Quantum dots (QDs) have sparked great interest due to their unique electronic, optical, and structural properties. In this review, we provide a critical analysis of the latest advances in the synthesis, properties, and applications of QDs. We discuss synthesis techniques, including colloidal and hydrothermal synthesis, and highlight how the underlying principles of these techniques affect the resulting properties of QDs. We then delve into the wide range of applications of QDs, from QDs based color conversion, light-emitting diodes and biomedicine to quantum-based cryptography and spintronics. Finally, we identify the current challenges and future prospects for quantum dot research. By reading this review, readers will gain a deeper understanding of the current state-of-the-art in QDs research and the potential for future development.
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Kushagra Agarwal et al 2023 Mater. Res. Express 10 062001
William Xaveriano Waresindo et al 2023 Mater. Res. Express 10 024003
Hydrogel is being broadly studied due to their tremendous properties, such as swelling behavior and biocompatibility. Numerous review articles have discussed hydrogel polymer types, hydrogel synthesis methods, hydrogel properties, and hydrogel applications. Hydrogel can be synthesized by physical and chemical cross-linking methods. One type of the physical cross-linking method is freeze-thaw (F–T), which works based on the crystallization process of the precursor solution to form a physical cross-link. To date, there has been no review paper which discusses the F–T technique specifically and comprehensively. Most of the previous review articles that exposed the hydrogel synthesis method usually mentioned the F–T process as a small part of the physical cross-linking method. This review attempts to discuss the F–T hydrogel specifically and comprehensively. In more detail, this review covers the basic principles of hydrogel formation in an F–T way, the parameters that influence hydrogel formation, the properties of the hydrogel, and its application in the biomedical field.
Ahmad Y Al-Maharma et al 2020 Mater. Res. Express 7 122001
In the present review, the effect of porosity on the mechanical properties of the fabricated parts, which are additively manufactured by powder bed fusion and filament extrusion-based technologies, are discussed in detail. Usually, additive manufacturing (AM) processes based on these techniques produce the components with a significant amount of pores. The porosity in these parts typically takes two forms: pores with irregular shapes (called keyholes) and uniform (spherical) pores. These pores are present at different locations, such as surface, sub-surface, interior bulk material, between the deposited layers and at filler/matrix interface, which critically affect the corrosion resistance, fatigue strength, stiffness, mechanical strength, and fracture toughness properties, respectively. Therefore, it is essential to study and understand the influence of pores on the mechanical properties of AM fabricated parts. The technologies of AM can be employed in the manufacturing of components with the desired porous structure through the topology optimization process of scaffolds and lattices to improve their toughness under a specific load. The undesirable effect of pores can be eliminated by using defects-free raw materials, optimizing the processing parameters, and implementing suitable post-processing treatment. The current review grants a more comprehensive understanding of the effect of porous defects on mechanical performance and provides a mechanistic basis for reliable applications of additively manufactured components.
Yangang Li et al 2022 Mater. Res. Express 9 122001
Two-dimensional (2D) transition metal dichalcogenides (TMDs) have attracted extensive attraction due to their unique properties in novel physical phenomena, such as superconductors, Moiré superlattices, ferromagnetics, Weyl semimetals, which all require the high quality of 2D TMDs. Mechanical exfoliation (ME) as a top-down strategy shows great potential to obtain 2D TMDs with high quality and large scale. This paper reviews the theoretical and experimental details of this method. Subsequently, diverse modified ME methods are introduced. Significantly, the recent progress of the Au-assisted ME method is the highlight. Finally, this review will have an insight into their advantages and limitations, and point out a rational direction for the exfoliation of TMDs with high quality and large size.
