Silica Carbide Research Articles

SSZ-13 membranes on novel silica carbide monoliths for efficient CO2 separation

The usage of normal alumina supports brings the uncertain and undesirable aluminum transformation to the high-silica zeolite membranes to reduce Si/Al ratio in framework. In this current study, a novel aluminum-free silica carbide (SiC) monolithic support is used for the synthesis of SSZ-13 membranes with enhanced Si/Al ratio for the first time. Moreover, this high-porosity and monolithic SiC support enables membrane to increase gas permeance and surface-to-volume ratio. High-quality SSZ-13 membranes were prepared after rational modification of synthesis parameters such as synthesis temperature and time and support material. The effects of test temperature, pressure drop, feed flow rate and humidity on separation performance of the monolithic membranes were studied. The formation mechanism of SSZ-13 membrane was also investigated. The Si/Al ratio and CO2 permeance of SSZ-13 membranes on SiC monolith were 100% and 60% higher than that of membrane on alumina monolith, respectively. This monolithic membrane had comparable separation performance but about 2.3 times higher surface-to-volume ratios to the reported tubular zeolite membranes. This solution could be suitable to prepare other high-silica and all-silica zeolite membranes.

Regulating synergistic micro-nano pore structure of CNT sponge to control EMI shielding performance

The aggregation in high-content carbon nanotube reinforced silica carbide composites (CNT/SiC) imposed constraints for further large-scale industrial applications. This study established a synergistic micro-nano pore structure by assembling CNT bundles to fabricate the CNT sponge preform, and then the SiC matrix was in-situ deposited by chemical vapor infiltration method, which facilitates composites with high density and exceptional properties. The pore size distribution and pore area can be regulated by simply adjusting the compression ratios (CRs) of the as-assembled CNT sponge. Samples with CR of 50 % exhibited noteworthy densification, significantly reduced porosity, and a remarkable 163.54 % extra increase in compression strength compared to uncompressed ones. Additionally, the CNT/SiC composites displayed excellent oxidation resistance and demonstrated improved electromagnetic interference (EMI) shielding performance, which exhibited a substantial increase with higher CRs. These findings underscore the significance of employing appropriate multi-level porosity in CNT preforms to fabricate advanced ceramic matrix composites with superior EMI shielding capabilities.

Ballistic impact performance of hybrid composite armors made of aluminum foam containing the dispersion of shear thickening fluid made of various synthetic nano-fillers

Hybrid composites armors made of closed-cell aluminum foam are developed for intended use in ballistic protective plates. The manufacturing process involved impregnation of shear thickening containing different micro and nano-fillers into aluminum foam panels which are subsequently bonded two AA 5086-H32 aluminum sheets that surrounded the targets, by using compression molding techniques. The effects of the addition of different nano-fillers as colloidal silica, gamma alumina, silica carbide, and Kevlar micro-fibers to the aluminum foam plates on the ballistic response of the hybrid composites armors were investigated. Scanning electron micrographs were used to investigate the interfacial interaction between specimen layers, and the influence of the nanoparticles impregnated within closed aluminum foam cells before and after high-velocity impacts. The ballistic impact resistance of the produced hybrid composite cell aluminum foam laminates was tested according to NATO standards using a semiautomatic 9 mm Beretta Cx4 Storm Rifle Luger. The results indicated that the performance of the hybrid composite armors made of aluminum foam were enhanced by the deposition of micro and nano-fillers into the surface of the closed-cell aluminum foam.Therefore, the ballistic impact resistance and energy absorption of the specimens were improved. The highest impact energy absorption capacity was achieved by the deposition of Kevlar micro-fibers, but the resulting plates have the highest target weight and thickness. Silica carbide powder followed by gamma alumina, and colloidal silica powder in that order, enhanced the impact energy absorption capability with the least target weight and thickness average. These findings indicate that introduction of micro and nano-fillers coating on closed-cell aluminum foam, improved a range from 4.9 to 30.9 J in comparison with untreated samples, therefore, it could be a promising method for strengthening interfacial bonding between layers of the aluminum foam composites.

