Synthesis Of Silicon Carbide Research Articles

Low density, three-dimensionally interconnected carbon nanotube/silicon carbide nanocomposites for thermal protection applications

Synthesis of silicon carbide (SiC) nanostructures and their composites has been a topic of interest for the scientific community due to the unique properties that can be obtained with nanoscale features. Herein, we report the scalable fabrication of anisotropic and low density, carbon nanotube/SiC (CNT/SiC) core-shell structures synthesized via chemical vapor infiltration (CVI) of silicon on aligned CNT foams followed by heat treatment at 1350 °C. Structures made of CNT/SiC nanotube networks with a thickness of 1 cm and length of 9 cm were prepared in the present work. Upon the removal of the CNT foam via calcination of the hybrid nanocomposite in air, a free-standing mechanically robust three-dimensional network of pure SiC nanotubes was left behind. The density of the synthesized CNT/SiC is the lowest reported for any C/SiC structure. Furthermore, the CNT/SiC hybrid nano-architecture demonstrated superb heat resistance and stability in ultrahigh temperature environment.

Potential for photovoltaic cell material by green synthesis of silicon carbide from corn cob through magnesiothermic reduction

Potential for photovoltaic cell material by green synthesis of silicon carbide from corn cob through magnesiothermic reduction

Dissociation of tetramethylsilane for the growth of SiC nanocrystals by atmospheric pressure microplasma

AbstractWe report on mass spectrometry of residual gases after dissociation of tetramethylsilane (TMS) during the synthesis of silicon carbide (SiC) nanocrystals (NCs) by an atmospheric pressure microplasma. We use these results to provide details that can contribute to the understanding of the formation mechanisms of NCs. Mass spectrometry reveals the presence of high‐mass polymerization products supporting the key role of neutral fragments and limited atomization. On this basis, we found that the loss of methyl groups from TMS, together with hydrogen abstraction, represents important paths leading to nucleation and growth. The combination of TMS concentration and NC residence time controls the NC mean size and the corresponding distributions. For higher precursor concentrations, the reaction kinetics is sufficiently fast to promote coalescence.

Studying the kinetics of extraction treatment of rice husk when obtaining silicon carbide

Silicon carbide is characterized by a wide range of beneficial electrophysical, anti-corrosion, and strength properties. A promising raw material for the synthesis of silicon carbide is the waste of rice production, which includes compounds of silicon and carbon-containing organic substances. The cheapness and availability of such raw materials necessitate the development of technologies to obtain silicon carbide from it. An important direction in silicon carbide synthesis technology is to obtain a high purity product. To remove impurities from rice husks, it is necessary to carry out its pre-extraction treatment. It has been established that the extraction treatment of rice husks with acid solution makes it possible to clean the raw materials from metal compounds and the excess amount of carbon-containing components. To remove impurities of metal compounds and the excess amount of carbon-containing compounds from rice husks, it has been proposed to perform the extraction with an aqueous solution of the mixture of 10 % sulfur and 15 % acetic acids. We have derived the time dependences of the degree of extraction of cellulose from rice husks. Two temporal sections of the process have been identified. It is shown that the extraction of cellulose from rice husks obeys a pseudo first-order reaction. We have calculated the constants of speed and activation energy in the course of extraction for the two time sections of the process. The activation energy of extraction over a first period is 10.75 kJ/mol; over a second period, the activation energy value is 26.10 kJ/mol. It has been established that an increase in the extraction temperature from 20 to 100 °C leads to a two-fold improvement in the process efficiency. It is shown that silicon carbide, synthesized from rice husk after its extraction treatment, is a pure crystalline material whose particles’ size is from 1 to 20 micrometers

Influence of pyrolyzed temperature on the formation of silicon carbide fiber from polycarbosilane in electrospinning method

The synthesis of silicon carbide (SiC) fibers by electrospinning method was done using polycarbosylane (PCS) as precursor and dimethylformamide (DMF)/toluene as solvent. Knowing the heat treatment of fibers consist of curing and pyrolisis, there were two steps in the major reaction. The curing process is by heating in air to make an oxidative cross-linking of the PCS. The pyrolysis process causes chemical decomposition from organic to inorganic compounds. These composition changes were described through Fourier Transform Infrared FTIR, Thermagravimetric analysis (TGA), X-Ray Diffraction (XRD) and Energy Dispersive X-Ray Spectroscopy (EDS) analysis. The products of electrospinning and curing were characterized by FTIR and TGA. The conversion to ceramic of PCS under various pyrolysis temperatures (1200, 1300, 1400, 1500) °C has been investigated and the products of this process were characterized by FTIR and XRD. Elemental analysis of the fiber as received and after cured showed that the ratio of H and C to Si decreased with holding time at the cure-temperature while the amount of oxygen increased. Meanwhile, the pyrolyzed generally produced silicon oxycarbide SiCxOy. Crystalline SiC β-SiC was found at temperature 1500 °C.

