Silicon Powder Research Articles

Vapor-phase conversion of waste silicon powders to silicon nanowires for ultrahigh and ultra-stable energy storage performanc

Vapor-phase conversion of waste silicon powders to silicon nanowires for ultrahigh and ultra-stable energy storage performanc

Enhanced thermoelectric performance of silicon powder arrays by remotely doping

We report improved thermoelectric (TE) properties of mesostructured silicon powder arrays simply prepared by die-pressing without sintering. In contrast to bromoethane's modest effect, the symmetric dibromoethane molecule coupling could significantly increase the conductivity of Si powder array TE device, from 12.7 S cm−1 of a silicon powder array to 62.3 S cm−1, which is possibly caused by the high electronic transmission probability of symmetric organic molecule–Si crystal coupling, and additionally enhanced by Si bandgap narrowing and defect states of an organic–inorganic interface identified by UV–vis absorption spectra and photoluminescence spectroscopy. Boosted by the very low thermal conductivity (0.58 W m−1 K−1), the dimensionless figure of merit, the ZT value of an Si powder array remotely doped by dibromoethane, ∼0.173, was obtained at 385 K, which is about 17 times higher than that of the bulk Si. An Si–organic hybrid TE device shows potentials to approach the threshold of practical applications with moderate ZT performance and low cost.

Contrasting tribocatalytic degradations of organic dyes by two different commercial silicon powders

Contrasting tribocatalytic degradations of organic dyes by two different commercial silicon powders

High-efficiency synthesis of colloidal silica via suppression of foam layer

As an important fundamental material, colloidal silica is widely used in many fields. Hydrolysis of elemental silicon is an important method for the preparation of colloidal silica. This method has been widely studied because of its simple process, low cost, easy control of colloidal particle size and good stability. However, this method has the problem of low reaction conversion rate (RCR). This paper proposed an efficient method to increase RCR of colloidal silica by inhibiting the formation of a foam layer. After the size of the silicon powder particle, reaction time, and the defoamer types were optimized, the defoamer of hydrophobic fumed silica could effectively inhibit the increase of foam layer and improve the yield of colloidal silica, the RCR was significantly increased from 54.8 % to 85 % within 4 h. This research provides an innovative strategy for the efficient chemical synthesis of colloidal silica.

Effect of silicon powder dosage on the microstructure and performance of SiC/Si3N4 composite ceramic microfiltration membranes

The SiC/Si3N4 composite ceramic microfiltration membranes were fabricated using the in-situ nitridation process of silicon powder at 1350 °C, utilizing SiC powder and silicon powder as the raw materials. The effects of silicon powder dosage on the phase composition, basic physical properties, pure water flux, pore size distribution, and microstructure of membrane materials were investigated. With an increase in the silicon powder quantity from 5 wt% to 20 wt%, the flexural strength of the membrane materials increased from 6.6 MPa to 42.4 MPa, while the apparent porosity remained stable at 37.0%–39.0 %. The experimental results indicated a substantial correlation between the pore size distribution and the pure water flux. As the average pore size of the ceramic membranes decreased from 463.87 nm to 132.68 nm, the pure water flux gradually decreased from 265.99 L/(m2⋅h⋅bar) to 50.34 L/(m2⋅h⋅bar). The systematic investigation reveals that the Si3N4 binding phase, generated from the in-situ nitriding reaction of silicon powder, is the primary factor responsible for enhancing the mechanical properties of the membrane material. The process of in-situ nitriding silicon powder is accompanied by an increase in volume, which is beneficial in filling and refining the pores. Moreover, the formation of silicon nitride whiskers during the nitriding process can enhance the material's mechanical properties and further divide and refine the pores.

