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Artykuły w czasopismach na temat "ZnO based Nanocomposites - Microstructure"
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Gallach, D., L. Le Brizoual, N. Gautier, M. D. Ynsa, V. Torres Costa, G. Ceccone, J. P. Landesman i M. Manso Silván. "Microstructure based optical modeling of ZnO- porous silicon permeated nanocomposites". Journal of Physics D: Applied Physics 48, nr 29 (26.06.2015): 295102. http://dx.doi.org/10.1088/0022-3727/48/29/295102.
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Platonov, Vadim B., Marina N. Rumyantseva, Alexander S. Frolov, Alexey D. Yapryntsev i Alexander M. Gaskov. "High-temperature resistive gas sensors based on ZnO/SiC nanocomposites". Beilstein Journal of Nanotechnology 10 (26.07.2019): 1537–47. http://dx.doi.org/10.3762/bjnano.10.151.
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Increasing requirements for environmental protection have led to the need for the development of control systems for exhaust gases monitored directly at high temperatures in the range of 300–800 °C. The development of high-temperature gas sensors requires the creation of new materials that are stable under these conditions. The stability of nanostructured semiconductor oxides at high temperature can be enhanced by creating composites with highly dispersed silicon carbide (SiC). In this work, ZnO and SiC nanofibers were synthesized by electrospinning of polymer solutions followed by heat treatment, which is necessary for polymer removal and crystallization of semiconductor materials. ZnO/SiC nanocomposites (15–45 mol % SiC) were obtained by mixing the components in a single homogeneous paste with subsequent thermal annealing. The composition and microstructure of the materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The electrophysical and gas sensing properties of the materials were investigated by in situ conductivity measurements in the presence of the reducing gases CO and NH3 (20 ppm), in dry conditions (relative humidity at 25 °C RH25 = 0) and in humid air (RH25 = 30%) in the temperature range 400–550 °C. The ZnO/SiC nanocomposites were characterized by a higher concentration of chemisorbed oxygen, higher activation energy of conductivity, and higher sensor response towards CO and NH3 as compared with ZnO nanofibers. The obtained experimental results were interpreted in terms of the formation of an n–n heterojunction at the ZnO/SiC interface.
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Sanmugam, Anandhavelu, Dhanasekaran Vikraman, Sethuraman Venkatesan i Hui Joon Park. "Optical and Structural Properties of Solvent Free Synthesized Starch/Chitosan-ZnO Nanocomposites". Journal of Nanomaterials 2017 (2017): 1–8. http://dx.doi.org/10.1155/2017/7536364.
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The objective of this work is to develop an environmentally friendly method for preparation of ZnO nanocomposites. ZnO nanocomposites were prepared by three natural fibers such as coir, sawdust, and chitosan using aqueous solution of zinc chloride and sodium hydroxide. The functional groups of ZnO, C=O for polysaccharide, and N-H bending vibration of amine were confirmed by FTIR spectroscopy. A new high intensity absorption band has been observed at 424 cm−1 which corresponds to the E2 mode of hexagonal ZnO. The crystallinity and phase formation of coir, chitosan, and sawdust combined ZnO nanocomposites were confirmed by X-ray diffraction patterns. XRD patterns revealed the polycrystalline nature of ZnO composites belonging to the hexagonal phase with (101) preferential lattice orientation. The microstructural parameters were calculated for coir, chitosan, and saw wood combined ZnO composites. Also texture coefficients were estimated for all the diffraction lines of ZnO based nanocomposites. SEM and TEM analyses confirmed evenly distributed nanosized grains in the ZnO composites. The UV-Vis absorption spectra were observed where the blue shift absorption peak was at 334 nm. The optical band gap values were estimated in the range of 3.18–3.26 eV. The emission peak was observed at ~388 nm and ~463 nm by photoluminescence spectroscopy.
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Chabri, Sumit, Arnab Dhara, Bibhutibhushan Show, Deepanjana Adak, Arijit Sinha i Nillohit Mukherjee. "Mesoporous CuO–ZnO p–n heterojunction based nanocomposites with high specific surface area for enhanced photocatalysis and electrochemical sensing". Catalysis Science & Technology 6, nr 9 (2016): 3238–52. http://dx.doi.org/10.1039/c5cy01573a.
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Mesoporous and core–shell like (p)CuO–(n)ZnO nanocomposites were prepared using microstructural refinement and solid state reactions, which showed enhanced photochemical and electrochemical performances.
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Pervaiz, S., N. Kanwal, A. Shahzad, M. Saleem i I. A. Khan. "Thermal and Dielectric Behaviour of Polymer-Based Nanocomposites Flexible Sheets as Highly Stable Dielectric Materials". International Journal of Polymer Science 2023 (5.01.2023): 1–12. http://dx.doi.org/10.1155/2023/3892823.
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The silica zinc oxide nanoparticles filled poly-vinylidene-fluoride (PVDF)-based nanocomposite flexible sheets (NC FSs) are synthesized by co-precipitation method. The X-ray diffraction patterns reveal the development of various diffraction planes related to zinc oxide (ZnO) and SiO2 phases. The crystallinity of ZnO phase is decreased with increasing weight percent (wt.%) of silica nanofillers (NFs). The scanning electron microscope microstructure of synthesized PVDF-based NCs FSs is changed with increasing wt.% of silica NFs. The energy-dispersive X-ray spectroscopy and Fourier-transform infrared spectroscopy analyses confirm the presence of different elements and the formation of chemical bonding between them. In high temperature region, the weight-loss of synthesized PVDF-based NCs FSs is decreased from 89.90% to 49.26% with increasing wt.% of silica NFs. The values of dielectric permittivity, loss-factor, impedance, and AC-conductivity of PVDF-based NC FSs synthesized for maximum amount of silica NFs are found to be 13.7, 0.03, 0.16 MΩ, and 19.9 × 10 − 6 S/m, respectively. Results show that the synthesized PVDF-based NC FSs are the potential candidates of light emitting diodes and energy storage devices.
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Albiter, Elim, Aura S. Merlano, Elizabeth Rojas, José M. Barrera-Andrade, Ángel Salazar i Miguel A. Valenzuela. "Synthesis, Characterization, and Photocatalytic Performance of ZnO–Graphene Nanocomposites: A Review". Journal of Composites Science 5, nr 1 (25.12.2020): 4. http://dx.doi.org/10.3390/jcs5010004.
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ZnO is an exciting material for photocatalysis applications due to its high activity, easy accessibility of raw materials, low production costs, and nontoxic. Several ZnO nano and microstructures can be obtained, such as nanoparticles, nanorods, micro flowers, microspheres, among others, depending on the preparation method and conditions. ZnO is a wide bandgap semiconductor presenting massive recombination of the generated charge carriers, limiting its photocatalytic efficiency and stability. It is common to mix it with metal, metal oxide, sulfides, polymers, and nanocarbon-based materials to improve its photocatalytic behavior. Therefore, ZnO–nanocarbon composites formation has been a viable alternative that leads to new, more active, and stable photocatalytic systems. Mainly, graphene is a well-known two-dimensional material, which could be an excellent candidate to hybridize with ZnO due to its excellent physical and chemical properties (e.g., high specific surface area, optical transmittance, and thermal conductivity, among others). This review analyses ZnO–graphene nanocomposites’ recent advances, addressing the synthesis methods and the resulting structural, morphological, optical, and electronic properties. Moreover, we examine the ZnO–graphene composites’ role in the photocatalytic degradation of organic/inorganic pollutants.
