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This study focuses on the fabrication and analysis of aluminum nickel phosphorus bronze (AlNPB) metal matrix composite (MMC), reinforced with synthesized TiCN + SiC nanopowders, for potential ballistic applications. The nanopowders were synthesized via mechanical milling and characterized through PXRD, FTIR, and FESEM analyses. The crystalline size from XRD data averaged 24.8 nm, while the FTIR analysis identified axiometic modes and functional groups of the nanocomposite. SEM images displayed the irregular morphologies of the composite powders. The AlNPB MMC was fabricated by incorporating 2%, 4%, and 6 wt. % of the TiCN + SiC nanocomposite with the bronze alloy, utilizing a stir casting technique. XRD and FESEM results confirmed the formation of the MMC and illustrated the composite's porous morphology. Mechanical performance, including tensile, compression, and hardness tests, showed optimal properties with 4 wt. % reinforcement, yielding a tensile strength of 753 MPa, a hardness of 448 HBW, and compression strength of 77.9 J, coupled with good corrosion resistance. Furthermore, a ballistic analysis of the MMC demonstrated a reduction in residual strain energy after bullet impact on a 4 wt% reinforcement target plate compared to the 2% and 6% TiCN + SiC nanoparticle-reinforced aluminum bronze matrix composites. This study therefore suggests that an AlNPB MMC with 4 wt% reinforcement offers the most promising balance of mechanical properties for ballistic applications. [ABSTRACT FROM AUTHOR]

Magnesium has been regarded as an intriguing anode material for chloride ion batteries (CIB) because of its abundant resources, multi-electron reaction feature, and high volumetric capacity. However, the passivation of magnesium in the electrolyte and formation of insulating MgCl2 discharge product lead to poor reaction activity of magnesium anode in CIBs. Herein, the Mg2Sn alloy prepared by mechanical alloying of magnesium and tin powders is first developed as the anode material with enhanced interfacial activity in the CIB using a metal chloride cathode. The cathode exhibits a significant increase in the discharge capacity from 82 to 175 mAh g−1 when an Mg/carbon anode was replaced by the Mg2Sn alloy anode. The discharge capacity can be further increased to more than 200 mAh g−1 when the graphene nanoplatelet is incorporated in the Mg2Sn alloy by mechanical milling, thus demonstrating the highly active alloy anode for chloride ion storage. This strategy also benefits the improvement in the cycling performance of the magnesium anode. [ABSTRACT FROM AUTHOR]

For practical applications of zinc oxide (ZnO) nanoparticles (NPs) in the field of optoelectronics, a control over particle size with proper understanding of defects in the NPs has become crucial nowadays. In the present study, an effort has been given to both controlling the size and understanding the evolution of defects in ZnO NPs synthesized using mechanical (ball) milling. Ball milling of ZnO nanopowder (of average size ~ 46.8 nm) in air ambient was found to reduce the size of NPs very fast reaching a value as small as ~ 16.3 nm for a ball milling time of 10 h. A size saturation of the NPs was seen beyond the time of milling of 10 hours. X-ray diffraction and optical absorption spectroscopy studies confirmed that the stress and the band gap of the NPs were found to increase with decrease in particle size due to increased surface to volume ratio of the NPs and the quantum confinement effects, respectively. Raman and photoluminescence spectroscopy studies revealed the increase in zinc interstitials (Zni) and decrease in oxygen vacancies (Vo) with increase in size of ZnO NPs. A correlation between NP size and the defects (Vo and Zni) in it is established. These correlations can be utilized for relative quantification of the defects in ZnO NP of a particular size. It is concluded that the defects in the small ZnO NPs are inherently induced because of the reduced size but not due to ball milling. So it is very unlikely to synthesize defect-free ZnO NPs. [ABSTRACT FROM AUTHOR]

Amorphization via high energy ball milling is a solid state processing technique in which continuously moving balls transfer kinetic/impact energy to the powder particles. It leads to welding, fracturing, fragmentation and rewelding of the particles. During ball milling, non-equilibrium phases such as supersaturated solid solution, metastable phases, quasicrystalline phases and nanostructure alloy may form other than amorphous phase depending on energy imparted to the powder materials. It has been observed that the total energy imparted to the system plays more important role in phase transformation or amorphization than impact energy of individual balls. Mechanical alloying/milling is one of the most versatile techniques through which large amount of amorphous powders of a wide range of compositions can be synthesized. Experimental results indicated that instead of individual parameter, total energy should be taken into consideration during amorphization. The current authors have also observed that the total energy plays an important role in amorphization of Al86Ni8Y6 glassy system. [ABSTRACT FROM AUTHOR]

This research explores the impact of Cu composition, heating temperature, and milling time on the production of copper-tin alloy nanoparticles. By employing design of experiments techniques, the study systematically evaluates these input variables and their effects on particle size, optical density, and number of colonies. The identification of new Cu3Sn phases in the nanoparticle structure contributes to the novelty of this research. The findings highlight the potential for optimizing copper-tin alloy nanoparticle synthesis and enhancing their antibacterial properties. Mechanical alloying is found to produce nanoparticles up to 15 nm in size. Increasing the percentage of copper leads to improved antibacterial properties. This work provides insights into the synthesis process of copper-tin mechanical alloying and their potential for antibacterial applications. [ABSTRACT FROM AUTHOR]

The sample of Bi0.9Ca0.1Fe0.9Mn0.1O3 was prepared using mechanical milling technique, and further was successively given heat treatment. The structural analysis (XRD data) suggests that the sample crystallizes in the rhombohedral (R3c) crystal structure. The co-substitution of Ca–Mn in Bismuth Ferrite (BFO) improves surface properties and enhances the reduction in particle size. A dielectric study on the sample was inspected on varying temperature and frequency range. The impedance study reveals the sturdy dependence of electrical properties on both frequencies as well temperatures having corresponded with the morphology. Room temperature ferroelectric hysteresis (P-E) loop shows the presence of ferroelectricity and a small reduction in leakage current was detected. The magnetic measurement divulges the enrichment in magnetization because of the distortion in structure and partial destruction of spin cycloid originating from co-substitution. The extent of interaction between the dipoles present in the ceramics can be estimated by the calculation of M-E coupling coefficient. The existence of ferroelectricity, ferromagnetism, and magneto-electric effect in the sample supports the strong enhancement in the multiferroism and magneto-electric coupling of BFO. [ABSTRACT FROM AUTHOR]

