The purpose of this study is to prepare WO3 nanopowders by high-energy milling in mixture gas (7 % H2+Ar) with various milling times (10, 30, and 60 min). The phase transformation, particle size and light absorption properties of WO3 nanopowders during reduction via high-energy milling are studied. It is found that the particle size of the WO3 decreases from about 30 μm to 20 nm, and the grain size of WO3 decreases rapidly with increasing milling time. Furthermore, the surface of the particles due to the pulverization process is observed to change to an amorphous structure. UV/Vis spectrophotometry shows that WO3 powder with increasing milling times (10, 30, 60 min) effectively extends the light absorption properties to the visible region. WO3 powder changes from yellow to gray and can be seen as a phenomenon in which the progress of the color changes to blue. The characterization of WO3 is performed by high resolution X-ray diffractometry, Field emission scanning electron microscopy, Transmission electron microscopy, UV/Vis spectrophotometry and Particle size analysis.

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.

세리아 입자의 합성을 위하여 분무열분해 시 유기 첨가제인 EG(ethylene glycol)과 CA(citric acid)를 첨가하여 중공성 및 다공성을 갖는 CeO2 마이크로 크기의 입자를 제조하였으며 첨가량에 따른 특성을 비교하였다. 분무열분해과정, 후소성 및 볼밀링 과정을 적절히 조합하여 만든 6가지 경로에 의해 나노 크기의 세리아 입자를 합성하였다. 6가지 경로 중 EG 및 CA가 0.05M 첨가된 Ce(III)가 전구체 수용액을 이용하여 분무열분해→후소성→볼밀링→후소성의 경로에 의해 얻어진 CeO2 입자에 대해 TEM 분석으로 측정한 입자의 평균 크기 24 nm(편차=3.8 nm)는 Debye-Scherrer식에 의해 계산된 1차 입자의 크기(20 nm)와 가장 유사한 크기를 나타내었다. 제조된 나노입자분말의 형태적 및 구조적 특성을 알아보기 위하여 SEM(Scanning Electron Microscopy), XRD(X-Ray Diffractometer) 및 TEM(Transmission Electron Microscopy)을 통하여 특성을 분석하였다.

Composites of P25 TiO2 and hexagonal WO3 nanorods are synthesized through ball-milling in order to study photocatalytic properties. Various composites of TiO2/WO3 are prepared by controlling the weight percentages (wt%) of WO3, in the range of 1–30 wt%, and milling time to investigate the effects of the composition ratio on the photocatalytic properties. Scanning electron microscopy, x-ray diffraction, and transmission electron microscopy are performed to characterize the structure, shape and size of the synthesized composites of TiO2/WO3. Methylene blue is used as a test dye to analyze the photocatalytic properties of the synthesized composite material. The photocatalytic activity shows that the decomposition efficiency of the dye due to the photocatalytic effect is the highest in the TiO2/ WO3 (3 wt%) composite, and the catalytic efficiency decreases sharply when the amount of WO3 is further increased. As the amount of WO3 added increases, dye-removal by adsorption occurs during centrifugation, instead of the decomposition of dyes by photocatalysts. Finally, TiO2/WO3 (3 wt%) composites are synthesized with various milling times. Experimental results show that the milling time has the best catalytic efficiency at 30 min, after which it gradually decreases. There is no significant change after 1 hour.

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.

Particle morphology change and different experimental condition analysis during composite fabrication process by traditional ball milling with discrete element method (DEM) simulation were investigated. A simulation of the three dimensional motion of balls in a traditional ball mill for research on the grinding mechanism was carried out by DEM simulation. We studied the motion of the balls, the ball behavior energy and velocity; the forces acting on the balls were calculated using traditional ball milling as simulated by DEM. The effect of the operational variables such as the rotational speed, ball material and size on the flow velocity, collision force and total impact energy were analyzed. The results showed that increased rotation speed with interaction impact energy between balls and balls, balls and pots and walls and balls. The rotation speed increases with an increase of the impact energy. Experiments were conducted to quantify the grinding performance under the same conditions. Furthermore, the results showed that ball motion affects the particle morphology, which changed from irregular type to plate type with increasing rotation speed. The evolution was also found to depend on the impact energy increase of the grinding media. These findings are useful to understand and optimize the particle motion and grinding behavior of traditional ball mills.