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Liu, Ming Ran. "Fabrication, Characterization and Investigation of Novel PVDF/ZnO and PVDF-TrFE/ZnO Nanocomposites with Enhanced β-Phase and Dielectricity". Materials Science Forum 977 (luty 2020): 277–82. http://dx.doi.org/10.4028/www.scientific.net/msf.977.277.
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To date, flexible, sensitive and biocompatible pressure sensors for fluctuation signals in human body have been mainly demonstrated for detecting body and muscle motion, pulse rate, heart rate and arterial blood pressure. However, because of the lack of sufficient sensitivity and flexibility, pulse signals with relatively low intensity cannot be identified and captured, such as signals derived from microcirculation in human body. As confirmed and validated by researchers, once PVDF and its copolymer based nanocomposite sensing material are applied in piezoelectric sensors, its sensitivity and piezoelectricity are highly relevant. Therefore, as one of the most effective methods to improve the permittivity and piezoelectricity of PVDF and its copolymer based nanocomposite, the effect of increasing the content of β-phase crystal was investigated in this work. In this project, the sensor possessing a novel sensing layer with the nanofiller was investigated and fabricated. The proposed sensor was designed in a simple but efficient sandwich structure. The sensing layer of the proposed sensor was made of polyvinylidene fluoride (PVDF) and polyvinylidenefluoride-trifluoroethylene (PVDF-TrFE) based nanocomposite with Zinc Oxide (ZnO) nanostructure acting as a filler portion which was fabricated by the method of Chemical Bath Deposition (CBD). The fabricated nanocomposite sensing layers were characterized. The microstructures and morphologies of pristine PVDF (P), PVDF-TrFE (PT), PVDF/ZnO (P/Z) and PVDF-TrFE/ZnO (PT/Z) with different concentration were characterized by Scanning Electron Microscope (SEM). The degree of crystallinity for P, PT, P/Z and PT/Z was obtained by X-ray Diffraction meter (XRD). In conclusion, PT exhibited better performance in both morphology and crystallinity as a sensing membrane material. More β‐phase in PT was obtained than that in P. ZnO, as a semiconductor filler, would have substantial influence on enhancing the dielectric constant by acting as a nucleating agent and forming a nanostructure with large aspect ratio.
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Singh, Mandeep, Sanjeev Kumar, Shervin Zoghi, Yerli Cervantes, Debaki Sarkar, Saquib Ahmed, Shaestagir Chowdhury i Sankha Banerjee. "Fabrication and Characterization of Flexible Three-Phase ZnO-Graphene-Epoxy Electro-Active Thin-Film Nanocomposites: Towards Applications in Wearable Biomedical Devices". Journal of Composites Science 4, nr 3 (4.07.2020): 88. http://dx.doi.org/10.3390/jcs4030088.
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Perovskite oxides have been used as sensors, actuators, transducers, for sound generation and detection, and also in optical instruments and microscopes. Perovskite halides are currently considered as optoelectronic devices such as solar cells, photodetectors, and radiation detection, but there are major issues with stability, interfacial recombination, and electron/hole mobility. The following work looks into the fabrication of non-toxic ZnO-based lead-free alternatives to perovskite oxides for use as secondary sensors or electron transport layers along with perovskite halides for application in stacked biomedical wearable devices. Three-phase, lead-free, Zinc Oxide-Graphene-Epoxy electroactive nanocomposite thin films were fabricated. The volume fraction of the Graphene phase was held constant at 10%, while the volume fraction of the ZnO phase was varied from 10–70%. The dielectric constant, capacitance, impedance, resistance, and conductance of the samples were measured using an impedance analyzer, and the results were compared as a function of volume fraction of ZnO to understand the electron transport performance of these thin films. The impedance and dielectric spectra of the nanocomposites were recorded over a frequency range of 20 Hz to 10 MHz. The microstructural properties and cross-section of the thin films were analyzed using a Scanning Electron Microscope. The high sensitivity and electron transport properties of the composite could be potentially utilized in biomedical devices at low- and high-frequency ranges.
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Farhadyar, Nazanin, i Mirabdullah Seyed Sadjadi. "Synthesis and Characterization of ZnO-SiO2/Epoxy Nanocomposite Coating by Sol-Gel Process". Journal of Nano Research 16 (styczeń 2012): 1–7. http://dx.doi.org/10.4028/www.scientific.net/jnanor.16.1.
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In this paper, we report preparation of hydrophilic hybrid nanocomposite coatings on glass substrates using Zinc acetate solutions based on 3-glycidoxypropyltrimethoxysilane (GPTMS), epoxy resin, aromatic amine (HY850), polyethylene glycol (PEG) and surfactant (polyoxyethylene(4)laurylether) by the sol-gel process. Furthermore, the effects of PEG addition to the precursor solutions on the hydrophilic property and microstructure of the resultant coating film were studied. The hydrophilic behavior study of the synthesized hybrid was performed by adding different amounts of polyethylene glycol precursor to the hybrid solution. Experimental results show that, among different amounts of PEGs, the best results are obtained by addition of PEGs (400) to the hybrid solution which can decrease the water contact angles down to 16 and using surfactant down to 0, and increase the free surface energy. Coated glass exhibits a higher strength than uncoated glass. Attenuated total reflectance infrared spectroscopic (ATR-IR) technique was used to characterize the structure of the hybrid films. The chemical structure of obtained network affects morphology of the coating. The morphology of the hybrid coatings was examined by transmission electron microscopy (TEM). The hybrid systems have a unit form structure and the inorganic phases were in the nanosize scale,
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Mu, Liwen, Jiahua Zhu, Jingdeng Fan, Zhongxin Zhou, Yijun Shi, Xin Feng, Huaiyuan Wang i Xiaohua Lu. "Self-Lubricating Polytetrafluoroethylene/Polyimide Blends Reinforced with Zinc Oxide Nanoparticles". Journal of Nanomaterials 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/545307.
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ZnO nanoparticle reinforced polytetrafluoroethylene/polyimide (PTFE/PI) nanocomposites were prepared and their corresponding tribological and mechanical properties were studied in this work. The influences of ZnO loading, sliding load, and velocity on the tribological properties of ZnO/PTFE/PI nanocomposites were systematically investigated. Results reveal that nanocomposites reinforced with 3 wt% ZnO exhibit the optimal tribological and mechanical properties. Specifically, the wear loss decreased by 20% after incorporating 3 wt% ZnO compared to unfilled PTFE/PI. Meanwhile, the impact strength, tensile strength, and elongation-at-break of 3 wt% ZnO/PTFE/PI nanocomposite are enhanced by 85, 5, and 10% compared to pure PTFE/PI blend. Microstructure investigation reveals that ZnO nanoparticles facilitate the formation of continuous, uniform, and smooth transfer film and thus reduce the adhesive wear of PTFE/PI.
