Micro-nano Composites Research Articles

Mechanical and tribological properties of high entropy carbide-based micro-nano ceramic composites

(NbTaTiWZr)C-based micro-nano composites were fabricated by spark plasma sintering employing multi-layer graphene (MLG), Ni, and Al2O3 as reinforcements. It is demonstrated that excellent mechanical properties were achieved for MLG, Ni, and Al2O3 hybrid addition with a hardness of 21.73 GPa, a flexural strength of 572.4 MPa, and a fracture toughness of 7.65 MPa m1/2. Enhanced densification together with inhibited grain growth contributed to the simultaneously improved hardness and flexural strength. The major toughening mechanisms were determined as microcracks, crack deflection, crack bridging, crack stopping, MLG wall, MLG pull-out, MLG bending, and MLG wrapping grains. Furthermore, outstanding tribological performance occurred to the (High entropy ceramic) HEC-Ni-Al2O3-MLG with a friction coefficient of 0.23 and wear rate of 4.32 × 10−7mm3N−1m−1, as a function of graphene acting as a lubricating friction layer and the enhanced mechanical responses.

MXene/In2S3 micro-nano composites for heighten the select specificity and rapid response to triethylamine

Molecular responsive materials with fast, stable, and specific selectivity are a key focus of chemical sensor technology research. In the field of triethylamine (TEA) sensor technology, developing TEA-selective responsive materials with superior performance is of great significance for promoting technological progress and industrialization of TEA sensor technology. In this study, MXene/In2S3 micro-nano powder was prepared by combining Ti3C2Tx-type MXene with nano-sized In2S3. The morphology, structure, and structure-performance relationship of the material were characterized and analyzed using SEM, TEM, XRD, HAADF, and XPS. Through experiments, it was confirmed that MXene/In2S3 exhibited outstanding specific selectivity to TEA. At a TEA concentration of 20 ppm and a temperature of 210 °C, the response value of the material to TEA was 8.74, while other typical gas molecules such as aldehydes, ketones, and aromatics showed almost no response, demonstrating excellent selectivity for TEA molecules. The response/recovery time was 19 s/42 s, and the response value was stable over 20 consecutive cycles, indicating excellent reliability of the material. In addition, in the concentration range of 1–500 ppm, the response value of the MXene/In2S3 material to TEA concentration followed an exponential fitting of the asymptotic model, with the formula y = a-b*cx and R2 of 0.99472. Furthermore, the selection and response process of MXene/In2S3 micro-nano materials and TEA molecules were analyzed from the molecular internal structure, and it was found that the selective response characteristics of the material to TEA were related to its microstructure, including shape adsorption.

“Litchi-like” metastable Al/Ti/CuO micro-nano composites with enhanced combustion reaction and their energy characteristics

To design and prepare multifunctional metastable intermixed composites (MICs) with excellent properties, the enhanced “litchi-like” core-shell structure Al/Ti/CuO MICs were prepared by high-energy ball milling (Al/Ti/CuO-B). The morphology, structure, composition, thermal reactivity, energy release and combustion performance of the prepared MICs were investigated by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and synchronous thermal analysis (DSC-TG), closed system constant volume combustion experiment, open system CO2 laser ignition experiment and high-energy laser-induced ablation experiment. This study reveals that, the obtained Al/Ti/CuO-B composites have a “litchi-like” core-shell structure, the components are evenly distributed and closely contacted. The exothermic reaction of Al/Ti/CuO-B should be divided into two stages. Due to the introduction of Ti and the special structure of litchi, Al/Ti/CuO-B has superior reactivity (Ea=178.15 kJ/mol), energy release (Q = 6443 J/g, Pmax =164.90KPa), shock wave propagation (v = 1028.33 m/s) and combustion performance than Al/Ti/CuO-P (simple physical mixing). The thrown Al/Ti/CuO composite particles will undergo secondary micro-reactions during the combustion, and a continuous multi-point “micro-explosion” phenomenon will occur, then self-sustainable combustion can be achieved through multi-level energy superposition release, which will enhance its reaction, combustion and energy release. Al/Ti/CuO-B undergoes an ultrafast reaction to generate plasma under high-energy laser induction, which expands and pushes the surrounding air to form a shock wave. The application of Al/Ti/CuO-B shows that the density, heat of detonation, shock wave overpressure, fireball diameter and temperature of composite structural explosive charge containing Al/Ti/CuO ring are all significantly improved.