Badrut Tamam Ibnu Ali et al 2022 Mater. Res. Express 9 125302
The selection of the solvent during the membrane preparation process significantly affects the characteristics of the resulting membrane. The large number of organic solvents available for dissolving polymers renders this experimental approach ineffective. A computational approach can select a solvent using the solvation energy value approach. In addition, no organic waste is generated from the computational approach, which is a distinct advantage. A computational approach using the DFT/B3LYP/def2-TZVP RIJCOSX method was used to optimize the structure of polyethylene terephthalate (PET). The PET for the experiment was obtained from the utilization of plastic bottle waste. In addition, a review of the thermodynamics, geometry, HOMO-LUMO orbitals, and vibrational frequencies was conducted to validate the PET molecule against the experimental results. A conductor-like polarizable continuum model was used to determine the best solvent for dissolving the PET plastic waste. The results demonstrated that the Fourier Transform Infra-Red and Fourier Transform Raman spectra obtained from computational calculations were not significantly different from the experimental results. Based on a thermodynamic approach, computationally the Gibbs free energy (−724.723), entropy (0.0428), and enthalpy (−724,723 Kjmol−1 ) values of the PET dimer molecule are not much different from the experimental values (−601, 0.042, and −488 Kjmol−1). The computational approach was successful in selecting solvents that can dissolve PET plastic bottle waste. Phenol solvent has the lowest solvation energy value (−101.879 Kjmol−1) and the highest binding energy (2.4 Kjmol−1) than other solvents. Computational and experimental results demonstrated that the phenol solvent was able to dissolve PET plastic bottle waste better than the other solvents.
Jianxin Wu et al 2022 Mater. Res. Express 9 032001
Aluminum and its alloys having lots of advantageous properties are among the most-used metallic materials. So, it is of immense importance to find suitable processes and methods leading to high-quality purified Al melt. In this regard, there are numerous challenges in achieving high purity Al melts, such as its propensity to react with air, oxygen, and water vapor, the presence of a variety of oxide, non-oxide, and solid particle inclusions that lead to the production of pores, cracks, pinholes, and dross, finally adversely influencing the overall quality of the product. The main methods of melt refining are fluxing, floatation, and filtration, but more sophisticated methods have also emerged. The best method for purification can be chosen based on the type of impurities and the desired level of purification. With the industrial development, the need to establish more cost-effective and simpler methods has increased, and in addition, methods should be considered for recycling large volumes of scarp Al parts that contain more impurities. Moreover, achieving high purity melt is also a vital issue for use in specific applications. The present article has been written to discuss the above issues and focus on the study of various methods of aluminum purification.
Muhammad Hafeez et al 2020 Mater. Res. Express 7 025019
Cobalt oxide nanoparticles (Co3O4-Nps) have many applications and now a days the green methods of synthesis of these NPs are preferred over other methods because of associated benefits. In this study, Co3O4-Nps were synthesized by using leaves extract of Populus ciliata (safaida) and cobalt nitrate hexa hydrate as a source of cobalt. The synthesized NPs were analyzed by different techniques such as fourier transform spectroscopy (FTIR), x-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Antibacterial activities of the synthesized Co3O4-Nps were evaluated against gram negative and gram positive bacteria and found active against Escherichia coli (E. coli), Klebseilla pneumonia (K. pneumonia), Bacillus subtillus (B.subtillus) and Bacillus lichenifermia (B. lichenifermia). The activity results were analyzed statistically by one-way ANOVA, with 'Dunnett's Multiple Comparison Test'. The maximum mean activity (21.8 ± 0.7) was found for B. subtilis and minimum mean activity (14.0 ± 0.6) was observed for E. coli.
Ruby Garg et al 2020 Mater. Res. Express 7 022001
To meet the energy needs batteries and supercapacitors are evolved as a promising candidate from the class of energy storage devices. The growth in the development of new 2D electrode materials brings a new revolution in energy storage devices with a comprehensive investigation. MXene, a new family of 2D metal carbides, nitrides and carbonitrides due to their attractive electrical and electrochemical properties e.g. hydrophilicity, conductivity, surface area, topological structure have gained huge attention. In this review, we discussed different MXene synthesis routes using different etchants e.g. hydrofluoric acid, ammonium hydrazine, lithium fluoride, and hydrochloric acid, etc showing that fluorine formation is compulsory to etch the aluminum layer from its precursor. Due to the advantage of large interlayer spacing between the MXene layers in MXene, the effect of intercalation on the performance of batteries and supercapacitors using MXene as electrodes by various sized cations are reviewed. Different MXene hybrids as supercapacitor electrodes will also be summarized. Lastly, the conclusion and future scope of MXene to be done in various supercapacitor applications are also presented.
