Preparation and Thermoelectric Properties of SiO_2/β-Zn_4Sb_3 Nanocomposite Materials

A series of SiO2/β-Zn4Sb3 core-shell composite particles with 3, 6, 9, and 12 nm of SiO2 shell in thickness were prepared by coatingβ-Zn4Sb3 microparticles with SiO2 nanoparticles formed by hydrolyzing the tetraethoxysilane in alcohol-alkali-water solution. SiO2/β-Zn4Sb3 nanocomposite thermoelectric materials were fabricated with these core-shell composite particles by spark plasma sintering （SPS） method. Microstructure, phase composition, and thermoelectric properties of SiO2/β-Zn4Sb3 nanocomposite thermoelectric materials were systemically investigated. The results show thatβ-Zn4Sb3 microparticles are uniformly coated by SiO2 nanoparticles, and no any phase transformation reaction takes place during SPS process. The electrical and thermal conductivity gradually decreases, and the Seebeck coefficient increases compared to that ofβ-Zn4Sb3 bulk material, but the increment of Seebeck coefficient in high temperature range remarkably increases. The thermal conductivity of SiO2/β-Zn4Sb3 nanocomposite material with 12 nm of SiO2 shell is the lowest and only 0.56 W·m^-1·K^-1 at 460 K. As a result, the ZT value of the SiO2/β-Zn4Sb3 nanocomposite material reaches 0.87 at 700 K and increases by 30%.

Synthesis and electrochemical performance of VO/NaVO nanocomposites as cathode materials for sodium-ion batteries

V2O5/NaV6O15 nanocomposites were synthesized by a facile hydrothermal method using VO2(B)nanoarrays as the precursor.X-ray diffraction,scanning electron microscopy and transmission electron microscopy,and galvanostatic charge-discharge test were used to evaluate the structures,morphologies and electrochemical performance of samples,respectively.The results show that the nanocomposites are composed of one-dimensional nanobelts,preserving the morphology of the precursor well,and the hydrothermal reaction time has a significant effect on the phase contents and electrochemical performance of the composites.Compared with pure V2O5,V2O5/NaV6O15 nanocomposites exhibit enhanced electrochemical performance as cathode for sodium-ion batteries.It should be ascribed to the synergistic effect between V2O5 with high capacity and NaV6O15 with good cycling performance,and the introduced massive interfacial areas which can provide additional ion storage sites and improve the electronic and ionic conductivities.

High-Strength Carbon Materials and Elastomers on the Basis of Carbon-Silicon Nanocomposites

The processes for obtaining C-SiO2 and C-βSiC nanocomposites from the rice hulls have been studied. On the basis of these composites, some carbon materials and rubber products with the increased physical and mechanical properties have been obtained. The tensile strength of the carbon products with C-SiO2 is 92-96 MPa and with C-βSiC： 112-118 MPa in comparison with 70-80 MPa for standard products from artificial graphite. Nominal strength and resistance to tensile strain of the carbon material with C-SiO2 increase by 15%-20% as compared to the carbon material with carbon black.

Arc erosion behavior of a nanocomposite W-Cu electrical contact material

The erosion behavior of a nanocomposite W-Cu material under arc breakdown was investigated. The arc erosion rates of the material were determined, and the eroded surfaces and arc erosion mechanisms were studied by scanning eleclion microscopy. It is concluded that the nanocomposite W-Cu electrical contact material shows a characteristic of spreading arcs. The arc breakdown of a commercially used W-Cu alloy was limited in a few areas, and its average arc erosion rate is twice as large as that of the former. Furthermore, it is also proved that the arc extinction ability and arc stability of the nanocomposite W-Cu material are excellent, and melting is the major failure modality in the make-and-break operation of arcs.