Highly sensitive and selective gas sensors based on 2D/3D Bi2MoO6 micro-nano composites for trimethylamine biomarker detection

Metal oxide semiconductor based gas sensors have been verified to be an effective way for food quality detection. However, the high operating temperature, insufficient sensitivity, and selectivity limit their wide application. Herein, one simplest Aurivillius oxide, Bi2MoO6 microspheres and a series of exfoliated g-C3N4/Bi2MoO6 hetero-composites were developed using a facile solvothermal route, which are used to detect trimethylamine (TMA, a volatile biomarker of fish freshness) at 22 °C. The introduction of E-g-C3N4 contributes to modulating the grain size of Bi2MoO6 and tuning the Bi/Mo cations valence states, thus improving the surface reactivity and electron transfer efficiency. Benefiting from the synergetic engineering of 2D/3D micro-nanostructure, crystal defects, and well-defined n-n heterojunctions, 1 wt% E-g-C3N4/Bi2MoO6 attained superior TMA sensing performance at 22 °C, including the highest response (Ra/Rg = 10.6 @ 20 ppm) and accelerated response/recovery speed, fine selectivity, and low detection limit (1.3 ppm), which is far satisfied with the detection requirement. Furthermore, the comprehensive evaluation based on the fish color and tissue state, sensing characteristics, PCA, and pH testing results reveal the fabricated TMA sensor can achieve rapid and non-destructive fish freshness detection. This work provides insights into designing low-power consumption chemiresistive gas sensors and devices with valid practicality.

Osteogenic differentiation of bone marrow stromal stem cells on a novel β titanium alloy-based micro-nano composite

The incorporation of nanoparticles into metallic biomaterials has been recognized as a significant approach to improve their bioactivity for biomedical applications. In this study, friction stir processing (FSP) was employed to incorporate TiO2 nanoparticles as bioactive reinforcement into the β titanium alloy Ti–35Nb–2Ta–3Zr (TNTZ) matrix to construct an integrated micro-nano composite layer. The effect of different TiO2 contents on the osteogenic capacity of rat bone marrow stromal stem cells (BMSCs) was studied. The TiO2/TNTZ composite layer exhibited a refined grain structure with a mean grain size of approximately 10 μm and a characteristic surface morphology of pronounced peaks and valleys with enhanced RSkw and RKur values. Moreover, TiO2/TNTZ significantly promoted the adhesion, proliferation, and spreading of BMSCs, upregulated the expression of genes related to osteogenesis (ALP and Runx2) up to nearly 1.5 times, and enhanced the expression of ALP and OCN (P < 0.05). The novel FSPed TiO2/TNTZ micro-nano composite possesses excellent surface characteristics and favorable biological activities, manifesting vast potential for upcoming clinical applications.

A facile integrated microfluidic chip based on Chitosan-Gold Nanoparticles-Anchored Three-Dimensional graphene fiber film for monitoring prostate specific antigen

Microfluidic electrochemical sensors are emerging as favorable platforms for rapid and precise detection of disease markers relying on their superiority of miniaturization, low electrolyte consumption, high precision and integration. Herein, an efficient and facile integrated microfluidic sensor with three-dimensional graphene fiber film/chitosan-gold nanoparticles (3D GF/CS-Au NPs) micro-nano composites as sensing interface was developed for the analysis of prostate specific antigen (PSA). The GF with 3D network structures modified by large amounts of CS-Au nanoparticles could facilitate the enhancement of electrochemical signals. The electrodes and microchannel were simply assembled and encapsulated by bolts, which made the microfluidic chip had excellent portability and operability. On the basis of this new microfluidic device and the 3D GF/CS-Au NPs composites, a sensitive determination of PSA could be realized with a low detection limit of 0.51 pg/mL and a wide response range from 0.001 − 200 ng/mL. Moreover, the proposed biosensor was further used to detect analytes in human blood samples, showing the satisfactory results. This novel microfluidic electrochemical immunosensor demonstrated superior performance for PSA detection, holding potential application in clinical diagnosis and personalized healthcare.

