Micron-sized Powders Research Articles

Low resistivity achieved through enhanced sintering activity in silver paste with submicron particles created through nanoparticle self-assembly

Silver powder’s size and dispersion affect the performance of conductive silver paste. Micron-sized silver powder has good dispersibility but poor sintering activity at low temperatures. In contrast, silver nano-powder sinters at low temperatures but tends to agglomerate. To address the aforementioned issues, this paper employs a chemical reduction method to prepare high-sintering-activity submicron spherical silver powder with a large number of nanoscale bumps on its surface. The study investigates the effects of various factors on the surface morphology and particle size distribution of the silver powder, including the amount of citric acid added, the speed of the reducing agent’s addition, the pH value, and the temperature of the reaction solutions. In addition, silver pastes with varying silver powder contents (60, 70, 80, and 85 wt. %) were prepared to test their resistivity. The results indicate that the lowest resistivity of 8.9 × 10−6 Ω cm was achieved when the silver powder content was 85 wt. % and the conductive silver paste was sintered at 250 °C for 30 min. Furthermore, the prepared conductive silver pastes maintained good resistivity even when sintered at low temperatures.

Development of an epoxy-metallic powder sublayer for the cold spray metallization of carbon-fiber reinforced thermoset composites

This paper investigates the development of a composite sublayer for the cold spray metallization of carbon-fiber reinforced thermoset composites. The hybrid sublayer/carbon-fiber reinforced structure is prepared using a vacuum assisted infusion process. The sublayer consists of a mixture of epoxy with micron-sized metallic powder particles and is directly embedded onto the carbon-fiber reinforced structure during the infusion process. During the cold spray metallization, the erosion of this biphasic sublayer has the capability to produce a metal-to-metal bonding between the cold sprayed powder particles and the sublayer powder particles. The mechanical response of the sublayer due to the high-speed collision of the cold spray powder is investigated using a computational analysis. A decohesion at the epoxy/metallic particle interface within the sublayer, along with the fragmentation of the epoxy matrix upon impact, eases an erosion that prevents the coating formation onto the sublayer. The erosion/coating formation strongly depends on the mechanical property of the spray powder compared to the powder of the sublayer. In the case of a sublayer made of soft metal particles, the plastic deformation during the high-speed collision is better absorbed by such a biphasic sublayer. This circumstance is conducive to an adhesion of the sprayed particles onto the sublayer despite an occurrence of an erosion. Thus, the cold spray deposition of Cu powder onto a biphasic epoxy/Al sublayer results in deposit formation, with Cu particles bonding to Al particles and anchoring to the epoxy matrix.

Role of the Magnus effect in additive manufacturing at the scale of the micron-sized powders within the supersonic gas flow of cold spraying

Role of the Magnus effect in additive manufacturing at the scale of the micron-sized powders within the supersonic gas flow of cold spraying

Post-outburst coal pulverization: Experimental insights with representative accident samples

ABSTRACT Coal and gas outburst accidents pose a serious threat to safe coal mining. Coal pulverization and transportation are integral to outbursts, aiding in understanding outbursts process and holding great potential for elucidating outburst mechanisms. However, the lack of on-site coal sample makes it challenging to assess coal pulverization characteristics during outbursts. We collected coal samples from the forefront of five outburst sites in typical tectonic areas over the past decade. Three coal powders and coal blocks underwent particle size, low-pressure N2/CO2 adsorption and adsorption/desorption experiments to characterize their coal-gas properties. The impact of coal pulverization on coal transportation and outburst initiation was evaluated based on energy conservation principles. The results indicate that the particle size range of coal blocks is 0.27 μm to 2.6 mm, with over 50% consisting of particles smaller than 50 μm. The formation of micron-sized outburst coal powder is associated with tectonic movements. Pulverization increases micropore and some mesopore pore volume, and specific surface area initially increases and then decreases with decreasing particle size. The ultimate adsorption capacity of outburst coal at three particle sizes ranges from 16.8 to 36.0 m3/t. Pulverization affects gas adsorption capacity by influencing micropore volume. The methane desorption velocity within the first 60 s ranged from 0.0091 to 0.0998 ml/g/s, with the minimum particle size being 1.6 to 4.4 times the maximum particle size. Coal pulverization leads to an increase in pore quantity, a reduction in pore length, and the disappearance of high adsorption potential pores, resulting in rapid methane desorption. In the five outbursts, 246 to 25,580 m3 (30°C, 0.1 MPa) of desorbed gas is involved in coal transport. This requires gas desorption velocities ranging from 0.014 to 0.171 ml/g/s, with coal particle sizes reaching 5–875 μm. The abundant presence of micron-sized coal powder is essential for outburst initiation and sustained coal ejection, considerably increasing the risk of outbursts in tectonic coal seams.

