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The Epoxy-based hybrid composites are attention in various engineering domains. Distinctively, natural fiber-made epoxy composites are advantageous over synthetic fiber-made composites and attracted in automotive applications such as set frames, interior panels, dashboards, etc. Moreover, due to its high moisture absorption nature, the epoxy composite formed with natural fiber is suspected to have poor adhesive quality compared to synthetic fiber composite. It leads to lower adhesive performance and limits the behaviour of composite. The prime objective of the current work is to ensure the adhesive behaviour of NaOH-treated sisal fiber (SF) epoxy composite featured with silicon carbide nanoparticles (SiC). This composite is prepared with the constant percentage of SF as 15 wt% and varied wt% of SiC through compression mould technology. Influences of treated SF and SiC on pressing behaviour of surface morphology, tensile & flexural strength, microhardness, and fracture toughness of composites are experimentally investigated with ASTM D638, D790, D4762, and D6110 policy, and its outcomes are compared to 15wt% treated SF epoxy composite. The surface morphology study confirms that the SF and SiC appearances in the epoxy matrix are uniform and homogenous. The 5wt% SiC embedded with 15wt% treated SF facilitates higher tensile (65.2 ± 1.1 MPa) & flexural strength (69.1 ± 1.3 MPa), microhardness (35.5 ± 0.5 HV), and fracture toughness (1.56 ± 0.01 MPam0.5). The enriched epoxy hybrid composite sample will recommended for automobile interior parts application. [ABSTRACT FROM AUTHOR]

The crack growth in atomic structures is one of the important phenomenon which can affect the mechanical properties of them under external forces. In this work, the crack growth in Ti-6Al-4 V alloys is described by using molecular dynamics (MD) approach. The results of our computational study are represented by temperature, total energy, crack length and ultimate strength of atomic alloy calculation. Our simulations predicted physical stability of modeled alloy in the presence of SiC nanoparticles. Also, MD outputs show that mechanical behavior of Ti-6Al-4 V alloy is improved by SiC nanoparticle adding to them. Between various ratios of nanoparticles, physical stability of pristine alloy is optimized in the presence of 5% SiC nanoparticle. Numerically, the crack length changes from 32.05 to 28.81 Å for pristine and reinforced alloy. Also, SiC nanoparticle using caused ultimate strength and Young's modulus of structures increased to 1384 and 71.85 MPa, respectively. Initial condition affected mechanical performance of modeled Ti-6Al-4 V-based samples. By pressure and temperature changes, the attraction force between various particles converged to different values. This procedure affected crack growth process and mechanical strength of modeled alloy. So, this atomic/mechanical behavior should be considered in actual applications of Ti-6Al-4 V alloy. [ABSTRACT FROM AUTHOR]

Due to ever-present applied pressure and thermal shocks, forged dies are in danger of durability and hardness reduction, surface cracks formation, and failure. Therefore, this study aims at investigating the effect of Direct Laser Metal Deposition Cladding (DLMD) power and powder composition as a repairing technology on mechanical properties and the microstructure of the forging dies fabricated out of hot work steel DIN 1.2714 (56NiCrMoV7). IN718 was used as the DLMD powder. However, its low wear and friction resistibility had already been improved via SiC nanoparticles. Results indicated that compared to pure In718, adding up to 5 wt% of SiC nanoparticles to IN718 increased its wear resistance and microhardness by 51% and 50%, respectively, and induced a 129% reduction in its friction coefficient. On the other hand, a laser power of 450 W led to a 127% and 112% increase in wear resistance and microhardness of the coating in comparison to a laser power of 450 W.

In this work, aluminum-copper composites reinforced with 50 nm and 250 nm SiC particles are fabricated on the interface of sheets by friction stir spot welding for the first time. In addition, the finite element method is used to study visual and understand the temperature distribution and mechanical characteristics of the composite with different nanoparticle sizes. Micro stress/strain field mainly simulated the impacts of particle size and particle distribution in the matrix. Results showed that large reinforcing particles lead to an increase in temperature distribution and grain size in the stir zone of the joint sample. It was also concluded that the addition of finer nanoparticle size causes higher shear tensile (5.4 MPa) and Von-Mises stress (260 MPa) in the workpiece due to higher homogeneous distribution and less agglomeration in the matrix. In addition, the thickness of the intermetallic compound (IMCs) layer at the interface of the joint interface was analyzed as SiC particles with different sizes are used due to higher interaction and intermixing between materials. The stress distribution and equivalent plastic strain of particles in the stir zone, with the uniform distribution of reinforcing particles for lower size (50 nm), increased. [ABSTRACT FROM AUTHOR]