Nonlinear Surface Conductivity Characteristics of Epoxy Resin-Based Micro-Nano Structured Composites

Nonlinear composite materials serve to homogenize electric fields and can effectively improve the local concentration of the electric field in power systems. In order to study the nonlinear surface conductivity properties of micro-nano epoxy composites, two types of epoxy micro-nano composite specimens were prepared in the laboratory using the co-blending method. The surface conductivity of the composites was tested under different conditions using a high-voltage DC surface conductivity test system. The results show that the surface conductivity of micro-nano structured composites increases and then decreases with the rise of nanofiller doping concentration. The nonlinear coefficient was 1.781 at 4 wt% of doped nanostructured SiC, which was the most significant nonlinear coefficient compared to other doping contents. For the same doping concentration, the micro-nano structured composites doped with nanostructured SiC have more significant surface conductivity at the same test temperature with a nonlinear coefficient of 1.635. As the temperature increases, the surface conductivity of the micro-nano structured composite increases significantly, and the threshold field strength moves towards the high electric field. Along with the increase in temperature, the nonlinear coefficients of micro-nano composites after doping with nanostructured SiC showed a gradually decreasing trend. The temperature has little effect on the nonlinear coefficients of the micro-nano structured composites after doping with O-MMT.

Formation of conductive MOF@Metal oxide micro-nano composites via facile self-assembly for high-performance supercapacitors

Metal-organic frameworks (MOFs), which are promising electrode materials, have been explored for clean energy applications such as electrochemical energy storage. In this study, to enhance the electrical conductivity without decreasing ion transfer efficiency and to balance both activity and stability, we used metal oxides that can directly react with organic ligands and consequently produce their micro-nanocrystallized composites. Furthermore, we investigated the growth process by adjusting the reaction time and by determining the relationship between facet exposure and reaction time. Subsequently, we tested their electrochemical performance and demonstrated that specific facet exposure and small size are critical for achieving high capacitance. This reveals not only the influence of the reaction time on the morphology of conductive MOF composites and size but also the influence of morphology and size on the electrochemical performance.

Tensile properties and fracture behavior of carbon nanotube-sheets/carbon fibers epoxy-impregnated bundle composites

An interesting technique for modifying carbon fiber-reinforced polymer matrix composites is through hybridization with carbon nanotubes (CNTs). Carbon nanotubes sheets/carbon fibers offer potential benefits of nanoscale reinforcement to the well-established fibrous composites by creating multiscale hybrid micro-nano composites. In this study, the tensile properties of high tensile strength polyacrylonitrile (PAN)- and high modulus pitch-based carbon fiber-reinforced polymer matrix composites incorporating CNT sheets (CNT-sh/CFs/Ep-H: CNT sheets/carbon fibers/epoxy hybrid composites) were investigated. To fabricate CNT sheets, CNT was vertically grown on a quartz glass plate by chemical vapor deposition. A solid-state drawing and winding technique was applied to transform the vertically aligned CNT array into horizontally aligned CNT sheets. The tensile modulus of the CNT-sh/CFs/Ep-H was higher than that of the composite in the as-received state (CFs/Ep: carbon fibers/epoxy bundle composite). The tensile strength of the CNT-sh/PAN-based CF/Ep-H was lower than that of the PAN-based CF/Ep, whereas the tensile strength of the CNT-sh/pitch-based CF/Ep-H was higher than that of the pitch-based CF/Ep.

Influence of Gamma Irradiation and Water Aging on the Space Charge Characteristics of Epoxy Micro-Nano Composites.

Epoxy micro-nano composites are well-known to exhibit enhanced electrical, mechanical as well as thermal properties compared to base epoxy resin. Yet, a clear understanding need to be achieved on the long-term aging performance of the epoxy micro-nano composites. The present review article is a comprehensive study on the impact of gamma irradiation and water aging on the space charge characteristics of epoxy micro-nano composites that are applicable as insulant in high-voltage power apparatus. Ion-trapping nanoparticles, which possess good oxidation resistance and high ion trapping ability, are being chosen as nanofillers along with silica micro fillers in epoxy micro-nano composite material for improving the reliability of electrical insulation structures. The epoxy micro-nano composite specimens were subjected to gamma irradiation (4 kGy and 8 kGy) and water aging (under room temperature and at 90 °C), to analyze the effect of aging on space charge accumulation and charge decay characteristics. The mean magnitude of accumulated space charge density of epoxy micro-nano composites tends to increase with an increase in gamma irradiation dose as well as an increment in water diffusion coefficient. The mean lifetime of the space charge decay during depoling has significantly reduced after gamma irradiation and is converse with water aged specimen. Voltage polarity reversal studies have indicated that a part of homo-charge injected from electrodes remained as hetero-charge just after polarity reversal and could result in the distortion of electric field thereby increasing the electric field enhancement factor.