MXene-Vitrimer Nanocomposites: Photo-Thermal Repair, Reinforcement, and Conductivity at Low Volume Fractions Through a Percolative Voronoi-Inspired Microstructure.

An innovative process to multifunctional vitrimer nanocomposites with a percolative MXene minor phase is reported, marking a significant advancement in creating stimuli-repairable, reinforced, sustainable, and conductive nanocomposites at diminished loadings. This achievement arises from a Voronoi-inspired biphasic morphological design via a straight-forward three-step process involving ambient-condition precipitation polymerization of micron-sized prepolymer powders, aqueous powder-coating with 2D MXene (Ti3C2Tz), and melt-pressing of MXene-coated powders into crosslinked films. Due to the formation of MXene-rich boundaries between thiourethane vitrimer domains in a pervasive low-volume fraction conductive network, a low percolation threshold (≈0.19vol.%) and conductive polymeric nanocomposites (≈350 Sm-1) are achieved. The embedded MXene skeleton mechanically bolsters the vitrimer at intermediate loadings, enhancing the modulus and toughness by 300% and 50%, respectively, without mechanical detriment compared to the neat vitrimer. The vitrimer's dynamic-covalent bonds and MXene's photo-thermal conversion properties enable repair in minutes through short-term thermal treatments for full macroscopic mechanical restoration or in seconds under 785nm light for rapid localized surface repair. This versatile fabrication method to nanocoated pre-vitrimer powders and morphologically complex nanocomposites is compatible with classic composite manufacturing, and when coupled with the material's exceptional properties, holds immense potential for revolutionizing advanced composites and inspiring next-generation smart materials.

Rapid Synthesis of Nanoporous Zn Powder by Selective Etching of Al from Micrometer-Sized Zn-Al Powder Particles Produced by Gas Atomization and Its Application in Hydrogen Generation.

The scalable synthesis of non-precious nanoporous metals, such as nanoporous zinc (NP-Zn), nanoporous iron (NP-Fe), and nanoporous aluminum (NP-Al), is crucial for large-scale production of hydrogen through the reaction between non-precious metals and water. The fabrication of bulk NP-Zn by selective removal of Al from sub-centimeter-sized arc-melted Zn-Al parent alloys through free corrosion dealloying usually takes a few days. Here, we demonstrate that this free corrosion dealloying process can be reduced from a few days to 4 min simply using micrometer-sized Zn-Al powder particles with nominal composition Zn40Al60 atomic % produced by gas atomization as the parent alloy. Reducing the size of the parent alloy significantly enhances the dealloying rate. Furthermore, Al and Zn are phase-separated in Zn-Al powder particles due to the gas atomization process, making removing the sacrificial Al phase easy. We used various techniques, including X-ray diffraction, Xe+ plasma focused ion beam/scanning electron microscopy (FIB/SEM), energy-dispersive spectroscopy (EDS), and inductively coupled plasma optical emission spectroscopy (ICP-OES) to thoroughly characterize these materials before and after free corrosion dealloying. The fabricated NP-Zn powder exhibits a hierarchical ligament/pore morphology, with tiny structures with a size of ≈10 nm coming from Zn nanoparticle aggregation during dealloying and large structures in the range of ≈50-200 nm coming from the removal of the sacrificial Al phase. We demonstrate that this NP-Zn can spontaneously react with water at near-neutral pH to produce hydrogen and zinc oxide solid byproducts with a hydrogen generation yield of ≈52% within 60 min.

