Silicon Content Research Articles

Frost Resistance of Alkali-Activated Concrete with Different Compositions – Parametric Study

Abstract Alkali-Activated Materials (AAM) are often considered to be very durable and also frost-resistant. However, there are also contrary experiences. This paper focuses on the frost resistance of AAMs of different compositions – different amounts of activator and different ratios between alkali (R2O) and silicon oxide content. Sodium water glass was used as the activator and its silicate modulus was modified by the addition of KOH. The R2O content was 4 -10 % and the R2O/SiO2 weight ratio was 33/67 (water glass only) up to 100/0 (KOH only). The frost resistance index was tested at the ages of 28, 91 and 365 days. Specimens were cured in foil or water and comparative specimens were also stored in foil or water. The results obtained are inconclusive. Firstly, when the reference specimens are stored in water, their bending strength decreases. This means that the frost resistance index is dependent on the use of the reference specimens – better results of frost resistance index are obtained for water-cured beams as reference specimens as they show lower strengths. The composition has a marginal effect on the frost resistance. Longer curing times also do not increase frost resistance.

Effects of Silicon Concentration and Synthesis Duration on Lignin Structure: A Spectroscopic and Microscopic Study.

Silicon (Si) is a highly abundant mineral in Earth's crust. It plays a vital role in plant growth, providing mechanical support, enhancing grain yield, facilitating mineral nutrition, and aiding stress response mechanisms. The intricate relationship between silicification and lignin chemistry significantly impacts cell wall structure. Yet, the precise influence of Si on lignin synthesis remains elusive. This study investigated the interaction between Si and lignin model compounds during invitro synthesis. Employing spectroscopic and microscopic analyses, we delineated how Si concentrations modulate lignin polymerization dynamics, particularly affecting molecular conformation and aggregation behavior over time. Fluctuations in the polymer structure are directly related to both the synthesis time and the concentration of silica. Our results demonstrate that lower Si concentrations promote the aggregation of lignin oligomers into larger particles, while higher concentrations increase the possibility of oligomer repulsion, thus preventing particle growth. These findings elucidate the intricate interplay between Si and lignin, which is crucial for understanding plant cell wall structure and stress resilience. Moreover, the results provide insights for developing lignin-silica materials with increasing applications in industry and medicine.

Silicon Enhanced Italian Ryegrass (Lolium multiflorum) Production and Induced Defense Responses Against Fall Armyworm (Spodoptera frugiperda)

The spread of invasive pests exacerbates the direct damage to host plants and the potential threat to the environment. Silicon has the potential to enhance host plant resistance to insects while also increasing plant yield. This study evaluated changes in Italian ryegrass biological yield and resistance to fall armyworm (Spodoptera frugiperda) larvae after silicon supplementation (sodium silicate and potassium silicate at 6 mmol·L−1 were denoted as groups T1 and T2, respectively). Silicon supplementation significantly increased the shoot biological yield (T1 by 30.26%, T2 by 23.05%) and silicon content (T1 by 22.61% and T2 by 12.43%) of Italian ryegrass. At the same time, silicon supplementation increased the protein, soluble sugar, and vitamin contents of Italian ryegrass, while also stimulating the improvement of its physical and chemical defenses. Therefore, even though the nutrient intake of fall armyworm increased, the synergistic physical-chemical defense formed by silica deposition, flavonoid content, and increased protease inhibitor activity in the Italian ryegrass still weakened the antioxidant capacity of the larvae and inhibited larval feeding and protein accumulation. The larval body weight of the T1 and T2 groups decreased by 20.32% and 15.16%, respectively. The comprehensive scores showed that sodium silicate and potassium silicate of the same concentration had similar effects on the growth and insect resistance of Italian ryegrass. These findings suggest that both sodium and potassium silicate are effective silicon supplements for host plants. Therefore, reasonable supplementation of silicon fertilizer may become an important alternative plan for optimizing the comprehensive pest control strategy in agricultural production areas in the future, but this still needs further field research verification.