Structure and Properties of Self-reinforced Material Made from Ultra-high Molecular Weight Polyethylene-montmorillonite Nanocomposite

High-strength and high-modulus ultra-high molecular weight polyethylene(UHMWPE), named self-reinforced material, was obtained by the elongation of UHMWPE-montmorillonite nanocomposite at melting temperature. According to the scanning electron microscope(SEM) analysis, a great deal of fibrillar texture formed in the direction of elongation, and the tensile fractured surface was similar to that of highly oriented fiber. The transmission electron microscope(TEM) and selective area electron diffraction(SAED) analyses reveal that the reinforced phase of the self-reinforced material is an extended chain crystal and its size is about 50_200 nm wide and several microns long, and the montmorillonite layers are broken up to pieces in the size from 100 to 10 nm. The broken layers which have a huge surface area interacting strongly with macromolecules reduces the entanglement density of UHMWPE and induces the chain orientation in flow field. It is supposed that the astriction of montmorillonite layers to polyethylene chains is not only end-tethered but also side-tethered. The differential scan calorimetry(DSC) analysis shows that there are two endothermal peaks for the self-reinforced material, of which the peak at a higher temperature(136.4 ℃) is ascribed to the melting of the reinforced phase.

Preparation, Characterization and Optical Properties of Host-guest Nanocomposite Material Mordenite-silver Iodide

Silver iodide nanoclusters were successfully prepared in the channels of mordenite by a heat diffusion method. Powder X ray diffraction, adsorption technique and infrared spectroscopy were used to characterize the prepared materials, which showed that the guest silver iodide had been encapsulated in the channels of mordenite. The optical properties of the solid phase diffuse reflectance absorption of nanocomposite material NaM AgI were studied, showing that the absorption bands of the diffuse reflectance absorption of the prepared material moved to the region of high energy. The absorption peak of the material prepared shifted to the region of high energy. Namely, blue shift was caused. This has demonstrated the incorporation of silver iodide into the channels of the zeolite. We observed the luminescence and surface photovoltage spectra of NaM AgI sample, proposing the mechanisms of the photoluminescence and photovoltaic responses.

Novel multifunctional epoxy based graphitic carbon nitride/silanized TiO_(2)nanocomposite as protective coatings for steel surface against corrosion and flame in the shipping industry

The chemical compound 3-(N-ethylamino)isobutyl)trimethoxysilane(EAMS)modified titanium dioxide(TiO_(2)),producing EAMS-TiO_(2),which was encased in graphitic carbon nitride(GCN)and integrated into epoxy resin(EP).The protective properties of mild steel coated with this nanocomposite in a marine environment were assessedusing electrochemical techniques.Thermogravimetric analysis(TGA)and Cone calorimetry tests demonstrated thatGCN/EAMS-TiO_(2)significantly enhanced the flame retardancy of the epoxy coating,reducing peak heat release rate(PHRR)and total heat release(THR)values by 88%and 70%,respectively,compared to pure EP.Salt spray testsindicated reduced water absorption and improved corrosion resistance.The optimal concentration of 0.6 wt%GCNEAMS/TiO_(2)yielded the highest resistance,with the nanocomposite achieving a coating resistance of 7.50×10^(10)Ω·cm^(2)after 28 d in seawater.The surface resistance of EP-GCN/EAMS-TiO_(2)was over 99.9 times higher than pure EP after onehour in seawater.SECM analysis showed the lowest ferrous ion dissipation(1.0 nA)for EP-GCN/EAMS-TiO_(2)coatedsteel.FE-SEM and EDX analyses revealed improved breakdown products and a durable inert nanolayered covering.Thenanocomposite exhibited excellent water resistance(water contact angle of 167°)and strong mechanical properties,withadhesive strength increasing to 18.3 MPa after 28 d in seawater.EP-GCN/EAMS-TiO_(2)shows potential as a coatingmaterial for the shipping industry.

