Silicon Carbide Content Research Articles

HVDC 케이블 접속재용 실리콘고무/나노 실리콘카바이드 콤포지트의 전기적 특성

In order to develop HVDC cable accessory, space charge exists at the interface between XLPE and EPDM composite or at the interface between XLPE and SiR. The larger the difference in ratio between the dielectric constant and the electrical conductivity of the two insulators, the greater the amount of space charge appears at the interface. The more and more space charges are stored at the interface, the higher the electric field distortion occurs. Therefore, in developing HVDC cable connection materials, Silicone rubber/nano silicon carbide (SiC) contents composites related to insulation and electrical conduction were manufactured. Nano SiC, a semiconducting inorganic material, has been modified to reinforce the interface of the composite mixed with silicon rubber.In addition, in order to study electrical ±HVDC dielectric breakdown characteristics and dielectric characteristics, modified ano SiC was filled with 0, 1, 3, 5, 7, 9wt%, dispersed, and nanocomposite was developed.

Triboinformatic modeling of dry friction and wear of aluminum base alloys using machine learning algorithms

Data-driven methods including machine learning (ML) algorithms can yield a better understanding of how tribological and material properties correlate. Correlations of friction and wear of aluminum (Al) base alloys with their material properties (hardness, yield strength, tensile strength, ductility, silicon carbide content), processing procedure, heat treatment, and tribological test variables (sliding speed, sliding distance, and normal load) studied using traditional and data-driven approaches. Five different ML algorithms, K Nearest Neighbor (KNN), Support Vector Machine (SVM), Artificial Neural Network (ANN), Random Forest (RF), and Gradient Boosting Machine (GBM) applied to experimental tribological data to predict the coefficients of friction (COF) and wear rates. Through performance analysis, we demonstrated that the ML models can satisfactorily predict friction and wear of Al alloys from material and tribological test variables data. Comparative analysis of model performance illustrated that RF outperformed other ML models in wear rate prediction, while KNN exhibited the best performance in COF prediction. Feature importance analysis further revealed that normal load, hardness, and sliding speed have the maximum influence in predicting the wear rate of the alloys. The variation in hardness of the alloys and sliding distance influenced the COF prediction the most.

Triboinformatics Approach for Friction and Wear Prediction of Al-Graphite Composites Using Machine Learning Methods

Abstract Data-driven analysis and machine learning (ML) algorithms can offer novel insights into tribological phenomena by establishing correlations between material and tribological properties. We developed ML algorithms using tribological data available in the literature for predicting the coefficient of friction (COF) and wear-rate of self-lubricating aluminum graphite (Al/Gr) composites. We collected data on effects of material variables (graphite content, hardness, ductility, yield strength, silicon carbide content, and tensile strength), processing procedure, heat treatment and tribological test variables (normal load, sliding speed, and sliding distance) on tribological properties and established two-parameter relationships. These data are analyzed using several ML algorithms: artificial neural network (ANN), K nearest neighbor (KNN), support vector machine (SVM), gradient boosting machine (GBM), and random forest (RF). The trained ML models can predict the tribological behavior from material variables and test conditions, beyond what is possible from two-parameter correlations. GBM outperformed other ML algorithms in predicting friction behavior, while RF had the best prediction of the wear behavior. ML analysis identified graphite content and hardness and as the most significant variables in predicting the COF, while graphite content and sliding speed were the most dominant variables for wear-rates.