In-situ construction of dual-coated silicon/carbon composite anode for fast-charging Li-ion batteries

Silicon (Si) is regarded as a promising candidate anode for next-generation high-energy–density batteries due to its ultrahigh theoretical capacity of 4200 mAh g−1. However, silicon anodes face tremendous challenges during cycling, including huge volume expansion, highly unstable interfaces and inherently low conductivity. In this study, the dual-coated silicon/carbon composite anode (Si@SiOx@C) with high silicon content of 85 % is obtained by high-energy ball milling and combined with phenolic resin-assisted encapsulation. The amorphous SiOx layer (∼3 nm) facilitates the rapid Li+ transport and mitigates the volume expansion, while the hard carbon layer (∼3 nm) improves the electronic conductivity and helps to protect against silicon oxide layer erosion from electrolyte, synergistically contributing to the fast-charging performance. With the synergistic effect of dual coating, the Si@SiOx@C anode shows a high initial Coulombic efficiency of 91 % and maintains a high capacity of 1250 mAh g−1 even after 500 cycles at a high rate of 4 A/g. Moreover, the volume expansion of silicon anode during cycling is significantly reduced. This work provides a novel strategy for high silicon content anode in developing fast-charging batteries through dual-coating regulation.

Optical Second‐ and Third‐Order Nonlinearities in Plasma‐Enhanced Chemical Vapor Deposition‐Grown Silicon Oxides and Silicon Nitrides

Optical second‐ and third‐order nonlinearities ( and ) in nonstoichiometric silicon oxides and silicon nitrides grown by plasma‐enhanced chemical vapor deposition are investigated by second‐harmonic generation (SHG) and electric field‐induced second‐harmonic (EFISH) measurements. The free‐space SHG measurements with a fundamental wavelength of 1030 nm allow us to determine the bulk values of both material platforms for various material compositions. It is demonstrated that the bulk values can be strongly enhanced by increasing the silicon content, reaching maximum values of the main tensor component of for silicon‐rich nitrides and for silicon‐rich oxides. EFISH measurements demonstrate that the values can be pushed even further by adding a static electric field to the materials. Similar to the values, the values are strongly enhanced by increasing the silicon content, leading to a maximum value of m2 V−2 for the silicon‐rich nitrides and m2 V−2 for the silicon‐rich oxides.

Process Metallurgy and Genetic Algorithm Multi‐Objective Optimization of Blast Furnace Hearth Working State

The working state of the blast furnace (BF) hearth is vital for achieving high efficiency, quality, low fuel consumption, and extended lifespan in BF production. In this study, optimizing the BF hearth by considering three key factors is focused on: hot metal temperature (HMT), silicon content ([Si]), and hearth activity index (HAI). A multi‐objective and multistep optimization method, combining prediction models of HMT, [Si], and HAI with a genetic algorithm, is proposed to enhance the hearth's performance. A Pareto optimal solution set screening method is also established based on target thresholds, weights, and operation priorities, improving its applicability in industrial production. Through this model, significant improvement in hearth working state is demonstrated, verified through case analysis and industrial applications. The prediction model achieves high accuracy in forecasting HMT, [Si], and HAI, with hit rates of 92.26%, 93.45%, and 94.64%, respectively. During the application, the pass rates of these indicators increase by 8.32%, 16.67%, and 13.51%, showcasing the effectiveness of the approach in industrial settings.

Microstructure evaluation of Si-modified aluminide coatings on IN625 deposited by slurry aluminizing process

Si-modified aluminide coatings are promising for improving oxidation and corrosion resistance in superalloys at high temperatures. This study investigated the effect of different silicon levels in the aluminizing slurry on the morphology and structure of Si-modified aluminide coatings on IN625. This process involved spraying a slurry of aluminum and silicon particles in an aqueous PVA solution onto IN625 samples, followed by heat treatment under controlled conditions - two atmospheres (air and argon) and two heating ramps (regular and flash). Surface morphologies, cross-sectional structures, elemental compositions, and phase formations were analyzed using FE-SEM, SEM, EDS, and XRD methods, while DTA analysis assessed AlSi alloy formation during heating. The results showed that higher silicon content in the slurry increased silicon incorporation in the coatings but did not reduce aluminum activity enough to deposit a low-activity aluminide coating. The inert atmosphere (argon) and flash heating promoted the co-deposition of Si and Al, resulting in Cr and Mo silicide-enriched outer layers in some samples. The aluminum content in all slurries was sufficient for consistent β-NiAl formation across different silicon levels. The average silicon content in coatings ranged from 5 to 15 wt% and depended on the slurry composition and heat treatment conditions. The Al30Si slurry produced the thickest coatings (~90 μm), with further increases in Si leading to reduced thickness. This study suggests that slurry aluminizing can be optimized to control silicon incorporation, depositing Si-modified aluminide coatings for durable, high-performance applications.