Fe-TiC composite powders are fabricated by planetary ball mill processing. Two kinds of powder mixtures are prepared from the starting materials of (a) (Fe, TiC) powders and (b) (Fe, TiH2, Carbon) powders. Milling speed (300, 500 and 700 rpm) and time (1, 2, and 3 h) are varied. For (Fe, TiH2, Carbon) powders, an in situ reaction synthesis of TiC after the planetary ball mill processing is added to obtain a homogeneous distribution of ultrafine TiC particulates in Fe matrix. Powder characteristics such as particle size, size distribution, shape, and mixing homogeneity are investigated. In case of (Fe, TiC) powder many coarse TiC particulates with size of several μm are unevenly distributed in Fe-matrix. The composite powder prepared from (Fe, TiH2, C) powder mixture showed a homogeneous dispersion of ulatrafine TiC particulates.

Lanthanum/gadolinium zirconate coatings are deposited via suspension plasma spray with suspensions fabricated by a planetary mill and compared with hot-pressed samples via solid-state reaction. With increase in processing time of the planetary mill, the mean size and BET surface area change rapidly in the case of lanthanum oxide powder. By using suspensions of planetary-milled mixture between lanthanum or gadolinium oxide and nano zirconia, dense thick coatings with fully-developed pyrochlore phases are obtained. The possibilities of these SPS-prepared coatings for TBC application are also discussed.

[ WO3 ]powders were ball-milled with an alumina ball for 0-72 hours. In2O3 doped WO3 was prepared by soaking ball-milled WO3 in an InCl3 solution. The mixed powder was annealed at 700˚C for 30 min in an air atmosphere. A paste for screen-printing the thick film was prepared by mixing the WO3:In2O3 powders with α-terpinol and glycerol. In2O3 doped WO3 thick films were fabricated into a gas sensor by a screen-printing method on alumina substrates. The structural properties of the WO3:InO3 thick films were a monoclinic phase with a (002) dominant orientation. The particle size of the WO3:InO3 decreased with the ball-milling time. The sensing characteristics of the In2O3 doped WO3 were investigated by measuring the electrical resistance of each sensor in the test-box. The highest sensitivity to 5 ppm CH4 gas and 5 ppm CH3CH2CH3 gas was observed in the ball-milled WO3:InO3 gas sensors at 48 hours. The response time of WO3:In2O3 gas sensors was 7 seconds and recovery time was 9 seconds for the methane gas.

A carbon doped (C-) photocatalyst, which shows good photocatalytic activity to Ultraviolet irradiation and visible irradiation, was successfully prepared by co-grinding of with ethanol or Activated Carbon(C), followed by heat treatment at in air for 60 min. Ethanol and C were used as a representative agent of liquid and solid for carbon doping. Their influence on improving photocatalytic ability and carbon doping degree was studied with degradation of methyl orange and XPS analysis. The product prepared by co-grinding of with Ethanol had Ti-C and C-O chemical bonds and showed higher photocatalytic activity than the product prepared by co-grinding of with C, where just C-O chemical bond existed. As a result, mechanochemical route is useful to prepare a carbon doped photocatalyst activating to visible irradiation, where the solid-liquid operation is more effective than solid-solid operation to obtain a carbon doped .

