Silicon最新文献

The primary purpose of this study is to gain a deeper understanding of the structure and mechanics of an ex-situ A356/Cu-coated with different weight percentages (x: 1, 3) of SiC stir-cast metal matrix composite. This study aims to improve silicon carbide's wetting and adhesion characteristics by fabricating a Cu-coated composite utilizing an electrolytic deposition technique based on aluminum. This green manufacturing method significantly reduces environmental impact compared to traditional coating processes, a crucial aspect in today's world. Examination of the optical microstructure of the SiC composite revealed a clustering of reinforcements within the matrix, potentially resulting from additional barriers formed during the stirring process that impede the movement of SiC particles. Furthermore, incorporating copper-coated SiC reinforcement led to a more even distribution of reinforcements in the matrix. The ultimate tensile strength, yield strength, and hardness of the 3 wt% copper-coated metal matrix composite cast are 225.97 MPa, 130.27 MPa, and 76.5 BHN, respectively, demonstrating superior mechanical properties compared to the other cast composites. The study opens potential paths for further advancements in composite technology.

A series of epoxy modified polymethylpenylsiloxane (EPMPS) emulsions for oil agent in carbon fibers production were synthesized with EPMPS resins and non-ionic emulsifier by phase inversion emulsification. The EPMPS resins with different epoxy content were prepared by non-hydrolytic sol–gel method. The influence of epoxy content on the chemical structure, molecular weight, surface tension and thermal stability of EPMPS resins were investigated by Fourier transform infrared (FTIR), gel permeation chromatography (GPC), contact angle meter and thermogravimetric analysis (TGA), respectively. The properties of EPMPS emulsions and their effects on polyacrylonitrile (PAN) precursor were investigated by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). It was found that the increase of epoxy content not only obviously decreased the molecular weight and surface tension of EPMPS, but also conduced to the processing of PAN precursor. With the decreasing of surface tension, the oil agent was easier to spread and film on the surface of PAN precursors. In addition, the TGA curves showed that the EPMPS resins had good thermal stability at low temperature and can be completed volatilized under high temperature conditions. Hence, the EPMPS emulsions could be used as oil agent for PAN precursors.

Adamantane and its derivatives are designed and analyzed for their hydrogen storage properties after scandium substitution using density functional theory approach. A total of nine structures are considered viz. adamantane (C₁₀H₁₆) denoted by C_adm, Si adamantane (Si₁₀H₁₆-Si_adm) Ge adamantane (Ge₁₀H₁₆-Ge_adm), germanium substituted adamantane (C₄Ge₆ (CG1) and Ge₄C₆(CG2)), silicon substituted adamantane (C₄Si₆ (CSi1) and Si₄C₆ (CSi2)), Si and Ge substituted adamantane (Si₄Ge₆ (SiG1) and Ge₄Si₆ (SiG2)). To enhance hydrogen uptake capacity, four hydrogen atoms in these structures are replaced with four Sc atoms. The negative Sc substitution energies for all the structures suggest that the substitution of Sc atoms is an endothermic process. The number of H₂ molecules adsorbed on these structures is either 24 or 28 with H₂ uptake capacity in a range of 6.08–13.4 wt% meeting the U.S. Department of Energy's 2025 target of 5.5 wt.%. The inorganic structures exhibit H₂ adsorption characteristics that fall between physisorption and chemisorption whereas the structures containing carbon atoms demonstrate a physisorption nature for H₂ molecules. The hydrogen molecules strongly bind with SiG1(Sc)₄ which is supported by its higher H₂ desorption energy and H₂ desorption temperature. In conclusion, the derivatives of adamantane show better hydrogen storage performance than adamantane.

Over the last decade, bioactive silicates have gained significant interest as bone graft substitutes due to their excellent ability to repair, replace, and regenerate damaged tissue in injured bone. In this work, a sol–gel combustion route was used to synthesize nanostructured barium-doped diopside (Ca_1-XBa_XMgSi₂O₆) using stoichiometric amounts of calcium nitrate, magnesium nitrate, and barium nitrate as oxidizers, and tartaric acid as a fuel. The resultant powder was examined by powder XRD to confirm the phase purity. Pure phase of diopside was achieved at 850 °C without any secondary phase. For functional group analysis, FT-IR was employed, and microscopic imaging (SEM/EDAX) was used to study morphological changes. Due to barium doping in the diopside matrix, the crystallite size was reduced, and the mechanical and degradation properties of the prepared pellets was enhanced after immersion in SBF medium over a period of time. The results show compressive strength of the doped diopside was found to be 169 MPa, closer to cortical bone strength and similar to previous findings. It can be concluded that barium can be considered as a dopant to improve bioactivity of Ca-Mg silicate for hard tissue application.