Hardness and Wear Behavior of Heat Treated Aluminium Silicon Alloy SiC Particle Reinforced Composite

The A356 Aluminium Silicon alloy is reinforced with Silica Carbide particles (SiCp) to form metal matrix composite by stir casting method to study the hardness and wear properties. The composites are prepared for weight fraction of 2, 4 and 6% of SiC with the base alloy and their characteristics are observed at post T6 full heat treated condition. The optical microscopic metallography observation shows the rosettes of uniform spheroidal grains of strain free eutectic silicon phase in proeutectic Aluminium matrix after heat treatment. The hardness and wear properties of the A356-SiC composites have increased with the increase in weight percentage of reinforcement particle in the base alloy. Maximum hardness and wear resistance is observed for 6% SiC which is the maximum percentage of inclusion of secondary element considered under this study. A comprehensive discussion is made on the strengthening of the A356 alloy on addition of hard SiC particles that has improved the hardness and wear characteristics of composites in heat treated conditions.

Tribological Properties of Lubricating Grease Additives Made of Silica and Silicon Carbide Nanomaterials

Nanomaterials have been widely used in many fields due to their special microstructure and quantum size effect. In addition, there are many advantages that other traditional materials do not have. Nanometer silicon dioxide and silicon carbide as inorganic nonmetal high-tech materials have high temperature resistance, no pollution and other properties, and are very suitable for making grease additives. At the same time, it is also possible to improve the tribological properties of grease additives by using unique characteristics such as innocuity and tastelessness. Correspondingly, grease is an additive that cannot be obtained in equipment manufacturing. It is very urgent to continuously study and improve the service performance. Therefore, the purpose of this paper is to explore new routes of grease additives and transmission based on the theory of nano-materials, analyze the development and fusion paths in the application of nano-technology technology, and explore the advantages and disadvantages of application. This article will use the research method of specific analysis of specific problems to make data comparison and draw a conclusion. Through theoretical innovation and exploration, we can find a suitable model to promote the development of industrial additives. The research results show that the amount of lubricating grease used in rolling bearings accounts for 80% of the amount of lubricating grease. Adding silica to lubricating grease can improve the stability of additives by 26% and effectively improve the use effect of lubricating grease. Therefore, combining with the characteristics of the current era, nano-technology is used to fully absorb and reform and actively innovate and improve the technological level. This paper analyzes the different application difficulties and explores the development prospects, thus proposing the realization path of improving chemical coatings. These theories are used to guide innovation and integration, providing valuable experience for the wide application of nanotechnology.

Investigation of mechanical properties of SiC particle reinforced Aluminium A356 / LM25 alloy composite

Aluminium Silicon alloy composites A356 - SiCp were prepared by varying weight percentage of Silica Carbide particle (SiCp) content in the Al- Si alloy by stir casting method and subjected to T6 heat treatment. The effects of SiCp (2% 4% and 6% weight fraction) in the A356 alloy composite on the basic mechanical properties like tensile strength, percentage elongation, compressive strength and impact strength were investigated. The cast A356 base alloy before heat treatment and after heat treatment were also assessed for its basic microstructural and mechanical properties. The virtues of post heat treatment effects such as release of residual stresses, grains refinement, precipitation strengthening and the phenomenal transformation of eutectic Si particles to spheroidal structures, have contributed to enhance the mechanical properties considered. The compressive strength of the composites has increased with increase in SiCp wt.%. The tensile strength of the composites has increased and is maximum for 4% reinforcement but for 6% SiCp inclusion there is slight decrease in the tensile strength when compared to 4% SiCp. The elongation property and impact strength values have been observed to be drooping with increase in the SiCp wt. % content in A356. A comprehensive discussion is made based on the analysis of the strengthening to weakening behavior of the strength, ductility and impact toughness of the fabricated composite.