Detonation synthesis of silicon carbide nanoparticles

Detonation of explosives was used to synthesize silicon carbide nanoparticles. Polycarbosilane was added to a mixture of 1,3,5-Trinitro-1,3,5-triazinane and 2,4,6-trinitrotoluene, which was subsequently detonated in an enclosed chamber backfilled with inert gas. X-ray diffraction analysis of the detonation soot was consistent with the presence of crystalline silicon with a diamond cubic structure and cubic silicon carbide, along with amorphous material. Further analysis by transmission electron microscopy revealed the presence of crystalline angular particles. High resolution imaging showed that the particles contained numerous stacking faults along the [111] direction and had an interplanar spacing of 2.5 Å, both of which are characteristic of beta (cubic) silicon carbide. This is the first report of the detonation synthesis of silicon carbide by dissolving a silicon-containing precursor into an explosive composition.

Low Temperature Synthesis of Mesoporous SiC in Dual-Confined Spaces via Magnesiothermic Reduction

Silicon carbide (SiC), especially mesoporous SiC has been in immense vogue for more than a decade because of its intriguing properties and wide applications. However, it is still challenging to synthesize mesoporous SiC with good structural integrality, large specific surface area and desirable porosity at a low temperature. In this study, we reported a “dual-confined spaces”-assisted synthesis of mesoporous SiC using well-assembled SiO2/carbon composite as precursor via a magnesiothermic reduction process. The well-crystallinity mesoporous SiC presented a mesopore structure with high specific surface area of 267.3 m2 g[Formula: see text] and large mesopore size of ca. 10[Formula: see text]nm can be directly fabricated at a temperature of at least 550∘C and the optimum synthesis temperature is 650∘C. During the synthesis, mesoporous carbon matrix and a pressure-tight stainless steel reactor were served as “dual-confined spaces” to avoid the aggregation of silica and the silicon residue left in the final SiC sample. Furthermore, the as-prepared mesoporous SiC showed prominent performance as catalyst support for the reduction of 4-nitrophenol to 4-aminophenol.

A facile approach to microwave heating synthesis of silicon carbide from unmixed silicon powders

A facile approach to microwave heating synthesis of silicon carbide from unmixed silicon powders

Synthesis of SiC Nanoparticles on Aluminum Metal Using a Dense Plasma Focus

Abstract: Synthesis of silicon carbide (SiC) nanoparticles was carried out using dense plasma focus technology with great potential for future industrial applications. The present work presents the synthesis and coating of aluminum metal with SiC nanoparticles using silica gel and acetylene gas. It also discusses the effects of molar ratio as well as the number of deposition shots on synthesis of SiC by dense plasma focus technology. The experimental results showed that SiC nanoparticles could be synthesized by the dense plasma focus technique. The SEM investigations showed a smooth surface with an average size of SiC particles of less than 1 μm with a SiC fiber-like microstructure.

Thermodynamic analysis of the interaction of components in the Si–C–O system in the carbothermic synthesis of silicon carbide

Phase equilibria in the Si–C–O system at temperatures of 1400–1700°C were modeled to theoretically determine the optimal conditions for implementing our proposed method of carbothermic synthesis of silicon carbide in reactors with an autonomous protective atmosphere. It was found that, depending on the ratio between the initial components and the synthesis temperature, the equilibrium products of the synthesis can be various combinations of silicon carbide, a gas phase, residual amounts of silicon oxide and carbon, andan oxide melt formed at high temperatures.

Magnesiothermic Reduction Synthesis of Silicon Carbide with Varying Temperatures: Structural and Mechanical Features

The search for finding effective ways to produce high quality of nanostructured materials have always been the never-ending work of many scientists and engineers from time to time. Important issues to address are reducing fabrication expense and lowering energy utilization to complete the synthesis. A specific circumstance is an investigation of using relatively low temperature to fabricate pure silicon carbide (SiC), one of the most notable materials due to its excellent properties, from naturally appearing minerals. In this current study, silicon carbide was prepared by means of magnesiothermic approach at some adjusting temperatures using argon gas furnace. The source of silicon and carbon were respectively initiated from naturally purified silica and sucrose. The X-ray diffraction (XRD) assessment clearly uncovered the pure moissanite-3c phase of silicon carbide, having a cubic crystal structure. The disappearing of magnesium, otherwise in the form of magnesium oxide, was also validated by the X-ray fluorescence (XRF) test. Furthermore, the chemical functional groups were clarified by Fourier-transform infrared (FTIR) spectroscopy, and the silicon-carbide interaction was evidently detected from the FTIR spectrum. Besides, the SiC products exhibited high Vickers hardness values, nearly 150 MPa for the sample with temperature synthesis of 800 °C.