Predicting the Mechanical Behavior of a Bioinspired Nanocomposite through Machine Learning

The bioinspired nacre or bone structure represents a remarkable example of tough,strong,lightweight,and multifunctional structures in biological materials that can be an inspiration to design bioinspired high-performance materials.The bioinspired structure consists of hard grains and soft material interfaces.While the material interface has a very low volume percentage,its property has the ability to determine the bulk material response.Machine learning technology nowadays is widely used in material science.A machine learning model was utilized to predict the material response based on the material interface properties in a bioinspired nanocomposite.This model was trained on a comprehensive dataset of material response and interface properties,allowing it to make accurate predictions.The results of this study demonstrate the efficiency and high accuracy of the machine learning model.The successful application of machine learning into the material property prediction process has the potential to greatly enhance both the efficiency and accuracy of the material design process.

An Approach for Preparation of Excellent Antiwear PTFE Nanocomposites by Filling As-prepared Carbon Nanotubes/Nanorods(CNT/CNR)Mixed Nano-Carbon Material

The one-dimensional carbon nanotubes/nanorods(CNT/CNR)mixed nano-carbon material was successfully prepared by halloysite nanotubes(HNTs)as the template for the first time,in which CNT was formed through PVA modification in internal surface of HNTs and CNR was obtained by nanocasting PVA in hollow nanostructure of HNTs.The CNT of the mixture with flexible structure has ca.20 nm in pore diameter and ca.500 nm in length,whereas the CNR with hard and solid structure shows ca.30 nm in diameter and ca.2μm in length.For application as fillers,the CNT/CNR mixed nano-material is used to reinforce the properties of polytetrafluoroethylene(PTFE).The mechanical and tribological properties of PTFE nanocomposites were intensively examined by a series of testing.The ring-on-ring counterface was used to evaluate the tribological behavior of the nanocomposites.The results showed that the volume wear rate of the CNT/CNR-reinforced PTFE nanocomposite after being filled with 0.3%of CNT/CNR was only 1/700 of that of the pure PTFE under a load of 200 N and a rotary speed of 200 r/min,while other mechanical and tribological performance was comparable to the performance of pure PTFE,which exhibited a desirable application prospect.

Effects of phase change material(PCM)-based nanocomposite additives on thermal decomposition and burning characteristic of high energy propellants containing RDX

A kind of phase change material(PCM)-based nanocomposite was prepared and added into high energy propellants containing RDX as additives to investigate its effect on thermal decomposition and burning characteristic of high energy propellants.The effect of PCM-based nanocomposites on thermal decomposition of high energy propellants is investigated by TG/DSC-FTIR-MS technology.Due to the delayed protection effect(PCM-based nanocomposites can absorb lots of heat at the range of certain temperature when it undergoes structure change or phase transitions)of PCM-based nanocomposites under the thermal decomposition condition,the thermal stability of high energy propellants modified with PCMbased nanocomposites is improved.At the same time,the concentration of N2,NO2,H2O and CO_(2)is increased during thermal decomposition of high energy propellants whereas NO and CO is decreased.The burning gaseous products and burning characteristic of high energy propellants are studied by the combination of closed bomb test and Fourier transform infrared spectrum.The main burning gaseous products are N2,CO_(2),CO,H2O,CH4,etc.After the high energy propellant modified with PCM-based nanocomposites,the concentration of CH4is increased while CO,CO_(2) and H2O is decreased under the high-pressure burning condition.The progressivity factor of high energy propellants is increased by22.2%compared with the control sample while the maximum pressure is merely decreased 1.25%after the addition of the PCM-based nanocomposite,thus PCM-based nanocomposites can be used to adjust the burning process and improve the burning progressivity of high energy propellants.This study is expected to boost the practical application of PCM-based nanocomposite to the propellant formulation and effectively control the burning characteristic of high energy propellants.

ZrO_2/Graphene Nanocomposites Synthesized in Supercritical Fluids: Highly Efficient Chemical Sensor Material for Ethanol

ZrO2/Graphene nanocomposites are fabricated from graphene oxide by one-step, green, facile and low-cost SCCO2 method. The as-prepared nanocomposites are characterized by means of X-ray photoelectron, transmission electron microscopy and catalytic chemiluminescence measurement. The ZrO2 nanoparticles with size of several nanometers are uniformly coated on the graphene surface. The chemiluminescence characteristic to ethanol of the as-prepared nanocomposite paper is also investigated. The nanocomposite paper obtained displays high catalytic chemiluminescence sensitivity and highly selectivity to the ethanol gas. This study provides a facile, green and low-cost route to prepare nanoscopic gas sensing devices with application in safe protection, food fermentation, medical process and traffic safe.