OVER-ALL EVALUATION OF COAL PROPERTIES FOR NON-TRADITIONAL USE AT THE STAGES OF SEARCH AND ESTIMATION WORKS

The present-day noitons about possible directions of non-traditional use of coals are considered, the choice of the optimal complex of material-genetic parameters and indices of coals quality at the stages of search and estimation works is substantiated, for their evaluation as a raw material for production of synthetic liquid fuel, wax, coal-humic preparations of various destination, coal-alkaline reagents, pigments, filtering materials, silica carbide, sulphocoals, thermoanthracite on the base of analysis and generalization of the laboratory research and modeling of treatment processes has been made.

Effect of cyclic shearing on contact surfaces of geo-materials under constant normal force

A large amount of research has been done on conforming surfaces in rock joints as well as on the contact between individual grains; however, not much exist in nonconforming contact surfaces subjected to friction, such as flat contacts between ballast particles, stone columns, or riprap; applications that involve the use of coarse gravel subjected to low vertical stresses. Therefore, this article aims to study changes in contact properties between nonconforming flat contacts between large geo-material particles that have been subjected to cyclic shearing under a constant low vertical force, using a direct shear apparatus. Two different silica carbide sandpapers that do not loose particles were used, to simulate different morphologies, a nominally fine and a coarse surface texture. The results show a passivation of the shear strength where a constant value of friction coefficient is reached after around 15 to 17 cycles for all tests, except the tests at the lowest vertical force. For the tests at the highest vertical force, similar friction coefficients were determined for the coarse and fine surfaces. The mass broken during the 10th and 20th cycles was collected at the end of the tests and seemed to show a linear relationship with the vertical force used in the test. Particle analysis, determined via microscopy, shows that the grading is dependent on the initial topography of the surfaces. Despite being subjected to 10 and 20 cycles of shearing, the broken particles look similar in shape with sharp, jagged edges and having different shapes and roundness values with a large variation, indicating that the breakage was not enough to fill in the space between the particles.

Synthesis and characterization of porous ceramics from spodumene tailings and waste glass wool

Glass wool waste remains a challenging waste fraction with relatively little utilization prospects. The present study investigated the development of porous ceramic materials from glass wool waste and spodumene tailings mainly made of quartz feldspar sand (QFS), with 0.05–0.5% silica carbide (SiC) as a pore-forming agent. The formulated compositions were sintered at 950 °C and analyzed in terms of mechanical properties, phase composition, and microstructure using X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray micro-computed tomography. The results showed that a synergetic effect of glass wool and SiC started to be significant from 15 wt% glass wool and 0.05 wt% SiC, the strength reducing and the porosity increasing with the increase of SiC. The porous ceramics were largely amorphous, with compressive strength ranging from 5 to 30 MPa while the water absorption and apparent density ranged from 2 to 10% and 0.7–1.2 g/cm3, respectively. The total porosity varied between 20 and 75%, and the wall thickness between 62 and 68 μm; besides, most of the prepared materials floated in water. These results are of interest for the repurposing of glass wool waste in the development of non-flammable lightweight materials for potential filtering or high-rise building applications.

MWCNTs Addition to Al2O3-SiC Binary Coating Deposited by Plasma Thermal Spray on Low Carbon Steel Substrate

Coating with alumina and silicon carbide on low alloy steel specimens surface was conducted by using plasma thermal spray technique. The coating was of different percentages of alumina and silicon carbide (75% alumina +25% silicon carbide, 50% alumina + 50% silicon carbide) and then carbon nanotube was added to the mixtures of powder with percentage of 1%. Cyclic hot corrosion test was done after coating and XRD and SEM were performed to all samples after corrosion. Coating thickness was measured by SEM cross-section micrographs. The weight change of bare and coated specimens after 50 hours of corrosion in 67% wt. V2O5 + 33% wt. Na2SO4 at 950 °C was measured. The maximum reduction in weight was shown by specimens coated with 50% wt. alumina +50%wt. silica carbide with addition of 1% carbon nanotube . X-Ray of coated samples indicated that no phase change occurred to the coating materials. Scanning electron microscopy imaging of surface layer clarified that surface layer has relatively moderate porosity and some coating layers contain micro-cracks.