Synthesis of SiC nanowires from retired wind turbine blades and their microwave-absorbing property

Retired wind turbine blades (RWTBs) mainly consist of glass fibers and resins, which have abundant of carbon and silicon resources. This study synthesized SiC nanowires (SiC NWs) by using the RWTBs for the first time. The RWTBs were grinded into powders and pyrolyzed at 600 °C for 2 h, the pyrolysis solid residues (P-RWTBs) mixed with apricot shell char (ASC) and silicon powder in a stoichiometric ratio (C/Si=4), and then the mixture calcined at 1550 °C for 4 h in an argon atmosphere. XRD, FTIR and XPS results indicating that SiC NWs had been successfully synthesized. SEM and TEM micrographs show that the produced SiC NWs exhibit a worm-like shape, with diameters of 50–100 nm, and interweave into a 3D network body. The minimum reflection loss (RLmin) of the SiC NWs 3D network body reached -18.17 dB at the thickness of 4.8 mm, which meet the requirements of microwave-absorbing materials. Its good microwave-absorption property is due to the various loss types of the electromagnetic waves that caused by the special structure. This study provides a new approach for high-value utilization of the RWTBs, which is of great significance in realizing the "green retirement" of glass fiber reinforced polymers.

Design of physical and functional properties of zeolitic porous monoliths by combining different foaming additives

Self-supporting zeolitic foams were synthesized by a geopolymer gel conversion process, employing silicon powder and hydrogen peroxide as foaming additives. The influence of silicon and hydrogen peroxide combination on the physical properties, mechanical characteristics, and pore distribution was studied. Correlations between these properties were drawn. This approach allows to manufacture porous monoliths tuned in terms of zeolite type and amount and characterized by bulk density ranging between 573 and 762 kg/m3 and thermal conductivity 0.33–0.53 W/mK. Pore structure, size, and distribution were dominated by the type of foaming agent: the foamed samples showed the presence of two classes of pores, the first of the order of magnitude of 1 μm, the second of the order of magnitude of 100 μm. The use of hydrogen peroxide enhanced the porosity in the meso-macropore range (0.1–5 μm). The hydrothermal treatment performed on the foamed geopolymer allowed to achieve the crystallization of zeolites within the solid geopolymer. Mainly FAU and LTA were the zeolitic phases present in the foams, whereas the use of silicon as foaming agent locally increased the Si/Al ratio on the geopolymer surface, promoting the nucleation of FAU.

Data quality in laboratory convergent-beam X-ray total scattering

Measurement of laboratory atomic pair distribution function data has improved with contemporary X-ray sources, optics and detectors, with acquisition times of the order of minutes for ideal samples. This paper examines resolution effects in pair distribution function data obtained using a convergent-beam configuration and an Ag X-ray tube from standard silicon powder and from 10 nm BaTiO3 nanocubes. The elliptical multilayer X-ray mirror reflects a non-trivial X-ray spectrum and introduces resolution effects not commonly treated in ordinary parafocusing divergent-beam laboratory diffraction. These resolution effects are modeled using the fundamental parameters approach, and the influence this has on interpretation and modeling of the resulting reduced atomic pair distribution function data is demonstrated.

Promotion of silicon–oxygen control and green sustainable recovery from diamond wire saw silicon powder waste based on the viscous flow mechanism

Diamond wire saw silicon powder (DWSSP) waste is a highly promising secondary resource for recycling high-purity silicon, which is crucial for the sustainable development of the photovoltaic (PV) industry. However, because DWSSP is prone to oxidation, the purity and yield of the recovered silicon are generally low. In this study, the oxidation mechanism of DWSSP in water was systematically investigated, and kinetics analysis and microstructure analysis were conducted to determine the relationship between water diffusion and the growth of the oxide layer. The results indicated that oxidation was determined by the kinetic parameter b in the Reisman model. At T < 328 K and particle size > 1.56 μm, b was less than 1, indicating that the oxidation process was governed by the diffusion of H2O molecules. Through temperature regulation to achieve b < 1, the oxidation was inhibited, which could enhance recovery efficiency. Overall, this study demonstrated the feasibility of inhibiting oxidation by regulating the viscous flow of SiO2 molecules to promote the recycling of silicon resources and support sustainable development.

Electrophysical and thermoelectric properties and crystal structure of the formed Mn4Si7 thin vacuum coatings

The necessary information on the formation of high manganese silicide (Mn4Si7) coating by magnetron sputtering method is presented in this work. The technology and basic modes of creating the necessary targets for a magnetron sputtering device are presented. Targets were created by adding silicon and manganese powders in the required amount and heating them under vacuum conditions at high temperature and pressure. Thin silicide films (thin coatings) of different thicknesses were formed on the surface of silicon dioxide from the produced targets using the method of magnetron sputtering. The electrophysical and thermoelectric properties of the produced films were studied using physical and optical methods.Due to the change in the structure of the coatings during subsequent heat treatment, the Seebeck coefficient noticeably increases.