Ion Transport Enhancement Mechanism in Polymer/Ceramic Composite Electrolyte with High-Entropy Li-Garnet

Given the growing demand for electrification, delivering safe, high power, and high energy in lithium-ion batteries is a key challenge. One possible approach is incorporating Li-ion conductive ceramics into a polymer electrolyte matrix. Benefiting from both components, composite electrolytes may deliver high safety, improved ionic conductivity, enhanced electrochemical stability, and feasible construction for solid-state batteries. Specifically, it is crucial to understand and verify the ion transport enhancement mechanism in such a composite electrolyte, as the conductivity in the electrolytes directly affects the overall cell performance and the electrolyte design principles for these systems may change.In this work, we investigate the ion transport enhancement mechanism in composites made with a single-ion conducting (SIC) polymer electrolyte with high-entropy Li-garnet (HE-LLZO) micron-sized powders. We use broadband dielectric spectroscopy (BDS), thermal gravimetric analysis (TGA), rheology measurement and proton nuclear magnetic resonance (1H NMR) to understand the ion transport kinetics in the composites. At 30 °C, 30 wt% HE-LLZO composites with SIC polymer showed almost 8-fold enhancement in conductivity. The addition of HE-LLZO leads to the different degree of polymerization compared to that of the pure polymer, implying that the substantial amount of unpolymerized monomer facilitated the conductivity in the composites. To further investigate the reaction mechanism in the composites, Fourier transform infrared (FT-IR) spectroscopy results will be presented along with 1H NMR data. Electrochemical properties and cell performance will be compared to further illustrate the effects of HE-LLZO on the composite. Acknowledgements This work was supported as part of the Fast and Cooperative Ion Transport in Polymer-Based Materials (FaCT), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences at Oak Ridge National Laboratory under contract DE-AC05-00OR22725.

Effect of powder size on the moldability and pore characteristics of porous tungsten by injection molding

Component shape and pore structure are crucial to the application of porous tungsten, and are significantly affected by the powder size. In this work, porous tungsten with complex shape and controllable pore structure were prepared by the combination of jet milling and injection molding, and the effects of powder size (5, 2 and 0.6 μm) on jet milling, injection molding and pore structure were systematically investigated. The results showed that in contrast to the complete dispersion observed with micron-sized powders, ultrafine powder still had residual agglomerations after jet milling, which further led to a relatively low critical solid loading (47 %) and moldability index (αstv=1.85) during injection molding. For porous pore structure, finer powder was more conducive to obtain smaller pore size and more complex pore structure. At the same porosity (27 %), with the decrease of powder size, the pore size decreased from 1028 nm to 552 nm and 350 nm, and the corresponding fractal dimension increased from 2.19 to 2.84 and 2.99. In contrast, the compressive strength increased as the powder size decreased, rising from 488 MPa to 640 MPa and 883 MPa. The establishment of the relationship between powder size, moldability, and pore characteristics provides valuable insights for the raw powder selection and pore structure control, which is of great significance for the precise preparation and application promotion of porous tungsten.

