SiC Nanocomposites Research Articles

The impact of single and combined amendment of elemental sulphur and graphene oxide on soil microbiome and nutrient transformation activities

BackgroundSulphur (S) deficiency has emerged in recent years in European soils due to the decreased occurrence of acid rains. Elemental sulphur (S0) is highly beneficial as a source of S in agriculture, but it must be oxidized to a plant-accessible form. Micro- or nano-formulated S0 may undergo accelerated transformation, as the oxidation rate of S0 indirectly depends on particle size. Graphene oxide (GO) is a 2D-carbon-based nanomaterial with benefits as soil amendment, which could modulate the processes of S0 oxidation. Micro-and nano-sized composites, comprised of S0 and GO, were tested as soil amendments in a pot experiment with unplanted soil to assess their effects on soil microbial biomass, activity, and transformation to sulphates. Fourteen different variants were tested, based on solely added GO, solely added micro- or nano-sized S0 (each in three different doses) and on a combination of all S0 doses with GO. ResultsCompared to unamended soil, nano-S0 and nano-S0+GO increased soil pH(CaCl2). Micro-S0 (at a dose 4 g kg−1) increased soil pH(CaCl2), whereas micro-S0+GO (at a dose 4 g kg−1) decreased soil pH(CaCl2). The total bacterial and ammonium oxidizer microbial abundance decreased due to micro-S0 and nano-S0 amendment, with an indirect dependence on the amended dose. This trend was alleviated by the co-application of GO. Urease activity showed a distinct response to micro-S0+GO (decreased value) and nano-S0+GO amendment (increased value). Arylsulfatase was enhanced by micro-S0+GO, while sulphur reducing bacteria (dsr) increased proliferation due to high micro-S0 and nano-S0, and co-amendment of both with GO. In comparison to nano-S0, the amendment of micro-S0+GO more increased soluble sulphur content more significantly. ConclusionsUnder the conditions of this soil experiment, graphene oxide exhibited a significant effect on the process of sulphur oxidation.

Studying The Effect of Gamma Rays on The Impact Strength and Wear Properties of Silicon Carbide SIC and Graphite Gr Nanocomposites

Studying The Effect of Gamma Rays on The Impact Strength and Wear Properties of Silicon Carbide SIC and Graphite Gr Nanocomposites

Enhancement of Polyacrylic Acid/Silicon Carbide Nanocomposites’ Optical Properties for Potential Application in Renewable Energy

Composites made from polymers and nanoparticles have promise to be effective solar collectors and thermal energy storage devices due to benefits including improved thermal characteristics and increased structural stability. This study intends to fabricate polyacrylic acid/silicon carbide (PAA−SiC) nanocomposites and examine the optical properties for use in solar collectors and thermal energy storage (TES) fields. The optical properties of PAA−SiC nanocomposites are investigated within the wavelength between 340 and 840 nm. The findings indicate that an increase in SiC concentration in the PAA aqueous solution to 50 g/L at a wavelength of λ = 400 nm causes an increase in the absorption by 50.2% besides a reduction in transmission by 6%. Furthermore, the energy band gaps were reduced from 3.25 eV to 2.95 eV to allow for the transition, and subsequently reduced from 3.15 eV to 2.9 eV to allow for forbidden transition as a result of the increasing SiC concentration from 12.5 g/L to 50 g/L. The optical factors of energy absorption and optical conductivity were also enhanced with a rising SiC concentration from 12.5 to 50 g/L. Specifically, an improvement of 61% in the melting time of PAA−SiC−H2O nanofluids is concluded. Accordingly, it can be said that the PAA−SiC−H2O nanofluids are suitable for renewable energy and TES systems.