Synthesis and Characterization of the Host-Guest NanocompositeMaterial Zeolite Y-Iron Bipyridine

This paper reports the synthesis of host-guest nanocomposite material [Fe(bpy)(3)]Y2+ (where bpy=2,2'-bipyridine) using the flexible ligand method. X-ray diffraction analysis. adsorption technique, and cyclic voltammetry were used to characterize the material. The results show that [Fe(bpy)(3)](2+) has been entrapped in the supercage of zeolite, its electron transfer is realized by electron hopping of [Fe(bpy)(3)](2+) within the supercage of zeolite.

Effect of high magnetic field on the crystallization of Nd_2Fe_(14)B/α-Fe nanocomposite magnets

Nd8.1Dy0.9Fe76.95Co8.55B5.5 nanocomposite magnets annealed with and without a 10 T magnetic field were investigated in this article. The ribbons with coexisting amorphous and crystalline phases were selected to do this study. The resuits of Moessbauer spectroscopy revealed that the content of α--Fe increased when annealed in high strength magnetic field. The size of the grains also increased considerably after the application of magnetic annealing. All these led to the decrease of the magnetic properties, especially the coercivity of the ribbons.

Carbonaceous Nanofibers-titanium Dioxide Nanocomposites: Synthesis and Use as a Platform for Removal of Dye Pollutants

A mild chemistry route was developed to prepare carbonaceous nanofibers-titanium dioxide(CNF-TiO_2) nanocomposites for removal of dye pollutants. In the process of the template-directed hydrothermal carbonization(HTC), ultrathin Te nanowires were adopted as templates and glucose as the carbon source, and TiO_2 was decorated on CNF via the hydrolysis of tetrabutyltitanate in the presence of CNF in ethanol. The as-prepared materials were characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM), energy-dispersive X-ray(EDX) and X-ray diffraction(XRD). SEM and TEM observations displayed that TiO_2 nanoparticles were anchored on the CNF. EDX and XRD data confirmed that the assynthesized samples were CNF-TiO_2, and TiO_2 belonged to anatase titania. Taking advantage of combined benefits of carbonaceous nanofibers and titanium dioxide, these CNF-TiO_2 nanocomposites exhibited higher removal efficiency in a short time and showed good reusability. It was showed that over 97% of Rhodamine B could be removed in 15 min without generating the solid and liquid wastes. The removal efficiency of dyes was still over 80% after reuse in five cycles. All the results demonstrate that the as-prepared CNF-TiO_2 composites are effective materials for fast and effective removal of dye pollutants and thus can provide a new platform for dye decontamination.

Nanocellulose-Graphene Hybrids: Advanced Functional Materials as Multifunctional Sensing Platform

Naturally derived nanocellulose with unique physiochemical properties and giant potentials as renewable smart nanomaterials opens up endless novel advanced functional materials for multi-sensing applications.However,integrating inorganic functional two-dimensional carbon materials such as graphene has realized hybrid organic-inorganic nanocomposite materials with precisely tailored properties and multi-sensing abilities.Altogether,the affinity,stability,dispersibility,modification,and functionalization are some of the key merits permitting their synergistic interfacial interactions,which exhibited highly advanced multifunctional hybrid nanocomposites with desirable properties.Moreover,the high performance of such hybrids could be achievable through green and straightforward approaches.In this context,the review covered the most advanced nanocellulose-graphene hybrids,focusing on their synthetization,functionalization,fabrication,and multi-sensing applications.These hybrid films exhibited great potentials as a multifunctional sensing platform for numerous mechanical,environmental,and human bio-signals detections,mimicking,and in-situ monitoring.