Conductance Current and Space Charge Characteristics of SiO2/MMT/LDPE Micro-Nano Composites.

Low-density polyethylene (LDPE) is one of the most comprehensive products used as insulation materials in power equipment. How to improve its dielectric properties by doping inorganic particles in LDPE has always been the focus of many researchers. In this paper, silica (SiO2) particles and montmorillonite (MMT) particles were added to LDPE, the order of adding particles was changed, and different micro-nano composites was made. The crystallization characteristics of composites were analyzed, the curves of the conductance current with the change of field intensity were analyzed, and the space charge distribution of each material were investigated. The results of crystallization show that the crystalline properties and crystallinity of the composites are higher than the matrix LDPE, the addition of SiO2 particles increases the composites’ crystallinity significantly, and the intercellular spacing of micro-nano composites is the smallest among all materials. The curve of conductance current versus electric field intensity shows that the tightness of the crystal structure can effectively hinder the movement of the molecular chain, inhibit carrier migration, while shortening the free travel of electrons, thereby reducing the electric conduction current of the material. The experimental results of the space charge accumulation curve further show that the compact crystal structure of the material is beneficial to the dissipation of space charge in the dielectric.

Mechanical Properties and Thermal Stability of Kaolinite/Emulsion Polymerization Styrene Butadiene Rubber Composite Prepared by Latex Blending Method

This study focused on the preparation method and evaluation of micro-nano composites based on emulsion polymerization styrene butadiene rubber (ESBR) and kaolinite. A novel method – latex blending was utilized to improve the dispersion of kaolinite in matrix and obtain a semi-exfoliation type clay/polymer composite. The results showed that the kaolinite particles presented a semi-exfoliation state and micro-nano scale dispersion in ESBR matrix. The micromorphology of layer-like particles in rubber matrix presented loose and blurry attributed to the interaction between kaolinite plate-like particles and rubber molecules in the latex mixing process, and thus resulted in the reduction of kaolinite crystal order degree. The maximum torque (MH), minimum torque (ML), and ΔM presented a gradually increase tendency with the increase of filler content and the reduction of kaolinite particle size. The mechanical properties of kaolinite/ESBR displayed a significant improvement, and the relative mechanical parameters increased as increasing filler content or reducing kaolinite particle size. The tensile strength and tear strength of the kaolinite/SBR composite reached at 15.1 MPa and 51.3 kN/m, respectively when the filler content at 80 phr. The thermal stability of kaolinite/ESBR composites presented a considerably improvement as decreasing kaolinite particle size or at a reasonable range of filler content. The characteristic decomposition parameters of kaolinite/SBR composite increased compared with those of pure ESBR. The above data indicating that the ESBR chains interacted with kaolinite particles by chemical interaction and the polymer molecules may be intercalated the surface group and interlayer of kaolinite, and thus resulted in the transformation of layer-like microstructure and the restriction on motion of rubber chains in the composite system.

Growth, characterization and thermo-mechanical analysis of Al/Al2O3 core/shell nanoparticles obtained under H2 atmosphere

In this work, growth, characterization and thermo-mechanical behavior of Al/Al2O3 core/shell nanoparticles (NP) is performed. The growth was carried out by gas condensation methods using H2 as carrier gas at a pressure of 100 Pa and with a temperature of the evaporation source of 1315 °C. The prepared NP were characterized by Energy Dispersive X-ray Spectroscopy for chemical information, transmission electron microscopy for morphological study, and electron diffraction patterns for structural information. The prepared Al NP exhibit a thin Al2O3 passivating oxide shell due to the air exposure when removed from the preparation vacuum chamber. Afterwards, the growth of the Al2O3 oxide shell of the Al NP and the thermo-mechanical interaction between this growing oxide shell and its Al core was studied by performing in-situ thermal X-ray diffraction from RT up to 505 °C. Coefficients of thermal expansion of both Al core and Al2O3 oxide shell were obtained by means of X-ray strain analysis. It was found that the thickness of the Al2O3 shell increases with temperature and the thermal stress induced in the system increases linearly with temperature. Our results highlight that these NP overcome higher values of fracture toughness compared with Al2O3 NP used in micro-nano composites, thus improving their mechanical properties for nanofluid applications.