Optimization of drilling parameters on delamination and burr formation in drilling of neat CFRP and hybrid CFRP nano-composites

Carbon fibre-reinforced polymer (CFRP) composites have exceptional mechanical advantages such as high specific strength and stiffness, lightweight, and high damping capacity, making them very attractive for aircraft, aerospace, automotive, marine, and sporting applications. However, various defects such as delamination, burr formation, and surface roughness are observed during the drilling of CFRP composites, which are influenced by various drilling process parameters. In this work, the drilling quality of uni-directional CFRP composites. and the hybrid Al2O3 and hybrid SiC nano-composites are investigated experimentally using different types of drills such as step drill, core drill, and twist drill, as there is a limited study done on the comparative analysis of the impact of the above drills on the delamination factor and burr area on the above CFRP and hybrid nano-composites. The design of the experiment table was developed using response surface methodology (RSM) for input process parameters of spindle speed, feed, drill diameter, and drill type. The output surface characteristics (delamination factor and burr area) of the hole were measured quantitatively using the stereo zoom optical microscope. The main effect plots, contour plots, and analysis of variance (ANOVA) were used to examine the effect of spindle speed, feed, drill diameter, and drill type on exit delamination and burr formation. The analysis of main effect plots, contour plots, and analysis of variance showcased the optimum process parameters, such as a high spindle speed of 5500 rpm, low feed of 0.01 mm/rev, and drill diameter of 4 mm. The step drill demonstrated the least damage mechanism among drill geometries, followed by the twist and core drills. The minimum drilling damage was observed for the Al2O3 hybrid nano-composite compared to the neat CFRP composites.

The Influence of the Casting Methods and Variables on the Microstructural Properties of A356–SiC Nanocomposite

The Influence of the Casting Methods and Variables on the Microstructural Properties of A356–SiC Nanocomposite

Synergetic effects of cryo-FSP on microstructural, mechanical and corrosion behavior of stir cast AA5083-2 wt% SiC nanocomposite

In recent past, a significant research attention has been given to the study of nanosize ceramic particles reinforced aluminium alloy composites due to its excellent mechanical and surface properties compared to unreinforced counterpart. Hence, the major aim of the present study is to investigate the effects of cryocooling friction stir processing (cryo-FSP) on microstructural evolution, and its effects on mechanical properties & corrosion behavior of a stir-cast 2 wt% nanosize SiC (n-SiC) particles reinforced AA5083 nanocomposite in comparison to the room temperature (RT) FSPed and as cast counterparts. The cryo-FSP was performed successfully using optimized process parameters of 1400 rpm and 40 mm/min traverse speed using a specially designed cryo-FSP setup extracting deformation heat efficiently by a flowing mixture of LN2 and methanol (−30 °C). Evolution of a finer equiaxed grain structure (∼2 μm) with a homogeneous distribution of n-SiC particles and precipitate phases is confirmed (through SEM-EBSD and STEM/TEM analysis) in the cryo-FSPed composite compared to RT-FSPed sample (∼4 μm). The cryo-FSPed sample exhibited a superior yield strength (i.e., YS = 230 ± 3 MPa) compared to the RT-FSPed sample (i.e., YS = 197 ± 4 MPa) with a reasonably good ductility for both (i.e., 14 %). The improved YS is attributed mainly to the grain boundary strengthening due to extra grain refinement induced by cryo-FSP and dispersion strengthening via second phase particles. Different strengthening mechanisms' analyses established a good correlation between the theoretical YS and experimentally obtained tensile YS. Fractography analysis corroborated well with the tensile properties of the corresponding samples. Compared to the interdendritic cast structure, both the FSPed samples exhibited a superior corrosion resistance due to an improved surface characteristic developed in the dynamically recrystallized matrix with uniform dispersion of second phase particles. However, due to more grain boundary active phenomenon and higher misorientation angles, a bit higher corrosion rate could be observed in the fine-grained cryo-FSPed sample compared to the RT-FSPed composite.

A modified artificial neural network to predict the tribological properties of Al-SiC nanocomposites fabricated by accumulative roll bonding process

This work highlights the major influence of SiC concentration and plastic deformation on boosting wear rates of aluminum composites supplemented with SiC particles comprising varied volume fractions (0–4%). It also shows how a basic neural network model augmented with a particle swarm optimizer can forecast wear rates and coefficients of friction for complicated composites. According to the experimental findings, increasing the quantity of accumulative roll bonding (ARB) enhances SiC particle dispersion homogeneity. Increasing the number of cycles and introducing additional SiC particles helped to reduce the wear rate and increase the friction coefficient. After nine ARB cycles, the Al-4 wt.% SiC nanocomposite had the best improvement in both wear rate and friction coefficient. The same sample was also used in efforts to enhance the characteristics of hardness, and it was selected as having the highest level of hardness, which has grown by 139%. All of the generated composites evaluated at four different wear loads were able to be predicted by the proposed model with great accuracy, with determination coefficient R2 values of 0.9768 and 0.9869 for the frictional coefficient and wear rates, respectively.

