones, through the use of zirconium oxide (ZrO₂) nanoparticles. Methods: A total of 128 disc-shaped specimens were created in rose silk and soft brown shades, each containing zirconium oxide concentrations of 0%, 1%, 2%, and 3% by weight. Color variation (ΔE*) was assessed initially and following 252, 750, and 1252 h of artificial aging, tested with a colorimeter. Surface roughness characteristics (R_a, R_q, R_t) were evaluated before and after 1252 h using atomic force microscopy (AFM). Structural, vibrational, and morphological characteristics were analyzed through X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and field emission scanning electron microscopy (FESEM). Results: Non-parametric tests (Friedman, Kruskal–Wallis, and Bonferroni-adjusted paired testing; p < 0.05) indicated that accelerated aging significantly increased ΔE* in all specimens. The addition of ZrO₂ reduced these changes; however, the optimal concentration differed by pigment: 1% for rose silk and 3% for soft brown. The effect on surface roughness depended on pigment type. Higher nanoparticle concentrations generally improved post-aging smoothness in soft brown samples, whereas rose silk showed a more variable response. XRD and FTIR analyses confirmed successful nanoparticle incorporation without altering the fundamental silicone structure, while FESEM demonstrated improved filler–matrix interaction in modified groups. Conclusions: Adjusting ZrO₂ concentration according to pigment type can improve the future color retention and surface characteristics of maxillofacial silicone. Full article

Silicon-graphite anodes offer a practical route to increase the energy density of lithium-ion batteries (LIBs), but their widespread adoption is hampered by cyclic instability due to huge volume changes of silicon during lithiation/delithiation process. Another fallout of LIBs capacity gain is growing safety concerns due to fire risks, associated with the uncontrolled release of chemical energy. Herein, we test a hexakis(fluoroethoxy)phosphazene (HFEPN) as a multifunctional electrolyte additive designed to mitigate both issues. The flammability of HFEPN-containing electrolytes was evaluated using a self-extinguishing time test, while the electrochemical performance was assessed in Si/C composite||NMC pouch cells under a progressively accelerated cycling protocol. It is shown that the additive fully imparts flame-retardant properties to the electrolyte at a 15 wt% loading. Despite forming a more stable solid–electrolyte interphase (SEI) with enhanced interfacial kinetics the additive did not improve the cycling stability of the Si/C-based cells. The cells with 15 wt% HFEPN retained 43% of capacity after 70 cycles, comparable to 46.5% for the reference electrolyte. The diffusion limitations imposed by the increased electrolyte viscosity are assumed to offset the interfacial benefits of the additive. Thus, alongside the improved synthetic route, this study demonstrates that while HFEPN functions as an effective flame retardant and SEI modifier, its practical benefits for silicon anodes are limited at high concentrations by detrimental effects on electrolyte transport properties and should be improved in future molecular design efforts. Full article

The development of the ceramic industry requires the creation of new innovative products with improved properties. Given the growing demand for high-quality finishing materials and the limited availability of traditional raw materials, the search for more efficient technologies for porcelain stoneware production is a relevant challenge. The aim of this study was to develop porcelain stoneware with enhanced performance characteristics. The research presents the results of a study aimed at improving the production technology of porcelain stoneware in Kazakhstan using local raw materials and microsilica. The raw materials from the Turkestan region were examined for their suitability for porcelain stoneware production. The influence of technological parameters (firing temperature, particle size) on the properties of porcelain stoneware was studied. New ceramic compositions with various microsilica contents, a by-product of silicon production, were investigated. Different compositions with varying raw material mixtures and microsilica content were prepared and fired at temperatures of 1100, 1150, and 1200 °C. The optimization of process parameters for producing porcelain stoneware in different compositions showed the degree of yield dependence on firing temperature and time as well as the effect of microsilica content. The temperature, time, and visually determined parameters at which different yield values were achieved were highlighted in different colors. The results showed that changes in the mixture composition and sintering temperature affect the quality of ceramic tiles. The final experimental conclusions demonstrated that the production of ceramic tiles containing up to 3% microsilica at a firing temperature of 1200 °C. The addition of microsilica increases the flexural strength of porcelain stoneware to 41 MPa (exceeding the standard), reduces water absorption to 0.023%, increases frost resistance to 107 cycles, and also enhances shrinkage. These findings open new prospects for the development of the domestic ceramic industry, the expansion of the product range, and the resolution of environmental issues. Full article

Silicon (Si)–containing compounds, such as silica (SiO₂), play a crucial role as fillers, binding phases, and linking agents in sustainable materials. Coating biochar with SiO₂ can enhance its performance as a carbon-negative filler in composites such as bioplastics, rubber, asphalt, and cement, making it more competitive with conventional fillers. Biochar, derived from biomass pyrolysis, contains a high concentration of biogenic SiO₂—typically 50–80% of its total inorganic content. However, conventional extraction methods such as solvent extraction or gasification detach SiO₂ from the biochar matrix, leading to energy-intensive and environmentally unfavorable processes. The objective of this study was to develop an environmentally friendly and energy-efficient approach to induce the migration of embedded biogenic SiO₂ from within biochar to its surface—without detachment—using ultrasonic treatment. Fifteen biochar samples were produced by pyrolyzing five biomass types (sugarcane bagasse, miscanthus, wheat straw, corn stover, and railroad ties) at 650, 750, and 850 °C. Each sample was subsequently subjected to ultrasonic irradiation in an isopropanol–water mixture for 1 and 2 min. Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray Spectroscopy (EDS) analyses confirmed that ultrasound treatment significantly enhanced SiO₂ migration to the biochar surface, with up to a 2.5-fold increase in surface Si and O concentrations after 2 min of sonication. The effect was most pronounced for biochar synthesized at 850 °C, corresponding to higher surface porosity and structural stability. Fourier Transform Infrared (FTIR) spectroscopy revealed an increased intensity of the Si–O–Si asymmetric stretching band at 1030 cm⁻¹, indicating surface enrichment of siloxane networks and rearrangement of Si-containing functional groups. Overall, the results demonstrate that ultrasound-assisted treatment is a viable and sustainable technique for enhancing SiO₂ surface concentration and modifying the surface chemistry of biochar. This SiO₂-enriched biochar shows potential for advanced applications in soil amendment, CO₂ capture, water purification, and as a reactive additive in cementitious and asphalt composites. Full article