Mariela Flores-Castañeda et al 2024 Mater. Res. Express 11 055005
This study presents a simple two-step synthesis method for the fabrication of Ag/ZnO nanocomposites to improve the photocatalytic response of ZnO. The synthesis involves ZnO nanoparticles that were fabricated from the thermal decomposition of commercial zinc acetate. In order to produce Ag/ZnO nanoparticles in a simple two-step process, ZnO nanoparticles were mixed with Ag nanoparticle suspensions previously obtained by the laser ablation of solids in liquids technique at three different fluences. Structural characterization of ZnO powders revealed the presence of single phase wurtzite ZnO nanoparticles with crystal sizes of 20 nm. On the other hand, XRD patterns for a composite sample revealed the presence of signals associated to both ZnO and Ag suggesting that silver nanoparticles were attached to the ZnO particles surface. Optical characterization of the ZnO powders, carried out by UV–vis spectroscopy, showed a strong absorption band centered at 380 nm, which is associated to excitonic transitions in ZnO nanoparticles, whilst absorption measurements of silver nanoparticles colloids revealed the presence of a strong band centered near 412 nm. This band shifts to shorter wavelengths with increasing fluence from 2.6 to 6.2 J cm−2, indicating changes in nanoparticles size. Photocatalytic degradation tests of methylene blue under UV irradiation were carried out using pure ZnO, Ag colloids and Ag/ZnO nanoparticles. After the first 30 min of irradiation, it was observed that the silver nanoparticles reached degradation percentages of 16, 22 and 29% for samples synthesized at 2.6, 4.2 and 6.2 J cm−2, respectively. Meanwhile the ZnO sample reached a value of 13% after 30 min. Regarding the Ag/ZnO composite sample, the percentage of degradation after 30 min was 36%, demonstrating a considerable enhanced photocatalytic activity as compared to ZnO. After 24 h irradiation, Ag/ZnO degraded 95% of the methylene blue solution. It was observed that decorating ZnO with laser produced silver nanoparticles accelerates the photocatalytic response of ZnO by enhancing the activity at short times.
Xi Huang et al 2020 Mater. Res. Express 7 066517
The oxidation behavior of 316L stainless steel exposed at 400, 600 and 800 °C air for 100, 500 and 1000 h was investigated using different characterization techniques. Weight gain obeys a parabolic law, but the degree of deviation of n index is increasingly larger with the increase of temperature. A double oxide film, including Cr2O3 and Fe2O3 oxide particles in outer and FeCr2O4 oxides in inner, is observed at 400 °C. As regards to samples at 600 °C, a critical exposure period around 100 h exists in the oxidation process, at which a compact oxide film decorated with oxide particles transforms to a loose oxide layer with a pore-structure. In addition, an oxide film containing Fe-rich outer oxide layer and Cr-rich inner oxide layer is observed at 600 °C for 500 and 1000 h. Spallation of oxide scale is observed for all samples at 800 °C regardless of exposure periods, resulting in different oxidation morphologies, and the degree of spallation behavior is getting worse. A double oxide film with the same chemical composition as 600 °C is observed, and the thickness increases over exposure periods.
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Shruti Sharma et al 2024 Mater. Res. Express 11 065502
The structural, magneto-electronic, thermophysical and thermoelectric properties of vanadium-based V2MnZ (Z = As, Ga) alloys have been investigated using density functional theory simulation scheme and semiclassical Boltzmann transport methods. First of all, the structural characterization has been performed in ferromagnetic and non-magnetic states which signifies that both the alloys crystallized in C1b type structure with space group F-43m. We also computed the various thermodynamical parameters such as heat capacity (Cv), Debye temperature (θD), and grüneisen parameter (γ) of these materials, with the help of quasi-harmonic approximation (QHA) at pressures ranging from 0 to 20 GPa and temperatures ranging from 0 to 900 K. We have used the Boltzmann transport theory with the constant relaxation approximation as a basis for calculating various thermoelectric coefficients such as the Seebeck coefficient, power factor, total thermal conductivity and figure of merit. The efficient half-metallicity and thermoelectric responses contribute to spintronics and green energy harvesting technology.