Characteristic of AA 7075-Reinforced Nano-SiC Composites Produced by Stir-Squeeze Casting and Open Die Cold Forging as An Armor Material Candidate

Characteristic of AA 7075-Reinforced Nano-SiC Composites Produced by Stir-Squeeze Casting and Open Die Cold Forging as An Armor Material Candidate

Si-C nanocomposites supported on vertical graphene sheets grown on graphite for fast-charging lithium ion batteries

Silicon/carbon (Si/C) anodes have been successfully used in commercial lithium-ion batteries because of their high capacity and excellent safety. Nevertheless, their cycling stability and fast-charging capability are still unsatisfactory due to large volume expansion and slow charge transport capability under industrial electrode conditions. Here, we fabricate a Si/C anode via homogeneously depositing amorphous SiC nanolayers on graphite armored with N-doped porous flexible vertical graphene sheets (VGSs) (named as Si-C/VGSs/graphite). SiC nanolayers consist of homogeneously dispersed sub-nanometer Si particles in 3D carbon skeleton, which effectively alleviate the volume change of Si, and hugely accelerate electron and Li-ion transport. The N-doped VGSs possess porous structure, good flexibility, numerous exposed edges, and directional ion transport channels, which provide rational space for accommodating volume change of Si, buffer the stress caused by the volume change, increase the electrical contact points between Si-C/VGSs/graphite, and accelerate Li-ion transport, respectively. Consequently, Si-C/VGSs/graphite delivers superior rate capacity and long cycle life under industrial electrode conditions. When matched with the cathode of Li[Ni0.8Co0.1Mn0.1]O2, the full cell demonstrates a predominant fast-charging capability (180.8 Wh kg−1, charging for 8.2 min, 5C) accompanied by long cycle life.

Processing and evaluation of nano SiC reinforced aluminium composite synthesized through ultrasonically assisted stir casting process

Aluminium composites were synthesized through an ultrasonically assisted stir casting method by reinforcing 0.5 wt%SiC, 1.0 wt%SiC, 1.5 wt%SiC and 2.0 wt%SiC nanoparticles. Ultrasonication was carried out to the composite melt to refine the grain size and to achieve uniform nano-SiC dispersion in the aluminium matrix. Scanning electron microscopy (SEM) reveals the uniform dispersion of nano-SiC particles in the 0.5 wt%, 1.0 wt% and 1.5 wt% SiC reinforced compose. However, the X-Ray Diffraction (XRD) peaks confirm the Al2Cu intermetallic phases in the Al- 2.0 wt% SiC composite. The mechanical properties of the synthesized composites were significantly enhanced with the incorporation of SiC reinforcements and the maximum hardness and ultimate tensile strength (U.T.S) of 163 BHN and 431 MPa was attained for 1.5 wt% SiC reinforced composite. Nevertheless, the generated brittle agglomeration at 2.0 wt% SiC reinforcements decreases the mechanical properties of the composite due to the variation of thermal expansion coefficients between the matrix and the agglomerations. The yield strength of the fabricated Al– SiC composites was analyzed through different strengthening mechanisms. Results concluded that the yield strength contribution due to thermal mismatch is more influenced followed by the Orowan strengthening and grain refinement strengthening mechanism. In addition to this, the contribution of the strengthening mechanisms was found to be increased with the addition of SiC nanoparticles. Fractography investigation for the fractured tensile specimens reveals the ductile fracture for unreinforced aluminium and brittle fracture for the SiC-reinforced composites due to the presence of cleavage texture of the fractured surfaces of Al–SiC nanocomposites.