In recent years, many researchers have focused on the preparation of carbon and basalt fiber-reinforced composites. As a result, the composites have gained popularity as an alternative to traditional materials such as wood, steel, and aluminum. Carbon and basalt fibers were used in a bidirectional woven mat, with particulates varying from 0 to 15 wt% nanoparticle SiC. The hybrid laminates were fabricated through vacuum bag infusion methods. The novelty of the research work lies in studying the influence of nanoparticle SiC-combined carbon and basalt fibers arranged in six stacking sequences, with LY556 used as polyester matrix. Specimens were prepared and tested as per ASTM standards. Tensile, flexural, impact, and hardness tests were performed on the obtained specimens and average values were obtained. It was found that 15% SiC filler addition enhanced (20%) the mechanical properties. Scanning electron microscope photos revealed the bonding between the fiber mat and the matrix of thecrystal structure. The obtained tensile strength was 346 MPa and the flexural strength was 388 MPa. Dynamic mechanical analysis showed that mechanical properties were improved with the addition of 15% SiCnanoparticles. Hence, this method can be used to manufacture structural applications and automotive parts. [ABSTRACT FROM AUTHOR]

Friction coefficients and specific wear rates of a multifunctional smart nanocomposite epoxy coating with embedded linseed oil-filled microcapsules and SiC nanoparticles were determined using six coatings synthesized with 15 wt% microcapsules and 1, 2, 3, and 4 wt% of SiC nanoparticles. In rotational pin-on-disk testing, all samples containing microcapsules and SiC nanoparticles exhibited reduced friction coefficients. The sample containing 3 wt% SiC nanoparticles showed the highest decrease in coefficient of friction by 31.79% and a specific wear rate by 59.04% compared with the neat epoxy sample. The results are discussed concerning lubricating rollers, polishing operations of SiC nanoparticles, a solid/liquid lubricant film, and electron microscopy (FESEM/EDX) studies. [ABSTRACT FROM AUTHOR]

In recent years, many researchers have focused on the preparation of carbon and basalt fiber-reinforced composites. As a result, the composites have gained popularity as an alternative to traditional materials such as wood, steel, and aluminum. Carbon and basalt fibers were used in a bidirectional woven mat, with particulates varying from 0 to 15 wt% nanoparticle SiC. The hybrid laminates were fabricated through vacuum bag infusion methods. The novelty of the research work lies in studying the influence of nanoparticle SiC-combined carbon and basalt fibers arranged in six stacking sequences, with LY556 used as polyester matrix. Specimens were prepared and tested as per ASTM standards. Tensile, flexural, impact, and hardness tests were performed on the obtained specimens and average values were obtained. It was found that 15% SiC filler addition enhanced (20%) the mechanical properties. Scanning electron microscope photos revealed the bonding between the fiber mat and the matrix of thecrystal structure. The obtained tensile strength was 346 MPa and the flexural strength was 388 MPa. Dynamic mechanical analysis showed that mechanical properties were improved with the addition of 15% SiCnanoparticles. Hence, this method can be used to manufacture structural applications and automotive parts.

A microarc oxidation (MAO) coating was fabricated on the surface of TC4 alloy by adding SiC nano-particle into the base electrolyte. The influence of nanoparticles on the microstructure and corrosion behavior of MAO coatings was investigated. The results show that the introduction of SiC nanoparticles into the base electrolyte makes the coating thickness of MAO coating increased, from 9.2, 12.8, 12.4μm to 12.0, 14.9, 20.0μm, respectively, under the conditions of 550, 600V and 650V. The surface roughness of the coating (2.65, 3.34μm and 3.61μm) fabricated in SiC-containing solution increases with increasing the applied voltage. The introduction of SiC nanoparticles can effectively inhibit the microcracks in the coating, the coating thickness increase, and reduce the anodic current density, and thus the corrosion property of MAO coating increases. The OCP(open circuit potential) and corrosion potential increase by MAO coating.