The effect of mechanical activation of the mixture of Fe2O3-Co3O4-ZnO reagents on thermal synthesis of cobalt-zinc ferrite (Co0.5Zn0.5Fe2O4) was studied using X-ray powder diffraction and thermal analyses. The initial oxide powders were mixed using a Retsch Emax high energy ball mill to homogenize the mixture and enhance the reactivity. Mechanical activation was performed in air for 30 and 60 min. Thermal synthesis was performed at 900 °C for 4 h. X-ray diffraction analysis revealed an increase in the intensity of reflections that belong to spinel phases at increased rotational speed of the grinding vials and grinding duration. The patterns of formation of the final ferrite phase depending on the modes of mechanical pre-activation were showed by thermal analysis. It was shown that mechanical pre-activation of a mixture of initial reagents in a high-energy ball mill facilitates the formation of the ferrite phase of the given composition. The Curie temperature was determined for Co0.5Zn0.5Fe2O4 ferrite (~ 178 °C) by thermal synthesis. Kindly check and confirm whether the corresponding author is correctly identified. Corresponding author identified correctl [ABSTRACT FROM AUTHOR]

In this study, a Mg22Al/10MgO composite could be produced at nearly full density by the field-assisted sintering technique at relatively low temperatures and for short time such as 400°C and 15 min under the vacuum-argon atmosphere. The Mg22Al matrix consists of 22 wt % Al, produced by mechanical alloying for 18h and then mixed 2 h with 10 wt % MgO as a reinforcement material. The microstructure of the sample was analysed using an optical microscope, SEM, EDS and XRD. Mechanical properties such as micro hardness, density and compression strength are also obtained. With a compression strength of 314.4 MPa and a hardness value of 137 HV, the composite obtained nearly theoretical density-TD of 0.99. The crystal distortion was measured and calculated by using XRD results. Furthermore, minor amounts of fine intermetallic compounds and oxides such as Al3Mg2, AlMg, γ-Al12Mg17 Al2O3 and MgO were detected. The field-assisted sintering technique, which allows rapid and low-temperature sintering, is used in this study to show that the mechanical properties of the mechanically alloyed microstructure are likely to be preserved during sintering. Furthermore, it demonstrates that when Al and Mg are mechanically alloyed, the alloying pair is a very suitable metal matrix material for composites in which a reinforcing phase, such as MgO, forms an insufficient interface. [ABSTRACT FROM AUTHOR]

Planetary ball milling is a high-energy ball milling technique that is widely used for the synthesis of alloy and composite powders with micrometer or nanometer particle sizes. The effect of process control agent (PCA) content (wt%) and milling time on the morphology, particle size and distribution, crystallite structure, apparent density and oxidation resistance of recycled T-6Al-4V alloy powders from lathe chips is investigated in this study. To investigate the effect of the PCA on the properties of the Ti-6Al-4V alloy particles, methanol is used as the PCA in various amounts of 0.5, 1 and 2 wt%. The milling is carried out using 20:1 of ball-to-powder ratio (BPR) and 400 rpm of milling speed. A morphological change from scrap form to flake-like shape, from flake-like morphology to irregular and semispherical shape and finally from semispherical form to spherical morphology is observed with increase in milling time for all PCA ratios. The results showed that the average particle sizes (D50) are 20, 18.1 and 21.8 μm after milling of 360 min with 0.5 wt%, 1 wt% and 2 wt% PCA, respectively. Results show that the most suitable recycled Ti-6Al-4V powders for powder-based manufacturing techniques are produced between 180 and 360 min of milling with 2 wt% PCA. [ABSTRACT FROM AUTHOR]

In this work, the thermal stability of nanocrystalline (NC) AZ31/TiB2 magnesium matrix composites was investigated, while the microstructure evolution and mechanical properties were analyzed. The results indicated the AZ31/TiB2 still maintained NC structure after annealing at 350 °C for 180 min. Even at the high annealing temperature of 400 °C and 450 °C for 180 min, their average grain size just reached about 124 nm and 155 nm, indicating excellent thermal stability. The TiB2 particles with sub-micron size uniformly distributed in Mg matrix had no change in size and no reaction with matrix during the annealing treatment. Due to the strong Zener pinning effect of TiB2 particles, the grain growth of Mg matrix at high temperature was effectively inhibited. Meanwhile, the solution and precipitation behavior of Al atoms were completed in a short time, due to the existence of many grain boundaries and structural defects. By calculation, the grain growth kinetics was described by the kinetics equation D 8 - D 0 8 = k t and the activation energy Eg for grain growth was 131.6 kJ/mol, which was much higher than that of pure Mg (92 kJ/mol). Due to their excellent thermal stability, the decrease in both compressive yield strength and ultimate compressive strength was no more than 12.2% after annealing treatment. Even annealing at 450 °C for 180 min, the CYS and UCS of the samples were still above 283 MPa and 295 MPa, respectively. [ABSTRACT FROM AUTHOR]

In the present work, a medium-entropy alloy, FeCoNiCu, was selected as a model system to demonstrate the possibility of fabricating solid solution-type alloy coatings by detonation spraying. A mixture of Fe+Co+Ni+Cu powders was first treated in a high-energy planetary ball mill. The evolution of the microstructure of the FeCoNiCu alloy particles with the milling time was investigated. After 20 min of milling, the powder was nearly a single-phase solid solution of face-centered cubic structure. A bulk alloy was obtained by consolidating the ball-milled powders by spark plasma sintering. The coatings and sintered material were studied by x-ray diffraction and scanning electron microscopy/energy-dispersive spectroscopy/elemental mapping. No oxidation of the material occurred during detonation spraying. The coatings and sintered alloy obtained from the powder mixture milled for 20 min were nearly single-phase with a major phase of face-centered cubic structure. The residual porosity of the coatings and sintered alloy was as low as ~1%. The hardness values of the coatings and sintered alloy were found to be close to each other (~400 HV300). This work showed that a combination of high-energy milling and detonation spraying is a viable route for the formation of nearly single-phase medium-entropy FeCoNiCu alloy coatings. [ABSTRACT FROM AUTHOR]

In mechanical milling, stearic acid can be used as a process control agent to reduce the interface energy between powders and contribute to the crushing of powder particulates. In this study, a super-hydrophobic coating with a contact angle of 153° ± 2° was fabricated by ball milling a copper powder and stearic acid mixture onto an aluminum foil. Fourier-transform infrared spectroscopy demonstrated that stearic acid was successfully transferred to the surface of the copper powder, and scanning electron microscopy revealed that the structure of the super-hydrophobic coating consisted of irregular particles and sheets. The combined effect of low surface free energy and rough structure of the copper-based coating contributed to the super-hydrophobicity. The reported method is beneficial to preparing super-hydrophobic materials by the solid-state synthesis. [ABSTRACT FROM AUTHOR]