Effect of using Palm Char and Coke as a Reductant in Production of Ferrosilicon

This research focused on the synthesis of ferrosilicon alloy by coke and palm char as a reductant. Raw materials which were iron ore, silica sand, coke and palm char mixed and compacted into pellets. The pellets were reduced at temperature of 1300°C using horizontal tube furnace with nitrogen gas flow. The pellets after reduction process were characterized by X-ray fluorescence (XRF), X- ray diffraction (XRD), Scanning electron microscope equipped with energy dispersive spectra (SEM/EDS). The results from XRD analysis indicated that the formation of FeSi, Fe3Si and SiC phases were appeared at 1300 °C for both reductants. The brighter phases were observed in SEM/EDS mapping analysis represents as iron and silicon. The EDX analysis showed the high amount silica developed for coke compared to palm char due to high content of silica and carbon. The results found that palm char as carbon reductant has the potential to produce ferrosilicon and silica carbide in sustainable way.

A comparison on microstructure and mechanical properties of electric discharge metal matrix nickel and silica composite coating on duplex stainless steel

Electric Discharge Alloying/Coating a thermal process of elemental deposition together with pyrolysis carbon enhance various properties. Nickel and silica both provide excellent property, but the solidification rate differs the material microstructural properties (amorphous) that improves its properties under diverse working conditions. In present study analysis of properties such as surface roughness, Microstructure, layer thickness, elemental composition, porosity, decarburizing depth is detailed through metallurgical characterizations and mechanical testing are compared to nickel and silica. Nickel holds a hardness value of 1272 HV and across 968 HV with minimal in carter, pokes, splatters having uniform boundaries that improves friction co-efficient, limiting wear resistant, phase transformation, oxidation, and graphite flakes confirm self-lubrication properties at room temperature under higher loading condition. Silica having 1284 HV on the surface and across it reaches to 980 HV due to dispersed elements and its phase transformation of silica to silica carbide directs secondary arching improves bonding by restrictive carbon deposition promotes passage to speak. This limits the porosity, coating layer thickness and increases metal matrix composition in decarburizing layer holds stability towards coating. Nickel affords surface properties limiting matrix composite, oxidation, and grain growth where else silica provides exceptional in metallurgical mixed composition improves the mechanical behaviour of coating.

Emissivity and absorption function measurements of Al2O3 and SiC particles at elevated temperature for the utilization in concentrated solar receivers

Solar thermal receivers collect and can store concentrated solar radiation using solid particles. Solid ceramic particles have shown to be a practical and efficient heat transfer media in solar-particle receivers, however, their emissivity and absorptivity at high temperatures are scarcely reported. This gap has led to large uncertainties in the assessment of solar thermal receivers’ efficiency. In this work, an experimental method was developed to measure the emissivity and absorption function of solar particles at elevated temperatures up to 1200 K. Two types of solar particles, aluminum oxide (Al2O3, ∼95% purity) and silica carbide (SiC, ∼99% purity), were studied, particularly aiming to understand the dependence of emissivity and absorption function on temperature. Using a heat transfer model, the emissivity of particles was evaluated based on the fitting of the cooling rate, while the particle absorption function was obtained by fitting of the heating rate, following a well-controlled heating radiation at 910 nm. It was found that the emissivity values of the two particles are independent of temperature, showing constant values of 0.75 ± 0.015 and 0.92 ± 0.012 for Al2O3 and SiC respectively, in the temperature from 300 to 1200 K. The absorption function was found to be increased nonlinearly with temperature for Al2O3, while that of SiC dropped slightly. These absorption functions are specified for 910 nm. Using the evaluated experimental values of emissivity and absorption function, the maximum temperature and the temperature rise time of micro-sized particles (hundreds of micrometers) under different radiation fluxes were simulated taking into account the effect of particle diameter.