실리콘/표면개질된 Nano SiC 충진함량별 복합재의 (+)HVDC IPT 트래킹 및 침식저항에 관한 연구

SiC(Silicon Carbide) is generally used for abrasives, grinding stones, ceramic coating paints, heat sinks for system LSIs, and next-generation semiconductors. However, in the power part, it is used by attaching to the end winding of the electric machine to reduce high voltage stress and prevent surface spark discharge. As for the measurement sample, a tracking sample was prepared by filling the surface-modified Nano SiC in SiR with a filling content of 1,3,5,7wt%. The experimental conditions for tracking and erosion were applied voltage (+)HVDC_4.5kV and the rate of contaminant was 0.25ml/min. Tracking and erosion tests can cause electrical erosion on the surface. The thermal conductivity of an insulator is related to its resistance to tracking and erosion. For that reason, in this study, we would like to confirm whether the resistance to tracking and erosion of SiR is improved by increasing the filling content of nano SiC in SiR. As the result of the experiment, as the SiC filling content increased, the thermal conductivity increased, and on the contrary, the tracking and erosion test results showed that the amount of erosion decreased. In addition, the leakage current pulse size also showed a result of weakening the dry versus arc current pulse.

The effects of SiC addition on the sintering densification, phases, microstructure and mechanical properties of W

Refractory tungsten(W) materials are widely used in high-temperature field due to their high melting point. But there are some problems with W, such as low strength and poor toughness. The grain boundaries are very sensitive to impurities, which is one of the most important reasons for the degradation of tungsten properties. In this paper, we use silicon carbide (SiC) as a deoxidizer, which is designed to react with the oxygen atoms in tungsten at high temperature to purify and strengthen the grain boundaries. The effects of SiC addition on the sintering densification, microstructure and mechanical properties of W were investigated. Results show that SiO2 and W2C are produced by the interface reaction between SiC and W, which reduces the free energy of sintering system and promotes the densification process, the maximum relative density reaches 99.4%. When SiC content is 1 wt%, compared to pure tungsten, the tensile strength significantly increases from 220 MPa to 431 MPa, the hardness increases up to 697.13 HV. Furthermore, the fracture mode of this W is mainly transgranular fracture, which is due to interface reaction strengthening and purification grain boundary strengthening.

Preparation of single-layer coating polyester cotton composites with electric loss of their electromagnetic properties

In this paper, single-layer coated polyester–cotton composites were prepared using PU-2540 waterborne polyurethane resin as the adhesive, graphite and silicon carbide as functional particles, and adopting a coating technology on the plain polyester–cotton fabric. First, the single-layer graphite-coated polyester cotton composite was prepared with graphite as the functional particle, and the influence of graphite content on the reflection loss and shielding effectiveness was studied. When the applied electric field frequency is 1610 MHz and the graphite content is 40 wt%, the minimum reflection loss is −26 dB; when the applied electric field frequency is 39.9 MHz and the graphite content is 50 wt%, the maximum shielding effectiveness is 12 dB. Then the single-layer silicon carbide-coated polyester–cotton composite was prepared with silicon carbide as the functional particle, and the influence of silicon carbide content on the reflection loss and shielding effectiveness was studied. With the applied electric field in the range 500∼3000 MHz the greater the content of silicon carbide, the smaller the reflection loss, the better the wave-absorbing ability, the larger the shielding effectiveness, and the better the shielding performance. Finally, the single-layer graphite/silicon carbide-coated polyester–cotton composites were prepared by doping graphite and silicon carbide in different proportions, and the influence of doping ratio on dielectric properties, reflection loss, and shielding effectiveness was investigated. The real part of the dielectric constant of the material was highest – that is, the polarization ability of the material was best when there were only graphite particles in the doping medium and the silicon carbide content was 0. The imaginary part of the dielectric constant and the tangent of loss angle of the material were the highest – that is, the loss and attenuation ability of the material were best – when the doping ratio of graphite to silicon carbide is 4:1. With the applied electric field in the range 500∼3000 MHz and with increasing graphite content, the reflection loss of the material became smaller, showing an enhanced wave-absorbing property, and the shielding effectiveness of the material increased, showing an enhanced shielding performance.