Many industrial and metallurgical processes require powders within a specific size range which may not be readily available from conventional processes. Thus, mechanical alloying (MA) has been exploited as an important attrition process for obtaining the desirable particle sizes of powders. However, MA is highly stochastic, depends on several parameters, and often relies on expensive and time-intensive experimentations. Therefore, developing a good model that can accurately predict the process can eliminate these challenges. This study, therefore, proposed an artificial neural network (ANN)-based mathematical equation for predicting the particle size of AZ61 magnesium alloy after MA. Three input parameters comprising rotation speed, charge ratio, and milling time were used to develop the model. Its s for training, validation, and testing datasets was greater than 93%, an indication of its high prediction ability. Furthermore, the proposed model was compared with a multilinear regression (MLR) model by means of root-mean-square error (RMSE) and mean absolute error (MAE) analyses. Results showed that the RMSE and MAE of the ANN model were considerably lower than that of the MLR model. This further established the accuracy and high predictability of the ANN model. Additionally, sensitivity analysis revealed that rotation speed was the most significant parameter influencing particle size during MA. The developed model is useful for predicting the particle size of AZ61 powder, optimizing the MA process, and eliminating expensive and time-intensive experimentations. [ABSTRACT FROM AUTHOR]

Based on X-ray photoelectron spectroscopy and X-ray diffraction data for zinc oxide powders prepared via mechanical milling in an attritor, we have identified inherent features of the chemical binding of carbon dioxide on the surface of the powders. The results thus obtained can be used in the fabrication of carbon dioxide sensors, catalysts, and photocatalysts with improved performance parameters. The powders milled for 3 h exhibit the most active interaction with atmospheric carbon dioxide and have the largest percentage of carbon chemisorbed in carbonate-like form. [ABSTRACT FROM AUTHOR]

Formation of Cr2AlC-MAX phase in solid state was observed during annealing of high-energy ball-milled Al-33at.%Cr powder blend, which contained about 2.4wt.% carbon, i.e., an overall composition of Al-31at.%Cr-7at.%C. The carbon content in the ball-milled powder blend originated from the process control agent, viz. toluene. The diffusion of carbon in the system led to the evolution of Cr2AlC phase during subsequent annealing at 600–850 °C. Formation of multiple Cr-Al phases in addition to Cr23C6 and other Cr-C hard phases was also observed in the annealed system even though the Cr-Al binary equilibrium phase diagrams predicted the presence of either α-Cr5Al8 (Space group: R3m) or α-Cr4Al9. (Space group: I43m), while the ternary Al-Cr-C phase diagram predicted the presence of Al4C3, Cr5Al8 and Cr4Al9 phases. The thermodynamic conditions responsible for the evolution of Cr2AlC and other phases were evaluated and discussed with experimental validation. [ABSTRACT FROM AUTHOR]

The effect of the mechanical milling of Sm2Fe17N3 nitride in a vibratory mill, in particular, the effect of the powder-to-ball mass ratio (m), milling time (tmill), milling medium, and concentration of added surfactants, has been systematically studied in order to determine optimum parameters for the high level of hysteresis properties of the magnetically anisotropic powder. It is shown that, as m increases from 15 to 50, the increase in the coercivity Hc of the powder at the beginning milling stages (tmill ≤ 4 h) is substantially accelerated; in this case, about 80% particles are less than 1 µm in size. As the milling time increases (tmill > 4 h), the coercivity continues to increase. However, the specific residual magnetization σr and maximum energy product (BH)max begin to decrease because of the developed process of particle agglomeration, which results in a deterioration of the powder allignment. The addition of a surfactant to the protective medium markedly intensifies the milling process and accelerates the kinetics of the increase of Hc at the beginning milling stages at m = 15. The best complex of magnetic hysteresis properties, σr ≥ 135 emu/g, Hc, ≥ 8 kOe, and (BH)max ≥ 18 MG Oe, is observed for powders milled in 5% solution of oleic acid in acetone, 5% solution of capronic acid in toluene, and 1% solution of methyl caproate in toluene. [ABSTRACT FROM AUTHOR]

Methods for preparing zeolites with the particle size of 50–200 nm using mechanical milling on bead mills (top-down approach) are analyzed. The milling can be described by a first-order rate equation, but mathematical models allowing prediction of the particle size and degree of crystallinity of zeolite after milling, based on the process parameters, are still lacking. The milling is accompanied by degradation of the zeolite lattice, leading to a decrease in the zeolite crystallinity and activity in catalytic reactions. Recrystallization and dealumination may be promising ways to restore the zeolite structure after milling; in this case, the choice of the conditions for such posttreatment is of crucial importance. Evolution of textural and acid properties of zeolites in the course of milling is considered, and the effect of milling conditions on the catalytic activity of zeolites in various reactions is discussed. The main outcome from a decrease in the size of zeolite catalysts is an increase in their activity and a decrease in the deactivation rate. [ABSTRACT FROM AUTHOR]

The PrMg12-type composite alloy of PrMg11Ni + x wt% Ni (x = 100, 200) with an amorphous and nanocrystalline microstructure were synthesized through the mechanical milling. Effects of milling duration and Ni content on the microstructures and electrochemical hydrogen storage performances of the ball-milled alloys were methodically studied. The ball-milled alloys obtain the optimum discharge capacities at the first cycle. Increasing Ni content dramatically enhances the electrochemical property of alloys. Milling time varying may obviously impact the electrochemical performance of these alloys. The discharge capacities show a significant upward trend with milling duration prolonging, but milling for a longer time more than 40 h induces a slight decrease in the discharge capacity of the x = 200 alloy. As milling duration increases, the cycle stability clearly lowers, while it first declines and then augments under the same condition for the x = 200 alloy. The high-rate discharge abilities of the ball-milled alloys show the optimum values with milling time varying. [ABSTRACT FROM AUTHOR]

The impact of mechanical milling of the mixture of Fe2O3–Li2CO3–ZnO reagents on thermal sintering of lithium–zinc ferrites of Li0.4Fe2.4Zn0.2O4 composition was studied using X-ray diffraction, dilatometric and kinetic analyses. The dilatometric analysis showed that mechanical pre-activation of the mixture of the initial reagents in a planetary mill reduces the initial shrinkage point and accelerates compaction of ferrite-pressed samples during sintering, which ultimately increases the density of the finished ferrite ceramics. The sintering of lithium–zinc ferrite from a non-milled mixture proceeds in two steps. At the first stage, the samples show linear expansion, and at ~ 720 °C, a sharp shrinkage occurs. The data obtained from milled samples indicate that shrinkage starts at lower temperatures and is in the range of 370–400 °C. This result allows simultaneous synthesis and sintering of lithium–zinc ferrite through one-stage heating of pressed samples to the sintering point. The resulting lithium–zinc ferrite ceramics exhibits high density, specific magnetization and Curie temperature. The kinetic analysis of ferrite compaction was performed, and kinetic parameters and the model to describe this process were found. [ABSTRACT FROM AUTHOR]