The Influence of AlN Intermediate Layer on the Structural and Chemical Properties of SiC Thin Films Produced by High-Power Impulse Magnetron Sputtering.

Many strategies have been developed for the synthesis of silicon carbide (SiC) thin films on silicon (Si) substrates by plasma-based deposition techniques, especially plasma enhanced chemical vapor deposition (PECVD) and magnetron sputtering, due to the importance of these materials for microelectronics and related fields. A drawback is the large lattice mismatch between SiC and Si. The insertion of an aluminum nitride (AlN) intermediate layer between them has been shown useful to overcome this problem. Herein, the high-power impulse magnetron sputtering (HiPIMS) technique was used to grow SiC thin films on AlN/Si substrates. Furthermore, SiC films were also grown on Si substrates. A comparison of the structural and chemical properties of SiC thin films grown on the two types of substrate allowed us to evaluate the influence of the AlN layer on such properties. The chemical composition and stoichiometry of the samples were investigated by Rutherford backscattering spectrometry (RBS) and Raman spectroscopy, while the crystallinity was characterized by grazing incidence X-ray diffraction (GIXRD). Our set of results evidenced the versatility of the HiPIMS technique to produce polycrystalline SiC thin films at near-room temperature by only varying the discharge power. In addition, this study opens up a feasible route for the deposition of crystalline SiC films with good structural quality using an AlN intermediate layer.

Thermodynamic Analysis of the Interaction of Components in the Si–C–O System in the Carbothermic Synthesis of Silicon Carbide

Thermodynamic Analysis of the Interaction of Components in the Si–C–O System in the Carbothermic Synthesis of Silicon Carbide

Synthesis, Optimization and Characterization of Silicon Carbide (SiC) from Rice Husk

Although Silicon carbide (SiC) has shown interesting engineering properties, its cost of production continues to limit its applications in the industry. Therefore, this paper reports a simple, inexpensive method to synthesize silicon carbide via pyrolysis of rice husk without the use of catalysts or complex set-ups. Pyrolysis of rice husk was carried out in a tube furnace at temperatures ranging from 1000°C to 1500°C and retention time ranging from 1 to 2 hours in an Argon atmosphere flowing at a rate of 2l/min. The morphology of the products was analysed by SEM while phase analysis was done using XRD. The yield of SiC from rice husk was found to be affected significantly by pyrolysis temperature and retention time. It was observed that the synthesized SiC powder was a mixture of whiskers and particulates.

Synthesis of nanosized SiC by low-temperature magnesiothermal reduction of nanocomposites of functionalized carbon nanotubes with MCM-48

Silicon carbide synthesis by a magnesiothermal method was investigated using MCM-48 as the silica source mechanically mixed with carbon nanotubes (CNTs) as the carbon source, and nanocomposites of MCM-48/functionalized CNTs (CNTF). SiC syntheses were carried out with different molar ratios of MCM-48, carbon and magnesium at 700 °C in argon. The MCM-48 and carbon nanotube starting materials and the SiC products were characterized by BET, XRD, FESEM, EDX and TEM. The effect of the carbon content and the type of CNTs (either functionalized or unfunctionalized) on the SiC synthesis was studied. The results show that an improved yield of SiC is obtained when the carbon nanotubes are functionalized, producing a better contact with the MCM-48. This improved contact between the reactants ensures a good degree of reaction in a stoichiometric mixture of silicon and carbon, with no improvement in product formation being achieved by the use of additional carbon. These findings suggest that the degree of contact between reactants is an important factor in the magnesiothermal synthesis of SiC. The SiC products from magnesiothermal synthesis of the functionalized nanocomposite precursors were shown by TEM and FESEM to have unusual nanofiber morphologies mimicking the morphology of the CNTF nanotubes.

Optimization of plasma dynamic synthesis of ultradispersed silicon carbide and obtaining SPS ceramics on its basis

Obtaining SiC ceramics with high physical and mechanical properties requires the use of high purity products with a single crystal structure of particles. Such a product can be obtained by the plasma dynamic synthesis based on using a pulsed arc discharge. This paper presents that the way of an arc discharge ignition significantly influences both the effectiveness of the precursor sublimation and the phase composition of the final ultradispersed product. The arc discharge ignition through a thermal breakdown mechanism is the most efficient way to implement the plasma dynamic synthesis of silicon carbide β-SiC and achieve its yield up to ~99 wt% of the product. The synthesized powder is characterized by a single crystal structure of particles and their average size of ~70 nm. Spark plasma sintering of the as-prepared materials allows improving the ceramics quality in comparison with the ceramics sintered from the commercial silicon carbide. This effect is especially observed at sintering the ceramics with the use of Al-B-C additives, when the higher mechanical characteristics (ρ = 98.8%, H = 26 GPa) are achieved.

