The structure and magnetic properties of composite powders prepared by ball milling a mixture of Fe2O3 ‧ (0.4-1.0)Fe were investigated. Hysteresis loops and differential scanning calorimetry (DSC) curves are used to characterize the materials and to examine the effect of the solid state reaction induced by ball milling. The results showed that a solid state reaction in Fe2O3 ‧ (0.4-1.0)Fe clearly proceeds after only 1 h of ball milling. The system is characterized by a positive reaction heat of +2.23 kcal/mole. The diffraction lines related to Fe2O3 and Fe disappeared after 1 h of ball milling and, instead, diffraction lines of the intermediate phase of Fe3O4 plus FeO formed. The magnetization and coercivity of the Fe2O3 ‧ 0.8Fe powders were changed by the solid state reaction process of Fe2O3 by Fe during ball milling. The coercivity of the Fe2O3 ‧ 0.8Fe powders increased with increasing milling time and reached a maximum value of 340 Oe after 5 h of ball milling. This indicates the grain size of Fe3O4 was clearly reduced during ball milling. The magnetic properties of the annealed powders depend on the amount of magnetic Fe and Fe3O4 phases.

Tungsten disulfide (WS2) nanosheets have attracted considerable attention because of their unique optical and electrical properties. Several methods for fabrication of WS2 nanosheets have been developed. However, methods for mass production of high-quality WS2 nanosheets remain challenging. In this study, WS2 nanosheets were fabricated using mechano-chemical ball milling based on the synergetic effects of chemical intercalation and mechanical exfoliation. The ball-milling time was set as a variable for the optimized fabricating process of WS2 nanosheets. Under the optimized conditions, the WS2 nanosheets had lateral sizes of 500–600 nm with either a monolayer or bilayer. They also exhibited high crystallinity in the 2H semiconducting phase. Thus, the proposed method can be applied to the exfoliation of other transition metal dichalcogenides using suitable chemical intercalants. It can also be used with highperformance WS2-based photodiodes and transistors used in practical semiconductor applications.

This study aimed to evaluate the changes in the content of functional components and antioxidant activity of rice and barley according to the milling process used. A considerable amount of γ-oryzanol was observed in unmilled rice and barley. However, γ-oryzanol was not detected in the rice and barley after the milling process. The highest content of γ-aminobutyric acid (GABA) was observed in the unmilled Keunalbori-1-ho barley. The contents of biotin in all samples also decreased in the milled grains compared to the unmilled grains. The highest content of total polyphenols and flavonoids was observed in the Heuksujeongchal barley, and the highest radical scavenging activity was also found in this grain. The milling process led to a decrease in the content of functional components, including γ-oryzanol, GABA, biotin, polyphenols, and flavonoids in both rice and barley. These results may be useful in the development of processed foods using cereal grains.

Recently, high-entropy carbides have attracted considerable attention owing to their excellent physical and chemical properties such as high hardness, fracture toughness, and conductivity. However, as an emerging class of novel materials, the synthesis methods, performance, and applications of high-entropy carbides have ample scope for further development. In this study, equiatomic (Hf-Ti-Ta-Zr-Nb)C high-entropy carbide powders have been prepared by an ultrahigh- energy ball-milling (UHEBM) process with different milling times (1, 5, 15, 30, and 60 min). Further, their refinement behavior and high-entropy synthesis potential have been investigated. With an increase in the milling time, the particle size rapidly reduces (under sub-micrometer size) and homogeneous mixing of the prepared powder is observed. The distortions in the crystal lattice, which occur as a result of the refinement process and the multicomponent effect, are found to improve the sintering, thereby notably enhancing the formation of a single-phase solid solution (high-entropy). Herein, we present a procedure for the bulk synthesis of highly pure, dense, and uniform FCC single-phase (Fm3m crystal structure) (Hf-Ti-Ta-Zr-Nb)C high-entropy carbide using a milling time of 60 min and a sintering temperature of 1,600oC.