Rozprawy doktorskie na temat "ZnO based Nanocomposites - Microstructure"
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Chamorro, Coral William. "Microstructure, chemistry and optical properties in ZnO and ZnO-Au nanocomposite thin films grown by DC-reactive magnetron co-sputtering". Thesis, Université de Lorraine, 2014. http://www.theses.fr/2014LORR0253/document.
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Les matériaux composites peuvent présenter des propriétés qu'aucun des composants individuels ne présente. En outre, à l'échelle du nanomètre les nanocomposites peuvent présenter de nouvelles propriétés par rapport à l'état massif ou à des macrocomposites des mêmes composants en raison d’effets de confinement et d’effets quantiques liés à la taille. Les nanocomposites semi-conducteur/métal sont très intéressants en raison de leurs uniques propriétés catalytiques et opto-électroniques et la possibilité de les ajuster facilement. Ce travail de thèse étudie les interactions spécifiques et les propriétés physiques qui se manifestent dans les films minces de ZnO et nanocomposites ZnO-Au synthétisés par pulvérisation magnétron réactive continue. Premièrement, il est observé qu’il est possible d'ajuster les propriétés microstructurales et optiques des couches de ZnO en réglant les paramètres expérimentaux. La croissance épitaxiale de ZnO sur saphir a été réalisée pour la première fois dans des conditions riches en oxygène sans assistance thermique. En outre, une étude des propriétés optiques met en évidence la relation étroite entre les propriétés optiques et de la chimie des défauts dans les couches minces de ZnO. Un modèle a été proposé pour expliquer la grande dispersion des valeurs de gap rencontrées dans la littérature. Deuxièmement, il a été possible de révéler l'influence profonde de l'incorporation de l'or dans la matrice de ZnO sur des propriétés importantes dans des films nanocomposites. En outre, la présence de défauts donneurs (accepteurs) au sein de la matrice ZnO se permet de réduire (oxyder) les nanoparticules d’or. Ce travail de recherche contribue à une meilleure compréhension des nanocomposites semi-conducteurs/métal et révèle le rôle important de l'état de la matrice semi-conductrice et de la surface des particules pour les propriétés finales du matériauComposite materials can exhibit properties that none of the individual components show. Moreover, composites at the nanoscale can present new properties compared to the bulk state or to macro-composites due to confinement and quantum size effects. The semiconductor/metal nanocomposites are highly interesting due to their unique catalytic and optoelectronic properties and the possibility to tune them easily. This PhD work gives insight into the specific interactions and resulting physical properties occurring in ZnO and ZnO-Au nanocomposite films grown by reactive DC magnetron sputtering. The results can be summarized in two points: First, it was possible to tune the microstructural and optical properties of ZnO. Epitaxial growth of ZnO onto sapphire was achieved for the first time in O2-rich conditions without thermal assistance. Also, a study of the optical properties highlights the close relationship between the bandgap energy (E_g ) and the defect chemistry in ZnO films. A model was proposed to explain the large scatter of the E_g values reported in the literature. Second, the deep influence of the incorporation of gold into the ZnO matrix on important material properties was revealed. Moreover, the presence of donor (acceptor) defects in the matrix is found to give rise to the reduction (oxidation) of the Au nanoparticles. This research work contributes to a better understanding of semiconductor/metal nanocomposites revealing the key role of the state of the semiconductor matrix
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Liu, Jinling. "High Volume Fraction Mg-based Nanocomposites: Processing, Microstructure and Mechanical Behavior". Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5810.
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Mg-based metal matrix nanocomposites (MMNCs) with mechanical properties, superior to those of coarse-grained composites, are promising structural materials for applications in the automotive and aerospace industries. The research in this area was primarily focused earlier on either micro-scaled reinforcements or nano-scaled reinforcements with very low volume fractions. MMNCs with high volume fractions have not been explored yet. In this research, we study the processing, microstructures and properties of MMNCs containing ceramic nanoparticles up to 30 vol.%. We first investigated the mechanical alloying of Al2O3 nanoparticles and pure Mg under high-energy ball milling conditions. The phase evolution and their distribution were evaluated as a function of milling time. Then, the thermal stability of the formed nanocomposites was investigated by annealing it at high temperatures. It indicated that an exchange reaction had occurred to a large extent between Mg and Al2O3 resulting in the formation of Al and MgO phases. Additionally, the reaction between Al and un-reacted Mg led to the formation of Mg-Al intermetallics. Due to the reaction between Mg and Al2O3 during the milling and annealing process, we attempted to synthesize Mg/SiC nanocomposites. The mixed powders containing 0, 5, 10 and 15 vol.% SiC were produced by high energy ball milling and then the powders were consolidated via spark plasma sintering. The phase constitutions and microstructures of the Mg/SiC nanocomposites were characterized. SiC nanoparticles (average particle size ~14 nm) appear to be homogeneously dispersed within the matrix, and the average inter-particle spacings of all the Mg/SiC nanocomposites were smaller than 50 nm. Microscopic methods, even at high magnifications did not reveal any significant porosity in the as-processed MMNCs. Mechanical characterization of the Mg/SiC nanocomposites was conducted using the microindentation test. Besides the microhardness test, different intermediate pause times and loading rates were used to evaluate the stiffness and loading rate sensitivity of our samples. The abnormal microhardness and loading rate sensitivity were showed for the Mg-15 vol.% SiC samples. At the same time, the monotonic increase of stiffness with volume fraction was exhibited in the Mg/SiC nanocomposites. Finally, we investigated the quasi-static and dynamic response of Mg/SiC nanocomposites and microcomposites, and discussed the underlying mechanisms. Strain softening was noticed in the milled Mg sample under quasi-static compression. Similarly, the strengthening effect leveling off was also observed in the Mg-15 vol.% SiC samples under either quasi-static or high-strain rate uniaxial compression conditions. No significant plastic deformation was observed in the Mg/SiC nanocomposites. The estimated strain rate sensitivity of all the Mg/SiC nanocomposites in this work was around 0.03, which is much smaller than 0.3 and 0.6, observed for 100 nm and 45 nm grain size pure Mg individually. In particular, the existing models fail in predicting the inverse volume fraction effect, and other mechanisms are yet to be explored. The presence of SiC nanoparticles may play an important role that leads to this difference.Ph.D.
Doctorate
Materials Science Engineering
Engineering and Computer Science
Materials Science and Engineering
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Liang, Xin. "Structure and Thermoelectric Properties of ZnO Based Materials". Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:11191.