Light-weight and flexible microwave absorbers are in increasing demand because of the electromagnetic (EM) pollution. Carbon fiber mats are promising as they have high flexibility and conductivity. However, the high permittivity of the carbon fibers leads to a strong impedance mismatch with free space. Thus, SiC was introduced to carbon fibers as it has an outstanding impedance match with free space. After the decoration of SiC nanoparticles, incident microwaves could penetrate into the SiC decorated carbon (C–SiC) nanofiber mats and be converted into internal energy instead of being reflected. Conductive loss and polarization relaxation loss from the SiC nanoparticles and conductive carbon nanofiber matrix consumed the EM energy. Additionally, the highly flexible carbon fiber matrix could bear the load of bending and twisting, leading to excellent flexibility and reliability. The C–SiC nanofiber mats exhibited a resistance change less than 20% after 200 times bending, and had excellent EM absorbing properties with the RL min of −53.7 dB at the thickness of 2.15 mm and the effective bandwidth of 7.11 GHz at the thickness of 2.6 mm. The proposed strategy may facilitate the design of highly reliable and flexible carbon based two dimensional (2D) EM absorbers for the broadband wave absorbing. Image 1 • A flexible and ultralight SiC nanoparticles decorated carbon fiber mat with broad-band microwave absorption. • Impedance match of carbon fiber can be adjusted by introducing SiC nanoparticles. • Carbon matrix can bear the load of bending and twisting, yielding excellent reliability. [ABSTRACT FROM AUTHOR]

The mechanism for outstanding resistance to He-ion irradiation-induced hardening of a novel dispersion-precipitation strengthened NiMo alloy has been investigated. Microstructural observations show the interface between Mo 2 C micro-particles and Ni matrix and between SiC nanoparticles and Ni matrix can effectively trap He bubbles, thus synergistically inhibiting the formation and growth of the dissociated He bubbles in the Ni matrix. It suggests that the reasonable high amounts of well-dispersed Mo 2 C micro-particles and SiC nanoparticles can effectively improve the inhibition efficiency of irradiation-induced hardening and are beneficial for the optimization and design of irradiation-resistant Ni-based alloys. The mechanism for outstanding resistance to He-ion irradiation-induced hardening of a novel dispersion-precipitation strengthened NiMo alloy has been investigated. Microstructural observations show the interface between Mo 2 C micro-particles and Ni matrix and between SiC nanoparticles and Ni matrix can effectively trap He bubbles, thus synergistically inhibiting the formation and growth of the dissociated He bubbles in the Ni matrix. It suggests that the reasonable high amounts of well-dispersed Mo 2 C micro-particles and SiC nanoparticles can effectively improve the inhibition efficiency of irradiation-induced hardening and are beneficial for the optimization and design of irradiation-resistant Ni-based alloys. Image, graphical abstract [ABSTRACT FROM AUTHOR]

The dispersion of ceramic nanoparticles is of significance to the microstructure and properties of particulate reinforced metal matrix composites. In this study, two hybrid enhancers, SiC-graphite and SiC-graphene nanosheets (GNSs), were incorporated into aluminum matrix composites using powder metallurgy. The dispersion of the reinforcements and microstructural evolution of the composites were characterized by using Scanning Electron Microscopy, X-Ray Diffraction, Transmission Electron Microscopy, and Raman spectroscopy. The results show that thin GNSs accelerated the deformation of the aluminum particles, and defects were introduced into the carbonaceous phases during the ball milling process. Al 4 C 3 needles generated during hot pressing, and were observed to bridge the aluminum grains. Compared with graphite, GNSs were more uniformly dispersed throughout the composite, which in turn restrained grain growth. As a result, a nanostructured composite (57.7 nm) was successfully produced upon the addition of SiC-GNSs. Image 1 • Graphene intensifies the deformation of Al composite during ball milling. • Ball milling brings about carbonaceous defects. • Al 4 C 3 needles are formed during hot pressing. • A nanostructured aluminum composite is prepared. [ABSTRACT FROM AUTHOR]

Copyright of Materials & Technologies / Materiali in Tehnologije is the property of Institute of Metals & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To enhance the ablation resistance of Ti6Al4V alloy, a SiC-modified nanocomposite ceramic coating was fabricated by a novel one-step liquid plasma-assisted particle deposition sintering (LPDS) method. A microarc oxidation (MAO) ceramic coating was prepared on the surface of titanium alloy as a comparison. The micromorphologies and formation mechanisms of two ceramic coatings were investigated with the assistance of scanning electron microscopy (SEM), X-ray diffractometer (XRD), and transmission electron microscopy (TEM). The thickness of the SiC nanocomposite coating (about 39 μm) was significantly increased by 129% compared to the MAO coating (about 17 μm). Additionally, ablation tests of Ti6Al4V alloy, MAO coating, and SiC nanocomposite coating were conducted at 1000 °C using a butane gas lance. Then, the variation of microstructure, phases, elemental composition, and thickness before and after ablation was also comparatively analyzed. The results indicate that the SiC nanocomposite coating exhibits the smallest thickening (29 μm) after ablation at 1000 °C for 360 s, which is 39% and 46% compared with the Ti6Al4V substrate and MAO coating, respectively. The nanocomposite coating is intact and cracks-free after the ablation test. SiO 2 , formed during the ablation of SiC nanocomposite coatings, blocks oxygen diffusion into the substrate, which plays a protective role in the coating. Therefore, the SiC nanocomposite coating by a novel LPDS technique exhibits superior ablation resistance to enhance the thermal protection performance of titanium alloy substrate. • A novel SiC nanocomposite coating by LPDS technique is prepared on the Ti6Al4V alloy. • No peeling occurred in the SiC nanocomposite coating after ablation for 360 s at 1000 °C. • The LPDS coating mainly contains SiC and SiO 2 to absorb the stress effect caused by thermal shock. • SiO 2 formed during the ablation of SiC nanocomposite coatings blocks oxygen diffusion into the substrate effectively. [ABSTRACT FROM AUTHOR]