Tribological behavior of hybrid Aluminum-TiB2 metal matrix composites for brake rotor applications

This research investigates the feasibility of hybrid aluminum metal matrix composites (MMC) incorporating TiB2 particles for brake rotor applications. The composites were produced by incorporating both in-situ, submicron-sized TiB2 particles and regular micron-sized TiB2 powders via stir and squeeze casting techniques into A206 aluminum alloy matrix. Systematic adjustments in the fractions of in-situ and ex-situ TiB2 particles were conducted to evaluate their impact on wear behavior and mechanisms. Combination of both particle types allowed composites with up to 10 vol% of reinforcements. Composites with higher proportions of ex-situ particles demonstrated increased wear resistance compared to those solely composed of in-situ particles, control specimens without TiB2, and conventional cast iron counterparts. The lowest wear rate for the hybrid composites sliding against phenolic brake pads was 1.1 × 10−5 mm3/Nm, signifying a 3-fold reduction relative to cast iron sliding against the same pads. Wear analysis elucidated distinctive mechanisms within the hybrid composites, characterized by mild fragmented abrasive wear, adhesive wear, and plastic deformation, accompanied by the formation of an intermixed tribo-oxide layer.

Anti-icing and de-icing properties of composite superhydrophobic coating with microwave heating performance on asphalt pavement

Severe icing on asphalt pavements significantly impacts traffic safety and efficiency. Superhydrophobic coatings exhibit excellent hydrophobic and anti-icing properties, making them suitable for asphalt pavements. However, the formation of dense and hard ice limits their anti-icing effectiveness in cold regions. Within this paper, we have developed a novel composite superhydrophobic coating (CSC) with microwave heating performance by constructing a hierarchical structure using carbon nanotubes and incorporating micron-sized iron powder as a primary microwave-absorbing material. Scanning electron microscopy, 3D confocal microscopy, and contact angle tests reveal that the optimally mixed CSC possesses a complex micro-nano hierarchical structure, superhydrophobic properties (contact angle of 155.4°), and excellent anti-icing properties. Microwave heating results show that the CSC achieves a maximum heating rate of 1.108 ℃/s and an energy utilization efficiency of 47 %, representing improvements of 118.1 % and 18.3 % compared to uncoated specimens. Durability tests indicate that after wear, the CSC's contact angle decreases by 6.2 %, and the microwave heating rate drops by 13.7 %. Despite these reductions, the coating still maintains high hydrophobicity and microwave heating performance. While the friction coefficient of CSC-coated pavement decreases to μ=0.63, it still meets regulatory requirements. Overall, the application of CSC can effectively increase de-icing efficiency and mitigate the adverse effects of ice and snow on pavements.

Preparation of CIP@Fe3O4 particles and their impact on the fenton reaction processing performance of single-crystal SiC

This study proposes the preparation of CIP@Fe3O4 composite magnetic particles, which maintain excellent magnetic properties while exhibiting superior Fenton reaction performance for the magnetorheological chemical polishing of single-crystal SiC. The CIP@Fe3O4 particles were prepared by coating a nanoscale layer of Fe3O4 onto micron-sized carbonyl iron powder (CIP) using the co-precipitation method. Their Fenton reaction performance and magnetic properties were characterized, and CIP@Fe3O4 was used as a solid-phase catalyst in Fenton reaction-induced etching, frictional wear, and polishing experiments on single-crystal SiC. The prepared CIP@Fe3O4 particles have a saturation magnetization of 184.3 emu/g, representing only an 8.7 % reduction compared to CIP, yet achieved a decolorization rate of 76.2 % for the methyl orange indicator (compared to only 17.2 % with CIP alone). The Fenton reaction using CIP@Fe3O4 resulted in a prominent corrosion layer on the surface of single-crystal SiC, with the oxygen atomic fraction reaching 22.15 %. The study examined material removal from SiC under Fenton reactions with different solid-phase catalysts: CIP, CIP@Fe3O4, and CIP + Fe3O4. Frictional wear results indicated that the maximum scratch cross-sectional removal area on the SiC surface under the Fenton reaction with CIP@Fe3O4 was 474.38 μm2, representing a 207.3 % increase compared to without the Fenton reaction. Additionally, Si-O compounds were identified in the debris. Polishing experiments showed that the material removal rate (MRR) with the Fenton reaction was 3295 nm/h, an increase of 220.2 % compared to without the Fenton reaction, and the surface roughness was reduced to Ra 0.895 nm, a 73.4 % reduction compared to without the Fenton reaction. This study provides additional evidence for the application of magnetorheological technology and the Fenton reaction in the polishing field of single-crystal SiC.