Size-dependent transverse and longitudinal vibrations of embedded carbon and silica carbide nanotubes by nonlocal finite element method

In this study, free vibration analyses of embedded carbon and silica carbide nanotubes lying on an elastic matrix are performed based on Eringen’s nonlocal elasticity theory. These nanotubes are modeled as nanobeam and nanorod. Elastic matrix is considered as Winkler–Pasternak elastic foundation and axial elastic media for beam and rod models, respectively. The vibration formulations of the beam and rod are derived by utilizing Hamilton’s principle. The obtained equations of motions are solved by the method of separation of variables and finite element-based Hermite polynomials for various boundary conditions. The effects of boundary conditions, system modeling, structural sizes such as length, cross-sectional sizes, elastic matrix, mode number, and nonlocal parameters on the natural frequencies of these nanostructures are discussed in detail. Moreover, the availability of size-dependent finite element formulation is investigated in the vibration problem of nanobeams/rods resting on an elastic matrix.

Corrosion behavior of hybrid coconut shell powder and silica carbide reinforced aluminium composite towards aggressive biofilm attack

This study enveloped innovative uses of a hybrid agro waste and silica carbide incorporated with aluminium as a new hybrid composite materials for marine application. In this study, the purpose of adding coconut shell powder (CSP) from the agro waste and silicon carbide (SiC) as reinforcement aluminium composites materials for combating corrosion problem. The CSP was incorporated into the molten aluminium alloys varies from 0%, 5%, 10%, 15% and 20% of weight percentages. The corrosion behaviour was determined by weight gain measurement (WGM), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PP). As a results, 5% CSP reinforcement in hybrid aluminum composites contribute to excellent corrosion resistance performance by shifting the polarization curve towards the positive region, increases the value of polarization resistance, Rp and reduces the Icorr value. It can be concluded that, by adding CSP into aluminium composite has significantly increase the corrosion resistance towards a severe biofilm attack.

Assessment of compacted-cementitious composites as porous restrictors for aerostatic bearings

Cementitious composites reinforced with silica, silicon carbide or carbon microfibres are designed, manufactured, characterised and tested as porous restrictor for aerostatic bearings. Carbon microfibres are residues obtained from the cutting process of carbon fibre-reinforced polymers. Porosity, permeability, flexural strength and stiffness are quite relevant in the design of aerostatic porous bearings. A 3141 full factorial design is carried out to identify the effects of particle inclusion and water-to-cement ratio(w/c) factors on the physical and mechanical properties of cementitious composites. Higher density material is achieved by adding silicon carbide. Higher porosity is obtained at 0.28 w/c level when silica and silicon carbide are used. Carbon microfibres are not effective under bending loads. Higher compressive strength is reached especially when silica particles are combined with 0.33 or 0.35 w/c. According to the permeability coefficient values the cementitious composites consisted of CMF (0.28 w/c), silica (0.30 w/c) or silicon carbide (0.30 w/c) inclusions are promising as porous restrictor; however, carbon microfibre porous bearings achieved the lowest air gap variation under the tested working conditions.

Highly anti-sintering and anti-coking ordered mesoporous silica carbide supported nickel catalyst for high temperature CO methanation

The inhibition of sintering and coking of supported nickel catalysts remains a great challenge in high-temperature carbon-monoxide (CO) methanation. Ordered mesoporous silica carbide (OM-SiC) was fabricated via a nanocasting technique as a nickel catalyst support for CO methanation. Compared with either SiC or SBA-15 supported nickel catalysts, the Ni/OM-SiC exhibited the best activity for CO methanation from 240 to 600 °C, originated from the highest dispersion of Ni. Below 800 °C, 1.0 MPa, and a gas hourly space velocity (GHSV) of 15,000 mL g−1 h−1, a superior activity is close to the theoretical values. In addition, the Ni/OM-SiC catalyst shows far superior anti-coking and anti-sintering properties than the other two kinds of catalysts. The improved catalytic performance can be attributed to a unique pore structure that offers a spatial confinement effect for the nickel particles, and the high thermal conductivity that avoids the formation of hot-spots during reaction. These findings are helpful to develop an efficient nickel-based methanation catalyst to produce synthetic natural gas.