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The present dissertation investigates the relationship between the structure and thermoelectric properties of ZnO based materials, with a focus on trivalent element doping on engineering the microstructure and altering the electrical and thermal transport properties. Within the solubility range, the addition of trivalent elements, such as In3+, Fe3+ and Ga3+, is observed to increase the electrical conductivity of ZnO and decrease the thermal conductivity.Engineering and Applied Sciences
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Doddapaneni, Venkatesh. "On the polymer-based nanocomposites for electrical switching applications". Doctoral thesis, KTH, Tillämpad fysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-202702.
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Recent research demonstrated that polymer based nanocomposites (PNCs) have been engineered in order to improve the arc interruption capability of the circuit breakers. PNCs are the combination of nano-sized inorganic nanoparticles (NPs) and polymers, opened up new developments in materials science and engineering applications. Inorganic NPs are selected based on their physical and chemical properties which could make multifunctional PNCs in order to interrupt the electrical arcs effectively. In particular, we presented the PNCs fabricated by using CuO, Fe3O4, ZnO and Au NPs in a poly (methyl methacrylate) (PMMA) matrix via in-situ polymerization method, recently developed method to avoid NPs agglomeration, leading to good spatial distribution in the polymer matrix. Thus, several samples with various wt% of NPs in PMMA matrix have been fabricated. These PNCs have been characterized in detail for the morphology of NPs, interaction between NPs and polymer matrix, and radiative/thermal energy absorption properties. In the next stage, PNCs are tested to determine their arc interruption performance and impact on the electrical arcs of current 1.6 kA generated using a specially designed test set-up. When PNCs interact with the electrical arcs, they generate ablation of chemical species towards core of the electrical arc, resulting in cooling-down the arc due to strong temperature and pressure gradient in the arc quenching domain. This thesis demonstrates for the first time that these engineered PNCs are easily processed, reproducible, and can be used to improve the arc interruption process in electrical switching applications.Ny forskning har visat att polymerbaserade nanokompositer (PNCs) har utformats för att förbättra strömbrytares förmåga att undvika ljusbågar vid överslag. PNCs är en kombination av nanostora oorganiska nanopartiklar (NP) och polymerer, som har öppnat upp för ny utveckling inom materialvetenskap och tekniska tillämpningar. Oorganiska NP väljs baserat på deras fysikaliska och kemiska egenskaper som kan hjälpa PNCs att motverka elektriska ljusbågar effektivt. I synnerhet, presenterade vi PNCs tillverkade genom användning av CuO, Fe3O4, ZnO och Au NP i en poly (metylmetakrylat) (PMMA)-matris via in situ-polymerisationsmetod, nyligen utvecklad för att undvika NP-agglomerering, vilket leder till god rumslig fördelning i polymermatrisen. Därför har flera prover med olika vikt% av NP i PMMA-matris tillverkats. Dessa PNCs har utvärderats i detalj för NP-morfologi, interaktion mellan NP och polymermatris, och strålnings- och värmeenergiabsorption. I nästa skede testas PNCs för att bestämma deras förmåga att undvika ljusbågar och påverkan på de elektriska ljusbågarna av 1,6 kA strömstyrka, genererade med hjälp av en specialdesignad test-set-up. När PNCs interagerar med de elektriska ljusbågarna, genererar de ablation av kemiska ämnen mot kärnan i den elektriska ljusbågen, vilket resulterar i nedkylning av ljusbågen på grund av starka temperatur- och tryckgradienter i området. Denna avhandling visar för första gången att dessa konstruerade PNCs är lätta att framställa, reproducerbara, och kan användas för att förbättra avbrottsprocessen för ljusbågen i elektriska kopplingstillämpningar.
QC 20170303
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Mahadevegowda, Amoghavarsha. "Processing, microstructure and properties of polymer-based nano-composite dielectrics for capacitor applications". Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:fb974b13-2ec5-4104-9f80-45d1cb97eb48.
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The processing and properties of novel polymer-based nano-composite (PNC) dielectrics for capacitor applications has been studied. PNCs were fabricated via a vacuum based deposition technique and their micro/nano-structure, chemical and dielectric properties investigated. After process development and optimisation, co-deposited Al and nylon-6 PNCs had a dielectric constant k∼7 at an approximate Al volume fraction of 0.3 that agreed with analytical predictions if it was assumed that the Al transformed to an oxide in-situ and/or after deposition. The significant effect of absorbed water vapour and temperature on PNC dielectric properties was revealed using different types of post-deposition heat treatment. Alternately-deposited PNCs consisting of Al or Ag 2-20 nm layers sandwiched between nylon-6 layers were fabricated in which the overall PNC Al or Ag volume fraction was controlled by varying the nominal Al or Ag layer thickness. Ag layers comprised of discrete nano-islands that produced a nano-capacitor network effect that increased k to ∼11. In the case of Al layers, when the layer thickness was ≥ 5 nm, corresponding to a nominal volume fraction of 0.1, Al (core)-oxide (shell) nanoparticles were formed and the PNC dielectric constant increased to ∼19. The detailed nano-structure of the core-shell particles was studied using various types of transmission electron microscopy (TEM), and the elevations in dielectric constant ascribed to multiple-interface polarisation effects dependent on the formation of the core-shell structure. PNCs based on alternate deposition of Ti sandwiched in nylon-6, and then both Ti and Ag in nylon-6 were also fabricated, with k reaching ∼73 for Ag+Ti/nylon-6 PNCs. As well as Ti-based core (metal)-shell (oxide) particles, the Ag volume fraction was sufficiently high in the 10 nm nylon-6 layers to again form a nano-capacitor network that contributed to the overall device capacitance and effective dielectric constant. Again, various types of high magnification TEM were critical in resolving the Ti-based core-shell structure and its role in high-k behaviour. The vacuum-based alternate deposition technique has been developed to offer ease of operation, reliability, flexibility and applicability to chemically different filler and matrix systems in the fabrication of high-k PNC based capacitors, in which high-k performance relies critically on the formation of core (metal)-shell (oxide) particles in both Al and Ti based systems.
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Sun, Qianying. "Conducting ceramics based on ZnO co-doped by (Al, Ti, Mg) : microstructure, electronic active defects and electrical properties". Thesis, Le Mans, 2020. http://www.theses.fr/2020LEMA1014.