Temperature-irrelevant superhydrophobic polyimide–SiO2 aerogels with a confined shrinkage strategy for high-temperature thermal protection (>400 °C)

Polyimide (PI) aerogels often experience substantial volume shrinkage when exposed to temperatures above 200 °C. Furthermore, research regarding the hydrophobic characteristics of PI aerogels under high-temperature conditions is limited. Herein, a confined shrinkage strategy was proposed, and the PI–SiO2 aerogels were prepared with ultralow thermal shrinkage and high-temperature superhydrophobic properties. Micrometer-sized silica aerogel powders were used in this strategy as shrinkage inhibitors during the production of PI aerogels. The silica aerogel powders were then pulled together using the PI chain and braced to each other, limiting the shrinkage of the PI aerogel matrix attached to the powders. Results indicated that the prepared aerogel experienced a shrinkage of only 6.2 % after heat treatment at 400 °C for 1 h in a muffle furnace. The surface area of the sample decreased from 669 m2/g to 649 m2/g after heat treatment, revealing a reduction of only 2.7 %. Previous studies have never reported this remarkable thermal stability. Furthermore, the aerogel exhibited superhydrophobic properties with a water contact angle of 157.4° and a water rolling angle of approximately 0° at 300 °C due to its high surface roughness.

Hierarchically Porous Structured Adsorbents with Ultrahigh Metal-Organic Framework Loading for CO2 Capture.

Metal-organic frameworks (MOFs) have emerged as promising candidates for CO2 adsorption due to their ultrahigh-specific surface area and highly tunable pore-surface properties. However, their large-scale application is hindered by processing issues associated with their microcrystalline powder nature, such as dustiness, pressure drop, and poor mass transfer within packed beds. To address these challenges, shaping/structuring micron-sized polycrystalline MOF powders into millimeter-sized structured forms while preserving porosity and functionality represents an effective yet challenging approach. In this study, a facile and versatile strategy was employed to integrate moisture-stable and scalable microcrystalline MOFs (UiO-66 and ZIF-8) into a poly(acrylonitrile) matrix to fabricate readily processable, millimeter-sized hierarchically porous structured adsorbents with ultrahigh MOF loadings (∼90 wt %) for direct industrial carbon capture applications. These structured composite beads retained the physicochemical properties and separation performance of the pristine MOF crystal particles. Structured UiO-66 and ZIF-8 exhibited high specific surface areas of 1130 m2 g-1 and 1431 m2 g-1, respectively. The structured UiO-66 achieved a CO2 adsorption capacity of 2.0 mmol g-1 at 1 bar and a dynamic CO2/N2 selectivity of 17 for a CO2/N2 gas mixture with a 15/85 volume ratio at 25 °C. Furthermore, the structured adsorbents exhibited excellent cyclability in static and dynamic CO2 adsorption studies, making them promising candidates for practical application.

Synthesis of uniform spherical silver powder without dispersants in a confined impinging-jet reactor