Influence of Zr Additions on Microstructure and Magnetic Properties of Nanocomposite Nd_(10.5)Fe_(78-x)Co_5Zr_xB_(6.5) (x=0～5) Alloys

The influence of Zr addition on the microstructure and magnetic properties of nanocomposite Nd_(10.5)Fe_(78-x)Co_5Zr_xB_(6.5) (x=0～5) alloys was investigated. It was found that the intrinsic coercivity could be significantly improved by the addition of 2% (atom fraction) Zr. The presence of small amount of amorphous phase is responsible for the low intrinsic coercivity for Zr-free alloy. The small amount addition of Zr may suppress the growth of grains of α-Fe and Nd_2Fe_(14)B phases. The more homogeneous microstructure with an average grain size of 20 nm can be obtained for Nd_(10.5)Fe_(76)Co_5Zr_2B_(6.5) alloy.

Research Progress on Nanostructured Radar Absorbing Materials

Nanostructured radar absorbing materials (RAMs) have received steadily growing interest because of their fascinating properties and various applications compared with the bulk or microsized counterparts. The increased surface area, number of dangling bond atoms and unsaturated co-ordination on surface lead to interface polarization, multiple scatter and absorbing more microwave. In this paper, four types of nanostructured RAMs were concisely introduced as follows: nanocrystal RAMs, core-shell nanocomposite RAMs, nanocomposite of MWCNT and inorganic materials RAMs, nanocomposite of nanostructured carbon and polymer RAMs. Their microwave properties were described in detail by taking various materials as

Effect of Zirconium Content on Microstructure and Magnetic Properties of Nanocomposite Bonded Magnets

Five kinds of bonded magnets with compositions of Nd(10.5)Fe(78.4-x)Co(5)Zr(x)B(6.1) (atom percentage x = 0, 1.0, 1.5, 2.0, 2.5) were prepared by rapid quenching, post heat treatment and mould-pressing. The microstructure and crystallization behavior were studied by X-ray diffraction (XRD), differential thermal analysis (DTA) and atomic force microscopy (AFM). The results suggest that high content of Zr can increase the glass formation ability (GFA) of alloys. When the content of Zr is controlled at a certain level, Fe,Zr with high melting point is formed in the alloys, and grain size is reduced consequently. At the same time, because of Zr addition, the coercivity and squareness of demagnetization loop are obviously improved, and the energy product is accordingly increased. As a result, optimal magnetic properties of Nd(10.5)Fe(78.4-x)Co(5)Zr(x)B(6.1) (B(t) = 0. 659 T, H(cj) = 628 kA center dot m(-1), H(cb) = 419 kA center dot m(-1) (BH)(m) 73 kJ center dot m(-3)) are obtained when x = 2.

Recent advances in nanomaterials for high-performance Li–S batteries

This article reviews nanotechnology as a practical solution for improving lithium-sulfur batteries. Lithiumsulfur batteries have been widely examined because sulfur has many advantageous properties such as a high crustal abundance, low environmental impact, low cost, high gravimetric(2600 W h kg-1) and volumetric(2800 W h L-1) energy densities, assuming complete conversion of sulfur to lithium sulfide(Li2S)upon lithiation. However, lithium-sulfur batteries have not yet reach commercialization due to demerits involving the formation of soluble lithium polysulfides(Li2Sn, n=3–8), low electrical conductivity, and low loading density of sulfur. These issues arise mainly due to the polysulfide shuttle phenomenon and the inherent insulating nature of sulfur. To overcome these issues, strategies have been pursued using nanotechnology applied to porous carbon nanocomposites, hollow one-dimensional carbon nanomaterials, graphene nanocomposites, and three-dimensional carbon nanostructured matrices. This paper aims to review various solutions pertaining to the role of nanotechnology in synthesizing nanoscale and nanostructured materials for advanced and high-performance lithium–sulfur batteries. Furthermore, we highlight perspective research directions for commercialization of lithium–sulfur batteries as a major power source for electric vehicles and large-scale electric energy storage.