Competitive amorphization scenarios in arsenic monosulphide AsS under nanostructurization from directly-synthesized β-As4S4 polymorph are identified employing ab-initio quantum-chemical modelling route with cluster-simulation code CINCA. Geometrically-optimized configurations of As4S4 cage-like molecule and its network-forming derivatives responsible for amorphization are simulated and parameterized. Most plausible are found to be single-broken As4S4 clusters keeping one hexagon and two adjacent pentagons in atomic arrangement, which are responsible for uncontrolled amorphization in directly-synthesized β-As4S4 polymorph. Completely-polymerized triple- and quadruple-broken As4S4 clusters in chain configurations without any small-ring entities are character for milling-driven amorphization in monoparticulate β-As4S4- and biparticulate β-As4S4-Fe3O4 composites. In contrast, in triparticulate 1⋅β-As4S4-4⋅ZnS-1⋅Fe3O4 solution, the amorphizing network is built of double-broken As4S4 molecules keeping pentagon-type rings. Combined configuration-enthalpic model showing amorphization diversity in mechanoactivated arsenic monosulphide is developed. [ABSTRACT FROM AUTHOR]

This review article presents the use of mechanical milling technique for the synthesis of a variety of fast fluoride ion conducting materials for different electrochemical device applications. The influence of various milling parameters such as milling time, type of the milling pot, and rotation speed on the structural and transport parameters of different fluoride-based materials is reviewed. The advantages and disadvantages of the milling technique in comparison to the other methods are outlined. The ionic conductivity values of different fast fluoride ion conducting materials prepared by various synthesis routes are compared. At the end, it is observed that mechanical milling is an easy and promising method for the synthesis of different fast fluoride ion conducting materials in comparison to the same by other methods and furthermore, their ionic transport results indicate an enhancement in conductivity values by two to four orders in the mechanochemically synthesized materials. [ABSTRACT FROM AUTHOR]

LiF–NixMn1−xO composites are prepared by the mechanical milling of LiF and NixMn1−xO (x ≤ 1) solid solution for 72 h. The obtained composites are examined by XRD, charge–discharge measurements, CV, and XPS. X-ray diffraction peaks of LiF–NixMn1−xO are broadened by milling. The diffraction peaks of NixMn1−xO in x < 0.5 are shifted to the higher angle by milling together with LiF. The discharge capacity and voltage of the LiF–NixMn1−xO composites changes with the molar ratio of NiO and MnO. The composite containing a large amount of Mn showed a lower discharge voltage and a larger discharge capacity. The composites containing a large amount of Ni show higher discharge voltage. The maximum discharge capacity among LiF–NixMn1−xO composites is obtained at x = 0.2, and its value is 279 mAh g−1 for cut-off voltages of 2.0–4.8 V at 0.1 C. The XPS measurement shows that the Mn2+ and Ni2+ ions are oxidized to Mn3+ and Ni3+ions in charging process and are reduced to Mn2+ and Ni2+ ions in the discharging. The oxidation and reduction process between Mn2+ and Mn3+ greatly contribute in the charge and discharge process of LiF–Ni0.5Mn0.5O composite. Discharge capacity of composite of LiF and Ni0.2Mn0.8O is 279 mAh g−1. [ABSTRACT FROM AUTHOR]

In the present paper, results of a study of the impact of high-energy effects on the surface morphology and on the formation of the internal structure in PMS-1 copper particles are reported. It is shown that the mechanical milling of the copper powder in a planetary mill leads to the formation of powder agglomerates with a layered structure consisting of numerous deformed ultrafine particles. It is found that the volume of the agglomerated particles involves the defects in the form of microcracks and closed micropores with some content of the initial gas. Subsequent treatment of the powder in an argon-helium plasma jet leads to the formation of dense particles as well as particles with distributed gas volumes or a single cavity. It was found that, as the molten metal interacted with localized gas volumes during the plasma treatment, local oxidation of the material occurred. A dispersion-strengthened structure with copper oxide compounds of a predominantly round shape, ranging in size from tens of nanometers to 7 µm and uniformly distributed over the particle volume, was formed. [ABSTRACT FROM AUTHOR]

In this paper, it is intended to analyze the influence of coarse grain (CG) phase on mechanical properties and wear performance of Al–2Cu-4 wt% B4C trimodal composite. Trimodal ultra-fine grained (UFG) composites with 30 and 50 wt% aluminum coarse grains (4-66-30) and (4-46-50) were prepared using powder metallurgy and hot extrusion. Wear tests were conducted for normal loads of 20 and 50 N at a sliding velocity of 0.6 m/s at room temperature. Results revealed that there was a direct relationship between the CG content and the plastic deformation of worn subsurface. Moreover, by adding 50 wt% CG, wear rate reached to around 0.02 × 10−3 (mm3/m) and plastic deformation increased significantly. Investigations on the microstructure indicated that wear mechanisms of the trimodal samples were a combination of abrasive, adhesive, and delamination wear in the tribological layer. [ABSTRACT FROM AUTHOR]

In this study, for the first time, antimicrobial properties of Al–Cu–Fe, Al–Cu–Fe–B and Al–Cu–Fe–Co quasicrystal powders were investigated in the leached and un-leached condition against Gram-negative (E. aerogenes, K. pneumoniae) and Gram-positive (B. cereus, K. rosea) bacterial environment. Leaching of the powders in 10 M NaOH aqueous solution resulted in the enrichment of Cu and Fe at the surface. Consequently, bacterial activities in the vicinity of the leached quasicrystal powders were inhibited, indicating good antimicrobial characteristics of the leached powders. All the three leached powder samples exhibited antimicrobial activities with a varying degree. From the diameter of inhibition zone, it was deduced that E. aerogenes are the most susceptible against the leached powders. The leached Al–Cu–Fe–B and Al–Cu–Fe–Co quasicrystal powders showed nanostructured features on the outer surface. During leaching, the icosahedral structure was retained in all the samples. [ABSTRACT FROM AUTHOR]

A green antibacterial material was successfully prepared using natural attapulgite and carvacrol by a facile mechanical milling. The stable hybrid nanocomposites were formed after the zeolitic water molecules of attapulgite was substituted by the carvacrol molecules under the effect of mechanical force. It was found that the 30 wt% of carvacrol added amount and the 30 min of grinding time were the appropriate parameters for preparation a stable hybrid. Furthermore, the fast release behavior of carvacrol molecules provided good antibacterial property for the obtained antibacterial material, and the minimum inhibitory concentration values against both Staphylococci aureus and Escherichia coli were 2.0 mg/mL. Therefore, it is expected to develop a facile and promising strategy for preparation green antibacterial material to replace the synthetic antibiotic used in animal feeding. [ABSTRACT FROM AUTHOR]