Optically selective SiC-based nanocomposite objects derived from titanium and boron-modified polycarbosilanes

Herein, we introduce a bottom-up material design approach of optically selective SiC-based nanocomposite objects. Precursors have been firstly synthesized by reaction of allylhydridopolycarbosilane with titanium and boron complexes before a pyrolysis at 1000 °C in flowing argon to deliver single-phase amorphous Si–Ti–C–N(B,H) ceramics. The later was then heat-treated up to 1800 °C under argon. Relatively dense nanocomposites made of TiCxN1-x (0 ≤ x ≤ 1) nanocrystals homogeneously formed in situ in a SiCxN4-x-type phases (0 ≤ x ≤ 4) have been isolated after heat-treatment at 1400 °C. Above 1400 °C, our experimental data showed a continuous evolution of carbon and nitrogen contents up to 1800 °C due to carbothermal reduction reactions forming carbide phases while releasing nitrogen-containing species. Thus, heat-treatment at 1800 °C led to porous and fully crystallized TiC(N)/SiC(B) nanocomposites that displayed a maximal optical selectivity of 1.67 measured at room temperature; a value significantly increased compared to the SiC(B) counterpart.

Development of Al 7075 alloy with nano SiC Composites through ultrasonic assisted stir casting Techniques and Mechanical Testing of Properties

ABSTRACT Al-7075 alloy with nano-SiC composite has superior mechanical properties that can be used in automobile, aerospace and defence sector to manufacture various components and body structures. In the present study, Al-7075 alloy with nano-SiC composite with different wt% of nano-SiC particles has been fabricated by the ultrasonic-assisted stir casting method. Uniform mixing of the nanosized SiC particles in the Al-7075 alloy has been achieved from ultrasonification and as-cast and T6 heat-treated samples were prepared. The diverse mechanical properties such as tensile strength, impact strength and hardness have been examined for the as-cast samples with different wt% of nano-SiC and T6 heat-treated samples.

Utilizing a unified conceptual dynamic model for prediction of particle size of duel-matrix nanocomposites during mechanical alloying

This work focused on developing an analytical fast and reliable model to predict the morphological changes in nanocomposite powders during mechanical alloying. A conceptual dynamic model was developed and applied to predict the particle size of magnesium-based hybrid composite powder reinforced with Ti and SiC fabricated by mechanical alloying. The effect of milling time on the morphology, microstructure, and particle size of composite powders was investigated. The experimental and model predictions demonstrated that the optimal milling times varies between pure metal, duel matrix alloy and duel-matrix nanocomposite because it was obtained as 32 h for Mg milled, 16 h for Mg-30 wt% Ti and Mg- 20 wt% Ti- 10 wt% SiC nanocomposite with an average particle size 4.91 μm, 6.95 μm, and 5.38 μm, respectively. Prediction results by the CD model for the mentioned samples were equal to 5.33 μm, 6.7 μm, and 6.04 μm, respectively. By increasing the time of ball milling, the crystalline structure of SiC from changed hexagonal to cubic. Another effect of increasing time occurred on the crystallite size and caused the largest decrease, which was equal to 61.91%, to occur for composite Mg-Ti-SiC.

Preparation, Morphological and Antibacterial Activity of PS–PC/MnO2–SiC Nanocomposites for Biomedical Applications

Preparation, Morphological and Antibacterial Activity of PS–PC/MnO2–SiC Nanocomposites for Biomedical Applications

Characteristics of nano-sized composites based on rare earth orthoferrites and hematite