Space Charge Characteristics and Electrical Properties of Micro-Nano ZnO/LDPE Composites

The synergistic effects of zinc oxide (ZnO) Micro/Nano particles simultaneously filled in low-density polyethylene (LDPE) on the space charge characteristics and electrical properties has been investigated by melt blending micro-scale and nanoscale ZnO additive particles into LDPE matrix to prepare Micro-ZnO, Nano-ZnO, and Micro-Nano ZnO/LDPE composites. The morphological structures of composite samples are characterized by Polarizing Light Microscopy (PLM), and the space charge accumulations and insulation performances are correlated in the analyses with Pulse Electronic Acoustic (PEA), DC breakdown field strength, and conductance tests. It is indicated that both the micro and nano ZnO fillers can introduce plenty of heterogeneous nuclei into the LDPE matrix so as to impede the LDPE spherocrystal growth and regularize the crystalline grains in neatly-arranged morphology. By filling microparticles together with nanoparticles of ZnO additives, the space charge accumulations are significantly inhibited under an applied DC voltage and the minimum initial residual charges with the slowest charge decaying rate have been achieved after an electrode short connection. While the micro-nano ZnO/LDPE composites acquire the lowest conductivity, the breakdown strengths of the ZnO/LDPE nanocomposite and micro-nano composite are, respectively, 13.7% and 3.4% higher than that of the neat LDPE material.

Microstructure and reaction properties of Ni/Al micro-nano composites produced by accumulative roll bonding process

Ni/Al micro-nano composites have received much attention due to their attractive properties, especially high energy density and stable strength. This presented work aims to propose a simple and cost-effective method for preparing Ni/Al micro-nano composites that have good reaction performance and specific tensile strength and explore their microstructure evolution and reaction property. The Ni/Al micro-nano composites were fabricated by the accumulative roll bonding (ARB) using pure nickel and Al foils. As the ARB cycles gradually increased, the foils get thinner and transition from a straight to a wavy shape, such as necking and fracture of Ni. The interface contact area was increased by the more uniform and slender nickel-aluminum layer distribution during ARB process. Furthermore, the energy density during the exothermic reactions of the Ni/Al composites firstly increased and then decreased with the decrease of interlayer thickness. The energy density of the Ni/Al micro-nano composite after 13th ARB cycles was 1362.5 J g−1, which was about 92% of the theoretical value. The initial reaction temperature of the composites decreased with the increase of rolling cycles. Al3Ni, Al3Ni2 and AlNi intermetallic phases were generated in exothermic reactions. Besides, the activation energies of Ni/Al composites calculated by Kissinger and Ozawa method were 52.91 and 59.68 kJ mol−1, respectively. After the 13th rolling cycle, the tensile strength was 368.70 MPa while the elongation was 4.2%.

The synergistic effects of the micro-BN and nano-Al2O3 in micro-nano composites on enhancing the thermal conductivity for insulating epoxy resin

Epoxy resin has been widely used in electrical and electronics industries due to its excellent adhesion and insulating properties. However, the low thermal conductivity limits its application in the devices, especially under the working conditions of high frequency. In this work, the epoxy resin composites filled with binary fillers of dopamine modified micro-BN and KH550 modified nano-Al2O3 were fabricated and the thermal conductivities, dielectric losses and breakdown strengths in high frequency and electrical field of the composites were studied. A high thermal conductivity of 1.182 W m−1K−1 was realized in the composite with 22.5 wt% BN and 7.5 wt% Al2O3, which was about 700% higher than neat epoxy resin. The results of breakdown experiments in high frequency and high voltage field showed that the positive effect of the thermal conductivity increase was greater than the negative effect of the dielectric loss increase, and the notably improved breakdown time of the composite was 406% higher than that of neat epoxy. The epoxy resin composites with high thermal conductivity and excellent dielectric strength could be a potential insulating material in the electrical and electronics industries.