Electromagnetic wave energies are consumed in the form of thermal energy, which is mainly caused by magnetic loss, dielectric loss and conductive loss. In this study, CNT was added to the nanocrystalline soft magnetic materials inducing a high magnetic loss, in order to improve the dielectric loss of the EM wave absorption sheet. Generally, the aspect ratio and the dispersion state of CNT can be changed by the pre-ball milling process, which affects the absorbing properties. After the various ball-milling processes, 1wt% of CNTs were mixed with the nanocrystalline base powder, and then further processed to make EM absorption sheets. As a result, the addition of CNT to Fe-based nanocrystalline materials improved the absorption properties. However, the increase of ball-milling time for more than 1h was not desirable for the powder mixture, because the ballmilling caused the shortening of CNT length and the agglomeration of the CNT flakes.

A visible-light photoactive photocatalyst was synthesized successfully by means of cogrinding of anatase- in ambient, followed by heat-treatment at in air environment. In general, it is well known that the grinding-operation induces phase transformation of a- to rutile . This study investigates the influence of the amount of gas on the phase transformation rate of a- and enhancement of visible-light photocatalytic activity, and also examines the relation between the photocatalytic activity and the period of grinding time. The phase transformation rate of a- to rutile is retarded with the amount of NH3 injected. And the visible-light photocatalytic activity of samples, was more closely related to the period of grinding time than amount injected, which means that the doping amount of nitrogen into more effective to mechanical energy than amount injected. XRD, XPS, FT-IR, UV-vis, Specific surface area (SSA), NOx decomposition techniques are employed to verify above results more clearly.

Mechanical coating process was applied to form 89 %-hydrolyzed poly vinyl alcohol (PVA) onto boron carbide (B4C) nanopowder using one step high energy ball mill method. The polymer layer coated on the surface of B4C was changed to glass-like phase. The average particle size of core/shell structured B4C/PVA was about 50 nm. The core/shell structured B4C/PVA was formed by dry milling. However, the hydrolyzed PVA of 98~99% with high glass transition temperature (Tg) was rarely coated on the powder. The Tg of polymer materials was one of keys for guest polymer coating on to the host powder by solvent free milling.

The effect of Cu content on hydrogen reduction behavior of ball-milled -CuO nanocomposite powders was investigated. Hydrogen reduction behavior and reduction percent() of nanopowders were characterized by thermogravimetry (TG) and hygrometry measurements. Activation energy for hydrogen reduction of nanopowders with different Cu content was calculated at each heating rate and reduction percent(). The activation energy for reduction of obtained in this study existed in the ranging from 129 to 139 kJ/mol, which was in accordance with the activation energy for powder reduction of conventional micron-sized

The p-type semiconductor thermoelectric materials were fabricated by melting, milling and sintering process and their thermoelectric properties were characterized. The compound materials were ball-milled with milling time and the powders were sintered by spark plasma sintering process. The ball milled powders had equiaxial shape and approedmately in size. The figure of meritz of sintered thermoelectric materials decreased with milling time because of lowered electrical resistivity. The thermoelectric properties of materials have been discussed in terms of electrical property with ball mill process.

The structural and magnetic properties of nanostructued alloy powders were investigated. Commercial alloy powders (Hoeganaes Co., USA) with purities were used to fabricate the nanostructure Fe-Si alloy powders through a high-energy ball milling process. The alloy powders were fabricated at 400 rpm for 50 h, resulting in an average grain size of 16 nm. The nanostructured powder was characterized by fcc and hcp phases and exhibited a minimum coercivity of approximately 50 Oe

Nanocrystalline powders of (x=0.45-0.6) have been synthesized by mechanochemical reaction at room temperature using high-energy ball milling from mixtures of Mn, Fe, P, and As Powders. It has been found that a mechanically induced self-propagating reaction (MSR) occurs within 2 hours of milling and it produces very fine polycrystalline powder having a hexagonal structure. Further milling up to 24 hours did not change the crystalline and average particle sizes or the phase composition of the milling product. When x is 0.65, no reaction among the reactants has been observed even after 24 hours of milling. As the P content decreases in , the incubation time for the MSR has increased and the lattice constants in both a and c axes have changed