Photocatalysts based on orthoferrites of rare earth elements are used to neutralize a number of harmful substances and organic dyes under the influence of visible light, which makes them to promise the introduction of resource-saving water purification technologies. The thermal-gravimetric analysis, X-ray phase analysis, scanning electron microscopy, and energy-dispersive spectroscopy was used to study nanoscale samples of orthoferrites of rare earth elements and hematite obtained by the chemical precipitation of aqueous solutions of inorganic salts of ferrum with lanthanides (La, Er, Sm, Dy, Nd, Yb ) and Y in a weakly alkaline environment and subsequent heat treatment of sediments at 800 and 1100 °C. It was found that during the simultaneous precipitation of hydroxide phases of ferrum and REE, their transformation under the influence of temperature is spatially separated due to the differences in the temperatures of phase transformations and the hydrogen index of the precipitation of precursor phases. It is shown that, depending on the chemical composition of the initial solutions, goethite is formed in the temperature range of 190-250 °C, and the formation of hematite takes place at 425-450 °C. Dehydroxylation of lanthanum hydroxide is observed at 300-330 °С, and the formation of lanthanum oxides continues in the range from 390 to 900 °С. The perovskite phase crystallizes at 960 °C. Using the X-ray phase analysis method, it was established that hematite and a mixture of REE oxygen phases are present in the sediments heat-treated at 800 °C. At 1100 °C, the structure of perovskite and hematite with particle sizes from 25 to 40 nm was identified in the composition of the powders. It was determined that the removal of auxiliary substances takes place at temperatures of 650-770 °C and no impurities of K, Na, S, Cl, or C in the powders fired at 1100 °C. Hematite and perovskite particles are well crystallized and form fragile aggregates, the specific surface area of the samples is several m2/h.

Potential effects of nano-cellulose and nano-silica/polyvinyl alcohol nanocomposites in the strengthening of dyed paper manuscripts with madder: an experimental study

In the present work, the composite cross-linked were used to consolidate the dyed paper manuscripts. Nanocomposites of mesoporous silica nanoparticle (MPSNP)/polyvinyl alcohol (PVA) and cellulose nanofiber (CNF)/PVA, which have never been used before, have been evaluated for the consolidation process of the dyed paper manuscripts with madder extract. Three concentrations 1%, 3%, and 5% have been prepared. Analysis and investigation methods like scanning electron microscope (SEM), transmission electron microscope (TEM), dynamic light scattering analysis (DLS), X-Ray diffraction Analysis (XRD), atomic force microscope (AFM), Fourier transform infrared spectroscopy (FTIR) and total color difference (ΔE) by spectrophotometer have been used in order to characterize the prepared nano-sized composites and evaluate the treated dyed paper samples before and after the aging process. The results of surface morphology by SEM revealed the effectiveness of MPSNP/PVA core–shell nanocomposite at 5% in the consolidation process, where the improvement of properties of the aged dyed paper samples. The fibers of the treated paper became strong and appeared clearly. The result of ΔE measurements showed that the treated sample with MPSNP/PVA nanocomposite at 5% gave the lowest ΔE (5.22), while, the treated sample with CNF/PVA nanocomposite at 5% gave the highest ΔE value (11.66). Mechanical measurements (tensile strength and elongation) revealed the efficiency of MPSNP/PVA nanocomposite at 5% in the treatment of the aged dyed paper samples. The treated sample with the mentioned material gave tensile strength and elongation values of 84.8 N/nm2 and 1.736%, respectively. In contrast, the treated sample with CNF/PVA nanocomposite at 1% gave the lowest tensile strength and elongation values 38.2 N/nm2, and 1.166%, respectively. FTIR analysis revealed an increase was noticed in the CH2 stretching band (refers to the crystallinity of cellulose), where the intensity of the treated sample with MPSNP/PVA nanocomposite was at a 5% increase compared to the control sample. The FTIR results supported the results of mechanical measurements. The intensity of the CH2 stretching band, which refers to the crystallinity index of cellulose, was increased with the use of MPSNP/PVA nanocomposite at 3% and 5%, which explains the improvement in mechanical properties. This may be due to the nano-mineral particles, which improve the mechanical properties. Additionally, they reduce the effect of accelerated thermal aging on the cellulosic fibers and give them stability. The detailed analysis of analytical methods used for evaluation revealed the novelty of MPSNP/PVA nanocomposite, especially at 5%. It has a potential role in strengthening and improving different properties of the dyed paper manuscripts with madder extract.

