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High Temperature Oxidation and Wear Resistance of In Situ Synthesized (Ti3Al?+?TiB)/Ti Composites by Laser Cladding
摘要： (Ti3Al + TiB)/Ti composites were prepared on Ti6Al4V by laser cladding. The microstructures of the coatings were analyzed; the high temperature wear and oxidation properties of the coatings were investigated and compared with Ti6Al4V. Ti3Al and TiB particles were in situ formed through the reaction between Ti and AlB2. The reinforcements exhibited some crystallographic orientation relationships with a-Ti matrix, and a semi-coherent interface (Ti3Al) or a coherent interface (TiB) was obtained. The weight gain of the coating under each combination of temperature and time condition was 20 to 30 pct of the value of Ti6Al4V under the same experimental parameters. A denser and well-bonded TiO2 + Al2O3 layer was formed, effectively hindering the oxygen diffusion compared with the TiO2 layer on Ti6Al4V. EBSD result showed that the Al2O3 mainly assembled into clusters and located close to the interface while the outer area of the oxidation layer was mainly TiO2. The friction coefficients and wear losses of the coatings were lower than those of the substrates at 300 °C to 750 °C. The oxidation was a crucial factor affecting the wear performance at high temperatures. The protective effect of the TiO2 + Al2O3 layer and the formation of transfer films on the worn surface contributed to the improved wear resistance of the coating.
关键词： TiB,Laser Cladding,Wear Resistance,Ti Composites,In Situ Synthesized,High Temperature Oxidation,Ti3Al
更新于2025-11-28 14:24:20
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Electrochemical synthesis of Al–Al <sub/>2</sub> O <sub/>3</sub> composites for selective laser melting
摘要： Novel electrochemical method for obtaining Al–Al2O3 composites for selective laser melting technology has been studied. The electrochemical cell with the flexible cathode and the anode device has been developed. The initial aluminum powder was characterized: aluminum content was more than 99.8 wt %; the average particle diameter was ～40 μm. Oxidized aluminum powder was studied: γ–Al2O3 in the surface oxide layer form was detected; the increase in the particle diameter was 10–20 μm. Electrochemical oxidation technological parameters have been studied. At 0.1 A cm cathodic current density electrolysis duration was 220 min, 24 V voltage along with 80 ° C electrolyte temperature reached. The oxidation mechanism of aluminum particles has been developed. The increase in the surface oxide layer occurred, and this led to an increase in voltage. The 3D object from the oxidized aluminum powder was synthesized by selective laser melting method. The 3D object was perfectly sintered and did not crumble. Good reinforcements distribution in the volume of the synthesized 3D object has been achieved.
关键词： reinforcements,anodic oxidation,electrolysis,aluminum–alumina composites,selective laser melting
更新于2025-11-21 11:24:58
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Conductive treatment of Piezoelectric Composite Material by low-temperature adhesion comparing with ion sputtering
摘要： The surface conductive treatment is an essential step for piezoelectric composite material being application, but until now there are many issues remain to be solved. A conductive adhesion with low curable temperature, low resistivity and high welding spot adhesion strength was obtained for the conductive treatment of piezoelectric composite material. The welding spot adhesion strength was defined at first time. The conductive and adhesion properties were studied comparing with samples treated by ion sputtering. The conductive adhesive with curing agent of EDA has the lowest resistivity of 1.973× 10-4 Ω·cm and the highest welding spot adhesion strength of 7.93MPa.
关键词： Surface conductive treatment,Silver compounds,Adhesive,Piezoelectric Composites
更新于2025-11-21 11:18:25
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Flexible and Ultrasensitive Piezoelectric Composites Based on Highly (00l)‐Assembled BaTiO <sub/>3</sub> Microplatelets for Wearable Electronics Application
摘要： Piezoelectric wearable electronics with flexibility and high sensitivity have received increasing attention in the fields of health monitoring, flexible robots, and artificial intelligence. Here, a flexible organic–inorganic hybrid composite for wearable electronics application based on (00l)-aligned BaTiO3 (BT) single-crystal microplatelets is prepared by layer-by-layer self-assembly technology. For the polyvinylidene fluoride-trifluoroethylene (P(VDF-TrFE))/BT single-crystal microplatelets composite film, the sensitivity is nearly 20 times higher than that of its counterparts of P(VDF-TrFE)/BT microparticles composite film and pure P(VDF-TrFE) film. The orderly alignment of BT microplatelets also has been found advantageous to the strength of the composite film. The tensile strength is up to 204.3 MPa even at a high inorganic phase content of 53.8 wt% in P(VDF-TrFE)/BT single-crystal microplatelets composite film, which is four times that of pure P(VDF-TrFE) film. Moreover, the flexible piezoelectric wearable device based on P(VDF-TrFE)/BT single-crystal microplatelets film effectively provides detailed information for monitoring human activities such as pronunciation, frequency, and waveform of pulse beating, and motion states. This high sensitivity, high strength, and flexible piezoelectric composite provides much potential on the applications of wearable equipments and health monitoring devices.