This work presents the performance of the Copper (Cu) based functionally graded coatings (FGCs) when subjected to corrosion in the 3.5 wt% NaCl aqueous solution and sliding wear under the different loads (2, 5, 8 and 10 N). The Cu FGC, with three layers of Cu (each 20 μm thick), has a gradual decrement in the crystallite size from bottom to the top surface. The Cu, Cu-SiC FGC consists of three-layered Cu FGC (each Cu layer 12 μm thick) followed by two layers of Cu-SiC nanocomposite (each 12 μm thick) with a steep increase in the amount of reinforced SiC nanoparticles from 2 to 7 vol% towards the top. A comparison is made among the equally thick (60 μm) electrodeposited FGCs, i.e., Cu FGC and Cu, Cu-SiC FGC, single-layered Cu coating with the finest microstructure (smallest crystallite size) and Cu-SiC nanocomposite coating with 7 vol% SiC. A drastic reduction in the corrosion and wear rate is observed in the Cu and Cu, Cu-SiC FGCs when compared with the same of single-layered Cu and Cu-SiC nanocomposite coatings, respectively. It is also observed that the Cu, Cu-SiC FGC has higher corrosion resistance than the Cu FGC. The Cu, Cu-SiC FGC is found to be more wear resistant than the Cu FGC at high load, while the latter shows lower specific wear rate at low loads. • Comparison between single-layered (SL) and functionally graded coating (FGC) of equal thickness • Cu FGC provides better cathodic protection than fine-microstructured SL Cu coating. • Cu, Cu-SiC FGC has the lower corrosion rate than SL Cu-SiC nanocomposite coatings. • FGCs show high wear resistance owing to hard surface and soft interior than SL coatings. • Cu FGC should be used at 2–8 N while Cu, Cu-SiC FGC is preferred above 10 N load. [ABSTRACT FROM AUTHOR]

The current work deals with a time-dependent study to track the antibacterial action of electrodeposited Cu, Cu-SiC functionally graded coating (FGC) against Escherichia coli NCIM 2931 (Gram-negative) and Bacillus subtilis NCIM 2063 (Gram-positive). After 24 h of incubation, the Cu, Cu-SiC FGC causes 7 Escherichia coli NCIM 2931 and 10 Bacillus subtilis NCIM 2063 log reduction of planktonic cells. The outer membrane permeabilization experiment proves that the intake of excessive Cu ions leads to the damage of bacterial cell membrane followed by lipid degradation. The thiobarbituric acid reactive substances assay reveals that Cu ions released from the surface of Cu, Cu-SiC FGC triggers the oxidative degeneration of phospholipids (most abundant constituent of bacterial cell membrane). This was further cross-verified using atomic absorption spectroscopy. From 0 to 24 h, the bacterial morphology is characterized using transmission electron microscope and scanning electron microscope which shows the cytoplasmic leakage and cell death. The Cu, Cu-SiC FGC also exhibits hydrophobic surface (contact angle of 144°) which prevents the bacterial adherence to the surface and thus, inhibits them to penetrate into its bulk. The observed results of antibacterial and anti-adhesion properties of Cu, Cu-SiC FGC are compared with single-layered metallic Cu and Cu-SiC nanocomposite coatings. Hence, the electrodeposited Cu, Cu-SiC FGC has the potential to serve as an inexpensive touch surface alternative for the healthcare industries. Unlabelled Image • Antibacterial and anti-adhesion activities of single-layered coating (SLC) and functionally graded coating (FGC) are compared. • Cu, Cu-SiC FGC and Cu-SiC SLC have higher lipid peroxidation and ROS products than Cu SLC. • Release of Cu ions from the sample's surface into the bacterial media is studied. • Time-dependent investigation of cell membrane damage by all samples is investigated. • Events ascribed to antibacterial action model of Cu, Cu-SiC FGC are presented. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Materials Engineering / Cailiao Gongcheng is the property of Journal of Materials Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Graphical abstract Highlights • Anodic current waveform dissolutes high energy sites offering smooth Cu surface. • In Cu functionally graded coating (FGC), crystallite size decreases along the thickness. • CTAB prevents coagulation of SiC nanoparticles by providing steric stabilization. • Cu, Cu-SiC FGC has gradient of Cu microstructure followed by increasing amount of SiC. • Compressive residual stress generated in Cu, Cu-SiC FGC is lesser than Cu-SiC coating. Abstract A Cu based functionally graded coating (FGC) has been deposited on an annealed Cu substrate by galvanostatic pulse reverse electrodeposition (PRED) route. The objective is to develop a hard surface with highly ductile and conductive interior. The cathodic current density (CCD) has been increased stepwise (from 50 to 200 mA/cm2) to synthesize Cu FGC on an annealed Cu substrate. It has three layers of Cu coating (20 μm each) with a gradual reduction in crystallite size along the thickness. Two layers of Cu-SiC nanocomposite coating with an increment in the amount of incorporated SiC nanoparticles (from 2 to 7 vol%) are electrodeposited on Cu FGC. This is done by introducing bath agitation (350 and 450 rpm) during deposition at CCD of 200 mA/cm2, which has resulted in Cu, Cu-SiC FGC with five layers (12 μm each). SiC nanoparticles are used to impart hardness to the coating through dispersion strengthening. The Cu, Cu-SiC FGC possesses higher hardness (∼3.8 GPa), lower residual compressive stress (∼291 MPa), and lower surface roughness (∼0.9 μm) as compared to electrodeposited single layer Cu-SiC nanocomposite coating. With such properties Cu, Cu-SiC FGC on annealed Cu substrate can serve as a novel prospective electrical contact material. [ABSTRACT FROM AUTHOR]