Varadhi Govinda et al 2024 Mater. Res. Express 11 065003
The treatment of toxic organic pollutants is extremely important for the conservation of clean air, soil, and water. In this study, (reduced graphene oxide) NiCo2O4/ rGO hybrid nanocomposite was prepared by a facile hydrothermal technique and employed for organic dye adsorption from wastewater. The synthesized NiCo2O4/rGO hybrid nanocomposite was studied using FTIR, XRD, SEM, TEM, BET, Raman spectroscopy, and UV–visible. The physical characterizations prove the deposition of NiCo2O4 particles on the rGO surface. The transmission electron microscope image demonstrated that the NiCo2O4 particles with an average size of ∼46 nm was dispersed on the rGO surface. The obtained nanoparticles show a higher specific surface area of 56.4 m2 g−1. Adsorption dynamics as investigated by time and concentration variation show that the adsorption data follows pseudosecond order kinetics and the Langmuir isotherm model, with a maximum adsorption capacity of 106.2 mg g−1, indicating homogeneous physiochemical adsorption of CR dye on the adsorbent surface. Besides, the catalytic effectiveness of synthesized nanocomposite towards Congo red (CR) dye reduction mediated by the electron (e−) transfer route of BH4− ions was explained in detail. The electrostatic interaction used between the NiCo2O4/rGO hybrid composite and Congo red increased the adsorption ion effectiveness of the dye sample.
Weiyi Zhang et al 2024 Mater. Res. Express 11 065002
The significant improvement of decolorization and disinfection technologies has been a hotspot in wastewater reutilization. In this study, we realized a novel construction of K-doped nano-ZnO and borneol based hydrogel composite material (K-ZnO/B-hydrogel) by low-temperature in situ sol–gel growth. The techniques such as fourier transform infrared (FTIR), X-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and X-ray energy dispersive spectroscopy (EDS) were applied to recognize the synthesized hydrogel. The results revealed that K-doped ZnO nanoparticles had been uniformly decorated onto the B-hydrogel. Ultraviolet-visible (UV–vis) absorption spectra showed that impurity doping of potassium element into ZnO could reduce the band gap, improving the visible light absorption efficiency. Under LED illumination, the photodegrading rate of K-ZnO/B-hydrogel was approximately 2.3 times greater than that of K-ZnO/B-hydrogel on methylene blue (MB) removal. Remarkably, aside from CO2 and H2O, no by-products were generated during the photodegradation process. In addition, the antimicrobial activities against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) of K-ZnO/B-hydrogel achieved up to 99.9%, which were at least 1.5 times higher than K-ZnO/B-hydrogel. This composite will push ahead with a closed-loop wastewater treatment system for dye and pathogenic microorganism disposal, which combines the excellent adsorption ability of hydrogel and the outstanding photocatalytic ability of ZnO nanoparticles with easy sample handling and separation, and help to eliminate secondary pollution.
Shu Xu et al 2024 Mater. Res. Express 11 065001
The particle size and pore size of spherical mesoporous silica materials play significant roles in their application. However, relatively limited systematic research has been conducted on how preparation conditions influence these properties. In particular, the effects of some important factors have not been adequately studied, including reaction time, reaction temperature, and organic solvent type. In this work, octane and water were used as solvents, and tetraethyl orthosilicate was used as the silicon source to systematically study the effects of reaction time, reaction temperature, different organic solvents, octane/water mass ratio, styrene template concentration, and surfactant (cetyltrimethylammonium bromide, CTAB)/H2O mass ratio on the particle morphology, particle size, and pore size of silica. The results suggest that the above-mentioned neglected factors exert a substantial influence on both particle size and pore size. In the experimental temperature range, the pore diameter decreases and the particle size increases with increasing temperature. The maximum particle size and pore size are achieved after a reaction time of 3 h, and a further increase in reaction time leads to a smaller particle size and pore size. As the number of carbon atoms in the organic solvent decreases, the pore size also gradually increases. Styrene and organic solvents that dissolve in CTAB micelles are crucial factors in pore formation, while the aggregation of the swollen CTAB micelles influences the particle size. The changes in the pore structure stability and hydroxyl density of the synthesized samples in water were also studied. After undergoing water treatment at temperatures ranging from 20 to 60 °C for 72 h, both the pore structure and morphology remain relatively unchanged. When the temperature increases, the surface hydroxyl density exhibits a more pronounced increase in the presence of water. After water treatment for 5 h, the surface hydroxyl density reaches saturation.
