• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.7 s.238
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• pp.1022-1027
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• 2005

In this study, ball milling process was applied to reduce the particle size of bio-material down to submicron size. The material used was Ibuprofen. The ball milling was performed at low temperature of about $-180^{\circ}C$. The effect of processing conditions (milling time, milling speed) on the particle size was determined. The results showed that the degree of crystallite of Ibuprofen was slightly reduced by the ball milling process. The results also showed that the size of Ibuprofen was significantly reduced by the ball milling process. The effect of milling time was significant within the milling time of six hours while it was small thereafter.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1205-1206
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• 2006

Dispersion-strengthened copper with $TiB_2$ was produced by ball-milling and spark plasma sintering (SPS).Ball-milling was performed at a rotation speed of 300rpm for 30 and 60min in Ar atmosphere by using a planetary ball mill (AGO-2). Spark-plasma sintering was carried out at $650^{\circ}C$ for 5min under vacuum after mechanical alloying. The hardness of the specimens sintered using powder ball milled for 60min at 300rpm increased from 16.0 to 61.8 HRB than that of specimen using powder mixed with a turbular mixer, while the electrical conductivity varied from 93.40% to 83.34%IACS. In the case of milled powder, hardness increased as milling time increased, while the electrical conductivity decreased. On the other hand, hardness decreased with increasing sintering temperature, but the electrical conductiviey increased slightly

• Korean Journal of Metals and Materials
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• v.48 no.5
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• pp.462-468
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• 2010

Carbon Nanotubes (CNTs) have recently emerged as a material with outstanding properties. It has shown promising potential for applications in many engineering fields as electronic devices, thermal conductors, and light-weight composites. Researchers have investigated their use as reinforcements in themetal matrix composites of CNTs. In the present work, we decorated CNTs with Ni particles by electroless plating. The CNTs were wet-ball milled for various milling times with a nickel sulfate solution. The precipitated Ni particles were observed mainly by FESEM. In this study, the dispersion of the CNTs and Ni particles was improved with the addition of the surfactant. Also, as the CNTs were shortened and widened by an increased ball milling time, the size of the precipitated Ni particles increased. It was estimated that the CNTs were deformed and caused some defects on their surface during the ball milling process. Those defects were assumed to be heterogeneous nucleation sites for the Ni particles.

• Applied Chemistry for Engineering
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• v.22 no.6
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• pp.605-609
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• 2011

We study on the oxygen behavior of $V_2O_5/TiO_2$ catalysts in the $NH_3$-selective catalytic reduction (SCR) prepared by the ball milling processing. There are not any changes in crystal structure and surface area of the $TiO_2$ catalyst by ball milling, but the maximal reduction temperature decreased in $H_2$-temperature programmed reduction (TPR) analysis. Experimental observations with various concentrations of oxygen indicate that all catalysts showed a very low NOx conversion rate in the absence of oxygen and the reactivity of ball milled catalyst higher depending on the oxygen. It is occurred because the degree of participation of atmospheric oxygen and lattice oxygen is great than that of the not-milled catalyst.

• Journal of the Korean Ceramic Society
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• v.35 no.4
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• pp.406-412
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• 1998

The reaction bonded alumina ceramics was prepared through the addition of each SiC and ZrO2 powder to the mixture of Al metal powder and Al2O3 The mono sized (3mm) and biodal sized (3mm+5mm) balls were used in attrition milling of Al and starting powders. The milling efficiency of both cases was compared by the analysis of particle size and X-ray diffraction. After the forming and sintering of each powder batchs the weight gains dimensional changes and densities were determined. The specimens were investigated by X-ray diffraction analysis and scanning electron microscope. Bimodal sized balls had better milling effect than single ball size in the milling of Al powder. However in the milling which ceramic powders mono sized the green body during the reaction sintering at 1$600^{\circ}C$ for 5 hour was about 10% The densities attained the values of 92-98% theoretical. The SiC added specimen that was milled with 3mm ball media had 96% theoretical density and dense microstructure.

• Journal of Powder Materials
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• v.10 no.2
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• pp.129-135
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• 2003

Nanocrystalline powders of $MnFeP_{1-x}As_x$(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 $Fe_2P$ 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 $MnFeP_{1-x}As_x$, the incubation time for the MSR has increased and the lattice constants in both a and c axes have changed.

• 한국초전도학회:학술대회논문집
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• 2008.08a
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• pp.76-76
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• 2008

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.154-154
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• 2008

Although the screen printing technology using photosensitive carbon nanotube (CNT) paste has many advantages such as low cost, simple process, uniform emission, and capability of mass production, the CNT paste needs to be improved further in CNT dispersion, printability, adhesion, electrical conductivity, population of CNT emitters, etc. Ball milling has been frequently employed to prepare the CNT paste as ball milling can mix its ingredients very well and easily cut the long, entangled CNTs. This study carried out a parametric approach to fabricating the CNT paste in terms of low-energy ball milling and a paste composition. Field emission properties of the CNT paste was characterized with CNT dispersion and electrical conductivity which were measured by a UV-Vis spectrophotometer and a 4-point probe method, respectively. Main variables in formulating the CNT paste include a length of milling time, and amounts of CNTs and conductive inorganic fillers. In particular, we varied not only the contents of conductive fillers but also used two different sizes of filler particles of ${\mu}m$ and nm ranges. Among many variations of conductive fillers, the best field emission characteristics occurred at the 5 wt% fillers with the mixing ratio of 3:1 for ${\mu}m$-and nm-sizes. The amount and size of fillers has a great effect on the morphology, processing stability, and field emission characteristics of CNT emitter dots. The addition a small amount of nm-size fillers considerably improved the field emission characteristics of the photosensitive CNT paste.

• Transactions of Materials Processing
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• v.13 no.1
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• pp.45-52
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• 2004

This research conducted milling tests to study effects of cutting environment conditions of ball end mills on the characteristics of hard milling process. KP4 steels and STD11 heat treated steels were used as the workpiece and WC-Co ball end mill tools with TiAlN coated were utilized in the cutting tests. Dry cutting without coolant and semi-dry cutting using botanical oil coolant were conducted and MQL(Minimum Quantity Lubricant) device was used to spray coolant. Cutting forces, tool wear and surface roughness were measured in the cutting tests. Results showed that dry cutting of KP4 and hardened STD11 specimens produced better surface quality and wear performance than MQL spray cutting did.

• Journal of Powder Materials
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• v.17 no.2
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• pp.130-135
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• 2010

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 $110\;{\mu}m$. After milling for 5 h, the shape of powders changed to round shape and their mean powder size was approximately $5\;{\mu}m$, 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 $7\;{\mu}m$ 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.