Human Gingival Epithelial Growth In Vitro on a Polymer-Infiltrated Ceramic Network Restorative Material.

To investigate the growth of primary human gingival epithelial (HGE) cells on polymer-infiltrated ceramic network (PICN) material (Vita Enamic) with different surface roughnesses. PICN material specimens were polished with either silica carbide paper (grit-polished) or the manufacturer's polishing wheels (wheel-polished), and the surface roughness (Ra ) measured. HGE cells were seeded and grown for 1, 3, or 6 days. Growth on tissue culture plastic was used as a control. Non-linear regression analysis was used to examine the effect of surface roughness on cell growth. HGE cell growth on tissue culture plastic fitted an exponential growth model over the 6-day experimental period (R2 = 0.966). Through day 6, cell density on PICN decreased with increasing surface roughness, with a fit to an exponential decay model (R2 = 0.666). A threshold Ra value of 0.254 μm (95% CI 0.177-0.332) was determined as an upper limit for exponential growth. Cell growth was greatest on the group of specimens with Ra value below 0.127μm. Specimens polished by the manufacturer's method produced surface roughness of 0.118 μm and below. PICN material polished to a smooth surface (Ra < 0.254 μm) resulted in exponential growth of HGE cell growth compared to rough surfaces. Polishing PICN material as smooth as possible (below a Ra of 0.127 μm) was found to maximize epithelial cell growth on the PICN material surface. The manufacturer's polishing method achieved a sufficiently smooth surface. These results are contrary to previous research regarding surface roughness of transgingival implant restoration components. The study results suggest that smoother restorative material surfaces could improve peri-implant soft tissue health.

Synthesis and mechanical characterization of magnesium reinforced with SiC composites

Abstract For constructional alloys, lightest metal Magnesium is used as origin. Magnesium based metal matrix composites have light weight, low density, good high temperature mechanical properties and good to excellent corrosion resistance. Due to this reason these are used widely in the applications of aerospace, structural, oceanic and automobile. To the base metal, metal matrix composite is to add in the inviting properties of metals and ceramics. The synthesis and mechanical characterization of Magnesium reinforced silica carbide powder with different volume percentages of SiC is given in this paper. By reinforcing of 4 amounts of SiC volume (i.e 3, 6, 9 and 12 vol%). Monolithic magnesium, the magnesium siC are grown and By stir casting method, its SiC composites are synthesized. According to the ASTM standards the specimens tensile strength are performed. Using X-ray diffractions microstructural verification is done. For various compositions of SiC the comparison of hardness values and SEM micrographs is done. According to ASTM standards the specimen with AZ91D/12% vol SiC compositions show greater tensile and hardness.

Wear Behavior Analysis of Silica Carbide Based Aluminum Metal Matrix Composites

Aluminum matrix composites (AMCs) refer to the class of light weight and high-performance aluminum centric material systems. The reinforcements like Al2O3, SiC, and graphite in volume fractions ranging from a few percent to 60% in AMCs could enhance the properties of this metal. Among them Silica Carbide (SiC) particles have been found to have an excellent compatibility with the aluminum matrix and can be obtained at low cost. The major part of applications of AMCs includes moving and sliding parts, hence the investigation of tribological properties of these materials is very important to understand the behavior of composite materials while in service application. Therefore, present study focused on tribological properties (friction and wear behavior) of Al2014 – SiC composite and also comparison with Al2014 composite. The Al2014-SiC composites were fabricated by stir casting method with 5 % volume fraction of SiC particles and pin of 8 X 30 mm diameter and height were cut with Wire Electric Discharge Machine (WEDM). The friction and wear behavior tests are carried at 3,6 and 9 kgs load at constant sliding speed of 1m/s using pin on disc wear testing equipment. From the results as, sliding distance increase the value of coefficient of friction and volume of material loss increases for both aluminum matrix alloy and silicon carbide-based aluminum metal matrix composites. As the Increase in loads, the value of coefficient of friction decreases for both aluminum matrix alloy as well as silicon carbide-based aluminum metal matrix composites.