Somepalli Narendra and V Vasugi 2024 Mater. Res. Express 11 066401
Red mud (RM) has drawn a lot of attention in the search for potential uses in the production of sintered artificial aggregate from industrial waste products. The main objective of the study is to produce an RM-based sintered artificial aggregate (SAA), with several blends (binary, ternary, and quaternary) using various industrial wastes. This study includes assessing the mechanical and physical properties of SAA as well as the sintering parameters in order to determine the appropriate material mix ratio. To achieve these objectives, a comprehensive experimental approach was adopted. A total of 35 different mixtures were formulated by incorporating various industrial wastes as binders and sintering additives. The green pellets were preheated at 105 °C for 24 h, and consecutively sintered at different temperatures, namely 700 °C, 900 °C, 1100 °C, and 1150 °C with a duration of 30 min. A compressive strength test was performed in order to find the mechanical property of SAA similarly water absorption and bulk density tests were conducted to find the physical properties of SAA. To characterize the SAA, scanning electron microscope analysis (SEM), X-ray diffraction (XRD) and energy dispersive x-ray analysis were conducted, and also data analysis was performed using Artificial Neural Network (ANN) tools, yielding accurate predictions. Successfully best compressive strength low water absorption SAA was produced. The best material weight mix ratio for the production of SAA was identified as (A18) RM: Fly Ash: Waste Glass Powder; 78:10:12. Out of all blends the ternary blend (A18) SAA exhibited impressive properties after 30 min of sintering at 1150 °C: high compressive strength of 22.92 MPa, water absorption of 4.26%, and bulk density of 1296.12 kg m−13. This was made possible by the high amount of Al2O3, SiO2, in the combination of fly ash, and waste glass powder with RM. SEM and XRD analysis also confirmed that the (A18) SAA achieved the best compressive strength, and low water absorption due to turning the surface and core area into a solid, reduced internal pores and formed quartz, and hematite phases. The findings of this study serve as a foundation for future work and pave the way for the development of sustainable construction materials.
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Qiaoqiao Lan et al 2024 Mater. Res. Express 11 052001
Bio-based polyurethanes are novel material with potential advantages for sustainable development, and their development play significant roles in promoting sustainability. Curcumin, a natural monomer, possesses high biological activity and features a symmetrical chemical structure with various functional groups such as phenolic hydroxyl, carbonyl and benzene ring. The presence of hydroxyl groups in the structure of curcumin provides essential conditions for its involvement in polyurethane synthesis. This review article provides an overview of the applications of curcumin as a chain extender, crosslinking agent and end-capper in polyurethanes, as well as its effects on the chemical structure, mechanical properties, and chemical stability of polyurethanes. Furthermore, the functional applications of curcumin-based polyurethanes in various fields such as medicine, food packaging, and coatings are discussed. Finally, considering the current research status and inherent properties of curcumin, the future prospects of curcumin-based polyurethanes are contemplated.
Tao Huang et al 2024 Mater. Res. Express 11 032003
As a kind of special energy field assisted plastic forming, electric pulse assisted plastic forming combines multiple physical fields, such as thermal, electrical, magnetic and mechanical effects, has multiple effects on metal. It has a good industrial application prospect in the fields of directional microstructure regulation of materials and preparation of new materials. The flow stress of metal materials can be effectively reduced by electro-pulse assisted forming. The action mechanism of pulse current includes thermodynamics (Joule heating effect) and kinetic (pure electro-plastic effect or athermal effect). Thermodynamically, electric pulses can be used to provide the energy for dislocation migration and atomic diffusion, and aid in microstructure changes such as recrystallization, phase transition and microcrack healing of metals. In terms of dynamics, electric pulse has an effect on the speed and path of dislocation structure evolution. On this basis, a series of theoretical models for accurately predicting the flow stress of materials in electrically assisted forming process were formulated by combining the stress–strain constitutive relationship considering the temperature rise effect and the pure electro-plastic effect. The accuracy of the predicting model is greatly enhanced by the introduction of electrical parameters. The mechanism for electrically assisted forming was further revealed.