关键词： organic–inorganic hybrids,wearable sensors,flexible piezoelectric composites,BaTiO3
更新于2025-11-21 11:01:37
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Vanadium salt assisted solvothermal reduction of graphene oxide and the thermoelectric characterisation of the reduced graphene oxide in bulk and as composite
摘要： The solvothermal reduction of graphene oxide (GO), modified by the addition of vanadium chloride, resulted in an increased reduction degree of the reduced graphene oxide (rGO), which is reflected by a remarkably increased electrically conductivity of up to 8.5 S/cm, a value 30 times higher than that of rGO prepared without vanadium salt addition. Parallel with this increase, the thermoelectrical properties of rGO are improved, with a reached maximum Seebeck coefficient of 13.7 μV/K. The rGOs were used as fillers in flexible styrene-butadiene-styrene triblock copolymer composites prepared by solution mixing. Compared to the traditionally prepared reduced graphene oxide, the new product provides up to 60 times higher conductivity to the composite, while the Seebeck coefficient is nearly the same. The highest power factor of 4.6 x 10-4 μW/(m·K2) was achieved at 100 °C with 30 wt% loading, which is 30 times higher than that of the traditional reduced graphene oxide containing composite.
关键词： nanomaterials,functional materials,energy materials,composites,polymers
更新于2025-11-19 16:56:35
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Growth Process and CQDs-modified Bi4Ti3O12 Square Plates with Enhanced Photocatalytic Performance
摘要： Bi4Ti3O12 square plates were synthesized via a hydrothermal route, and their growth process was systematically investigated. Carbon quantum dots (CQDs) were prepared using glucose as the carbon source, which were then assembled on the surface of Bi4Ti3O12 square plates via a hydrothermal route with the aim of enhancing the photocatalytic performance. XRD (X-ray powder diffraction), SEM (scanning electron microscopy), TEM (transmission electron microscopy), UV-vis DRS (diffuse re?ectance spectroscopy), XPS (X-ray photoelectron spectroscopy), FTIR (Fourier transform infrared spectroscopy), PL (photoluminescence) spectroscopy, EIS (electrochemical impedance spectroscopy) and photocurrent spectroscopy were used to systematically characterize the as-prepared samples. It is demonstrated that the decoration of CQDs on Bi4Ti3O12 plates leads to an increased visible light absorption, slightly increased bandgap, increased photocurrent density, decreased charge-transfer resistance, and decreased PL intensity. Simulated sunlight and visible light were separately used as a light source to evaluate the photocatalytic activity of the samples toward the degradation of RhB in aqueous solution. Under both simulated sunlight and visible light irradiation, CQDs@Bi4Ti3O12 composites with an appropriate amount of CQDs exhibit obviously enhanced photocatalytic performance. However, the decoration of excessive CQDs gives rise to a decrease in the photocatalytic activity. The enhanced photocatalytic activity of CQDs-modi?ed Bi4Ti3O12 can be attributed to the following reasons: (1) The electron transfer between Bi4Ti3O12 and CQDs promotes an ef?cient separation of photogenerated electron/hole pairs in Bi4Ti3O12; (2) the up-conversion photoluminescence emitted from CQDs could induce the generation of additional electron/hole pairs in Bi4Ti3O12; and (3) the photoexcited electrons in CQDs could participate in the photocatalytic reactions.
关键词： photocatalytic mechanism,photodegradation of RhB,CQDs@Bi4Ti3O12 composites,Bi4Ti3O12 square plates,CQDs
更新于2025-11-19 16:46:39
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A facile synthesis of palladium encased Ag nanowires and its effect on fluorescence and catalysis
摘要： A facile polyol synthetic route was designed to prepare an ultra thin Pd nano sheath over Ag nanowires (NWs) forming metal-metal core–shell nanocomposites. Here we report the one pot synthesis of Pd assembly onto growing Ag NWs. Pd salts were reduced over varied time intervals during the growth process of the Ag NWs. The Pd salt was introduced after 20, 30- and 40-minutes to the growing Ag NWs. The product was designated as Ag@Pd 20, 30, and 40 on basis of introducing interval. The morphology and constituents of each product was observed using SEM coupled with EDX. XRD was employed to characterize composite material. UV-Visible was used to determine the SPR of each material along with the pure Ag NWs and palladium nanoparticles. Similarly, ?uorescence of each product was characterized using PL spectrophotometer, which was correlated with core and sheath. Finally, the catalytic reduction of nitrophenol into amino phenol by ultra thin sheet of Pd of each product was investigated and reaction order was ascertained.