Enhancing heat transfer in the heat exchange medium of energy piles

As systems for utilizing geothermal energy, energy piles have been widely employed in many engineering applications, and they offer various advantages. A significant amount of research has been devoted toward developing methods to enhance the heat exchange efficiency of these systems, including studies on the shape of the heat exchange tube and the shape and spacing of the energy piles. After around four decades of research and development, existing methods for improving the heat exchange efficiency have become relatively mature, thus hindering further improvements. Therefore, it is essential to develop an alternative approach for enhancing the heat transfer and improving the heat exchange efficiency of these systems. To this end, this paper first summarizes the conventional heat transfer model and then elaborates on the selection of the concrete pile material as the heat transfer medium. In this study, samples of graphite concrete and silicon carbide (SiC) concrete were prepared. Subsequently, several tests on the heat transfer behaviors and mechanical performances of the samples were conducted, in order to determine the physical and mechanical properties of the modified concrete. The results showed that, at the same ambient temperature, when the graphite content exceeded 15%, the heat transfer coefficient increased, leading to a significant improvement in heat transfer. However, the compressive strength decreased noticeably. With an increase in the SiC content, the thermal conductivity of the concrete gradually increased, while the compressive strength of the concrete with SiC increased considerably. The results proved that modifying the concrete used in energy piles is a feasible method for improving heat transfer.

Investigations into dry‐sliding wear behaviour of a novel composite (aluminium‐magnesium‐silicon‐copper‐silicon carbide) produced by powder metallurgy route

AbstractMetal‐matrix aluminium composites are satisfactory successor not only for steels, but also for aluminium‐alloys in several automotive units and components. There are various paths to get light‐weight materials with‐out compromising their toughness, strength and safety demands. Tests on dry‐sliding or un‐lubricated pin‐on‐disc tests can be performed to obtain the wear‐characteristics of metal‐matrix composites built on aluminum. In the present study, we studied the behavior of wear resistance during sliding of metal matrix aluminium composites (AMMC) at sliding speeds of 1.5 m/s and loads of 20 N and 40 N in a normal environment, and experiments have been conducted using pin‐on‐disk tribometer (Make: DUCOM tribometer). The composites were manufactured by powder treatment and presented a number of problems, such as defective bonds and inter‐facial product reactions, which alter the tribological and mechanical properties. The results have shown that wear‐rates of the prepared composites are much lesser than those of matrix‐alloy and decreased further with increasing silicon carbide content. As the normal loads increases, the cracks and combination of abrasions, delimitation and wear of the adhesives of silicon carbide particles were observed. The composite samples were studied using a scanning electron microscope before and after the wear tests and systematically analysed.

Enhancement of Fracture toughness for Nano SiC reinforced AA7075 MMC’s By Tensile tests and FEM Analysis

After the second world war, The Design and development activities in the field of Aerospace took place with a great acceleration and that resulted in to Evolution of new Aluminum alloy materials for Aircraft Structure. Recent research work reveals that particle reinforced Metal matrix composites (PAMC) of aluminum alloy reinforced with silicon carbide reinforcement have shown better mechanical and wear properties. In this work, AA7075 is chosen matrix and Nano silicon carbide(500nm) in the range of (0-8%) were added in terms of weight percentage as reinforcement. Cast MMC samples were fabricated stir casting techniques. Further the specimens were made for XRD study, and for Tensile Test. The 500nm silicon carbide content varies with the 0%, 2%, 4%, 6% &8%wt. fractions. Theoretical Stress intensity values of Compact tension specimen were compared with FEM analysis. And it was observed that higher values of toughness were obtained as the weight percentage increased. Results were compared with pure matrix material in this paper.

Influence of silicon carbide on structural, optical and magnetic properties of Wollastonite/Fe2O3 nanocomposites