Addressing Fundamental Challenges of Si/Gr Electrodes with High Silicon Contents Using Innovative Bilayer Electrode Structure Design

Addressing Fundamental Challenges of Si/Gr Electrodes with High Silicon Contents Using Innovative Bilayer Electrode Structure Design

External Short-Circuit Scenarios under Different Mechanical Pressures Applied to Lithium-Ion Cells with Silicon-Dominant Anodes

Abstract The safety behavior of lithium-ion cells using high contents of silicon as new anode active material was barely investigated. This work investigates the short-circuit behavior of self-manufactured single-layered pouch cells using 70%wt microscale silicon and NCA cathodes in a novel dual reference cell setup consisting of a gold wire and a lithium metal reference electrode. Six cells were externally shortened at three different compression levels using a novel developed quasi-isothermal calorimetric shortcircuit test bench. The same current plateaus and transition zones were observed for all pressure settings, as reported in the literature for graphite-containing anodes. In addition, a direct dependency of the short-circuit intensity and the heat generation is measured for the differently compressed cells. This higher short-circuit intensity was quantitatively explained by the decreasing impedance at increased pressure levels. The built-in reference electrodes allow for monitoring of the negative terminal voltage, revealing potentials of up to 3:508 V versus Li+/Li and thus explaining the measured over-discharge in the range of ≈25% SoC. The post-mortem analysis reveals copper deposition on both electrodes and the separator, confirming the electrochemically measured over-discharge. Linear scans and potential trajectories reveal 3.379 V versus Li+/Li as oxidation potential for copper dissolution using copper||lithium-metal coin cells.

Decreasing Carrier Mobility under Concentrated Illumination and Its Effect on the Series Resistance and Conversion Efficiency of Silicon Concentrator Solar Cells

The carrier mobility of solar cell materials is a critical physical parameter that determines the series resistance. Furthermore, series resistance is an essential factor affecting the conversion efficiency of concentrator solar cells under high sunlight illumination. However, there has been slight discussion regarding the relationship between these factors. In the previous study, it was reported that concentrated illumination decreased carrier mobility; however, the scattering mechanism has not yet been clarified. Moreover, carrier–carrier scattering was discussed; however, it did not cause a mobility reduction. Thus effective mass changes are discussed as a possible cause of the decrease in carrier mobility under concentrated illumination. The cause of the decrease in mobility under concentrated sunlight illumination cannot be fully elucidated; however, it is a change in lattice scattering. Furthermore, the effect of the decrease in mobility due to concentrated illumination on the series resistance and conversion efficiency of Si solar cells using numerical calculations is clarified. The increase in the series resistance caused by the mobility reduction is ≈10% under 30 suns.

Amorphous silica production from Colombian rice husk: demonstration in scaled-up process Products

Introduction: the agroindustry generates significant waste, posing environmental, health, and economic challenges. Among these, rice husk, a byproduct of the food industry, stands out due to its potential as a source of silicon. Due to its silicon content, rice husk offers a unique opportunity for sustainable energy production and the extraction of high-value products, such as amorphous silicon dioxide (SiO2). However, optimizing processes for its efficient conversion remains a challenge.Objective: the aim of this study was to optimize the nitric acid concentration for the pretreatment of Colombian rice husk in order to produce high-purity amorphous SiO2 and demonstrate the feasibility of scaling up the process.Methods: a two-stage process was developed, which involved treating rice husk with nitric acid, followed by calcination at 620 °C. The nitric acid concentration was optimized to achieve the highest SiO2 purity. Material characterization was performed using thermogravimetric analysis (TGA), X-ray diffraction (XRD), X-ray fluorescence (XRF), and nitrogen adsorption-desorption. To assess the scalability of the process, the treatment was replicated on a larger scale using the optimized acid concentration.Results: the optimized process using a nitric acid concentration of 0.2 M yielded amorphous SiO2 with a purity of 94.9% and a surface area of 298 m²/g. When scaled up, the process achieved SiO2 with a purity of 95.5%, confirming the feasibility of the methodology for industrial applications. Conclusions: the treatment of rice husk with nitric acid followed by calcination proves to be an effective and scalable approach for producing high-purity amorphous SiO2. This process not only holds potential for industrial applications but also provides a sustainable solution for valorizing agroindustrial waste, contributing to the circular economy.