Understanding the structure–property relations for metal matrix nanocomposites reinforced with nanoparticles is a key factor for a reliable and optimal design of such new material systems. In the present study, coefficient of thermal expansion of silicon carbide (SiC) nanoparticle-reinforced aluminum (Al) matrix nanocomposites is predicted using a three-dimensional unit cell based micromechanical approach. The model takes into account the aluminum carbide (Al4C3) interphase region formed due to the reaction between SiC nanoparticles and surrounding Al matrix. The effects of some critical parameters, including volume fraction and diameter of SiC nanoparticles, interphase features such as geometry and material properties on the coefficient of thermal expansion of Al nanocomposite are extensively investigated. The obtained results clearly reveal the high influence of the interphase region on the coefficient of thermal expansion of Al nanocomposite. Based on the simulation results, the coefficient of thermal expansion of Al nanocomposite nonlinearly decreases with the increase in the interphase thickness or decreasing SiC nanoparticles diameter. Furthermore, the role of interphase in the thermal expansion behavior of Al nanocomposite becomes more prominent with the reduction in the nanoparticle diameter. Also, the coefficient of thermal expansion of Al nanocomposite linearly decreases as SiC nanoparticle volume fraction increases. [ABSTRACT FROM AUTHOR]

Abstract In the present work, elastic modulus of a hybrid aluminum matrix nanocomposite (HAMNC) reinforced with silicon carbide (SiC) whiskers and SiC nanoparticles is analyzed. To this end, a new multi-scale analytical model is developed to calculate the effective elastic modulus of the HAMNC. The SiC nanoparticle aggregation into the HAMNC, frequently encountered in real engineering situations, is simulated. The elastic modulus of HAMNC estimated by the analytical micromechanical model is compared with that directly measured by the experimental method and a good agreement is found between the two sets of results. The effects of volume fraction, aspect ratio and dispersion type of SiC whiskers as well as volume fraction, size and aggregation degree of SiC nanoparticles on the HAMNC elastic modulus are extensively investigated. It is found that the elastic modulus of the SiC whisker-reinforced composite is significantly improved due to the addition of SiC nanoparticles. The results show that the nanoparticle aggregation has a damaging effect on the HAMNC elastic modulus. It is observed that the HAMNC elastic modulus can be enhanced by (i) increasing SiC content, (ii) aligning the SiC whiskers, (iii) increasing the SiC whisker aspect ratio (iv) decreasing the SiC nanoparticle size and (v) uniform dispersion of SiC nanoparticles into the hybrid nanocomposite. The reported results by means of the analytical model can be actually useful to guide design of general hybrid metal matrix nanocomposites with superior effective properties. Highlights • A new micromechanical model is proposed to analyze the HMMNC elastic properties. • SiC nanoparticle aggregation into the HMMNCs is simulated. • A very good agreement is obtained between the predictions and experiment. • SiC nanoparticles are indeed a very effective strengthening agent for the MMCs. [ABSTRACT FROM AUTHOR]