The influence of adding 10, 20 and 30% molar ratio of silicon carbide (SiC) separately to a composite of wollastonite (W) with a fixed content of 10%Fe2O3 prepared by wet precipitation method was studied. The crystal structure of the annealed composite powders was inspected by X-ray diffraction (XRD); revealing multi-phase structure. The highest estimated crystallite size investigated by Scherrer equation of W, SiC, WFe:SiC10, WFe:SiC20 and WFe:SiC30 were 53.89, 54.6, 56.3, 48.5 and 54.6 nm respectively; demonstrating the formation of nanocomposites. Particles shape, size and crystallinity of the samples were studied using high resolution transmission electron microscope (HR-TEM). The band gap Eg values of the nanocomposites increased with SiC content having an intermediate value that lies between that of γ-Fe2O3 (maghemite) and SiC. Ferromagnetic and paramagnetic contributions were observed in the magnetic hysteresis loops for the composites. This study highlighted that the coercive field (Hci) of the composites improved with increasing the SiC content. The innovative wollastonite/Fe2O3/SiC with amended magnetic properties elicited attention due to their promising application in bone filler and industrial purposes.

Characterization of fusion welded ceramics in the SiC-ZrB2-ZrC system

Various SiC-ZrB2-ZrC ceramics were joined by fusion welding to determine the maximum silicon carbide content that could be joined. Commercial powders were hot pressed, machined, and preheated to 1450 °C before joining with a tungsten inert gas welding torch at 160–200 A. Resulting welds were cross-sectioned and analyzed to determine which compositions were weldable and to characterize microstructural evolution in welded samples. As compositions approached the ternary eutectic, the welds had smaller SiC grains and exhibited better weldability. Penetration depth of welds was controlled by a combination of current input and welding speed. The ternary eutectic in the system was found at 36.9 ± 1.3 vol% SiC, 42.7 ± 1.5 vol% ZrB2, and 20.4 ± 1.9 vol% ZrC and its melting temperature was 2330 ± 23 °C. A ternary phase diagram for the SiC-ZrB2-ZrC was constructed and proposed via microstructural analysis of arc melted pellets on binary joins between each binary eutectic and the ternary eutectic in the system.

Electrical Resistivity of Partially Transformed Silicon Carbide Made from Coal

The bulk resistivity of coal that has been partially transformed to silicon carbide (SiC) over the temperature range 25-1600°C was investigated with an emphasis on temperature, SiC content, bulk density, and presence of elemental silicon. The materials were 0%SiC (wt%), 30%SiC, 69%SiC, and 72%SiC. Only the 72%SiC sample contained elemental silicon in substantial amounts. At low temperatures, there is high variation among all the materials, but at high temperatures the differences are less severe, as the results are all the same magnitude. The difference of the materials with the highest and lowest resistivity was around 30 mΩm between the 30%SiC and the 69%SiC at 1500°C. The mechanical strength of the material is lowered upon conversion to SiC but is raised once elemental silicon begins to form. In addition to temperature, the resistivity seems to respond to SiC content, bulk density, and the presence of silicon. An increase in bulk density consistently leads to a decrease in the resistivity, except with the presence of silicon. SiC content may have some effect, but it is lesser compared to the other factors examined so far.

Development and characterization of aluminium silicon carbide composite materials with improved properties

In the recent years Metal Matrix Composites (MMCs) have proved great application potential in the field of aerospace and automotive industries due to their superior strength to weight quantitative relation and resistance to high temperature. Due to high manufacturing cost of the particulate metal matrix composites component and several technical challenges associated with casting technology, its widespread application for engineering purpose is restricted. The main aim of the present study is to cast and evaluate properties of the composite by increasing the stirring time and limiting the weight percentage of reinforcement. In this study, Aluminium (Al) is used as the pure matrix material and Silicon carbide (SiC) is used as the reinforcement material for the stabilization of the matrix. Stir casting is used to make aluminium matrix composites (AMC) by varying SiC content (0 to 5% wt. %) with the help of four blade motor stirrers rotating at a speed of 550 rpm for 20 min. A detailed study of mechanical and micro structural properties of Al-SiC composites is performed using Scanning Electron Microscopy for the characterization of the composite properties. The results indicated that the mechanical properties of the composite have been improved considerably with the addition of SiC in Al matrix. It was also observed that SiC was uniformly distributed over Al matrix due to continuous stirring in the mould and presence of few clustering was revealed in Micro structural observation.