Graphene Oxide-Enhanced Nucleation and Growth of Calcium-Silicate-Hydrate Gel at Nanoscale: A Molecular Dynamics Study.

Graphene oxide (GO) enhances the performance of cement-based materials by optimizing the microstructure of calcium-silicate-hydrate (C-S-H). However, the influence of GO on the nucleation and growth of C-S-H gel at nanoscale is unexplored. This study investigates this mechanism by molecular dynamics simulation at nano scale. Results show that GO can reduce the activation energy during the polymerization reaction of silicon oxide tetrahedra during the reaction process, and can increase the content of polymer Q3 and Q4. The influence of GO with epoxy (-O-), hydroxyl (-OH) and carboxyl (-COOH) groups on the radial distribution function (RDF), mean square displacement (MSD), and atomic spatial distribution of monomers are studied. Results show that GO-OH exhibits excellent performance, with the highest number of bridging oxygen atoms (about 0.6), the lowest Q0 monomer content (just 26.8%), the highest RDF (27.18), and the highest MSD (calcium and silicon content around 20,000 Å2). This paper elucidates the nucleation and growth mechanism of C-S-H influenced by GO to develop high performance cement.

Effect of sintering temperature on the properties of ceramic binders synthesized from coal gangue-based geopolymer

ABSTRACT As a by-product of the coal industry, the effective use of coal gangue presents significant implications for environmental protection and sustainable development upon effective utilization. Given the rich content of silicon and aluminum in coal gangue, this study converts it into a precursor for ceramic binders used in grinding wheels through the geopolymerization reaction process. Ceramic binders of the SiO2-B2O3-Al2O3-RO-R2O system were prepared at sintering temperatures ranging from 590 to 740°C, and the performance of each sample was tested. The research found that the flexural strength of the ceramic binder reached a peak of 31 MPa when sintered at 690°C. Additionally, the hardness was observed to be the highest at a sintering temperature of 640°C, reaching 211.8 hV. It was observed that as the sintering temperature rose, wettability tended to decrease. Using techniques including XRD, SEM, and EDS, the effect of sintering temperature on the microstructure and phase transformation of the material was analyzed, and these changes determined the properties of the material. This study not only confirmed the potential value of coal gangue in the abrasive tools industry but also opened up new strategies and technical solutions for the field of solid waste resource utilization.

Study of Microstructural Evolution and Strain Analysis in SiOx/C Negative Electrodes Using In‐situ X‐ray Tomography and Digital Volume Correlation

AbstractIncreasing the silicon content in batteries is expected to enhance their capacity. However, its implementation comes with challenges, as silicon exhibits a large volumetric expansion. This expansion is a significant factor contributing to the decreased lifespan of these batteries. One of the critical degradation mechanisms from a mechanical perspective is the delamination of electrode structure. The cyclability of these negative electrodes is noted to be influenced by the interaction between the binder and particles during battery cycling. The heavy local strain experienced by particles in these electrodes often leads to binder failure, resulting in particle isolation, detachment, or delamination over multiple cycles. A good understanding of the local evolution of the strain is essential in advancing the mechanical modelling of the degradation mechanism and in realizing the complete potential of silicon‐based electrodes. In this work, in situ global and local strain measurements were performed by combining synchrotron tomography with Digital Volume Correlation (DVC). The measurements showed that there is significant local strain in these electrodes which can lead to delamination. In addition to this, the spatial variability of the composite electrodes was characterized by estimating the characteristic length to strain, which can be used to replicate the strain field and model the delamination.