Oxide dispersion-strengthened (ODS) steel has excellent high-temperature properties, corrosion resistance, and oxidation resistance, and is expected to be applicable in various fields. Recently, various studies on mechanical alloying (MA) have been conducted for the dispersion of oxide particles in ODS steel with a high number density. In this study, ODS steel is manufactured by introducing a complex milling process in which planetary ball milling, cryogenic ball milling, and drum ball milling are sequentially performed, and the microstructure and high-temperature mechanical properties of the ODS steel are investigated. The microstructure observation revealed that the structure is stretched in the extrusion direction, even after the heat treatment. In addition, transmission electron microscopy (TEM) analysis confirmed the presence of oxide particles in the range of 5 to 10 nm. As a result of the room-temperature and high-temperature compression tests, the yield strengths were measured as 1430, 1388, 418, and 163 MPa at 25, 500, 700, and 900oC, respectively. Based on these results, the correlation between the microstructure and mechanical properties of ODS steel manufactured using the composite milling process is also discussed.

In this study, acoustic and viscosity data are collected in real time during the ball milling process and analyzed for correlation. After fast Fourier transformation (FFT) of the acoustic data, changes in the signals are observed as a function of the milling time. To analyze this quantitatively, the frequency band is divided into 1 kHz ranges to obtain an integral value. The integrated values in the 2–3 kHz range of the frequency band decrease linearly, confirming that they have a high correlation with changes in viscosity. The experiment is repeated four times to ensure the reproducibility of the data. The results of this study show that it is possible to estimate changes in slurry properties, such as viscosity and particle size, during the ball milling process using an acoustic signal.

Tungsten heavy alloys (W–Ni–Fe) play an important role in various industries because of their excellent mechanical properties, such as the excellent hardness of tungsten, low thermal expansion, corrosion resistance of nickel, and ductility of iron. In tungsten heavy alloys, tungsten nanoparticles allow the relatively low-temperature molding of high-melting-point tungsten and can improve densification. In this study, to improve the densification of tungsten heavy alloy, nanoparticles are manufactured by ultrasonic milling of metal oxide. The physical properties of the metal oxide and the solvent viscosity are selected as the main parameters. When the density is low and the Mohs hardness is high, the particle size distribution is relatively high. When the density is high and the Mohs hardness is low, the particle size distribution is relatively low. Additionally, the average particle size tends to decrease with increasing viscosity. Metal oxides prepared by ultrasonic milling in high-viscosity solvent show an average particle size of less than 300 nm based on the dynamic light scattering and scanning electron microscopy analysis. The effects of the physical properties of the metal oxide and the solvent viscosity on the pulverization are analyzed experimentally.

This study investigated the effect of the grinding media of a ball mill under various conditions on the raw material of copper powder during the milling process with a simulation of the discrete element method. Using the simulation of the three-dimensional motion of the grinding media in the stirred ball mill, we researched the grinding mechanism to calculate the force, kinetic energy, and medium velocity of the grinding media. The grinding behavior of the copper powder was investigated by scanning electron microscopy. We found that the particle size increased with an increasing rotation speed and milling time, and the particle morphology of the copper powder became more of a plate type. Nevertheless, the particle morphology slightly depended on the different grinding media of the ball mill. Moreover, the simulation results showed that rotation speed and ball size increased with the force and energy.

In this study, 5 um sized ZrSiO4 was ground to 1.9 um, 0.3 um, and 0.1 um sized powders by wet high energy milling process, and the sintering characteristics were observed. Pure ZrSiO4 itself can-not be sintered to these levels of theoretical density, but it was possible to sinter ZrSiO4 powder of nano-scale size of, −0.1 um to the theoretical density and to lower the sintering temperature for full density. Also, the decomposition of ZrSiO4 with a size in the micron range resulted in the formation of monoclinic ZrO2; however, in the nano sized range, the decomposition resulted in the tetragonal phase of ZrO2. So, it was possible to improve the sintering characteristics of nano-sized ZrSiO4 powders.