Enhanced irradiation-resistance of polymer-derived SiC by incorporation of multiwalled carbon nanotubes

In this work, multiwalled carbon nanotubes were introduced into polycarbosilane to fabricate carbon nanotubes reinforced nano-SiC composites (MWCNTs/ PCS-nano-SiC). Radiation effects on MWCNTs/ PCS-nano-SiC were studied by irradiation with 2 MeV Au2+ ions at room temperature and doses ranging from 2 × 1014 to 8 × 1014 ions/cm2. The sample pyrolyzed at 1400 °C and containing 3 wt% carbon nanotubes exhibited excellent overall performances. The multiple graphite layers in the MWCNTs provided "absorption traps" for defects, improving the efficiency of defect recombination. Tightly combined MWCNTs/ PDC interface is required to enable the two phases to protect each other during irradiation. The critical amorphization dose was increased upon structural optimization, and the hardness degradation was significantly reduced. The rise of Young's modulus at a high damage dose was discovered because of the "interface-driven shrinkage" of nano-SiC. The present study provides insight into SiCf/ SiC design for an advanced nuclear system.

Dry dechlorination of polychlorinated biphenyls in contaminated soil by using nano-sized composite of metallic Ca/CaO and its mechanism

Soil contamination by PCBs is still known as a serious problem across the world, and the development of new technologies or the improvement of existing ones (e.g. higher efficiency, shorter processing time, lower input energy) are more and more important. Moreover, understanding the chemistry of the entire process, from a mechanistic point of view, can accelerate the process of improvement. In these circumstances, we attempted a clarification of the highly efficient degradation of PCBs by nano-sized particle of metallic Ca in CaO (“nCa”) at 250 °C in dry solid state conditions. The reaction involved the hydrodechlorination, simple reduction, reductive coupling and hydroxylation processes. The detoxification efficiency reached over 99%. A tentative pathway and mechanism is proposed for explaining the final reactions products. Finally, the process was applied to real PCBs-contaminated soil, containing various amounts of PCBs, with a total success in completely eliminating the toxic polychlorinated compounds.

Microstructure-Based Modeling and Mechanical Characteristics of Accumulative Roll Bonded Al Nanocomposites with SiC Nanoparticles

This research work aims to fabricate the Al-4 wt.% SiC nanocomposite using the accumulative roll bonding (ARB) technique. Moreover, a finite element model based on real microstructure representative volume element representation and cohesive zone modeling was developed to predict the mechanical response of the produced composites. The results demonstrated that SiC particles were homogenously distributed inside the Al matrix after five passes. The tensile strength and hardness were improved by increasing the number of ARB passes. The microhardness of an Al-4%SiC composite subjected to five ARB passes was increased to 67 HV compared to 53 HV for Al sheets subjected to the same rolling process. Moreover, owing to greater bonding and grain refinement, tensile strength was increased by a factor of three compared to pure Al. The result of the proposed micro-model successfully predicts the experimentally obtained results of the Al–SiC macro composite. The numerically obtained stress–strain curve was comparable with the experimental one. The results also showed that the size of the used RVE was significantly influential in the prediction of the stress–strain behavior.

Microstructural characterization and enhanced tensile and tribological properties of Cu–SiC nanocomposites developed by high-pressure torsion

In this study, an attempt has been made to fabricate Cu–SiC nanocomposites by flake powder metallurgy and high-pressure torsion processing techniques at room temperature. Pure Cu and a mixture of Cu and nano-sized SiC powders were mechanically milled separately for 3 h and then green compacts were prepared by uniaxial pressing under 1 GPa pressure. The green compacts experienced 6-turn high-pressure torsion under a pressure of 6 GPa to prepare bulk Cu and Cu–SiC samples. The microstructures of the consolidated samples were characterized using an X-ray diffractometer and a high resolution scanning/transmission electron microscope, and the mechanical properties were evaluated by microhardness, tensile and wear tests. The results show that almost full density samples with ultrafine-grained (UFG) microstructure and well-dispersed nanoparticles in the metal matrix were obtained by the method used. The addition of the nanoparticles reduced the grain size and microstructural gradient between the center and edges of the disk samples. SiC nanoparticles improved copper microhardness by 35%, yield strength by 23% and tensile strength by 9% by implementing various strengthening mechanisms. The produced material showed a reduced coefficient of friction and high wear resistance. Delamination was determined as the major wear mechanism in HPTed Cu–SiC nanocomposite.