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Les céramiques conductrices à base de ZnO suscitent un important intérêt pour leurs applications comme varistances, capteurs de gaz, électrodes transparentes, dispositifs piézoélectriques, électro-optiques ou thermoélectriques. Le dopage de ZnO confère aux céramiques formées des propriétés électriques et optiques remarquables caractérisées par une transparence optique modulée, des énergies de liaison élevées pour les excitons, et des conductivités électriques atteignant 0.1 MS.m-1. La grande conductivité de ZnO est intimement liée aux éléments dopants, à la microstructure des céramiques et aux conditions de synthèse et traitements. Les joints de grains, la structure cristalline, le désordre structural et les défauts électroniques contribuent au comportement électrique des matériaux. Le présent travail de thèse s'inscrit dans ce contexte et porte sur la mise en œuvre de méthodes de fabrication de céramiques à base de ZnO co-dopées par des éléments (Al, Ti, Mg) et l'étude de leurs caractéristiques physiques incluant la structure cristalline, la microstructure et le comportement électrique. Ainsi, des études exhaustives ont été menées par des méthodes structurales (RX, Raman), microscopies (MET, MEB) et de résonance magnétique (RPE, RMN) sensible à l'ordre local et aux défauts électroniques actifs. La conductivité est ajustée par la nature des éléments dopants, l'atmosphère de frittage et les méthodes de fabrication par solutions solides ou par frittage flash (SPS). La corrélation "Préparation - Structure - Conductivité" a été établie pour la réalisation de céramiques à base de ZnO avec de fortes conductivités ouvrant la voie à des applications technologiques potentiellesZnO based ceramics with appropriate doping elements show excellent electrical and optical properties such as high exciton binding energies, a modulated optical transparency and high electrical conductivities. Therefore, ZnO based conducting ceramics have been extensively investigated in the aim of their application as resistors, visitors, gas sensors, transparent electrodes, solar cell windows, piezoelectric, electro-optical and thermoelectric devices. The high conductivity of ZnO ceramics up to 0.1MS·m-1 is closely related to the doping elements along with the ceramic microstructure and the processing conditions with particular effects of grain boundaries, crystalline structure and structural disorder within the ceramics. Thus, the present thesis is devoted to the fabrication by sintering under defined conditions (sintering atmospheres, processes) of ZnO based ceramics co-doped by (Al, Ti, Mg) , the investigations and deep analysis of their related properties including crystalline structure, micro-structure and the electrical behavior. Exhaustive studies were developed on the doped ceramics by using structural methods (XRD, Raman), microscopy (TEM, SEM) and magnetic resonance (EPR, NMR) probing the local order and electronic active defects. The conductivity is adjusted by the nature of the structure influenced by the doping elements, the sintering atmosphere, and the sintering method. The correlation "Preparation - Structure - Conductivity" has been established to pave the way for the potential technological applications of highly conducting ZnO-based ceramics
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Lomello, Fernando. "Optimization of nanostructured oxide-based powders by surface modification". Lyon, INSA, 2010. http://theses.insa-lyon.fr/publication/2010ISAL0028/these.pdf.
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This thesis is divided into two parts. The first part deals with the study of surface modification of a transition alumina nanopowder and the second part is devoted to the production and mechanical characterization at room- and high-temperature of Alumina 5 vol. % YAG nanocomposites. In order to study, the effect of the dispersion on a transition alumina several physico-chemical characterization techniques were employed such as the DTA-TG analysis, XRD, BET Specific Surface Area, HR-TEM and the FT-IR spectroscopy. In particular, the transition aluminas present metastable phases which suffer transformations during sintering and induce the formation of a vermicular microstructure, consisting of a network of large pores. As a consequence, the final density and the microstructure have been improved thanks to the dispersion which allowed to achieved higher densities and promotes the transformation into alpha-phase. Moreover , the influence of the dispersion on the transformation kinetics (Kissinger Method), as well as, on the sintering kinetics (SID Method) has been evaluated. In the second part, it is presented the development of Alumina/YAG nanocomposites from two commercial nanopowders naturally sintered and sintered by non-conventional methods, such as HP and SPS. The mechanical characterization at room temperature (Hardness, Toughness, Elastic modulus) has been correlated to a microstructural study (ESEM). Interesting values regarding hardness and toughness have been measured in samples sintering by SPS and HP, around 20GPA and 7 MPA. M1/2, respectively. For the characterization at the high temperature, creep tests were carried in a 4-point bending fixture at 1200°C and an applied stress of 100 Mpa. The results show that mechenical properties depend on the second phase distribution into the alumina matrix. In all cases, the obtains results were interesting
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Pan, Wen-Hsuan, i 潘玟璇. "Relationships between Microstructure and Electrical Properties of ZnO-based Multilayer Varistor". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/79687763111138165381.
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碩士國立臺灣大學
材料科學與工程學研究所
96
The performances of ceramics depend strongly on their microstructures. Recently, ZnO-based multilayer varistors (MLVs) have become available. In the present study, AgPd inner electrodes are used in the multilayered ZnO-based varistors. The microstructure of ZnO-based MLV is affected by sintering temperature, dwell time, layer thickness, additives and so on. The relationships between microstructures and electrical properties of the ZnO-based multilayer varistors are therefore investigated. The results indicate that the breakdown voltage (VB) and nonlinear coefficient (α) are directly controlled by the layer thickness after sintering at 1000°C for 60 min. Although the average size of ZnO grains within MLVs increases with the increasing sintering temperature and time, the effects of secondary phases and discontinuity of AgPd electrodes also affect the electrical properties profoundly. A pyrochlore phase is formed due to the interaction between Bi-rich liquid and spinel phase during heating and cooling stages. The Bi2O3–rich liquid phase can penetrate into the inner electrode and reacts with AgPd to form PdBi2O4. Discontinuity of AgPd electrodes induces the increase of the breakdown voltage and decrease of nonlinear properties. The optimum microstructure and nonlinear ohmic characteristic of the ZnO-based MLV with layer thickness of 10 μm can be obtained by sintering at 1000°C for 60 min.
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Pan, Wen-Hsuan. "Relationships between Microstructure and Electrical Properties of ZnO-based Multilayer Varistor". 2008. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-1707200816273600.
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Wei-TingChen i 陳威廷. "Studies on microstructure and electrical properties of the ZnO-based multilayer varistors with passivation layers". Thesis, 2013. http://ndltd.ncl.edu.tw/handle/50728105711320584190.