Elastic-plastic and thermal expansion responses of aluminum (Al) matrix nanocomposites reinforced with silicon carbide (SiC) nanoparticles are investigated through a micromechanics analytical unit cell method. The formation of the interphase region between SiC nanoparticles and Al matrix is taken into account in the modeling of nanocomposites. The influences of some important parameters such as the thickness and material properties of the interphase, volume fraction and diameter of SiC nanoparticles on the elastic modulus, coefficient of thermal expansion (CTE) and elastoplastic stress-strain curve of the Al nanocomposites are studied in detail. The results clearly reveal high contribution of the interphase region to the overall mechanical and thermal behaviors of Al nanocomposites. It is found that when nanoparticle diameter is lower than about 150 nm, the decrease of SiC nanoparticle diameter leads to (i) an increment in mechanical properties both in the elastic and plastic regions and (ii) a reduction in CTE of the metal matrix nanocomposites. Also, the effect of interphase on the elastic modulus and CTE of Al nanocomposites becomes more important with the reduction of SiC nanoparticle diameter. Finally, the micromechanical model is employed to predict the elastoplastic behavior of SiC nanoparticle-reinforced Al nanocomposites subjected to multi-axial loading conditions in the presence and absence of the interphase region. [ABSTRACT FROM AUTHOR]

In this work, SiC and Cu particles were utilized to enhance the thermal and mechanical properties of Al matrix composites. The ball-milling and cold-compact methods were applied to prepare Al matrix composites, and the uniform distribution of SiC and Cu particles in the composite confirms the validity of our preparation method. After characterizing the thermal conductivity and the compressibility of the prepared composites, results show that small particles have a higher potential to improve compressibility than large particles, which is attributed to the size effect of elastic modulus. The addition of SiC to the Al matrix will improve the compressibility behavior of Al matrix composites, and the compressibility can be enhanced by 100% when SiC content is increased from 0 to 30%. However, the addition of SiC particles has a negative effect on thermal conductivity because of the low thermal conductivity of SiC particles. The addition of Cu particles to Al-SiC MMCs could further slightly improve the compressibility behavior of Al-SiC/Cu MMCs, while the thermal conductivity could be enhanced by about 100% when the Cu content was increased from 0 to 30%. To meet the need for low density and high thermal conductivity in applications, it is more desirable to enhance the specific thermal conductivity by enlarging the preparation pressure and/or sintering temperature. This work is expected to supply some information for preparing Al matrix composites with low density but high thermal conductivity and high compressibility.

Highly dispersed β-SiC nanoparticles and core-shell structure nanoparticles were synthesized by sol-gel and carbothermal reduction methods, in which corn husks and tetraethoxysilane (TEOS) were respectively employed as carbon and silica precursors, with different masses of cobalt nitrate as additive. The SiC nanoparticles and core-shell structure nanoparticles have diameters of 20–80 nm. They are perfect candidates to study the structure effect of SiC nanoparticles on their optical properties. Photoluminescence properties of core-shell structure nanoparticles were different from those of traditional nanoparticles. The core-shell structure nanoparticles show an abnormal blue shift when the excitation wavelength moves from 290 to 330 nm, which is likely caused by core-shell structures and core-shell interface defects. A possible growth mechanism is proposed to interpret the synthesis process. [ABSTRACT FROM AUTHOR]

Modified solar distillation system with different nanofluids was an emerging application area, which added various nanoparticles in saline water to enhance the ability of solar energy absorption and storage. However, there are lacked of exploration with the performance of nanofluids with saline water. Therefore, the stability, optical properties and thermal conductivity of SiC/saline water based nanofluids were systematically investigated in this study. The experimental results showed that SiC nanofluids have good effects for enhancing the thermal conductivity with respect to base fluids (>6% increase at 0.4 vol% SiC nanofluids) and have good capacity of solar absorption (<1% luminousness at 0.4 vol% SiC nanofluids). With increase of salt concentration, some negative effects will affect nanofluids both in stability and thermal conductivity. Therefore, an appropriate salt concentration range and nanoparticles load should be measured in practical application. Moreover, 0.4 vol% SiC nanofluid was prepared with natural seawater and had sufficient stable period. The thermal conductivity of seawater based nanofluid was enhanced about 5.2% with respect to base fluid. Good stability, low luminousness and effective thermal property of SiC nanofluids confirmed the feasibility of nanofluids application in solar distillation system. [ABSTRACT FROM AUTHOR]

