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.
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.
Veera Prabakaran Elanjeitsenni et al 2022 Mater. Res. Express 9 022001
Thin film sensors are used to monitor environmental conditions by measuring the physical parameters. By using thin film technology, the sensors are capable of conducting precise measurements. Moreover, the measurements are stable and dependable. Furthermore, inexpensive sensor devices can be produced. In this paper, thin film technology for the design and fabrication of sensors that are used in various applications is reviewed. Further, the applications of thin film sensors in the fields of biomedical, energy harvesting, optical, and corrosion applications are also presented. From the review, the future research needs and future perspectives are identified and discussed.
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.
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Dan Lin et al 2024 Mater. Res. Express 11 055201
The in situ Ti43Zr27Mo5Cu10Be15 amorphous composites were investigated for their corrosion properties in solutions of NaCl, HCl, H2SO4 and NaOH. Electrochemical testing, SEM, EDS and XPS analyses revealed that pitting in NaCl and HCl solutions caused local surfaces damage. Amorphous matrix corrodes slightly in H2SO4 solution. Uniform corrosion occurred in NaOH solution without passive film formed, leading to the worst corrosion resistance. The optimal corrosion performances for NaCl and HCl solution are achieved at 0.5 mol l−1 and 0.75 mol l−1 separately which is related to the shortage of oxygen content in the solutions. While, the best corrosion performances for H2SO4 and NaOH solution are at 0.25 mol l−1. Moreover, the research on the effect of temperature was conducted in 3.5 wt% NaCl solution, it was found that Ti43Zr27Mo5Cu10Be15 amorphous composites exhibited good corrosion resistance at 298 K, while the Ecorr declined with increasing solution temperature.
Ye Makhambetov et al 2024 Mater. Res. Express 11 056523
The article presents the results of comprehensive thermodynamic modeling and laboratory tests conducted for smelting a complex ferroalloy of silicon, manganese, and chromium (Fe-Si-Mn-Cr) from chromium, medium-grade manganese ores, and high-ash coals from Kazakhstan. Thermodynamic analysis was performed using HSC Chemistry software to model the Fe-Si-Mn-Cr smelting process over a temperature range of 900 °C–1800 °C. This analysis involved six actual charge compositions with solid reductant (Csolid) consumption ranging from 5 to 20 kg per 100 kg of Cr and Mn ore mixture. The mechanism of the combined carbothermic reduction of Cr, Mn, Si, and Fe was investigated using the Cr-Si-Al-Ca-Mn-Mg-O-C system. According to thermodynamic data, the optimal consumption of Csolid per 100 kg of ore mixture is 17 kg, and the optimal temperature range for smelting ferroalloys is between 1600 and 1700 °C. Laboratory tests were conducted in a high-temperature Tamman furnace at 1700 °C, resulting in experimental samples of the new complex ferroalloy with an average composition of 14.85% Fe, 14.05% Si, 7.55% Mn, 57.54% Cr, and 6.01% C, with P < 0.03% and S < 0.02%. The phase composition included (Cr, Fe, Mn)3Si and carbides Cr23C6 and (Fe, Mn)3C. The resulting alloy is suitable for alloying high-carbon and tool steels.
Adithya Hegde et al 2024 Mater. Res. Express 11 056522
Die Sink Electric Discharge Machining is a widely used manufacturing process for shaping hard and electrically conductive materials. This study investigates the effects of various electrode materials such as, Ti-6Al-4V-SiCp, Brass and Copper on the machining performance of AISI 316 l Stainless Steel workpieces using EDM. The methodology involved optimizing parameters such as Electrode Material, Discharge Current, Gap Voltage, Spark Gap, Pulse-on Time, and Pulse-off Time. From the extensive experimantation it was observed that the combination of Ti-6Al-4V-SiCp electrode material, 8Amp Discharge Current, 90 V Gap Voltage, 75 μm Spark Gap, 100 μs Pulse-on Time and 15 μs Pulse-off Time has resulted in lowest electrode eear rate, higher machining time, and low electrode surface roughness ratio. Ti-6Al-4V-SiCp electrodes possess higher hardness and electrical conductivity compared to Brass and Copper Electrodes leading to higher wear resistance against repeated thermal shocks during electric discharge machining operation. Feed Forward Artificial Neural Network is successfully applied to predict the output characteristics of the experimentation with high accuracy of 98.3% (Electrode Wear Rate), 94.6% (Machining Time) and 93.8% (Electrode Surface Roughness Ratio). Further, microstructure analysis concludes that lowest wear is observed in Ti-6Al-4V-SiCp electrodes compared to Brass and Copper electrodes.