Sliver powder is the most common and extensively utilized precious metal powder in electronics, primarily for electronic paste. Herein, micron-sized spherical silver powder was synthesized via a liquid phase reduction method employing silver nitrate as the source of silver and ascorbic acid as the reducing agent in a confined impinging jet reactor (CIJR). The impact of the molar ratio between silver nitrate and ascorbic acid, the flow rate, and the temperature on the particle size of silver powder was investigated. The optimal process conditions for silver powder are as follows: maintain a molar ratio of 1:1 and control the feeding rate at 10 ml/min while operating at 50 ° C. The confined impinging jet reactor offers enhanced control over reaction conditions during the synthesis of silver powder, surpassing the capabilities of traditional batch reactors. The aforementioned optimized methodology was employed to successfully synthesize uniform and spherical silver powder (with an aspect ratio approaching 1) in the low Reynolds number jet, resulting in an average particle size of d50 = 0.83 μm and a standard deviation of 0.07, without the addition of dispersant. The synthesis method presented here improves the performance of silver powder, simplifies the production process, reduces energy consumption, and minimizes waste generation. These advances yield significant environmental and economic benefits. In the future, with the continuous development and optimization of microreactor technology, this synthesis method is anticipated to play a more prominent role in the commercial-scale production and application of micrometer-sized silver powder.

Chemical strengthening of glass powder particles

It is well known that chemical strengthening of glass brings the benefit of increased fracture strength. Despite extensive research on processing and mechanics at the macroscale, the effectiveness of chemical strengthening on glass elements with all three dimensions in the micrometer regime remains largely unexplored. Here, we develop a novel process for chemical strengthening of micrometer-sized spherical glass powder particles and study the fracture behavior of these particles with in-situ particle compression tests inside a scanning electron microscope. Cross-sectional microscopy and energy dispersive spectroscopy measurements confirm ion exchange and show an increase in diffusion depth with an increase in processing time and temperature. We report a higher fracture strength for chemically strengthened powder particles compared with the as-received ones. We show that the increase in fracture strength is associated to the compressive residual stress resulting from ion exchange during chemical strengthening.

Achieving high strength and ductility in Inconel 718: tailoring grain structure through micron-sized carbide additives in PBF-LB/M additive manufacturing

ABSTRACT Few attempts have been made so far to develop modifiers for in situ use in Inconel 718 PBF-LB/M fabrication. Reports show an increase in tensile strength compared to unmodified counterparts. However, significant ductility reduction is observed, outweighing the mere tensile strength improvements when considering practical applications. In this study, micron-sized powder modifiers (NbC, TiC, and B4C) were added in proportions of 0.6 wt.% (NbC and TiC) and 0.2 wt.% (B4C) to Inconel 718 powder for PBF-LB/M processing. These modifiers allowed for grain structure control during heat treatment, including hot isostatic pressing. The addition of NbC resulted in a finer grain structure, while the addition of TiC preserved the as-built grain structure after heat treatment. Carbide precipitates led to uniform GND distribution and promoted uniform stress distribution. We show that the trade-off between strength and ductility in carbide-modified IN718 can be overcome by careful PBF-LB/M processing and heat treatment.

Rheological Behavior of SiO2 Ceramic Slurry in Stereolithography and Its Prediction Model Based on POA-DELM.

Ceramic slurry is the raw material used in stereolithography, and its performance determines the printing quality. Rheological behavior, one of the most important physical factors in stereolithography, is critical in ceramic printing, significantly affecting the flow, spreading, and printing processes. The rheological behavior of SiO2 slurry used in stereolithography technology is investigated in the current research using different powder diameters and temperatures. The results present the apparent non-Newtonian behavior. The yielding characteristics occur in all cases. For single-powder cases, the viscosity decreases when the powder diameter is increased. When the nano-sized and micro-sized powders are mixed in different proportions, a more significant proportion of micron-sized powders will decrease the viscosity. With an increase in the nano-sized powders, the slurry exhibits the shear thinning behavior; otherwise, the shear thickening behavior is observed. Thus, the prediction model is built based on the use of the pelican optimization algorithm-deep extreme learning machine (POA-DELM), and the model in then compared with the fitted and traditional models to validate the effectiveness of the method. A more accurate viscosity prediction model will contribute to better fluid dynamic simulation in future work.