The powder mixture of the iron and hexagonal boron nitride subjected to mechanical milling using the high energy ball mill to obtain hard magnetic material has been investigated by XRD, SEM, DSC, and VSM methods. The components ratio in the mixture has been selected as 1 : 1. The initially soft magnetic powder shows hard magnetic properties already after 7 hours of mechanical milling. Increasing time of milling from 7 to 60 h leads to increase the coercivity of the powder mixture. The following annealing changes the phase composition and magnetic properties of the mechanical activated powder. The maximum magnetic properties values have been obtained after annealing at 500°C within 5 h in the nitrogen atmosphere: saturation magnetization σS = 70 emu/g, coercivity = 42 kA/m (525 Oe). [ABSTRACT FROM AUTHOR]

Nanocrystalline/amorphous LaMg12-type alloy–Ni composites with a nominal composition of LaMg11Ni + x wt% Ni (x = 100, 200) were synthesized by mechanical milling. Effects of Ni content and milling time on the gaseous hydrogen storage thermodynamics and dynamics of alloys were systematically investigated. The hydrogen desorption properties were studied by Sievert apparatus and a differential scanning calorimeter (DSC). Thermodynamic parameters (ΔH and ΔS) for the hydrogen absorption and desorption of alloys were calculated by Van't Hoff equation. Hydrogen desorption activation energy of alloy hydride was estimated by Arrhenius and Kissinger methods. The increase in Ni content has a slight effect on the thermodynamic properties of alloys, but it significantly enhances the hydrogen absorption and desorption kinetics performance of alloys. Moreover, variation of milling time clearly affects the hydrogen storage properties of alloys. Hydrogen absorption capacity ( C 100 a ) and hydrogen absorption saturation ratio ( R 10 a ) (a ratio of the hydrogen absorption capacity at 10 min to the saturated hydrogen absorption capacity) have maximum values with milling time varying. But hydrogen desorption ratio ( R 20 d ) (a ratio of the hydrogen desorption capacity at 20 min to the saturated hydrogen absorption capacity) always increases with milling time prolonging. Particularly, prolonging milling time from 5 to 60 h makes R 20 d increase from 10.89% to 16.36% for the x = 100 alloy and from 13.93% to 21.68% for the x = 200 alloy, respectively. [ABSTRACT FROM AUTHOR]

Oxide dispersion strengthening is an effective method to improve the high-temperature mechanical properties of the alloys in which various reinforcements are added in the alloy matrix by mechanical milling and consolidating the mixture by different techniques like hot pressing, hot isostatic pressing and spark plasma sintering. This work presents the development of IN 718 ODS alloy by dispersing yttria in IN 718, which has improved mechanical properties at high temperatures. Yttria powder was added to IN 718 alloy powder in different weight fractions of 0.25, 0.5 and 1% and mechanically milled. The composite powders were consolidated by hot pressing and hot isostatic pressing (HIP). A small fraction of isolated porosities in the matrix was observed in hot-pressed samples which caused degradation of the mechanical properties. Percentage of porosities increased with the increase in yttria content. The hot-pressed samples were HIPed to heal the porosities. 0.5 wt% yttria-dispersed Inconel 718 hot-pressed compact exhibited better properties at 850 °C and showed 50 MPa improvement in ultimate compressive strength compared to Inconel 718 alloy. [ABSTRACT FROM AUTHOR]

Magnesium hydride (MgH2) is a very promising hydrogen storage material due to its high hydrogen storage capacity (7.6 wt %) and low cost. It has been paid increasing attention as it may be employed in supplying hydrogen on-board. However, the production of MgH2 in high purity is still a challenging issue because the process requires high pressure and prolonged time. In this paper, high purity of MgH2 was achieved by the process of pre-milling assisted hydriding of Mg powder under a hydrogen pressure as low as 0.5 MPa. The effects of hydrogen pressure as well as hydriding and mechanical milling parameters, such as ball-to-powder ratio and milling time were investigated systematically. The relationship between the morphologies and the purities of products were discussed in detail. Our results revealed that MgH2 purity of 94.19 wt % can be achieved by hydriding with heating up to 853 K followed by cooling down to 593 K and keeping this temperature for 5 h after the milling pretreatment of Mg powder, at 400 rpm milling speed, 20 : 1 ball-to-powder ratio and 40 min milling time. SEM observation of the morphology of products indicated the achievement of the purity of MgH2 under a hydrogen pressure as low as 0.5 MPa was related to the structural defects and activation of Mg powders caused by the mechanical milling. [ABSTRACT FROM AUTHOR]

Temperature-modulated DSC TOPEM® method was applied to study amorphization in directly synthesized high-temperature polymorph of tetra-arsenic tetra-sulfide β-As4S4 affected to high-energy mechanical milling in a dry mode with 100-600 min−1 rotational speeds. The appeared amorphous phase is shown to possess dual nature, being related to As-rich glassy-like substances with low- and high-temperature glass transition midpoints. In respect of DSC TOPEM® studies, the crystalline-amorphous heterogeneity of chemical environment around β-As4S4 crystallites results in incongruent double-peak melting revealed through two endothermic effects at~ 305 °C and ~ 315 °C. Amorphous phase continuously generated under ball milling with increased rotational speed is identified as compositionally authentic to arsenic monosulfide, but different in medium-range order from stoichiometric As2S3. The overall amorphization in commercial arsenic sulfide prepared by direct synthesis from elemental constituents under high-energy ball milling occurs from two sources, these being high-to-low-Tg amorphous phase transformation and direct vitrification of β-As4S4 phase. These data testifies in favor of "shell" model treated solid-state amorphization in terms of defect generation in parent β-As4S4 phase, the amorphous substance being nucleated heterogeneously from grain boundaries followed by stretching into crystalline grain interior. [ABSTRACT FROM AUTHOR]

In the present study, two three-layer feed-forward artificial neural networks (ANNs) and multiple linear regression (MLR) models were developed for modeling the effects of material and process parameters on the powder particle size characteristics generated during high-energy ball milling of Al and B4C powders. The investigated process parameters included aluminum particle size, B4C size and its content as well as milling time. The median particle size (D50) and the extent of size distribution (D90–D10) were considered as target values for modeling. The developed ANN and MLR models could reasonably predict the experimentally determined characteristics of powders during mechanical milling. [ABSTRACT FROM AUTHOR]