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博士國立成功大學
電機工程學系碩博士班
101
Multilayer varistors (MLVs) that have the advantage of a small size, low voltage, and high peak current (PC) capability can fully meet the requirements of electronic equipments. Zinc oxide varistor has become important protection components because of its exceptional non-linear ohmic characteristic. The electrical properties of varistor are associated with microstructure. Thus, many efforts are put on controlling the quantity of grain boundary and homogeneous grain size for better electrical properties. Due to ZnO’s semi-conductive characteristic, a passivation layer needs to be selectively fired on the exposed surface of ZnO-based varistor to prevent over-plating on ZnO surface during the conventional plating process. Moreover, withstand the possible etching through grain boundaries when post application. Therefore, in this dissertation, we study the influence of quantity of grain boundary and grain size on electrical properties. In addition, study the effect of thermal processes on microstructure and properties of ZnO-based multilayer varistor with 3 kinds of passivation layers. Then, propose a better method for having small and homogeneous grain size for better electrical properties. In the first part, ZnO-based multilayer varistor (MLV) with two different dielectric layers (12 and 24 μm) are sintered from 900 to 1000 ℃ for 2 hours. The results show that the grain size linearly increases with sintering temperature, which results in an increase in the capacitance of ZnO-based MLVs. In contrast, the number of grain boundaries between two adjourn electrodes linearly decreases with sintering temperature associated with a decrease in breakdown voltage, leakage current and nonlinear coefficient of ZnO-based MLVs. The energy absorption capabilities determined from the peak current (PC) measurements of ZnO-based MLVs with sintering temperature are reported. The optimum peak currents of ZnO-based MLVs can be obtained by sintering at 950℃. In the second part, The chemical and morphological modification of zinc phosphates as a protection layer for ZnO-based varistor has been made through the addition of Mg or Ca species to the conversion solution combined with the calcinations of zinc phosphates. The results showed that the aspect ratio of as-coated zinc phosphates grains can be greatly reduced through the addition of Mg or Ca species. Moreover, the introduction of calcination to zinc phosphate not only makes the coating layer more dense, smooth, and resistive, but also results in the increase in capacitance, non-linear coefficient (α). On the other hand, loss tangent and breakdown voltage are both slightly decreased with increasing calcination temperatures. In the third part, cofiring (Zn0.9Mg0.1)TiO3 (ZMT) as passivation layer is investigated. A semi-conducting ZnO-based multilayer varistor (MLV) is cofired with a passivation layer with ZMT composition to prevent ZnO-based MLV from over-plating during plating process. The cofiring results show that no de-lamination between ZMT and ZnO can be found; suggesting good co-firing compatibility between ZMT and ZnO though the anisotropic densification of ZMT is noted. However, the microstructure and electrical properties of ZnO based MLV is greatly influenced since ZMT is cofired with ZnO-based MLV. Reduction of grain size of ZnO-based MLV from 4 to 2.7 μm that is presumably attributed to constraining sintering of ZnO-based MLV by ZMT is observed after cofring ZMT. Simultaneously, the reduction of grain size of ZMT covered ZnO-based MLV results in a decrease of capacitance and in an increase of breakdown voltage. On the other hand, a decrease of non-linear coefficient and an increase of leakage current of ZMT covered ZnO-based MLV are observed as well. The results are associated with the change of slope of I–V curve for ZMT covered ZnO-based MLV due to the formation of a semi-conducting Zn2TiO4 phase, which is resulted from the diffusion of titanium ion into the matrix of ZnO-based MLV during co-firing. In the forth part, Al2O3-based constrained layers as passivation layers are investigated. The result showed that performance of a ZnO-based multilayer varistor is affected strongly by the homogeneity of its microstructure. A homogeneous microstructure of a ZnO-based multilayer varistor is attained by using constrained sintering, when nonreactive borosilicate glass + 90 wt% alumina (Al2O3) was used as the constraining layer laminated on both sides of the multilayer ZnO-based multilayer varistor (MLV). The mean grain size and the distribution of grain size of a ZnO-based MLV fired by constrained sintering are both reduced, because an in-plane tensile stress results from constrained sintering in the x–y plane of the multilayer device, which could modify the densification rate of the ZnO-based MLV materials. The leakage current and nonlinear coefficient (α) of ZnO-based MLVs can be greatly improved due to the inhibition of ZnO grain growth when constrained sintering was used instead of free sintering. Note that the energy absorption capabilities in terms of peak current (PC) measurements of ZnO-based MLVs fired by constrained sintering are remarkably improved due to a homogeneous microstructure.
Książki na temat "ZnO based Nanocomposites - Microstructure"
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ZnO bao mo zhi bei ji qi guang, dian xing neng yan jiu. Shanghai Shi: Shanghai da xue chu ban she, 2010.
Znajdź pełny tekst źródłaCzęści książek na temat "ZnO based Nanocomposites - Microstructure"
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Matsui, Tatsuji, Akira Yamakawa i Koichi Niihara. "Fabrication, Microstructure, and Some Properties of Si3N4-Based Nanocomposites". W Grain Boundary Controlled Properties of Fine Ceramics, 219–26. Dordrecht: Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-011-1878-1_22.
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Zahmouli, N., S. G. Leonardi, A. Bonavita, M. Hjiri, L. El Mir, Nicola Donato i G. Neri. "High Performance VOCs Sensor Based on ɣ-Fe2O3/Al-ZnO Nanocomposites". W Lecture Notes in Electrical Engineering, 25–30. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-04324-7_4.
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Pyrz, Ryszard. "Optical and Piezoelectric Properties of ZnO Nanowires and Functional Polymer-Based Nanocomposites". W Frontiers in Materials Science and Technology, 107–10. Stafa: Trans Tech Publications Ltd., 2008. http://dx.doi.org/10.4028/0-87849-475-8.107.
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Liu, Feng Hua, Gao Jie Xu, Lei Duan, Ya Li Li i Ping Cui. "Effect of B2O3 Doping on the Microstructure and Electrical Properties of ZnO-Based Varistors". W High-Performance Ceramics V, 497–99. Stafa: Trans Tech Publications Ltd., 2008. http://dx.doi.org/10.4028/0-87849-473-1.497.
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Cai, Jing Nan, Yuan Hua Lin, Rong Juan Zhao, Ce Wen Nan i Jin Liang He. "Microstructure and Electrical Properties of ZnO-Pr6O11-Dy2O3-Based Varistor Ceramics Doped with La2O3". W Key Engineering Materials, 680–83. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-410-3.680.
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Madkour, Loutfy. "Corrosion Resistance Potential of Metal-Matrix Composites Reinforced With Carbon Nanofibers and Carbon Nanotubes". W Handbook of Research on Corrosion Sciences and Engineering, 135–88. IGI Global, 2023. http://dx.doi.org/10.4018/978-1-6684-7689-5.ch006.
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Carbon nanotubes are attractive and promising fillers due to their chemical inertness and high mechanical, electrical, and thermal properties. From the conjugation of carbon nanotubes with inorganic hybrid, it is expected to obtain nanocomposite coatings that combine high anti-corrosion efficiency with improved mechanical stability. This book chapter presents a concise review of microstructure and corrosion behaviour of different nanotube composite coatings. In the first section, the authors briefly explain the science behind the corrosion and corrosion resistance of nanotube composite coatings, followed by a selection of current state and recent advances on promoted nanotube composite coating: Al, Cu, Mg, Fe, Ni, Mg–Zn, Mg–Al, NiCo, and ZnCo-carbon nanotube composite and based matrix composites coatings. Recent development of graphene reinforced metal matrix nanocomposites has been studied. Challenges needed to be rectified before the synthesis of metal-matrix nanocomposites. Finally, the authors discuss the relevant topics, highlighting recent progress and unresolved questions.
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Rocha, Lizandra Viana Maurat da, Paulo Sergio Rangel Cruz da Silva i Maria Inês Bruno Tavares. "Comparative Study Of Poly (Butylene Adipate Co-Terephthalate) Nanocomposites With Zinc And Molybdenum Oxides". W COLLECTION OF INTERNATIONAL TOPICS IN HEALTH SCIENCE- V1. Seven Editora, 2023. http://dx.doi.org/10.56238/colleinternhealthscienv1-122.