Electrochemical etching of polycrystalline SiC is used in order to form SiC nanoparticles. During the process, both SiC and carbon-related nanoparticles like onion like carbon are formed. The two different species can be selected by centrifugation. Both nanoparticles have been functionalized for dispersion in non-polar liquids. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Anodized composite films containing SiC nanoparticles were synthesized on Ti6Al4V alloy by anodic oxidation procedure in COHNa electrolyte. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) were employed to characterize the morphology and composition of the films fabricated in the electrolytes with and without addition of SiC nanoparticles. Results show that SiC particles can be successfully incorporated into the oxide film during the anodizing process and preferentially concentrate within internal cavities and micro-cracks. The ball-on-disk sliding tests indicate that SiC-containing oxide films register much lower wear rate than the oxide films without SiC under dry sliding condition. SiC particles are likely to melt and then are oxidized by frictional heat during sliding tests. Potentiodynamic polarization behavior reveals that the anodized alloy with SiC nanoparticles results in a reduction in passive current density to about 1.54×10 A/cm, which is more than two times lower than that of the TiO film (3.73×10 A/cm). The synthesized composite film has good anti-wear and anti-corrosion properties and the growth mechanism of nanocomposite film is also discussed. [ABSTRACT FROM AUTHOR]

Abstract: SiC nanoparticles with different contents (5–20wt%) were mixed with liquid polyborosilazane. The compound was used to prepare SiC nanoparticle/polymer-derived SiBCN ceramics (SiC/PDCs-SiBCN). Thermal gravity tests (25–1400°C) in air and helium atmosphere were used to investigate the thermal stability of SiC/PDCs-SiBCN. Dielectric and microwave-absorption properties of SiC/PDCs-SiBCN were determined at frequencies of 8.2–12.4GHz by waveguide method. Results show that the addition of SiC nanoparticles increased the thermal stability of SiBCN ceramics. The permittivity, dielectric loss and absorption coefficient of ceramics increased as an elevated SiC content, resulting from the increase of carrier concentration. To understand the high-temperature dielectric property of SiC/PDCs-SiBCN, the permittivity of SiBCN ceramics with 15wt% of SiC was measured at temperatures of 293–773K. The composite ceramics were found to have a visible increase in the permittivity and dielectric loss, indicating their great potential as the high-temperature microwave absorption materials. [Copyright &y& Elsevier]

• C-coated β-SiC nanoparticles with size of about 8 nm were prepared by plasmas. • SiO 2 -coated SiC nanoparticles were synthesized by heat treatment in the air. • SiO 2 layers enhanced the blue-green PL emission due to the surface/defect states. • C-coated SiC exhibited strong microwave absorption with optimal RL of −38.4 dB. Plasma-generated SiC nanoparticles are easily functionalized due to their ability to be easily oxidized. In this study, SiC nanoparticles were synthesized in non-thermal arc plasmas via hexamethyldisilane decomposition, and the products were modified by heat treatment under air atmosphere. Results indicated that the plasma-generated SiC nanoparticles were C-coated SiC nanoparticles with an average size of 8 nm, while the heat treatment transformed the initial carbon coating layers into SiO 2 layers to form SiO 2 -coated SiC nanoparticles by surface oxidation. The formation of SiO 2 layers enhanced the photoluminescence performance in the blue-green emission region, and also resulted in a blue-shift in the photoluminescence peak mainly due to the surface/defect states. The C-coated SiC nanoparticles exhibited excellent microwave absorption ability, and the optimal reflection loss approached −38.4 dB at 11.7 GHz under an absorber thickness of 2.0 mm; however the formation of SiO 2 layers after modification decreased the conduction loss of SiC nanoparticles, thus weakening their microwave absorption. These results afford a new strategy for designing and synthesizing C/SiO 2 -coated SiC nanoparticles. [ABSTRACT FROM AUTHOR]

Abstract: Background: Silicon carbide (SiC) presents noteworthy properties as a material such as high hardness, thermal stability, and photoluminescent properties as a nanocrystal. However, there are very few studies in regard to the toxicological potential of SiC NPs. Objectives: To study the toxicity and biodistribution of silicon carbide (SiC) nanoparticles in an in vivo rat model after acute (24h) and subacute (28days) oral administrations. The acute doses were 0.5, 5, 50, 300 and 600mg·kg−1, while the subacute doses were 0.5 and 50mg·kg−1. Results: SiC biodistribution and elemental composition of feces and organs (liver, kidneys, and spleen) have been studied by Particle-Induced X-ray Emission (PIXE). SiC and other elements in feces excretion increased by the end of the subacute assessment. SiC did not accumulate in organs but some elemental composition modifications were observed after the acute assessment. Histopathological sections from organs (stomach, intestines, liver, and kidneys) indicate the absence of damage at all applied doses, in both assessments. A decrease in the concentration of urea in blood was found in the 50mg·kg−1 group from the subacute assessment. No alterations in the urine parameters (sodium, potassium, osmolarity) were found. Conclusion: This is the first study that assesses the toxicity, biodistribution, and composition changes in feces and organs of SiC nanoparticles in an in vivo rat model. SiC was excreted mostly in feces and low traces were retrieved in urine, indicating that SiC can cross the intestinal barrier. No sign of toxicity was however found after oral administration. [Copyright &y& Elsevier]