Graphene powders as new contact nanopesticides: Revealing key parameters on their insecticidal activity for stored product insects

The overuse and reliance on pesticides has caused insects to develop resistance with global concerns. To address this problem extensive research is directed to find new and sustainable alternatives using chemical-free and resistance-free solutions for pest control. This paper presents a comprehensive investigation of the insecticidal properties of several types of industrially produced graphene powder materials such as graphene and graphene oxide (GO) with micro- and nano size and different structural and chemical properties as new contact nanopesticides against three major stored grain insects: the rice weevil Sitophilus oryzae (L.), the lesser grain borer, Rhyzopertha dominica (F.)˙ and the larger grain borer, Prostephanus truncatus Horn. Bioassays were performed using different concentrations, i.e., 0, 100, 500 and 1000 ppm of graphene powders on the mortality of selected adult insects recorded after 3, 7, 14, and 21 days of exposure and progeny production after 65 days. Results showed that graphene oxide (GO) has no insecticidal efficacy while graphene powders with nano-size particles showed significantly enhanced insecticidal performance compared to micron-size graphene powders. The observed insecticidal effects are explained by the higher probability that nano-sized graphene particles adhere on the insect body compared to large particles. The mortality is proposed as the result of physical mode of action of attached graphene nanoparticles causing stronger interruption of the protective cuticle layer, gas respiratory functions and faster mortality. The findings of this study revealed that it is important to select graphene materials with optimal structural and interfacial properties to achieve the highest insecticidal performance in potential development of a new generation of sustainable insecticides.

Synthesis of Mesoporous Tetragonal ZrO2, TiO2 and Solid Solutions and Effect of Colloidal Silica on Porosity.

Metal oxides possessing a large surface area, pore volume and desirable pore size provide more varieties and active industrial potentials. Nevertheless, it is very challenging to produce crystal metal oxides while keeping satisfactory porosity features, especially for ternary compositions. High temperature is usually needed to produce crystal metal oxides, which readily leads to the collapse of the pore structure. Herein, by employing a 'soft' dispersant agent and a hard silica template, ZrO2, TiO2 and Zr-Ti solid solutions having a tetragonal crystal structure are produced and the silica-leached materials are characterized from macroscopic to atomistic scales. The micron-sized particulate powders are composed of nanoscale 'building blocks', with crystallite sizes between ~8 and 21 nm. These polycrystalline ceramic powders exhibit a high specific surface area (up to ~200 m2·g-1) and pore volume (up to 0.5 cm3·g-1), with a pore size range of ~5-20 nm. Importantly, the Zr/Ti-O-Si-OH chemical bonds exist on the particle surface, with about two-thirds of the surface covered by silica. The hydroxyl groups can further post-graft organic ligands or directly associate with species. Synthesized mesoporous metal oxides are highly homogenous and could potentially be used in various applications because of their tetragonal structure and porosity features.

Thermal plasma synthesis of Si-multi walled carbon nanotube nanocomposite as an anode for lithium-ion batteries

The Si-MWCNT (multi-walled carbon nanotube) nanocomposite, which is considered a promising replacement for graphite as an anode material for lithium-ion batteries, was prepared using a triple DC thermal plasma jet system. We used micron-size silicon powder and MWCNT powder as raw materials. We varied the main parameters by mixing silicon and MWCNTs or individually injected into the plasma jet and adjusting the mass ratio to 2:1 and 1:2. The location of injection for the raw materials played a critical role in the formation of Si-MWCNT nanocomposites as the temperature at the injection site has a significant impact on the vaporization of silicon and sublimation of carbon nanotubes. Additionally, it was influenced by efficient heat transfer of silicon and the structural change of MWCNT. As a result, the Si-MWCNT nanocomposite was easily produced under separate injection conditions, and silicon nanoparticles of 20 nm or less were attached to the surface of the MWCNT. We evaluated the electrochemical performance of the synthesized material by assembling a CR2032-type coin cell using it as an anode electrode material.