This study focuses on fabricating silver flake powder by a mechanical milling process and investigating the formation of flake-shaped particles during milling. The silver flake powder is fabricated by varying the mechanical milling parameters such as the amount of powder, ball size, impeller rotation speed, and milling time of the attrition ballmill. The particle size of the silver flake powder decreases with increasing amount of powder; however, it increases with increasing impeller rotation speed. The change in the particle size of the silver flake powder is analyzed based on elastic collision between the balls, taking energy loss of the balls due to the powder into consideration. The change in the particle size of the silver flake powder with mechanical milling parameters is consistent with the change in the diameter of the elastic deformation contact area of the ball, due to the collision between the balls, with milling parameters. The flake-shaped silver particles are formed at the elastic deformation contact area of the ball due to the collision. Keywords: Flake powder, Milling, Ball collision, Elastic deformation

The milling and particulate characteristics of Al alloy-Al2O3 powder mixtures for a reaction-bonded Al2O3 (RBAO) process were studied. A commercially available prealloyed Al powder with Zn, Mg, Cu and Cr alloying elements (7475 series) was mixed with a calcined sinter-active Al2O3 powder and then milled in centrifugal milling equipment for ~48 hrs. The Al alloy-Al2O3 powder mixtures after milling were characterized and evaluated in various ways to reveal their particulate characteristics during milling. The milling efficiency of the Al alloy increased with a longer milling time. Comminution of the Al alloy particles started with its elongation, showing a high aspect ratio. With a longer milling time, the elongated Al alloy particle changed in terms of its shape and size, becoming equiaxially fine particles. Regardless of the milling efficiency of the Al alloy particles, all of the Al alloy particles repeatedly experienced strong plastic deformation during milling, giving rise to higher density of surface defects, such as microcracks, and leading to higher residual microstress within the Al alloy particles. The chemical reactions, oxidation behavior and hydration behavior of the Al alloy particles and the hydrolysis characteristics of their reaction with the environment were also observed during the milling process and during the subsequent powder handling steps.

The purpose of this paper was to investigate the effect of a high-energy milling (HEM) process on the particle morphology and the correlation between a thermal treatment and tetragonal/monoclinic nanostructured zirconia powders obtained by a precipitation process. To eliminate chloride residue ions from hydrous zirconia, a modified washing method was used. It was found that the used washing method was effective in removing the chloride from the precipitated gel. In order to investigate the effect of a pre-milling process on the particle morphology of the precipitate, dried Zr(OH)4 was milled using a HEM machine with distilled water. The particle size of the Zr(OH)4 powder exposed to HEM reduced to 100~150 nm, whereas that of fresh Zr(OH)4 powder without a pre-milling process had a large and irregular size of 100 nm~1.5 μm. Additionally, modified heat treatment process was proposed to achieve nano-sized zirconia having a pure monoclinic phase. It was evident that two-step calcining process was effective in perfectly eliminating the tetragonal phase, having a small average particle of ~100 nm with good uniformity compared to the sample calcined by a single-step process, showing a large average particle size of ~300 nm with an irregular particle shape and a broad particle size distribution. The modified method is considered to be a promising process for nano-sized zirconia having a fully monoclinic phase.

In the present work, Al- composite powders were fabricated using a mechanical milling process and its milling behaviors and mechanical properties as functions of sizes ( , 500 nm and 50 nm) and concentrations (1, 3 and 10 wt.%) were investigated. For achieving it, composite powders and their compacts were fabricated using a planetary ball mill machine and magnetic pulse compaction technology. Al- composite powders represent the most uniform dispersion at a milling speed of 200 rpm and a milling time of 240 minutes. Also, the smaller particles were presented, the more excellent compositing characteristics are exhibited. In particular, in the case of the 50 nm added compact, it showed the highest values of compaction density and hardness compared with the conditions of and 500 nm additions, leading to the enhancement its mechanical properties.

In this study, a high energy ball milling process was employed in order to improve the densification of direct nitrided AlN powder. The densification behavior and the sintered microstructure of the milled AlN powder were investigated. Mixture of AlN powder doped with 5 wt.% as a sintering additive was pulverized and dispersed up to 50 min in a bead mill with very small beads. Ultrafine AlN powder with a particle size of 600 nm and a specific surface area of 9.54 was prepared after milling for 50 min. The milled powders were pressureless-sintered at for 4 h under atmosphere. This powder showed excellent sinterability leading to full densification after sintering at for 4 h. However, the sintered microstructure revealed that the fraction of yitttium aluminate increased with milling time and sintering temperature and the newly-secondary phase of ZrN was observed due to the reaction of AlN with the impurity.