Study on plasma modified silica powder epoxy resin composites

This work uses micrometer scale silicon powder as raw material, conducts plasma interface modification in a nitrogen atmosphere, and adds nitrogen elements to generate active groups such as amino groups on its surface to improve the dispersion of silicon powder, enhance the interface interaction between silicon powder and epoxy resin, and form Si–N bonds. To a certain extent, the absorption performance of silicon powder has been improved, which indicates the effectiveness of plasma modification of Si powder. The hardness of the modified composite material increased from 75.52 to 85.34 HA. Mechanical experiments have shown that the addition of 3% wt significantly improves the tensile strength of epoxy resin, increasing it from 16.47 to 22.67 Mpa. Further increase in dosage will lead to a decrease in tensile strength. After modification, the 3%, 5%, and 10% modified epoxy composite materials increased from 22.67, 9.94, and 5.67 Mpa before modification to 24.15, 14.52, and 12.75 Mpa, respectively. Using molecular dynamics simulation to verify the feasibility of plasma modification on epoxy composite materials, it was found that the simulation results were consistent with the experimental results, and the ultimate tensile strength of the modified composite materials was improved. The electrochemical impedance spectroscopy and salt spray test results show that the low-frequency impedance modulus of the composite coating modified by plasma interface is about one order of magnitude higher than that of the unmodified silicon powder composite coating. The coating containing 5 wt% plasma modified silicon powder exhibits the best corrosion resistance.

Influence of foaming additives on the porous structure and properties of lightweight geopolymers based on ash–slag waste

Lightweight geopolymer is a promising thermal insulation material that conserves energy used for heating and cooling buildings. This study investigates foaming agents that influence the porous structure and properties of geopolymer foams based on ash–slag waste from thermal power plant using a 12 M sodium hydroxide solution, waterglass, and foaming agents (30 % hydrogen peroxide solution, aluminum, silicon, and zinc powders). The study demonstrates the feasibility of foaming geopolymers by water evaporation without foaming additives, where the best density of 949 kg/m3 and compressive strength of 4.2 MPa were achieved in samples foamed by microwave radiation, but such properties cannot attribute geopolymers as lightweight. Foaming with H2O2 is hard to synchronize with geopolymerization reactions. Aluminum and silicon powders lead to rapid reactions in alkaline conditions, resulting in uneven pore sizes. Zinc powder was the most effective foaming agent, producing materials with a density of 331 kg/m3 and compressive strength of 1.17 MPa, and it also integrates into the geopolymer gel structure. The foaming process should occur at room temperature. Elevated temperatures increase curing rates and result in incomplete geopolymerization, preventing uniform pore formation. Synthesized geopolymers are suitable for building insulation, basements, underground pipelines, and utility networks.

Process Monitoring of Gold Recovery from a Thiosulfate Leaching Solution Using Silicon Powder: Measurement of Gold Potential

Process Monitoring of Gold Recovery from a Thiosulfate Leaching Solution Using Silicon Powder: Measurement of Gold Potential

Analysis of magnesia-carbon bricks erosion in vanadium extraction converters: Insights from dynamic experiments and interface characterization

This paper uses a rotary furnace to simulate the dynamic erosion behavior of various magnesia-carbon bricks within a vanadium extraction converter, focusing on the effects of carbon content and antioxidants on erosion. The results indicate that vanadium-rich slag primarily consists of oxide solid solutions, iron vanadium spinel, and metallic Fe. Adding aluminum and silicon powders to the bricks reduces apparent porosity, increases body density, and improves slag erosion resistance. However, an increase in carbon content (12.54 wt% to 18.59 wt%) within magnesia-carbon bricks correlates with decreased high-temperature strength, exacerbating the reaction propensity with slag and consequent structural damage. Analysis of the interface phase between magnesia-carbon bricks and vanadium slag reveals a predominance of metal phase, spinel phase, and liquid slag phase. Thermodynamic calculations suggest an initial reaction between MgO and C on the brick surface, yielding Mg vapor and CO gas, while C reacts with slag to produce Cr and V elements, leading to surface structure degradation. Subsequent slag encasement and dissolution of remaining MgO via decarburization channels further erode magnesia-carbon bricks. Cumulative erosion iterations ultimately culmi nate in performance failure of magnesia-carbon bricks.