Investigation of phase transformation and mechanical properties of silicon addition on AlCrFeMnNi high entropy alloys

Abstract This paper examines the impact of silicon in the AlCrFeMnNi high-entropy alloy system, focusing on both its microstructural and mechanical properties. Alloys with varying silicon content (x = 0, 0.3, 0.6, 0.9 atomic ratio) were synthesized using vacuum arc melting. The phase formation of these high-entropy alloys was analyzed using X-ray diffraction to comprehend the alloying process behaviour. The findings revealed that the solidification of the AlCrFeMnNi alloy occurred in dendritically, with dendrite cores containing Cr, Fe, and Ni, while interdendritic regions were enriched in Al and Ni after adding Silicon. Increasing the silicon content from 0 to 0.9 led to significant improvements in microhardness and wear resistance. This improvement is attributed to the reinforcement of grain boundaries provided by silicon. The formation of an Al and Ni rich B2 phase is crucial in resisting dislocation motion and preventing further deformation. Additionally, the addition of silicon led to improved corrosion resistance, as demonstrated by potentiodynamic polarization measurements. However, a trade-off was observed between compressive strength and ductility: compressive strength increased with higher silicon concentrations, but at the expense of ductility.

Positive association between foliar silicon and extrafloral nectar in Vicia faba with application of methyl jasmonate

Plants have evolved direct and indirect defences against herbivores, which may come at a cost to other plant functions. Many plants can uptake and deposit large amounts of silicon within plant tissue, creating structures which can reduce herbivore performance. Silicon uptake can increase plant defenses against herbivores, but it has also been shown to trade-off with defensive phenolic compounds due to interference with jasmonic acid (JA) signaling. Additionally, plants can recruit predacious insects with extrafloral nectar (EFN), a sugar secretion not involved in pollination. It is currently unclear whether silicon uptake reduces other putative defences associated with the JA pathway, like EFN production. We used faba bean (Vicia faba) to identify potential trade-offs between silicon accumulation, phenolic content, and EFN production. We grew four genotypes of faba bean that varied in tannin content in control soil, or soil supplemented with silicon. After five weeks of growth, we exposed plants to either a buffer or methyl jasmonate (MeJA) solution to simulate an herbivory response. We measured EFN production at 24 and 48 hours after treatment, and harvested leaves to quantify silicon and phenolic content. We found silicon supplementation, but not MeJA treatment, increased foliar silicon concentration. Silicon supplementation did not affect foliar phenolic content or EFN sugar content. Silicon concentration (ppm) and MeJA treatment did not decrease foliar phenolic content or EFN sugar content. However, we found an interaction between silicon concentration (ppm) and MeJA treatment with EFN sugar content: across MeJA-treated plants, we detected a positive association between foliar silicon concentration and the amount of sugar (mg) in EFN. This study is the first to show MeJA can interact with leaf silicon concentration to alter EFN response, with the potential for cascading effects on other trophic levels.

Effect of GPa-level pressure on the microstructure and properties of Cu-8Ni-1.8Si alloy

Reducing or completely eliminating the reticular grain boundary phases in alloys is crucial for enhancing the mechanical and electrical properties of Cu-Ni-Si alloys with high nickel and silicon content (Ni + Si > 5wt.%). In this study, we investigated the microstructure, mechanical properties, and electrical conductivity of Cu-8Ni-1.8Si (wt.%) alloy prepared by high-pressure solidification (HPS) and subsequent aging treatment. The interfacial growth stabilizes as the pressure reduces the crystal growth rate, inhibits the diffusion of solute atoms, and increases the solute partition coefficient. The reticulated Ni31Si12 and granular Ni2Si phases disappear under 6GPa pressure, forming a complete Cu (Ni, Si) solid solution. After direct aging treatment, the precipitated phase of the HPS alloy is β-Ni3Si at the early stage of aging. At the peak aging state, β-Ni3Si and δ-Ni2Si phases coexist in the matrix. Additionally, the Avrami equations for the phase transition kinetics of HPS alloys at different aging temperatures were derived from the electrical conductivity data, and the strength contributions from solid solution strengthening and precipitation strengthening were calculated. The alloy aged at 450 °C exhibited the largest volume fraction and the smallest average size of precipitates, resulting in a more pronounced obstruction effect of nano precipitates on dislocation bypassing and demonstrating the best precipitation strengthening effect. At the peak aging states, the alloy's hardness reaches 367.5 HV, and the compressive yield strength reaches 788.2MPa. These results indicate that high pressure is an effective method to improve the solid solution degree of alloying elements and enhance the mechanical properties of Cu-Ni-Si alloys.