In this study, the effect of milling time on the microstructure and phase transformation behaviors of Ni-12 wt.%B powders was investigated using vibratory ball milling process. X-ray diffraction patterns showed that the phase transformation of mixed Ni-B elemental powder occurred after 50 hours of milling, with a formation of nickel boride phases. Through the study of microstructures in mechanical alloying process, it was considered that ball milling strongly accelerates solid-state diffusions of the Ni and B atoms during mechanical alloying process. The results of X-ray photoelectron spectroscopy showed that most of B atoms in the powder were linked to Ni with a formation of nickel boride phases after 200 hours of milling. It was finally concluded that mechanical alloying using ball milling process is feasible to synthesize fine and uniform nickel boride powders.

In this study, an analytical realization of end-milling system was introduced using recursive parametric modeling analysis. Also, the numerical mode analysis of end-milling system with different conditions was performed systematically. In this regard, a recursive least square modelling algorithm and the natural mode for real part and imaginary one was discussed. This recursive approach (RLSM) can be adopted for on-line end-milling identification. After experimental practice of the end-milling, the end-milling force was obtained and it was used for the calculation of FRF (Frequency response function) and mode analysis. Also the FRF was analysed for the prediction of a end-milling system using recursive algorithm.

In this research, the indium dissolution properties of the waste LCD panel powders were investigated as a function of milling time fabricated by high-energy ball milling (HEBM) process. The particle morphology of waste LCD panel powders changed from sharp and irregular shape of initial cullet to spherical shape with an increase in milling time. The particle size quickly decreased to 15 until the first minute, then decreased gradually about 6 with presence of agglomerated particles after 5 minutes, which increased gradually reaching a uniform size of 13 consist of agglomerated particles after 30 minutes. The glass recovery, after dissolution, was over 99% at initial cullet, which decreased to 90.1 and 78.6% with increasing milling time of 1 and 30 minute respectively, due to a loss in remaining powder of the surface ball and jar, as well as the filter paper. The dissolution amount of indium out of the initial cullet was 208 ppm before milling, turning into 223 ppm for the mechanically milled powder after 1 minute, and nearly 146~125 ppm with further increase in milling time because of the reaction surface decrease of powders due to agglomeration. With this process, maximum dissolving indium amount (223 ppm) could be achieved at a particle size of 15 with 1 minute of milling.

In this research, the optimal manufacturing conditions of fine Si powders from Si scrap were investigated as a function of different initial powder size using the high-energy ball milling equipment, which produces the fine powder by means of an ultra high-energy within a short duration. The morphological change of the powders according to the milling time was observed by Scanning electron microscopy (SEM). With the increasing milling time, the size of Si powder was decreased. In addition, more energy and stress for milling were required with the decreasing initial powder size. The refinement of Si scrap was rapidly carried out at 10min ball milling time. However, the refined powder started to agglomerate at 30 min milling time, while the powder size became uniform at 60 min milling time.

Sm-16.7wt%Co alloy powders were prepared by high energy ball milling under the conditions of various milling time and the content of process control agent (PCA), and their microstructure and magnetic properties were investigated to establish optimum processing conditions. The initial powders employed showed irregular shape and had a size ranging from 5 to . After milling for 5 h, the shape of powders changed to round shape and their mean powder size was approximately , which consisted of the agglomerated nano-sized particles with 15 nm in diameter. The coercivity was reduced with increasing the milling time, whereas the saturation magnetization increased. As the content of PCA increased, the powder size minutely decreased to approximately at the PCA content of 10 wt%. The XRD patterns showed that the main diffraction peaks disappeared apparently after milling, indicating the formation of amorphous structure. The measured values of coercivity were almost unchanged with increasing the content of PCA.