One-pot method fabrication of superparamagnetic sulfonated polystyrene/Fe3O4/graphene oxide micro-nano composites

In this work, using monodispersed sulfonated polystyrene (SPS) microspheres as carriers, FeCl3·6H2O and FeSO4·7H2O as precursors, NaOH as precipitant in the presence of graphene oxide (GO), SPS/Fe3O4/GO micro-nano composites were fabricated by a simple one-pot method employing an inverse coprecipitation in-situ compound technology. The SPS/Fe3O4/GO micro-nano composites were characterized by scanning electron microscopy, transmission electron microscopy, X-ray powder diffractometer, Fourier transform infrared spectroscopy, nitrogen adsorption/desorption isotherms and vibrating sample magnetometer. The results show that the SPS/Fe3O4/GO micro-nano composites were fabricated with SPS as core, GO and Fe3O4 nanoparticles as shell. The SPS/Fe3O4/GO micro-nano composites had larger BET specific surface area, average pore width and micropore volume than the pure SPS microspheres. Meanwhile, the SPS/Fe3O4/GO micro-nano composites had superparamagnetism and hydrophilic property. The saturation magnetization (Ms) of the SPS/Fe3O4/GO micro-nano composites was 10.86 emu/g, which was enough to ensure the convenient magnetic separation of solid and liquid phase.

The Synergistic Effects of the Micro and Nano Particles in Micro-nano Composites on Enhancing the Resistance to Electrical Tree Degradation

A new method of increasing the durability and reliability of polymer dielectrics has been proposed by designing a composite structure of the micro and nano particles. The synergistic effects of the micro particles and nano particles are found to enhance the resistance to electrical tree and extend the lifetime of polymer dielectrics for insulations. Epoxy loaded with the micro and nano SiO2 particles at different concentrations are prepared as micro-nano composites. The micro particles show the blocking effects on the electrical tree channel and the interfaces of the nano particles lead to the inhibiting effects on the tree inception and propagation. The lifetime of the micro-nano composite samples in the experiments extends to 4 times of the neat epoxy. The new type of micro-nano composites can be widely applied in future electronic and electrical energy areas.

Optimization of spark plasma sintering parameters of Si3N4-SiC composite using response surface methodology (RSM)

The Si3N4-SiC micro-nano composites were fabricated via the spark plasma sintering method using MgSiN2 as an additive. Response surface methodology and central composite design were applied to optimize the spark plasma sintering process for the fabrication of Si3N4-SiC/MgSiN2 with improved density. The relation between the three parameters of sintering including temperature, pressure, and holding time was modeled and the optimized parameters were obtained. The best sintering results obtained for the sintering temperature, holding time, and pressure are 1700°C, 487s, and 49MPa, respectively. The addition of MgSiN2 as an additive and SiC as a secondary phase were also investigated in the present work. The Si3N4−5vol% SiC composite exhibited high hardness (19GPa) and fracture toughness values (6.5MPam1/2) at room temperature.

A Micro/Nano Composite for Combination Treatment of Melanoma Lung Metastasis.

The successful treatment of malignant disease generally requires the use of multiple therapeutic agents that are coordinated in a spatiotemporal manner to enable synergy. Here, a porous silicon-based micro/nano composite (MNC) that is capable of simultaneously delivering chemotherapeutic agents and small interfering RNA (siRNA) to the lungs following intravenous injection is designed. The pores of the silicon microparticles are loaded with B-Raf proto-oncogene serine/threonine kinase (BRAF) siRNA-containing liposomes, while the surface is conjugated with docetaxel-encapsulated polymeric nanoparticles. The synergistic antitumor effect of the MNC is demonstrated in vitro in melanoma cells and in vivo using a mouse model for melanoma lung metastasis. The MNC displays superior therapeutic efficacy and increased accumulation in metastatic melanoma lesions in the lungs in comparison to combination therapy with liposomes and polymers. The results indicate that the MNC can be used as an effective delivery vehicle for simultaneous enrichment of multiple therapeutic agents in the lungs.