Cell wall structure/composition differences between dicots and Poales may affect their responses to metals and Silicon. Impacts of excess Fe, Zn and their interactions with Si on phenolics/lignin metabolism of monocot and dicot roots were investigated. Monocot (rice and wheat) and dicot (canola and cotton) plants were exposed to excess Fe (150 mg L⁻¹) or excess Zn (150 µg L⁻¹) with or without Si (1.5 mM) and assessed for growth and phenol/lignin metabolism in root apical (AP) and basal parts (BP). Excess Fe compromised plant biomass, but Si improved it. Excess Zn provoked similar responses except in canola. In the monocot root AP, excess Fe increased phenylalanine ammonia lyase (PAL), cell wall peroxidase (POD) and polyphenol oxidase (PPO) activities. Phenolics accumulated mostly in monocots roots under excess Fe whereas lignin accumulated in nearly all roots and similar but weaker effects observed under excess Zn. Under excess Fe, Si stimulated cell wall POD activity and declined phenolics in monocot roots. The corresponding responses were much weaker in dicot roots. FTIR data differentiated altered cell wall functional groups in monocots and dicots after treatments, however, monocots data were more diverse than dicots. Si is more efficient to substitute for lignin metabolism in monocots than in dicots under excess Fe. Response of phenolic/lignin metabolism to heavy metal stress and Si depends on both plant and heavy metal species. Si application brings about more changes in the root cell wall of monocots than dicots through modulation of the root cell wall structure and function.

In this paper, laterite nickel ore was combined with NaOH to extract SiO₂ by medium temperature roasting. Firstly, in the single factor experiment, the calcination temperature was 400 °C, the calcination time was 2 h, and the alkali ore ratio was 1.2:1, which was the best calcination conditions. At the same time, the dissolution rate of SiO₂ could reach 98.87%. Then, in order to explore the influence order of different experimental factors on the dissolution rate of SiO₂, the orthogonal experiment was used to determine that the calcination time had the greatest influence on the dissolution rate of SiO₂, followed by the calcination temperature, and finally the alkali ore ratio. Finally, combining kinetic and thermodynamic analysis, the rate equation of the reaction was determined: 1-(1-α)1/3 = 4.9761 × 104 × exp[-5730/(RT)]t, and the reaction process was controlled by the interfacial reaction. Thermodynamic analysis showed that the reaction could proceed spontaneously under certain conditions.

This study explores the synthesis and characterization of a novel silicone-based hybrid hard coating material system for application on glass, metal, and polymer surfaces. Comprehensive analytical methods including Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), modulated differential scanning calorimetry (MDSC), dynamic mechanical analysis (DMA), thermal conductivity measurements, X-ray diffraction (XRD), and contact angle analysis were employed. The in-situ incorporation of ceramic nano powders (5 wt%) during the pre-polymeric stage into the polymer matrix was found to affect the curing process minimally, as indicated by FTIR. TGA results showed reduced thermal stability, while the addition of nanoparticles enhanced the specific heat capacity and thermal conductivity, attributed to the high thermal conductivity of the ceramic powders. DMA tan δ graph indicated an increase in glass transition temperature (Tg) from 273.83 °C (P-Neat) to 320.82 (P-SiC), 348.51 (P-BC), 352.1 (P-BN) due to the restriction of polymer chain mobility. XRD analysis revealed an increase in crystallinity. The contact angle (θ) data showed increase in contact angle from 84.23° (P-Neat) to 92.55° (P-SiC), 96.8° (P-BC), 99.63° (P-BN). The surface morphology of the P-Neat sample changed from smooth morphology to a distinctive “sea-island” structure as revealed by the FE-SEM study. Further scratch resistance tests showed that P-Neat, P-SiC, P-BC, and P-BN samples all withstood the scratch tests at respective loads of 1100 g, 1200 g, 1300 g, and 1300 g, respectively.