Abstract: Oxidation behavior of nanostructured Ni-5Al HVOF coatings was studied. For this purpose, isothermal oxidation of the free standing coatings was performed at 950°C. Lattice parameter determination technique was used for evaluating aluminum depletion to characterize oxidation behavior. The results showed that Al-depletion rate of the nanostructured coating was less than that of the conventional one, suggesting superior oxidation resistance of the nanostructured one. One reason, besides the one usually ascribed to grain size refinement and distribution of Nano oxides, lies in the coating integrity which imply the absence of any notable discontinuities including inter-splat oxides and porosities. On the other hand, vacuum heat treatment revealed that the nanostructured coating exhibited a phenomenon called diffusional creep, which is thought to be the most effective one in all densification mechanisms responsible for metallurgical consolidation processes. It was argued that this mechanism must also be active during oxidation in air and therefore can help retain the coating integrity, providing a sound metallic base for durable surface supply of aluminum throughout oxidation process. Therefore, coating integrity also is central to the formation of the protective α-Al2O3 subscale, as observed and argued in this paper for the nanostructured Ni-5Al coating. [ABSTRACT FROM AUTHOR]

Graphene (multilayer graphene) was chosen as an additive to improve the hydrogen uptake and release properties of magnesium (Mg). Five weight percent of graphene was added to pre-milled Mg by milling in hydrogen (reaction-involving milling). The hydrogen uptake and release properties of the graphene-added Mg were investigated. The activation of Mg-5graphene, which was prepared by adding 5 wt% graphene to Mg pre-milled for 24 h, was completed after the second cycle (cycle number, CN = 2). Mg-5graphene had a high effective hydrogen-storage capacity (the quantity of hydrogen absorbed for 60 min) of 6.21 wt% at CN = 3 at 593 K in 12 bar H2. At CN = 1, Mg-5graphene released 0.46 wt% hydrogen for 10 min and 4.99 wt% hydrogen for 60 min. Milling in hydrogen is believed to create defects (leading to facilitation of nucleation), produce cracks and clean surfaces (leading to increase in reactivity), and decrease particle size (leading to diminution of diffusion distances or increasing the flux of diffusing hydrogen atoms). The added graphene is believed to have helped the sample have higher hydrogen uptake and release rates, weakly but partly, by dispersing heat rapidly. [ABSTRACT FROM AUTHOR]

The effect of mechanical milling on the oxidation kinetics of ultrafine iron powders was investigated by thermogravimetric (TG) analysis. The initial α-Fe powder with average particles size of 100 nm was made by the electric explosion of wire. The milling of iron powder was carried out by AGO-2S planetary ball mill using a rotation speed of 2220 rpm and the milling times of 15 and 40 min. According to the XRD data, the main content of α-Fe was observed in all samples. However, a certain amount (~ 20 mass%) of wustite phase (FeO) is formed after ball milling of ultrafine iron powders. From TG analysis, the powders milling leads to increase in the temperature of thermal oxidation onset and shifts the reaction to higher temperatures. A model-free isoconversional method of the Friedman analysis was employed only in a first qualitative approximation. More accurate kinetics parameters were obtained using the multivariate nonlinear regressions, where three-step reaction with branching set of n-order equations for each step was chosen. [ABSTRACT FROM AUTHOR]

Abstract: The prime objective of this study is an investigation on the effects of mechanical milling process, incorporation of silicon carbide reinforcement phase and different amounts and types of coarse-grained aluminum powders (30 and 50 wt% unmilled Al5083 and Al2024) on microstructure, mechanical properties and fracture behavior of trimodal SiC reinforced Al5083/Al2024 aluminum alloy matrix nanocomposites. These composites were prepared through mechanical milling and hot extrusion processes. Results indicated that nanocrystalline structures of Al5083 alloy and Al5083-5 wt%SiC composite powders were formed during mechanical milling time of 50 h. Al5083-5 wt%SiC nanocomposite sample revealed strength and hardness superior to the coarse-grained aluminum sample. However, its elongation decreased down to a minimum value of 0.98%. Addition of 30 wt% unmilled Al2024 particles to the nanocomposite powder caused considerable improvement in the ductility, slight decrease in strength and hardness values and change in fracture mechanism from brittle to brittle-ductile mode, compared to that of Al5083-5 wt%SiC nanocomposite sample.Graphical Abstract: [ABSTRACT FROM AUTHOR]

This study focuses on the performance of nanostructured banana peels in lanthanide-laden mine water treatment. Specifically, nanostructure formation via mechanical milling, characterization in detail and application of this sorbent media in rare earth elements (REEs) removal from synthetic and real mine water are thoroughly investigated. The sorbent samples were characterized by transmission electron microscopy, Brunauer-Emmett-Teller, X-ray diffraction and Fourier transform infrared analyses, while the amount of REEs adsorbed was analysed using inductively coupled plasma optical emission spectroscopy. Results revealed that the particle and crystallite sizes were reduced from <65,000 to <25 nm and 108 to 12 nm, respectively, as the milling progressed. Furthermore, the fracture of particles resulted in a surface area increment from 1.07 to 4.55 m2 g−1. Through Fourier transform infrared analysis, the functional groups responsible for the coordination and removal of metal ions were found to be carboxylic group (at absorption bands of 1730 cm−1) and amine groups (889 cm−1). The Langmuir maximum adsorption capacity was 47.8 mg g−1 for lanthanum and 52.6 mg g−1 for gadolinium. Meanwhile, results revealed that banana peels have a high affinity for Sm, Eu, Nd, Pr, Gd, Tb and Lu compared to other lanthanides present in the mine water samples. The results obtained so far indicate that nanostructured banana peel is a potential adsorbent for REEs removal from mine water. However, for any application, the water matrix to be treated substantially influences the choice of the sorbent material. [ABSTRACT FROM AUTHOR]

Nanocrystalline and amorphous LaMg12-type LaMg11Ni + x wt% Ni (x = 100, 200) alloys were synthesized by mechanical milling. Effects of Ni content and milling time on the gaseous and electrochemical hydrogen storage kinetics of as-milled alloys were investigated systematically. The electrochemical hydrogen storage properties of the as-milled alloys were tested by an automatic galvanostatic system. And the gaseous hydrogen storage properties were investigated by Sievert apparatus and a differential scanning calorimeter (DSC) connected with a H2 detector. Hydrogen desorption activation energy of alloy hydrides was estimated by using Arrhenius and Kissinger methods. It is found that the increase of Ni content significantly improves the gaseous and electrochemical hydrogen storage kinetic performances of as-milled alloys. Furthermore, as ball milling time changes, the maximum of both high rate discharge ability (HRD) and the gaseous hydriding rate of as-milled alloys can be obtained. But the hydrogen desorption kinetics of alloys always increases with the extending of milling time. Moreover, the improved gaseous hydrogen storage kinetics of alloys are ascribed to a decrease in the hydrogen desorption activation energy caused by increasing Ni content and milling time. [ABSTRACT FROM AUTHOR]