Complex elements of aerospace equipment from reaction silicon carbide ceramics

The results of studying the process of obtaining complex-profile elements of the substrate of mirrors of optical telescopes from reaction-sintered silicon carbide ceramics are presented. It is shown that the strength of silicon carbide ceramics depends on the dispersion of the silicon carbide powder and on the temperature of reaction sintering. An increase in the sintering temperature from 1500 to 1650 °C leads to an increase in strength by 60 MPa, and to 1800 °C – to a decrease in strength by 40 MPa. An increase in strength is explained by a decrease in free silicon and an increase in the content of secondary silicon carbide, a decrease in strength is explained by an increase in the size of carbide grains. The study of the influence of the modes of soldering of hexagonal elements to obtain a complex-profile element of the substrate of the mirror of an optical telescope on the strength of the soldered seam showed that the introduction of silicon carbide powder 7 μm in size and amorphous boron in an amount of 6 % into the solder composition based on silicon carbide has a positive effect on the strength of the soldered seam. Tests of the brazed specimens at three-point bending showed that fracture occurs along the body of the specimens being brazed, and not the brazed seam. The structure of the brazed joint depends on the composition of the braze alloy and the gap between the samples to be brazed.

The effect of expansive agent and cooling rate in the performance of expanded glass lightweight aggregate as an internal curing agent

Lightweight aggregates can provide internal curing (IC) in concrete and reduce autogenous shrinkage and related cracking, but they produce a reduction in concrete strength. Expanded glass lightweight aggregates (EG-LWAs) allow for design and engineer their properties to develop better IC agents. Expansive agent silicon carbide (SiC) content and post-expansion cooling rates were systematically varied in order to develop a competitive IC agent with a controlled reduction in concrete strength. Slow cooling produced the EG-LWA with the highest intrinsic strength, but with limited water delivery capacity. Rapid cooling produced EG-LWA with lower intrinsic strength, but with the highest water delivery capacity; they reduced autogenous shrinkage at 28 days by 34% and 50% for specimens with 2.5% and 5.5% of SiC, respectively. The results of this research indicated the possibility to maximize the capacity of EG-LWA as IC agent through an optimum SiC dosage and cooling treatment.

Single-step synthesis of silicon carbide anchored graphitic carbon nitride nanocomposite photo-catalyst for efficient photoelectrochemical water splitting under visible-light irradiation

Visible-light active, silicon carbide (SiC) anchored graphitic carbon nitride (g-CN) nanocomposites (g-CN-SiC), with different SiC concentrations were synthesized using pulsed laser ablation in liquid (PLAL). Initially g-CN was synthesized by simple thermal pyrolysis, and subsequently SiC was loaded on the g-CN polymer network by PLAL to obtain g-CN-SiC polymeric-inorganic nanocomposites. The proper formation of g-CN-SiC nanocomposites is proven by XRD, SEM, TEM, and the elemental composition and the variation of elemental peaks in the nanocomposite due to the change of chemical environment was studied by XPS analysis. The synthesized g-CN-SiC were tested for their applicability as a catalyst in the process of photo-electrochemical water splitting for hydrogen production, a simple step ahead towards the realization of energy efficient fuel cells. The hydrogen production was quantified by measuring photocurrent density in the linear sweep voltammetry, and it was found that when g-CN-SiC is used in the photoanode, the measured photocurrent is consistently more than that produced by g-CN photoanode, with the highest observed photocurrent density for g-CN-SiC with 10 % SiC content, accounting for a seven-fold increase of photocurrent compared to pure g-CN. Enhanced visible light absorbance, and reduced photo-generated charge recombination in g-CN-SiC, observed in the absorption and photoluminescence spectra respectively can be attributed to the improved photo electrochemical activity of g-CN-SiC based photoanode in the process of water splitting.