关键词： core@shell,?uoroscence,catalytic reduction,Pd-Ag composites
更新于2025-11-19 16:46:39
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Dielectric tunable properties of Ba0.5Sr0.5TiO3?Mg2TiO4?MgO composite ceramics prepared by spark plasma sintering
摘要： Ba0.5Sr0.5TiO3?Mg2TiO4?MgO composite ceramics were prepared by spark plasma sintering (SPS) technique and their phase composition, microstructures and dielectric tunable properties were studied. With increasing Mg2TiO4?MgO content, the dielectric peaks of Ba0.5Sr0.5TiO3?Mg2TiO4?MgO composite ceramics were broadened and suppressed. The tunability of Ba0.5Sr0.5TiO3?Mg2TiO4?MgO composite ceramics first increased and then decreased with the increase of Mg2TiO4?MgO content. For Mg2TiO4?MgO content ≤ 50 wt%, Ba0.5Sr0.5TiO3?Mg2TiO4?MgO composite ceramics showed higher tunability and lower permittivity than pure Ba0.5Sr0.5TiO3, which can be attributed to the suppression of the doping effect by SPS. The contradiction between reduced permittivity and enhanced tunability in ferroelectric-dielectric composites was resolved.
关键词： Dielectrics,Ferroelectric ceramics,Spark plasma sintering,Composites
更新于2025-11-14 17:28:48
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Engineered thiol anchored Au-BaTiO3/PVDF polymer nanocomposite as efficient dielectric for electronic applications
摘要： In modern electronic and electric appliances industries, polymer nanocomposites-based capacitors comprising of high dielectric constant ceramics (eg. BaTiO3 (BT), SrTiO3, CaCu3Ti4O12, etc.) and polymers (eg. polyvinyledene fluoride (PVDF), polyethylene terephthalate (PET), polycarbonate (PC), etc.) are becoming attractive for electrical energy storage applications. High dielectric constant fillers improve the energy density of the capacitors but at the cost of decreased efficiency, large dielectric loss as well as electrical conduction at high fields. In this paper, we present novel dielectric core-satellite BT-Au NPs for high energy density capacitor application. Hydroxylated barium titanate nanoparticles (BTO NPs) were immobilized with gold (Au) nanoparticles of size ~4 nm and were used as fillers into PVDF polymer matrix. The results show that the incorporation of Au on BaTiO3 nanoparticles improved the dielectric constant, energy density as well as efficiency, while reduction in the dielectric loss. To further improve the dielectric properties, Au-BTO NPs were coated with 2,3,4,5,6-Pentafluorothiophenol (PFTP) layer. The dielectric properties were further tuned with different PFTP concentrations. The PFTP serves as the bridge between nanoparticle and PVDF polymer by forming hydrogen bonding. The dielectric properties were measured at two different PFTP concentrations (PFTP1 and PFTP1.5, where 1 and 1.5 refers to the molar ratio of PFTP and Au decorated BaTiO3). The lower PFTP concentration results in improved dielectric properties, while increasing the concentration decreases the overall performance of the capacitors. The energy density of PFTP1@Au@BTO/PVDF was 2.04 J cm-3 at ~2100 kV cm-1 which was ~21% higher than that of PVDF and 70% higher than biaxially oriented polypropylene (BOPP), a present state-of-the art dielectric polymer. Thus, the combination of both, Au decoration on BT NPs and hydrogen bonding of PFTP with PVDF chains are responsible for improved dielectric properties and make these nanocomposites a promising candidate for energy storage applications.
关键词： Dielectrics,BaTiO3 nanoparticles,Polymer composites,Capacitors
更新于2025-11-14 17:28:48
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Matrix-Independent Highly Conductive Composites for Electrodes and Interconnects in Stretchable Electronics
摘要： Electrically conductive composites (ECCs) hold great promise in stretchable electronics due to their printability, facile preparation, elasticity, and possibility for large area fabrication. A high conductivity at steady state and during mechanical deformation is a critical property for ECCs, and extensive efforts have been made to improve the conductivity. However, most of those approaches are exclusively functional to a specific polymer matrix, restricting their capability to meet other requirements such as the mechanical, adhesive and thermomechanical properties. Here we report a generic approach to prepare ECCs with conductivity close to that of bulk metals and maintain their conductivity during stretching. This approach iodizes the surfactants on the commercial silver flakes, and subsequent photo exposure converts these silver iodide nanoparticles to silver nanoparticles. The ECCs based on silver nanoparticles-covered silver flakes exhibit high conductivity because of the removal of insulating surfactants as well as the enhanced contact between flakes. The treatment of silver flakes is independent of the polymer matrix and provides the flexibility in matrix selection. In the development of stretchable interconnects, ECCs can be prepared with the same polymer as the substrate to ensure strong adhesion between interconnects and the substrate. For the fabrication of on-skin electrodes, a polymer matrix of low modulus can be selected to enhance conformal contact with the skin for reduced impedance.
关键词： conductive composites,human-machine interface,on-skin electronics,electrophysiological monitoring,iodization,silver nanoparticles,silver flakes
更新于2025-11-14 17:28:48