The main focus of this study is concentrated on the effect of mechanical milling on graphite-boron carbide hybrid reinforced ZA27 nanocomposites. With this respect, nano-sized graphite (Gr) and boron carbide (B4C) reinforced ZA27 matrix nanocomposites were fabricated via a combination of mechanical milling (MM) and hot pressing techniques. MM method was used to produce a ZA27-based hybrid nanocomposite (ZHNC) that nanosized additives dispersed homogenously in ZA27 matrix. Microstructural and mechanical properties of the nanocomposites were scrutinized as a function of milling time using X-ray diffractometer, scanning electron microscope, hardness and tensile testing machines. Results show that MM method can be utilized for homogeneously distributing the nano-sized additives. Flake-shape morphology negatively influences physical and mechanical properties. It was also found that grain and particle size is decreased after 12 h milling process. With increasing MM time, homogeneous microstructure of the nanocomposite bulk materials was obtained and subsequently their mechanical properties were improved considerably. [ABSTRACT FROM AUTHOR]

Zn(BH4)2 made in our former investigation and Ni were mixed with MgH2 to promote the hydrogen absorption and release features of Mg. A 96 w/o MgH2 + 2 w/o Ni + 2 w/o Zn(BH4)2 sample [named MgH2-4NZ] was prepared by milling in a planetary ball mill in a hydrogen atmosphere. The proportion of the additive was small (4 w/o) in order to increase hydrogen absorbing and releasing rates without majorly sacrificing the hydrogen-storage capacity. The hydrogen absorption and release features of the MgH2-4NZ were inspected in detail and compared with those of 99 w/o MgH2 + 1 w/o Zn(BH4)2 [named MgH2-1Z] and 95 w/o MgH2 + 2.5 w/o Ni + 2.5 w/o Zn(BH4)2 [named MgH2-5NZ] samples. The activation of the MgH2-4NZ was not required. The MgH2-4NZ had a useful hydrogen-storage capacity (the quantity of hydrogen absorbed after 60 min) of about 5.5 w/o at the first cycle. At the first cycle, the MgH2-4NZ absorbed 3.84 w/o hydrogen after 5 min and 5.47 w/o hydrogen after 60 min at 593 K in 12 bar hydrogen. The MgH2-4NZ had a higher releasing rate, larger amounts of hydrogen absorbed and released after 60 min, and a better cycling capability than the MgH2-1Z. Staying of Ni (as Mg2Ni) and a larger amount of Zn among particles is believed to have led to the better cycling capability of the MgH2-4NZ. [ABSTRACT FROM AUTHOR]

To support the development of technology to utilize low-grade Ti-Nb-bearing Fe concentrate, the reduction of the concentrate by coal was systematically investigated in the present paper. A liquid phase formed when the Ti-Nb-bearing Fe concentrate/coal composite pellet was reduced at temperatures greater than 1100°C. The addition of CaCO3 improved the reduction rate when the slag basicity was less than 1.0 and inhibited the formation of the liquid phase. Mechanical milling obviously increased the metallization degree compared with that of the standard pellet when reduced under the same conditions. Evolution of the mineral phase composition and microstructure of the reduced Ti-Nb-bearing Fe concentrate/coal composite pellet at 1100°C were analyzed by X-ray diffraction and scanning electron microscopy-energy-dispersive spectroscopy. The volume shrinkage value of the reduced Ti-Nb-bearing Fe concentrate/coal composite pellet with a basicity of 1.0 was approximately 35.2% when the pellet was reduced at 1100°C for 20 min, which enhanced the external heat transfer to the lower layers when reduced in a practical rotary hearth furnace. The present work provides key parameters and mechanism understanding for the development of carbothermic reduction technology of a Ti-Nb-bearing Fe concentrate incorporated in a pyrometallurgical utilization flow sheet. [ABSTRACT FROM AUTHOR]

Raw ulexite (U-3 mm) mineral used as a initial material was milled by using mechanical milling method, the milling time of which is from 0 to 8 h. Particle size, morphology, elemental and crystal structure measurements of the U-3 mm material and milled powder (U_3%, process control agent amount: 3%) were performed. In particle size analysis, minimum $$d_{50},d_{10}$$ and $$d_{\mathrm{min}}$$ values of U_3% powder have been found to be 5.921 $$\upmu \hbox {m}$$ , 641 nm and 240 nm, respectively. Therefore, it has been reached to submicron level in particle size for the U_3% powder. Besides, optimum milling time has been detected to be 0.5 h. In morphology analysis, the U_3% powder has been observed to be more homogeneous compared to the U-3 mm material. In the analysis of element, the U_3% powder has been determined not to be a pure compound ( $$\hbox {Na}_{2}\hbox {O}{\cdot }2\hbox {CaO}{\cdot } 5\hbox {B}_{2}\hbox {O}_{3}{\cdot } 16\hbox {H}_{2}\hbox {O}$$ ). In crystal structure analysis, crystalline size of the U_3% powder has reduced to 10.3 nm at the end of 8 h. Moreover, crystal structure deformation caused by milling process of the U-3 mm material has improved thanks to PCA. The findings obtained from this work will be beneficial for nanoworks and industrial applications, e.g., civil engineering-pavement engineering materials, of ulexite (boron mineral) material. [ABSTRACT FROM AUTHOR]

To improve the hydrogen storage properties of Mg-based alloys, a composite material of MgH + 10wt%LaH + 10wt%NbH was prepared by a mechanical milling method. The composite exhibited favorable hydrogen desorption properties, releasing 0.67wt% H within 20 min at 548 K, which was ascribed to the co-catalytic effect of LaH and NbH upon dehydriding of MgH. By contrast, pure MgH, an MgH + 20wt%LaH composite, and an MgH + 20wt%NbH composite only released 0.1wt%, 0.28wt%, and 0.57wt% H, respectively, under the same conditions. Analyses by X-ray diffraction and scanning electron microscopy showed that the composite particle size was small. Energy-dispersive X-ray spectroscopic mapping demonstrated that La and Nb were distributed homogeneously in the matrix. Differential thermal analysis revealed that the dehydriding peak temperature of the MgH + 10wt%LaH + 10wt%NbH composite was 595.03 K, which was 94.26 K lower than that of pure MgH. The introduction of LaH and NbH was beneficial to the hydrogen storage performance of MgH. [ABSTRACT FROM AUTHOR]