Abstract: Hybrid preforms containing SiC whiskers and nanoscale SiC particles were made by wet blending. The Al-based hybrid composites, with 20vol.% SiC whiskers and 0, 2, 5, 7vol.% SiC nanoparticles, were fabricated by squeeze casting route. The optimum squeezing casting parameters, especially infiltration pressure for fabricating the (SiCw·SiCp)/Al hybrid composites were obtained from the infiltration tests. The reinforcements distribute homogeneously in the matrix of the as cast composites, and the strength of the composites is found to increase with increasing content of the nanoparticles. [Copyright &y& Elsevier]

Abstract: The use of ultrasonic non-linear effects to disperse nano-sized ceramic particles in molten metal has been studied and nano-sized SiC particle reinforced AZ91D magnesium composites were fabricated. The microstructure of the composites was investigated by high-resolution scanning electron microscopy (SEM), X-ray photo spectroscopy (XPS), and high-resolution X-ray diffractometer (XRD) techniques. Experimental results show a nearly uniform distribution and good dispersion of the SiC nanoparticles within the magnesium matrix, although some of small agglomerates (less than 300nm) were found in matrix. Detailed study reveals that the SiC nanoparticles were partially oxidized. The microhardness of composites have been improved significantly compared to that of pure AZ91D. The interaction between SiC nanoparticles and the matrix was investigated. The interaction between ultrasonic waves and nanoparticles was also discussed. The ultrasonic fabrication methodology is striking to rapidly produce a wide range of nano-sized particles reinforced metal matrix composites. [Copyright &y& Elsevier]

The present work reports the preparation of Ni-W-SiC thin films obtained by pulse current (PC) electrodeposition using a watt-type nickel plating solution, which contains SiC nanoparticles (NPs). Effects of the initial SiC NP concentration on the morphology, structure, crystal size, microhardness, and corrosion resistance of the resulting Ni-W-SiC thin films were investigated using by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic force microscopy (AFM), microhardness tests, and electrochemical workstation. The results indicated that the surface of Ni-W-SiC films that were treated using 9 g/L SiC NPs had a fine-grained, smooth, and very uniform surface. Incorporating SiC NPs into the Ni-W-SiC thin-film influenced the metal grain sizes and microhardness of the layers. When the concentration of SiC NPs was 9 g/L, the average crystal size was 67 nm, and the microhardness was 881.7 HV. Moreover, the as-obtained film produced with a concentration of 9 g/L SiC had the minimum corrosion current value of 1.5 × 10−3 mA/cm2, which demonstrates its excellent corrosion resistance. • The film deposited at 9 g/L was dense and smooth. • SiC concentration affected the microhardnesses of the films. • The film produced at 9 g/L had excellent corrosion resistance. [ABSTRACT FROM AUTHOR]

In this work, SiC and Cu particles were utilized to enhance the thermal and mechanical properties of Al matrix composites. The ball-milling and cold-compact methods were applied to prepare Al matrix composites, and the uniform distribution of SiC and Cu particles in the composite confirms the validity of our preparation method. After characterizing the thermal conductivity and the compressibility of the prepared composites, results show that small particles have a higher potential to improve compressibility than large particles, which is attributed to the size effect of elastic modulus. The addition of SiC to the Al matrix will improve the compressibility behavior of Al matrix composites, and the compressibility can be enhanced by 100% when SiC content is increased from 0 to 30%. However, the addition of SiC particles has a negative effect on thermal conductivity because of the low thermal conductivity of SiC particles. The addition of Cu particles to Al-SiC MMCs could further slightly improve the compressibility behavior of Al-SiC/Cu MMCs, while the thermal conductivity could be enhanced by about 100% when the Cu content was increased from 0 to 30%. To meet the need for low density and high thermal conductivity in applications, it is more desirable to enhance the specific thermal conductivity by enlarging the preparation pressure and/or sintering temperature. This work is expected to supply some information for preparing Al matrix composites with low density but high thermal conductivity and high compressibility. [ABSTRACT FROM AUTHOR]