M Zaghdoudi et al 2024 Mater. Res. Express 11 056406
BiOI nano-leaves were deposited on to TiO2 nanotubes (NTs) using the Successive Ionic Layer Adsorption and Reaction (SILAR) technique, which was developed using the electrochemical anodization method. Various SILAR cycle numbers (three, five, and seven cycles) were employed in the experiment. The as-prepared nanocomposites (NCs) were characterized by several technique, the morphology of the elaborated NCs samples was examined using a S − 4800 field emission scanning electron microscope (SEM), the Reflectance and diffuse reflectivity of the NCs samples were measured by a Shimadzu UV-3100S spectrophotometer in the spectral range [300 –1200 nm] and the XRD diffraction was used to identify the crystalline structure of the processed BiOI/TiO2 NTs nanocomposites. A diffractometer with a Cu Kα anode (λ = 0.1542 nm) operating at 40 kV and 30 mA was used. The as-prepared NCs, specifically BiOI/TiO2 NTs, were designed for the photocatalytic degradation of methylene Blue (MB). X-ray diffraction analysis revealed the formation of the TiO2 anatase phase and polycrystalline BiOI films in all processed NCs. UV/Vis measurements indicated a shift in the nanocomposite's active region from UV to visible light. The highest absorption and the lowest bandgap energy (Eg value, ∼2 eV) were observed in the NCs with 5 BiOI cycles. The photocurrent density reached 27 μA cm−2, approximately three times higher than the photocurrent density exhibited by TiO2 nanotubes under similar conditions. The optimal photocatalytic rate was achieved with BiOI/TiO2 NCs processed after five SILAR cycles.
Miad Ali Siddiq 2024 Mater. Res. Express 11 056304
Yttrium zinc oxide (Zn0.85Y0.15O) nanostructures were stoichiometrically prepared by co-precipitation method. XRD, EDX, XPS, SEM, and TEM spectroscopy were examined to investigate structure, composition, and morphological characteristics. The synthesized nanocomposite exhibited polycrystalline structure with small crystallite size ∼ nm in which the particles appeared in sheets like shape with high atomic density on surface. The optical parameters including energy gap and refractive index were investigated from (T%) and (R%) measurements through wavelength range from 300–900 nm. Al/Y:ZnO/p-Si/Ag Schottky diode was fabricated using thermal evaporating technique and its current–voltage was analyzed using different models. The photodiode showed non-ideal behavior with ideality factor greater than unity and small potential barrier. Under various illuminations, the photodiode has revealed high photosensitivity attributed to trapped charge carriers at the interface. The charge carrier density and built-in voltage were estimated from Mott Schottky (M–S) function suggesting high Schottky diode efficiency.
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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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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.
Liu et al
The oxidation resistance of Zn-9Al-2.5Mg-xBe (x=0,0.005,0.01,0.05,0.1) alloys was investigated in this study through isothermal oxidation experiments. The alloy microstructure, morphology, and composition of the oxide film were analyzed using scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD). The oxidation kinetics and thermodynamics of Zn-9Al-2.5Mg were calculated, and the oxidation mechanism was discussed. The results show that the Zn-9Al-2.5Mg-0.05Be alloy exhibits a fine dendritic microstructure, with a large quantity of Zn-MgZn2 binary eutectic and Zn-Al-MgZn2/Mg2Zn11 ternary eutectic phases uniformly distributed. The Zn-9Al-2.5Mg-0.05Be alloy has the lowest oxidation rate among the tested alloys, with an oxide weight gain of 12 mg/m², which is only 0.67 times that of the Zn-9Al-2.5Mg alloy. The oxide film on the alloy surface is dense and retains the metallic appearance. The main constituents of the oxide film are Zn, Al, Mg17Al12, Mg2Zn11, and BeO, with no formation of Al2O3 or MgO. The oxidation mechanism of the Zn-9Al-2.5Mg-0.05Be alloy is attributed to the reaction of Be with oxygen, forming BeO, or the displacement reaction of Be with Al2O3 and MgO to form BeO, which inhibits the formation of Al2O3 and MgO.
Demir et al
Objective :
To compare the shear bond strength values of current CAD/CAM materials and to evaluate the color changes resulting from immersion in coloring solutions.
Material and Methods:
A total of 160 specimens were prepared from 4 CAD/CAM blocks; lithium disilicate glass ceramic (IPS E.max CAD[EC]), zirconia reinforced lithium silicate ceramic (Vita Suprinity[VS]), polimer infitrated glass ceramic (Vita Enamic[VE]) and hybrid ceramic (GC Cerasmart [GC]). The ceramic specimens were immersed in tea, coffee, cherry juice and distilled water solutions. Color measurements were made. To compare the shear bond strength values, all specimens were bonded to resin cement. Then the specimens were aged with 5000 thermocycling. The failure modes were classified according to stereomicroscope analysis and than scanning electron microscopy images for surface topography were obtained.
Results:
The color change values were significantly greater in coffee compared to other solutions and the highest color change was seen in GC and VE. The highest bond strength values were seen in VS and VE. The shear bond strength values are listed as follows: VS>VE>EC>CS.
Conclusions:
EC and VS can be used, especially in aesthetic restorations, due to their high color stability. Additionally, considering the bond strength values of VS, it appears to be a highly satisfactory material.