Convolutional Neural Network and Bidirectional Long Short-Term Memory (CNN-BiLSTM)-Attention-Based Prediction of the Amount of Silica Powder Moving in and out of a Warehouse

Raw material inventory control is indispensable for ensuring the cost reduction and efficiency of enterprises. Silica powder is an essential raw material for new energy enterprises. The inventory control of silicon powder is of great concern to enterprises, but due to the complexity of the market environment and the inadequacy of information technology, inventory control of silica powder has been ineffective. One of the most significant reasons for this is that existing methods encounter difficulty in effectively extracting the local and long-term characteristics of the data, which leads to significant errors in forecasting and poor accuracy. This study focuses on improving the accuracy of corporate inventory forecasting. We propose an improved CNN-BiLSTM-attention prediction model that uses convolutional neural networks (CNNs) to extract the local features from a dataset. The attention mechanism (attention) uses the point multiplication method to weigh the acquired features and the bidirectional long short-term memory (BiLSTM) network to acquire the long-term features of the dataset. The final output of the model is the predicted value of silica powder and the evaluation metrics. The proposed model is compared with five other models: CNN, LSTM, CNN-LSTM, CNN-BiLSTM, and CNN-LSTM-attention. The experiments show that the improved CNN-BiLSTM-attention prediction model can predict inbound and outbound silica powder very well. The accuracy of the prediction of the inbound test set is higher than that of the other five models by 7.429%, 11.813%, 15.365%, 10.331%, and 5.821%, respectively. The accuracy of the outbound storage prediction is higher than that of the other five models by 14.535%, 15.135%, 1.603%, 7.584%, and 18.784%, respectively.

Silicon powder production from organosilicon waste by a beneficiation-metallurgy combination process

A large amount of waste contact is produced in the preparation of organosilicon monomer. The current researches are mainly focused on copper extraction, with little attention paid to silicon. Moreover, the large accumulation of decoppered residue from organosilicon waste causes environmental pollution and resource waste. In this study, a novel beneficiation-metallurgy combination process was developed for the extraction of silicon from decoppered residue, which was defined as high gradient magnetic separation followed by roasting and acid leaching. The results showed that high gradient magnetic separation was effective in separating silicon from metallic impurities. Under the optimum conditions, the removal efficiencies of metallic impurities are more than 80 %. Fe content in the non-magnetic product can be further reduced to 0.82 % by cleaning. The non-magnetic products obtained by a roughing-cleaning process are subjected to roasting and acid leaching experiments. Under the optimum conditions, the removal efficiency of C and O can reach 94.26 % and 96.32 %, respectively. The final silicon powder product meets the standard of "YS/T1109–2016", which can be reused in the production of methylchlorosilane. This process is suitable for large-scale treatment of decoppered residue and is simple enough to help solve the problem of large-scale output of organosilicon waste.

Demonstration of neutron time-of-flight diffraction with an event-mode imaging detector.

Neutron diffraction beamlines have traditionally relied on deploying large detector arrays of 3He tubes or neutron-sensitive scintillators coupled with photomultipliers to efficiently probe crystallographic and microstructure information of a given material. Given the large upfront cost of custom-made data acquisition systems and the recent scarcity of 3He, new diffraction beamlines or upgrades to existing ones demand innovative approaches. This paper introduces a novel Timepix3-based event-mode imaging neutron diffraction detector system as well as first results of a silicon powder diffraction measurement made at the HIPPO neutron powder diffractometer at the Los Alamos Neutron Science Center. Notably, these initial measurements were conducted simultaneously with the 3He array on HIPPO, enabling direct comparison. Data reduction for this type of data was implemented in the MAUD code, enabling Rietveld analysis. Results from the Timepix3-based setup and HIPPO were benchmarked against McStas simulations, showing good agreement for peak resolution. With further development, systems such as the one presented here may substantially reduce the cost of detector systems for new neutron instrumentation as well as for upgrades of existing beamlines.