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studies on nanocomposites of biodegradable polymers such as polybutylene adipate co-terephthalate (PBAT) are justified. This polymer is certified for composting; it is printable, suitable for food contact, water resistant, and performs similarly to polyethylene[1, 2] . Metal oxide nanoparticles (NPs) such as MoO3 and ZnO are potential fillers to, in addition to improving mechanical properties, confer antimicrobial, anti-UV activity and modulate the biodegradability of polymer matrices such as that of PBAT[3, 4, 5] . The effects of different concentrations of ZnONPs were observed and compared to MoO3 NPs, whose relevant properties still lack further study. In this work, seven films prepared by casting with CHCl solvent evaporation were studied3 . The tags PBAT, Z1, Z3, Z5, M1, M3 and M5 correspond to the pure polymer samples and their combinations with 0.1; 0.3 and 0.5 % of zinc and molybdenum oxide NPs, by mass, respectively. The Fourier transform infrared spectroscopy (FTIR) ratified the total removal of the solvent and the maintenance of the bands of the main functional groups of the polymeric matrix, even after the incorporation of the NPS. In the thermogravimetric analysis (TGA), only one degradation event was observed for all samples; in M1 and especially in M3 the thermal resistance increased, while, with the addition of zinc oxide, especially in Z5 and Z3, this property was reduced. There was no expressive change in the degradation onset temperature (Tonset ) of M5 in relation to PBAT, suggesting that this concentration of MoO₃ cannot promote increment in the thermal property of this matrix. The X-ray diffraction (XRD) results of M1 and M3 suggested a better dispersion than M5, the only composite in which there was no increase in the degree of crystallinity in relation to pure PBAT, indicating possible agglomeration. In time domain nuclear magnetic resonance (TD-NMR) analysis, the curves of M3 present a narrower base, indicating greater homogeneity and especially good dispersion in this system, corroborating the other analyses. The reduced return time of the magnetization to the longitudinal axis (T1 H) of M5 and the increased molecular mobility of this system were associated with the crystalline rearrangement. When measuring the water activity (aw ) thinking in the application of these films as active packaging, Z3 and M1 stood out, with lower propensity to microbiological attack, and a linear trend (R² > 0.9) was observed for this property with the incorporation of molybdenum nanotrioxide in poly(butylene adipate co-terephthalate). The worst aw data were observed in Z1, with M3 and M5 being similar to Z5. Still, all observed aw values were below the recommended value for food packaging, 0.7 (the value at which susceptibility becomes most relevant). Thus, it was shown to be possible to incorporate zinc and molybdenum metal oxides in the PBAT matrix, via casting, with good distribution and better dispersion of fillers in the range of 0.3% by mass. Moreover, it was observed that different types and proportions of particles resulted in different effects on the microstructure of the matrix (thermal resistance, crystallinity, molecular mobility and water activity), without causing interaction capable of affecting the molecular composition of the material, at levels detectable by FTIR-ATR.
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Goswami, Lalit, Anamika Kushwaha, Shivani Goswami, Yogesh Chandra Sharma, TaeYoung Kim i Kumud Malika Tripathi. "Nanocarbon-based-ZnO nanocomposites for supercapacitor application". W Nanostructured Zinc Oxide, 553–73. Elsevier, 2021. http://dx.doi.org/10.1016/b978-0-12-818900-9.00008-5.
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"Graphene-Based ZnO Nanocomposites for Supercapacitor Applications". W Graphene as Energy Storage Material for Supercapacitors, 181–208. Materials Research Forum LLC, 2020. http://dx.doi.org/10.21741/9781644900550-7.
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Saraswat, Vibhav K. "ZnO nanofillers–based polymer and polymer blend nanocomposites". W Nanostructured Zinc Oxide, 157–86. Elsevier, 2021. http://dx.doi.org/10.1016/b978-0-12-818900-9.00023-1.
Pełny tekst źródłaStreszczenia konferencji na temat "ZnO based Nanocomposites - Microstructure"
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Billings, Christopher, Changjie Cai i Yingtao Liu. "Investigation of 3D Printed Antibacterial Nanocomposites for Improved Public Health". W ASME 2021 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/imece2021-72092.
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Abstract Bacterial infections have been recognized as a critical challenge to public health, resulting in substantial morbidity, mortality, and enormous costs. In this paper, a digital light processing (DLP) based 3D printing system is employed to rapidly manufacture photocurable thermoset polymers and nanocomposites for potential antibacterial applications. This work shows how nanoparticles that present antibacterial properties can be added to traditional DLP manufacturing and their effects on the physical properties. In this paper, titanium dioxide (TiO2) and zinc oxide (ZnO) nanoparticles in the 10 to 30-nm range are mixed with photocurable resins for rapid 3D printing and prototyping. The two resins used are a standard photopolymer rapid resin and an ABS-like photopolymer rapid resin. A 1% composite percentage is utilized to avoid the requirement of modification to the printing system due to greatly increased viscosity. Tensile testing data, contact angle data, and abrasion data are performed on a total of four different composites and two controls. These composites have shown a tensile strength of 29.53 MPa. At the 1% nanoparticle weight concentration, the 3D printing nanocomposites are transparent and demonstrate a complete penetration of particles throughout the entire print. The detailed experimental characterization will be conducted to understand the 3D printed material’s mechanical properties and microstructures fully. This research can enhance public health by providing a novel approach to control the spread of bacteria and other microbial.
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Zhao, Yingjun, Kenneth J. Loh i Donghee Chang. "Piezoelectric and Mechanical Performance Characterization of ZnO-Based Nanocomposites". W 19th Analysis and Computation Specialty Conference. Reston, VA: American Society of Civil Engineers, 2010. http://dx.doi.org/10.1061/41131(370)11.
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Nair, Manjula G., Meenakshi Malakar, Saumya R. Mohapatra i Avijit Chowdhury. "Synthesis of ZnO nanorods and observation of resistive switching memory in ZnO based polymer nanocomposites". W 2ND INTERNATIONAL CONFERENCE ON CONDENSED MATTER AND APPLIED PHYSICS (ICC 2017). Author(s), 2018. http://dx.doi.org/10.1063/1.5032506.
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Lin, Jin-Chein, M. H. Nien i L. C. Chang. "Microstructure and Magnetic Properties of NdFeB Based Nanocomposites to Shock Compression". W ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems collocated with the ASME 2005 Heat Transfer Summer Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/ipack2005-73230.