Ane Lasa et al 2024 Mater. Res. Express 11 032002
All plasma facing surfaces in a fusion reactor, whether initially pure or an alloy, will rapidly evolve into a mixed material due to plasma-induced erosion, migration and redeposition. Beryllium (Be) erosion from the main chamber, and its transport and deposition on to a tungsten (W) divertor results in the growth of mixed Be-W layers, which can evolve to form beryllides. These Be-W mixed materials exhibit generally less desirable properties than pure tungsten or pure beryllium, such as lower melting points. In order to better understand the parameter space for growth of these alloys, this paper reviews the literature on Be-W mixed material formation experiments—in magnetically confined fusion reactors, in linear plasma test stands, and during thin-film deposition—and on computational modeling of Be-W interactions, as well as briefly assesses the Be-W growth kinetics. We conclude that the following kinetic steps drive the material mixing: adsorption of the implanted/deposited ion on the metal surface; diffusion of the implanted/deposited ion from surface into the bulk, which is accelerated by defects; and loss of deposited material through erosion. Adsorption dominates (or prevents) material mixing in thin-film deposition experiments, whereas diffusion drives material mixing in plasma exposures due to the energetic ion implantation.
Meng Xu et al 2024 Mater. Res. Express 11 032001
Heavy metal ions and organic pollutants cause irreversible damage to water environment, thereby posing significant threats to the well-being of organisms. The techniques of adsorption and photocatalytic degradation offer versatile solutions for addressing water pollution challenges, attributed to their inherent sustainability and adaptability. Silicates exhibit exceptional practicality in the realm of environmental protection owing to their structural integrity and robust chemical/thermal stability during hybridization and application process. Furthermore, the abundance of silicate reserves, coupled with their proven effectiveness, has garnered significant attention in recent years. This detailed review compiles and analyzes the extensive body of literature spanning the past six years (2018–2023), emphasizing the pivotal discoveries associated with employing silicates as water purification materials. This review article provides a comprehensive overview of the structure, classification, and chemical composition of diverse silicates and offers a thorough descriptive analysis of their performance in eliminating pollutants. Additionally, the utilization of diatomite as either precursors or substrates for silicates, along with the exploration of their corresponding purification mechanisms is discussed. The review unequivocally verifies the efficiency of silicates and their composites in the effective elimination of various toxic pollutants. However, the development of novel silicates capable of adapting to diverse environmental conditions to enhance pollution control, remains an urgent necessity.
Arijit Mitra et al 2024 Mater. Res. Express 11 022002
Magnetic materials at the nanometer scale can demonstrate highly tunable properties as a result of their reduced dimensionality. While significant advancements have been made in the production of magnetic oxide nanoparticles over the past decades, maintaining the magnetic and electronic phase stabilities in the nanoscale regime continues to pose a critical challenge. Finite-size effects modify or even eliminate the strongly correlated magnetic and electronic properties through strain effects, altering density and intrinsic electronic correlations. In this review, we examine the influence of nanoparticle size, shape, and composition on magnetic and tunneling magnetoresistance (TMR) properties, using magnetite (Fe3O4) as an example. The magnetic and TMR properties of Fe3O4 nanoparticles are strongly related to their size, shape, and synthesis process. Remarkably, faceted nanoparticles exhibit bulk-like magnetic and TMR properties even at ultra-small size-scale. Moreover, it is crucial to comprehend that TMR can be tailored or enhanced through chemical and/or structural modifications, enabling the creation of 'artificially engineered' magnetic materials for innovative spintronic applications.
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Wei et al
A new process for the development and utilization of titanium-iron sand ore from Yunnan province is proposed. We provide a detailed analysis of the chemical composition and mineral structure of the raw material, and describe a pretreatment involving low-temperature oxidation and reduction, hydrofluoric acidolysis, and hydrochloric acid leaching to remove impurities and generate titanium-rich materials. Hydrofluoric acid was used to break down the complex titanite, silica-titanium, and calcium-titanium mixture in the starting mineral into simple oxides. The results have indicated that the thermal reduction process should not be conducted at elevated temperatures. Optimal process conditions are established for the leaching process: leaching temperature of 80°C; leaching time of 240 min; hydrofluoric acid concentration of 3%; liquid-solid ratio of 6 mL/g. Under these conditions, the extent of TFe leaching reached 96%, while the leaching of Ca and Mg reached 94%. The TiO2 grade of the final titanium-rich material was 89.95%, with a CaO content of 0.39%, a MgO content of 0.15%, and a TFe content of 7.5%. This material can serve as raw material for subsequent chlorination.