A facile synthesis of silicon carbide nanoparticles with high specific surface area by using corn cob

Corn cob, which possesses low ash and high carbon contents, is a common waste material that accounts for a large amount of agricultural waste. This paper reports about a facile method to synthesize silicon carbide (SiC) nanoparticles with high specific surface area by using corn cob as a carbon source. The method is accomplished by carbothermal reduction at 1350 °C using corn cob as carbon source and silicon monoxide as silicon source. Fourier transform infrared (FT-IR) and Raman spectra results confirmed the formation of synthesized SiC particles. X-ray diffraction (XRD) results indicated the major phases of 3C-SiC. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images showed that the SiC particle size is in the range of 40–100 nm and mainly composed of sphere-shaped nanoparticles. The Brunauer–Emmett–Teller (BET) specific surface area of samples is 80.25 m2/g. In addition, we proposed the formation mechanism of SiC nanoparticles with high specific surface area by adsorption and vapor–solid mechanism. This facile method for synthesizing SiC nanoparticles provides a new idea for high-value application of corn cobs and new raw material for the preparation of silicon carbide.

Fabrication of Silicon Carbide from Recycled Silicon Wafer Cutting Sludge and Its Purification

Around the world, silicon carbide (SiC) is used as a raw material in several engineering applications because of its various beneficial properties. Currently, though the Acheson method is one of the most emblematic to manufacture SiC, the direct carbonization of metallic silicon is simple and beneficial. In this reaction, silicon wafer cutting sludge can be used as an alternative silicon source material. The silicon wafer sludge contains silicon, ethylene glycol, cooling water, and a small amount of impurities. In this study, SiC was synthesized using silicon wafer sludge by a carbothermal process. In a typical experiment, the silicon sludge was mixed with carbon at different molar ratios. Then, the mixture was turned into pellets, which were placed in alumina crucibles and heat-treated at a temperature from 1400 °C to 1600 °C to fabricate SiC. To deduce the optimum condition for the synthesis of SiC, an investigation was carried out on the effects of different mixing ratios, temperatures, and heating times. To ensure sufficient carbonization, excess carbon was mixed, and the synthesized SiC was characterized by X-ray diffraction (XRD). Subsequently, purification of the synthesized SiC products by oxidation of excess carbon was performed. The removal of extra carbon could be confirmed by XRD and attenuated total reflectance (ATR) spectroscopy. This process can give basic information for the development of a technology to produce SiC using recycling Si wafer cutting sludge waste.

Synthesis and Structural Analysis of Silicon Carbide from Silica Rice Husk and Activated Carbon Using Solid-State Reaction

Synthesis of Silicon Carbide (SiC) has been performed using a solid-state reaction method. We used silica and activated carbon as raw materials. The silica was synthesized from silica rice husk using an alkali extraction and a sol-gel method. The purified silica was then mixed with the activated carbon at the same ratio, homogenized, and then cold pressed into pellets by adding polyvinyl alcohol to glue them perfectly. The pellets were then sintered in a vacuum of a high-temperature furnace in an inert arc-furnace at 1200, 1300, and 1400 °C for 6 hours. The samples were characterized for their particle size, surface area, phase composition, microstructure, and resistivity. The XRD data analysis showed that the samples are dominated by the SiC phase in the form of 3C-SiC and 6H-SiC, CO (Carbon (II) oxide), and SiO2 phases. The weight fractions of SiC samples were respectively fallen to 68, 98, and 69% for 1200, 1300 and 1400 °C sintering temperatures.

Intrinsic structural and electronic properties of the Buffer Layer on Silicon Carbide unraveled by Density Functional Theory

The buffer carbon layer obtained in the first instance by evaporation of Si from the Si-rich surfaces of silicon carbide (SiC) is often studied only as the intermediate to the synthesis of SiC supported graphene. In this work, we explore its intrinsic potentialities, addressing its structural and electronic properties by means of Density Functional Theory. While the system of corrugation crests organized in a honeycomb super-lattice of nano-metric side returned by calculations is compatible with atomic microscopy observations, our work reveals some possible alternative symmetries, which might coexist in the same sample. The electronic structure analysis reveals the presence of an electronic gap of ~0.7 eV. In-gap states are present, localized over the crests, while near-gap states reveal very different structure and space localization, being either bonding states or outward pointing p orbitals and unsaturated Si dangling bonds. On one hand, the presence of these interface states was correlated with the n-doping of the monolayer graphene subsequently grown on the buffer. On the other hand, the correlation between their chemical character and their space localization is likely to produce a differential reactivity towards specific functional groups with a spatial regular modulation at the nano-scale, opening perspectives for a finely controlled chemical functionalization.