Influence of Si-addition on tribological and corrosion properties of Ta-Si-C coatings

Ta-Si-C coatings with Si content varying from 2.7 to 30.8 at.% were synthesized by magnetron co-sputtering. Their microstructure, tribological properties and corrosion performance were investigated. The coatings exhibited two distinct structural forms: a Ta(C, Si) solid solution for the lower silicon contents (2.7 and 5.6 at.% Si) and a Ta(C, Si)/a-C:Si nanocomposite for higher Si content (13.7, 20.8 and 30.8 at.% Si). Notably, the Ta(C, Si) solid solution at 5.6 at.% Si demonstrated the highest hardness of 44±2.7 GPa, resulting from the solid solution strengthening. Furthermore, this solid solution also demonstrated the lowest wear rate (1.21×10-6 mm3N-1m-1), due to its superior hardness and H3/E2 ratio. Additionally, the coating with 5.6 at.% Si displayed the most outstanding corrosion resistance, attributed to its higher crystalline quality and denser structure, which effectively prevented the permeation of corrosive media through the coating to the substrate.

Fiber morphological characteristics of bamboo Ferrocalamus strictus culms from different geographical distribution regions

The fiber index including fiber length, width, wall thickness and lumen diameter of Ferrocalamus strictus culms (1, 2, and ≥ 3 years) from Jinping, Mojiang and Lvchun counties of Yunnan Province was determined and the elemental content of the soil was also determined to analyze the fiber characteristics. The average relative fiber index measured for F. strictus culms were fiber length (1.30 mm), width (21.57 μm), slenderness ratio (60.79 μm), wall thickness (4.21 μm), lumen diameter (7.22 μm), and runkel ratio (1.22 μm), which belonged to the range of middle and long fibers. The fiber length increased with the culm age. The proportion of long fiber increased while short fibers decreased along with culm maturing. The fiber morphology did not show a specific trend with the culm height. Fiber length reached the maximum in the bottom portions of the culms. There is a correlation between fiber morphology and soil elements, the content of organic matter, total potassium, total sulfur, total aluminum, total zinc, total iron, total boron, alkali-hydrolyzed nitrogen and available silicon in the soil affects fiber morphology. The content of organic matter, total boron and alkali-hydrolyzed nitrogen in the soil from Mojiang County was largest. Comparatively, the culm fiber in Mojiang County had the best fiber index performance for utilization, since the greatest proportion of medium and long fibers and the optimal distribution of fiber length frequency was obtained from the culms in Mojiang County. This study can provide a theoretical basis for large-scale bamboo forest cultivation and the development and utilization of bamboo culm fiber.

Determination of phytochemical quality of leaves Vaccinium vitis-idaea L. and Vaccinium myrtillus L. from the polluted and non-polluted areas

Elemental composition of Vaccinium myrtillus L. and Vaccinium vitis-idaea L. has not been determined yet in detail. In our study, a scanning electron microscope coupled with an energy dispersive X-ray analyser (SEM–EDX) ensured the determination of 15 elements in the leaves of Vaccinium sp. growing in the control and the mine polluted locality. The soil elemental analyses showed a higher content of 11 elements from all determined in the mine-influenced samples. Elemental analyses of the control leaves showed the highest contents of all determined elements for V. vitis-idaea, except for carbon. The impact of pollution on V. myrtillus leaves caused significant increase in oxygen, natrium, magnesium, sulphur, chlorine, potassium and calcium content. The contents of carbon, nitrogen and silicon decreased substantially. In the case of the V. vitis-idaea leaves, the content of most of elements reduced, and in the case of six elements, even significantly. A significant increase was recorded for carbon, iron and copper. The effect of the environment has influenced the production of phytochemicals, assessed by HPLC–DAD. The production of flavonoids (hyperoside, isoquercetin) increased significantly in V. myrtillus and decreased to a detectable minimum in V. vitis-idaea. In the case of chlorogenic acid, arbutin and hydroquinone, their levels changed minimally in V. myrtillus, but significantly more in the V. vitis-idaea leaves. The importance of elemental analyses lies in detecting the presence of toxic elements or their harmful concentrations in plants that are the source of food or dietary supplements.