Tychsen et al
Porous Materials, such as sintered fiber felts (SFFs), can contribute to
the reduction of aircraft noise by acting as a low-noise trailing edge (TE). A rolling
process with a time-varying rolling gap was sucessfully used to tailor the aeroacoustic
properties of SFFs. To ensure the suitability of rolled porous materials for application,
the mechanical properties after rolling must be investigated. The objective of this
study was to clarify the effect of the rolling process on the damage evolution during
tensile loading. A SFF consisting of a functional layer and a support grid made
of alloy 1.4404 was used for rolling. Interrupted tensile tests in combination with
computed tomography (CT) were used to investigate the damage evolution of asreceived
material, uniformly rolled material and material rolled with a gradient in
thickness reduction. Metallographic examination and fracture surface analysis using
scanning electron microscopy (SEM) complemented the CT analysis. Uniformly rolled
material with a low degree of deformation (-0.74 ≤ φ < 0) failed identically to the
as-received material. The functional layer failed first, starting from the center. The
support grid subsequently failed due to the incremental failure of individual wires. The
material rolled with a gradient in thickness reduction failed accordingly. A significant
change in damage evolution occured for material rolled at high degrees of deformation
φ≤-1.53, where the support grid fails first and the functional layer second. The rolling
process using a time-varying rolling gap does not result in a detrimental mechanical
behavior under tensile load. The results improve the general understanding of the
effects of rolling processes on the properties of porous materials and allow the damage
behavior to be taken into account with regard to its application as a TE.
Nsar et al
In this review, an introduction to nanostructured films focusing on cerium oxide (CeO2) as high dielectric constant (k) material for silicon-based metal-oxide-semiconductor devices, and subsequently background of using low k silicon dioxide as well as the transition to high k materials was presented. Moreover, the properties of CeO2 in general and the applications of CeO2 and doped CeO2 films as high k passivation layers were reviewed. The beneficial effect of using CeO2 seed layers on the characteristics of CeO2 nanostructures was discussed. Moreover, challenges faced by CeO2 and the potential of doping trivalent cations into the CeO2 lattice for enhancement of passivation properties were thoroughly discussed.
Yuan et al
The honeycomb structures have been widely adopted as the aerospace engineering for the impact dynamic performance. To reveal the in-plane crushing behavior and improve the energy absorption ability, the influence of typical parameters including impact velocity and geometrical factors including central angle of arc-curved hexagonal honeycomb on the impact dynamic are investigated. The impact dynamic performance of traditional honeycomb structure is studied under different impact velocity and wall thickness. The deformation behavior of arc-curved hexagonal honeycomb with in-plane impact is researched. Results show that three typical deformation model including Ⅰ, V and X shape are exhibited for traditional and arc-curved types. The deformation model would transfer from X to Ⅰ shape with the increasing of impact velocity, and the impact load would be more unstable. With the increasing of central angle of arc-curved hexagonal honeycomb, the global deformation occurs instead of local deformation including X and V model, and stronger energy absorption ability is exhibited for the larger angle.
HUANG et al
In view of the serious harm caused by sulfur ion to alumina production and the high cost of desulfurization in Bayer dissolution process of high sulfur bauxite leaching at high temperature and high pressure, the supported compound desulfurizer was prepared by melt infiltration method to realize simultaneous desulfurization in Bayer dissolution process. In this paper, Zn(NO3)26H2O and Cu(NO3)23H2O as the main components, kaolin, sepiolite, activated alumina as the active carrier, the supported compound desulfurizer was prepared. The active carrier was optimized and the optimum preparation parameters were determined by means of DSC, IR, TG, SEM and XRD. The results show that kaolin is more suitable as the active carrier of compound desulfurizer. The best melting temperature of the precursor is 100℃, the best calcination temperature is 400℃, and the best calcination time is 2h. The supported compound desulfurizer mainly consists of ZnO, CuO, AlOOH, SiO2 and Al2SiO5. The results provide a basis for the active preparation of the supported compound desulfurizer.