Collecting urine samples from cats is a significant challenge for veterinarians due to their instinctive behavior to bury waste. The introduction of superhydrophobic cat soil, which prevents urine absorption, offers an innovative solution. This not only simplifies the diagnostic process for veterinarians but also significantly reduces stress for pets and their owners. In this study, we synthesized a hydrophobic coating using zinc oxide/silica composite nanoparticles (ZnO/SiO₂ CNPs) modified with perfluorodecyltrichlorosilane (FDTS) compounds for various surfaces such as soil, sand, stone, and glass. Tetraethoxysilane (TEOS) and zinc acetate dihydrate were used as precursors, while FDTS was employed for surface modification. The prepared ZnO/SiO₂ composite sol was sprayed onto different coatings, and the resulting hydrophobicity was confirmed by water contact angles, with an average angle of 110.3° for cat soil. Structural and morphological features of the synthesized ZnO/SiO₂ CNPs were analyzed using XRD, FTIR, EDX, and FESEM techniques. The chemical resistance of the coated stone was tested in acidic and neutral environments, showing better hydrophobicity in the neutral condition. The study highlights the potential of this composite to enhance agricultural practices in arid regions, facilitate pet urine collection in veterinary medicine, and offer various environmental benefits.

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This study intends to improve the dielectric properties of PMMA/PEG/SiO₂/SiC nanostructures for use in flexible pressure sensors and electrical nanodevices. PMMA/PEG films and PMMA/PEG films doped with SiO₂ and SiC NPs were created using a casting technique. The structural properties of PMMA/PEG/SiO₂/SiC nanostructures were examined using FTIR and an optical microscope. The dielectric properties were assessed using an LCR meter across a frequency range from 100 Hz to 5 MHz. The analysis of the structural features of PMMA/PEG/SiO₂/SiC nanostructures showed a significant presence of SiO₂ and SiC nanoparticles in the PMMA/PEG material and strong integration between SiO₂ and SiC nanoparticles and the PMMA/PEG matrix. The dielectric properties showed an increase in the dielectric parameters of PMMA/PEG as the concentration of SiO₂-SiC NPs increased. The dielectric constant and AC electrical conductivity of PMMA/PEG rose by approximately 39% and 49%, respectively, with low dielectric loss values ranging from 0.14 to 0.275 at 100 Hz. These findings suggest that PMMA/PEG/SiO₂/SiC nanostructures may be suitable for a variety of nanoelectronics applications. The dielectric properties of PMMA/PEG/SiO₂/SiC nanostructures changed as the frequency increased. The structure and dielectric properties of the PMMA/PEG/SiO₂/SiC nanostructures suggest they can be used in a variety of flexible nanoelectronics applications due to their low-cost, high-energy storage capability, and minimal energy loss. An investigation was conducted on the pressure sensor application of PMMA/PEG/SiO₂/SiC nanostructures. The results indicated that the PMMA/PEG/SiO₂/SiC nanostructures exhibit high sensitivity to pressure, exceptional flexibility, and strong environmental resilience in comparison to other sensors.

Nickel silicon carbide (Ni-SiC) nanocomposite coatings are extensively used in the engineering field due to their exceptional mechanical characteristics. In this study, pulsed electrodeposition from a nickel Watts bath on a cast iron (CI) cylinder liner produced a Ni-SiC nanocomposite coating. The current study concentrated on multi-objective optimization to maximize microhardness and minimize surface roughness of the composite coating by grey relational analysis (GRA) and the contribution of coating parameters was analyzed by analysis of variance (ANOVA). The GRA-ANOVA-ANOVAt shows that the effects of the square term of duty cycle (Y²), the linear term of current density (Z), and the square term of frequency (X²) are most significant and affect the coating characteristics at a 95% confidence level. The inclusion of SiC particles altered the preferred coating crystallographic orientation from (200) to (111). The optimal coating parameters of frequency 100 Hz, duty cycle 80%, and current density 0.5 A/cm² produced the best mechanical properties for Ni (79.38 wt%), Si (0.76 wt%), and C (19.86 wt%). According to the ANOVA, the linear term of current density (Z) and the quadratic terms of duty cycle (Y2) and frequency (X) have a significant influencing role with contributions of 27.74, 24.18, and 22.90%, respectively. EDX analysis of the Ni-SiC coating showed that carbon is the dominant element, comprising 54.52 wt. % and 19.86 wt. %, followed by nickel and silicon.