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Three typical Nd-Fe-B permanent magnetic alloys of Nd13Fe75B6Al6, Nd13Fe79B6Si2 and Nd13Fe80B6Zr1 have been presented to study the effect of annealing and shock compression on the microstructure, magnetic and mechanical properties. The response of NdFeB based nanocomposites mixed with medium particle morphologies of Al, Si and Zr, respectively were conducted under high shock pressure. The starting materials were prepared by rapidly quenching and melt-spinning of NdFeB based powders under vacuum at different temperatures. The magnetic properties on Br, Hci and (BH)max tend to increase with rising annealing temperature, and reach their highest value at either 700° or 750°C. The addition of Zr and Si enhance the chemical short range reaction and stablize the residual amorphous matrix. For recovery shock-consolidate compression, Br and Hci reach to a peak value at about 5.5 GPa which can be closely associated with the retention of nanostructure and strong exchange coupling between hard and soft magnetic phases. Secondly, the main work is to experimentally investigate the mechanics of the deformation processes leading to shock-induced chemical reaction. The results showed that the fracture mechanism on three specific magnetic alloys reveal that the Nd13Fe79B6Si2 sample, and the addition of Zr in NdFeB will lead to embrittlement of the ductile morphology.
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Zhang, C., M. Debliquy i H. Liao. "Microstructure and NO2 Sensing Performance of APS ZnO Coatings". W ITSC2010, redaktorzy B. R. Marple, A. Agarwal, M. M. Hyland, Y. C. Lau, C. J. Li, R. S. Lima i G. Montavon. DVS Media GmbH, 2010. http://dx.doi.org/10.31399/asm.cp.itsc2010p0302.
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Abstract This work studied the possibility of using a sensor based on plasma-sprayed zinc oxide (ZnO) sensitive layer for NO2 detection. The atmospheric plasma spray process was employed to deposit ZnO gas sensing layer and the obtained coating structure was characterized by scanning electron microscopy and X-ray diffraction analysis. The influences of gas concentration, working temperature, water vapor in testing air on NO2 sensing performance of the ZnO sensors were studied. ZnO sensors showed a good sensitivity and selectivity to NO2 at an optimal working temperature.
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Youssef, Ahmed, i Islam EL-Nagar. "Preparation and Characterization of PMMA Nanocomposites Based On Zno-Nps for Antibacterial Packaging Applications". W The 5th World Congress on New Technologies. Avestia Publishing, 2019. http://dx.doi.org/10.11159/icnfa19.105.
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Guan, Huanan, Jialiang Jiang, Dandan Chen, Wei Wang, Yan Wang i Jiaying Xin. "Acetylcholinesterase biosensor based on chitosan/ZnO nanocomposites modified electrode for amperometric detection of pesticides". W 2015 International Conference on Materials, Environmental and Biological Engineering. Paris, France: Atlantis Press, 2015. http://dx.doi.org/10.2991/mebe-15.2015.39.
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Abdul-kareem, Asma Abdulgader, Noura AlSanari, Amal Daifallah, Radwa Mohamed, Jolly Bhadra, Deepalekshmi Ponnamma i Noora Al-Thani. "Piezoelectric Nanogenerators based on Pvdf-Hfp/Zno Mesoporous Silica Nanocomposites for Self-Powering Devices". W Qatar University Annual Research Forum & Exhibition. Qatar University Press, 2020. http://dx.doi.org/10.29117/quarfe.2020.0054.
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Due to the rising global concern over energy catastrophe and environmental issues, attention has been diverted towards future energy. In recent times, rechargeable power and renewable energy sources have been considered as an attractive substitute for resolving the future environmental problems. Among them, mechanical energy is one of the most abundant energy sources, and easily transformable to other useful energy forms, such as electrical energy. For such purposes, piezoelectric materials with ability to convert the mechanical energy generated by various activities into electrical energy. In this research work, we have investigated the morphology, structure and piezoelectric performances of neat polyvinylidene fluoride hexafluoropropylene (PVDF-HFP), PVDF-HFP/ZnO, PVDFHFP/ Mesoporous silica, PVDF-HFP 1% and PVDF-HFP 3% ZnO-Mesoporous silica nanofibers, fabricated by electrospinning. Both SEM and TEM images of ZnO nanoparticles shows formation of uniform flake of about 5nm diameter and Mesoporous silica shows uniform spherical morphology with average diameter of 5 μm. EDX plot justifies the presences of Zn, O and Si. An increase in the amount of crystalline β-phase of PVDF-HFP has been observed with the introduction of ZnO and mesoporous silica in the PVDF-HFP matrix are observed in FTIR spectra. All the XRD peaks observed in neat PVDF has the strongest intensity compared to rest of the other XRD peaks of polymer nanocomposite. The XRD spectra of all the nanocomposites have peaks at 17.8°, 18.6° correspond to α- crystalline phase, the peaks observed at 19°, 20.1° correspond to the γ- crystalline phase, and the peak at 20.6° corresponds to the β- crystalline phase. The flexible nanogenerator manipulated from the polymer nanocomposite with 1% ZnO-Mesoporous silica exhibits an output voltage as high as 2 V compared with the neat PVDF-HFP sample (~120 mV). These results indicate that the investigated nanocomposite is appropriate for fabricating various flexible and wearable self-powered electrical devices and systems.
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Skandani, Amir Alipour, Ayoub Yari Boroujeni i Marwan Al-Haik. "Temperature Dependent Viscoelastic Behavior of FRP/ZnO Nano-Rods Hybrid Nanocomposites". W ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-63326.
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The inclusion of nanomaterials within fiber reinforced plastics (FRPs) could improve their resistance against time dependent deformation. Conceivable high temperature applications of such hybrid composites make it crucial to investigate their temperature-dependent properties as well as their durability. In this study, zinc oxide (ZnO) nano rods were grown on the surface of carbon fibers and the hybridized reinforcement was formed in a laminate composites. The viscoelastic behavior was probed utilizing dynamic mechanical analysis (DMA). The time/temperature superposition principle (TTSP) was invoked to obtain the viscoelastic properties of FRPs based on fibers with different surface treatments. Results indicated that the presence of ZnO nano rods at the interface between the carbon fibers and the epoxy matrix enhances the composite’s creep resistance at elevated temperatures and prolonged duration.
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Cao, Guoping, Hiromi Konishi i Xiaochun Li. "Study on Mechanical Properties and Microstructure of Magnesium/SiC Nanocomposites Fabricated by Ultrasonic Cavitation Based Solidification Processing". W ASME 2007 International Manufacturing Science and Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/msec2007-31165.
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Magnesium, the lightest structural metal, is of significance to improve energy efficiency in various applications. Mg/SiC nanocomposites were successfully fabricated by ultrasonic cavitation based dispersion of SiC nanoparticles in Mg melts. As compared to pure magnesium, the mechanical properties including tensile strength and yield strength of the Mg/SiC nanocomposites were improved significantly, while the good ductility of pure Mg casting was retained. The grain size of the pure magnesium was refined when SiC nanoparticles were added. In the microstructure of Mg/SiC nanocomposites, there are still quite some SiC clusters, but in the areas free of large clusters, the SiC nanoparticles were dispersed very well. TEM study of the interface between SiC nanoparticles and magnesium matrix indicates a good bonding, but no chemical reaction between SiC nanoparticles and magnesium matrix.