LiF-NiO composites are synthesized by the mechanical milling of LiF and Li-doped NiO (d_NiO) for 72 h. Li-d_NiO is prepared by the calcination of a mixture of LiCO and NiO. The X-ray diffraction peaks of NiO are shifted by the doping and milling processes, while those of LiF disappear after milling. Rietveld analysis shows that the composites obtained by milling form solid solutions and that the Li and Ni ions in them are disordered. LiF and Li-d_NiO samples milled individually do not exhibit a noticeable discharge capacity, while the composites show large values. The composite formed using undoped NiO without ball-milling shows a discharge capacity of 144 mA h g at 0.05 C between 2.0 and 5.0 V, while the composite of LiF and 20% Li-d_NiO exhibits a discharge capacity of 247 mA h g. The rate capabilities of the composites increase with the Li content, and the discharge capacity of the LiF-Li-d_NiO (20%) is 146 mA h g at 1 C for voltages of 2.0-4.8 V. Graphical Abstract: [ABSTRACT FROM AUTHOR]

The volume fraction of reinforcement and milling time are two important factors in fabricating aluminum metal matrix composites via powder metallurgy (P/M) techniques. In the present work, the effects of volume fraction of reinforcement and milling time on the microstructure, relative density, hardness, and compressive strength were studied. The Al7075 and SiC powders were mixed by a planetary ball mill for about 4 and 8 h, and Al7075-x vol.% SiC specimens (x = 4, 6, 8) were fabricated by a uniaxial cold press and sintered at 873 K (600°C) for 1 h. The crystallite size and morphology of the powder particles were analyzed with X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The results showed that with increasing milling time and volume fraction of the reinforcement phase, the hardness and compressive strength increased. The SEM illustrates that the number of voids increases as SiC content increases, but their size decreases. [ABSTRACT FROM AUTHOR]

Oxide dispersion strengthened (ODS) steels have very high thermal stability and creep resistance due to reinforcement of hard and stable nano-sized ceramic dispersoids in metallic matrix which act as barriers to dislocation motion. This study established the role of Ti in the structural evolution of yttria during mechanical milling and subsequent annealing in a Fe-15 wt% YO-5 wt% Ti model ODS alloy, using electron microscopy and XRD techniques. The alloy was synthesized in a high energy planetary ball mill in Ar atmosphere by varying the milling durations in the range of 0 (un-milled) to 60 h. The XRD result revealed amorphisation of YO/Ti during milling and evolution of YTiO complex oxide upon annealing at 1273 K for 1 h. The electron microscopy studies revealed the refinement of alloy powders from ~50 μm to few nanometers during milling. Electron diffraction analysis and high resolution transmission electron microscopy of 60 h milled as well as and annealed powder showed formation of different types of Y-Ti-O complex oxides such as YTiO, YTiO and YTiO. [ABSTRACT FROM AUTHOR]

Deep rolling is one of the most widely used surface mechanical treatments among several methods used to generate compressive residual stress. This process is usually used for axisymmetric components and can lead to improvements of the surface quality, dimensional accuracy, and mechanical properties. In this study, we deduced the appropriate deep rolling parameters for Al−3vol%SiC nanocomposite samples using roughness and microhardness measurements. The nanocomposite samples were fabricated using a combination of mechanical milling, cold pressing, and hot extrusion techniques. Density measurements indicated acceptable densification of the samples, with no porosity. The results of tensile tests showed that the samples are sufficiently strong for the deep rolling process and also indicated near 50% improvement of tensile strength after incorporating SiC nanoparticle reinforcements. The effects of some important rolling parameters, including the penetration depth, rotation speed, feed rate, and the number of passes, on the surface quality and microhardness were also investigated. The results demonstrated that decreasing the feed rate and increasing the number of passes can lead to greater surface hardness and lower surface roughness. [ABSTRACT FROM AUTHOR]

In the current research, silver (Ag) nanoparticles were synthesized by chemical reduction method and polyethylene-silver nanocomposites containing different Ag contents (0-30 mass%) were fabricated by mechanical milling method. All samples were characterized by X-ray diffraction, UV-Vis spectroscopy, scanning electron microscopy, and transmission electron microscopy. Thermal behavior of these nanocomposites was investigated using differential scanning calorimetry (DSC) and thermogravimetric analysis. The results of the DSC tests showed that although the melting temperature ( T ) of PE and its nanocomposites has the same value, the crystallization temperature ( T ) increases by addition of silver nanoparticles (Ag NPs) in the PE matrix, indicating that the Ag NPs act as nucleation sites. Also, crystallinity index of PE and its nanocomposites was calculated. Results show that the crystallization index changes from 45.74 to 57.36% as Ag NPs content increases from 0 to 30%. The mass loss of nanocomposites was lower than that of the pure PE, which could be attributed to the undecomposed Ag NPs. [ABSTRACT FROM AUTHOR]

Nanocrystalline/amorphous LaMgNi+ xNi ( x=100%, 200%, mass fraction) composite hydrogen storage alloys were synthesized by ball milling technology. The effects of Ni content and milling time on the gaseous hydrogen storage thermodynamics and dynamics of the alloys were systematically investigated. The hydrogen desorption properties were studied by Sievert's apparatus and a differential scanning calorimeter (DSC) connected with a H detector. The thermodynamic parameters (Δ H and Δ S) for the hydrogen absorption and desorption of the alloys were calculated by Van't Hoff equation. The hydrogen desorption activation energy of the alloy hydride was estimated using Arrhenius and Kissinger methods. The results indicate that a variation in the Ni content has a slight effect on the thermodynamic properties of the alloys, but it significantly improves their absorption and desorption kinetics performances. Furthermore, varying milling time clearly affects the hydrogen storage properties of the alloys. All the as-milled alloys show so fast hydrogen absorption rate that the absorbed amount in 10 min reaches to at least more than 95% of the saturated hydrogen absorption capacity. Moreover, the improvement of the gaseous hydrogen storage kinetics of the alloys is found to be ascribed to a decrease in the hydrogen desorption activation energy caused by increasing Ni content and prolong milling time. [ABSTRACT FROM AUTHOR]

In the past few years, considerable research work has been carried out in order to understand the origin of ferromagnetism in un-doped oxide semiconductors. The debate is still open, but most of the experimental and theoretical studies suggested that defects may induce room-temperature ferromagnetic order. This brief review will focus on some very recent works based on the use of mechanical milling as a processing approach in order to induce defects and transform the initial diamagnetic or paramagnetic powders to ferromagnetic order. [ABSTRACT FROM AUTHOR]