Influence of SiC and TiO2 on the cure characteristics and mechanical properties of natural rubber composites

Natural rubber composites were prepared using silicon carbide and titanium dioxide as filler in different proportions. Curing characteristics were investigated as a function of filler loading and filler proportion. Mechanical properties like tensile strength, tear strength, hardness, elongation at break and modulus were determined. Both tensile strength and modulus were found to increase with SiC (Silicon carbide) content which may be due to the restrictions offered by filler particles to the rubber chain mobility. Cure properties also support the reinforcing capacity of SiC filler in the natural rubber matrix.

SiC‐based porous ceramic carriers for heat‐conductive phase change materials through carbothermal reduction method

AbstractIron tailings remain the environment‐damaging waste from the iron ore, and high porosity porous ceramics are an attractive material to “turn waste into treasure.” To improve the thermal conductivity, porous ceramics with high silicon carbide content have been prepared by carbothermal reduction sintering process using argillaceous fine‐grained iron tailings with high silica content. The carbothermal reduction reaction mechanism and the components and properties of samples in sintering process are investigated. The results show that reaction components in the tailings are mainly SiO2 and Fe2O3 and liquid phase is generated rapidly between 1200°C and 1300°C, producing foaming effect and significantly improving the porosity. Moreover carbothermal reduction of SiO2 occurs above 1300°C. After sintering at 1600°C for 2 hours, the apparent porosity and thermal conductivity of porous iron tailing ceramics are 81.1% and 0.58 W/(m·K), respectively. Compared with the ordinary porous iron tailing ceramics with the same porosity, the thermal conductivity of those herein is increased by 6.6 times. This study is instructive for the development of low‐cost preparation technology of phase change material carriers.

Paraffin/SiC as a Novel Composite Phase-Change Material for a Lithium-Ion Battery Thermal Management System

A lithium-ion battery thermal management system has always been a hot spot in the battery industry. In this study, a novel high-thermal-conductivity composite phase-change material (CPCM) made by paraffin wax and silicon was adopted to facilitate heat transfer. Moreover, high resistance or even insulation of CPCM is capable of preventing short circuits between the cells. The heat transfer mechanism of CPCMs was determined under a scanning electron microscope. A thermogravimetric analyzer was employed to determine the thermal stability. A differential scanning calorimeter was used to explore the thermophysical properties of the composite samples. By comparing the results of the experiment, it was reported that under the silicon carbide content of 5%, the parameters were better than others. The phase-change enthalpy of CPCM was 199.4 J/g, the leakage rate of liquid was 4.6%, and the melting point was 53.6 °C. To verify the practicality of CPCM, a three-dimensional layered battery pack model was built in the COMSOL Multiphysics software. By simulating the thermal runaway inside the battery packs of various materials, it was reported that the addition of CPCM significantly narrowed the temperature range of the battery pack from 300–370 to 303–304 K. Therefore, CPCM can effectively increase the rate of heat transfer to prevent the chain of thermal runaway reactions. It also enables the battery pack to run at a stable temperature.

Modeling of volumetric deformation during compaction of Al-SiC composite materials based on mechanically activated batch

AnnotationA 3D Spline model of the effect of the silicon carbide content Csic and the cold compaction pressure p on the bulk deformation of the powder molding ॉν during the cold compaction of the Al-SiC charge was constructed. The nonlinear character of the dependence ॉν(p) is established for the studied values of the silicon carbide content. The two-stage nature of the cold compaction of the Al-SiC powder mixture was revealed, which is characterized by intensive compaction at the initial stage. A sigmoidal model of cold compaction of a powder mechanically activated Al-SiC charge, which takes into account the initial stage of lightweight structural compaction, is constructed. The dependences of the influence of the SiC powder content on the coefficients of the sigmoidal cold compaction equation are established. A logistic model of the influence of CsiC on the coefficients of the sigmoidal equation of cold compaction and the average size of agglomerates formed during the mechanical activation of a mixture of Al-SiC composite powder material is proposed. The energy equation of hot compaction is obtained, the value of the compressibility coefficient is determined, and a linear equation is constructed that relates the relative densities before and after hot compaction of the Al-SiC composite material.