In-situ synthesis of SiC/SiO2 nanowires by catalyst-free thermal evaporation of silicon powder and their photoluminescence properties

Core-shell structured SiC/SiO2 nanowires (SiC/SiO2 NWs) were synthesized by a simple thermal evaporation method without a catalyst. The influence of the growth temperature and holding time on the microstructure and composition of the nanowires were investigated. The results indicate that within the temperature range of 1150 to 1550 °C, the color of SiC/SiO2 nanowires gradually transitions from pure white to off-white with increasing temperature. During this process, the average diameter of SiC/SiO2 increases from ∼74 nm to ∼291 nm, while the surface SiO2 layer thickness decreases from ∼17 nm to ∼5 nm, with nanowires can reach lengths of hundreds of micrometres. Variations in supersaturation of SiO and CO at different temperatures lead to discrepancies in nanowire diameter and SiO2 shell thickness. At 1350 °C, prolonged holding time enhances silicon powder reaction, resulting in increased structural disorder of the obtained SiC/SiO2 nanowires. The nanowire growth follows a vapor-solid (VS) mechanism. Additionally, the study demonstrates that the photoluminescence (PL) characteristics of the nanowires exhibit a blue shift attributable to their nanoscale dimensions, while variations in emission spectra correlate with stacking faults, SiC diameter, and SiO2 thickness. This work may be provide a theoretical basis for preparing SiC/SiO2 nanowires with different diameters and SiO2 shell thicknesses, which is crucial for advancing the development and application of SiC/SiO2 nanoceramics.

Experimental investigation on characterization of friction stir processed AZ31-based composite

Present study has been conducted to characterize the Mg alloy namely AZ31-based composite joined by Friction stir processing (FSP) technique. This study deals with the effect of single and double passes in FSP of AZ31 Mg alloy. The single pass run in FSP is followed at tool rotation speed (N) of 1000 to 1400 rpm. Also, the double pass run in FSP was followed at these speeds without using reinforcements. The feedstock particles namely SiC, Al2O3, Cr, and Si powders were used in fabrication process. The hardness, impact strength, and tensile strength characteristics were assessed in the stir region zone, and the results indicated significant improvement in these properties. The highest values of mechanical strength were seen in the FSPed area with N = 1000 rpm at a constant transverse speed (r) of 40 mm/min. Also, the tensile strength of the two passes FSPed plates is much higher than that of the single section without any reinforcement, as revealed in previous study also. The Scanning electron microscopy (SEM) analysis is done at two different magnifications for the Silicon carbide, Alumina, Chromium, and Silicon powder reinforced composites fabricated at speed of 1000 rpm. The microstructure shows that reinforced particles were uniform dispersed into FSPed region and agglomerated with Mg matrix. Si powder produces finer microstructure as compare to SiC, Al2O3, Cr. FSP decreases the grain size of processed material. Optical Microscopy results revealed that the reinforcement particle produced a homogenous microstructure and, a refined grain and equally dispersed in matrix material without split to the particle.

Дослідження оптичних та електрофізичних властивостей покриттів Mn4Si7 різної товщини

Studies of Mn4Si7 coatings of different thicknesses have shown that magnetron deposition practically does not change the composition of the coating in comparison with the composition of the target. The technology and basic modes of creating the necessary targets for a magnetron sputtering device are presented. Targets were created by adding silicon and manganese powders in the required amount and heating them under vacuum conditions at high temperature and pressure. Thin silicide films (coatings) of different thicknesses were formed on the surface of silicon dioxide from the produced targets using the method of magnetron sputtering. Studies of the transmission, absorption, and reflection coefficients of coatings in the visible region of the spectrum have shown that for the Mn4Si7 coating, the reflection coefficient is practically the same at all wavelengths. It was found that the Seebeck coefficient varies from 16 µV/K to 22 µV/K, and the resistance decreases from 77 Ω to 20 Ω with increasing thickness of the thin Mn4Si7 coating.