• Nuclear Engineering and Technology
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• v.26 no.2
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• pp.190-196
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• 1994

In order to investigate the ball-milling effect on the property changes of UO$_2$ ex-AUC powder, the sinterability of ball -milled powder was studied in terms of the ball -milling time. Spherical shape was found to be kept for ball-milled UO$_2$ powder and the particle size showed a bimodal distribution, which seems to have a higher packing ratio compared with those having monomodal gaussian distribution. The increase of sintered density of the ball -milled UO$_2$ powder is assumed to be mainly affected by the packing ratio, which increase with longer ball -milling time. It is confirmed that the sinterability of UO$_2$ ex-AUC powder is improved by the ball-milling process.

• Tribology and Lubricants
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• v.27 no.1
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• pp.1-6
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• 2011

The possibility of Cu-Al-Ni intermetallic coating on the mild steel through the combustion synthesis has been investigated. In particular, the effect of the ball milling energy on the microstructure of the coating layer was examined to obtain the best coating condition. Experimental results show that Cu-Al-Ni powder compact was explosively synthesized and successfully coated with the steel matrix. It was revealed that the formation of $Cu_9Al_4$ intermetallic decreased with increase in the ball milling energy. This result supports that the high energy ball milling would be effective for obtaining the most suitable microstructure for Cu-Al-Ni coating layer. However, the excessive ball milling energy seems to decrease the bonding strength between the coating layer and the matrix.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.12
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• pp.852-856
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• 2015

In this study, we investigate the effect of high-energy ball milling on thermoelectric transport properties in double-filled $CoSb_3$ skutterudite ($In_{0.2}Yb_{0.1}Co_4Sb_{12}$). $In_{0.2}Yb_{0.1}Co_4Sb_{12}$ powders are milled using high-energy ball milling for different periods of time (0, 5, 10, and 20 min), and the milled powders are consolidated into bulk samples by spark plasma sintering. Microstructure analysis shows that the high-energy ball milled bulk samples are composed of nano- and micro-grains. Because the filling fractions are reduced in the bulk samples due to the kinetic energy of the high-energy ball milling, the carrier concentration of the bulk samples decreases with the ball milling time. Furthermore, the mobility of the bulk samples also decreases with the ball milling time due to enhanced grain boundary scattering of electrons. Reduction of electrical conductivity by ball milling has a decisive effect on thermoelectric transport in the bulk samples, power factor decreases with the ball milling time.

• Transactions of the Korean hydrogen and new energy society
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• v.17 no.4
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• pp.418-424
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• 2006

In order to improve the activation properties of the $AB_2$ type hydrogen storage alloys for Ni-MH battery, the alloy surface was modified by employing high energy ball milling. The $Zr_{0.54}Ti_{0.45}V_{0.54}Ni_{0.87}Cr_{0.15}Co_{0.21}Mn_{0.24}$ alloy powder was ball milled for various period by using the high energy ball mill. As the ball milling time increased, activation of the $AB_2$ type composite powder electrodes were enhanced regardless of additives. When the ball milling time was small discharge capacities of the $AB_2$ type composite powder electrodes increased with the milling time. On the other hand for large milling time it decreased with increasing milling time. The maximum discharge capacity was obtained by ball milling for 3-4 min.

• Journal of Powder Materials
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• v.17 no.3
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• pp.242-250
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• 2010

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.

• International Journal of Precision Engineering and Manufacturing
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• v.4 no.4
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• pp.19-24
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• 2003

In end milling process, which is characterized by the use of a rotating tool, the undeformed chip thickness varies periodically with phase change of the tool. Although many efforts have concentrated on the study of end milling process, the analysis of shear and chip-tool friction behaviors has not been reported. Recently, a model has been proposed to simulate the shear and friction characteristics of an up-end milling process in terms of the equivalent oblique cutting. In the current study, the varying undeformed chip thickness and the cutting forces in a down-end milling process are replaced with the equivalent ones of oblique cutting. Then it is possible to simulate the shear and the chip-tool friction characteristics of a down-end milling process. The proposed model has been verified through two sets of cutting tests i.e., down-end milling and the equivalent oblique cutting tests. The experimental results show that the proposed model is suitable to analyze the shear and chip-tool frictional characteristics of down-end milling process. The specific cutting energy decreases with increase in equivalent undeformed chip thickness in a down-end milling process.

• Journal of Powder Materials
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• v.19 no.1
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• pp.32-39
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• 2012

This study investigated refinement behaviors of TiC powders produced under different impact energy conditions using a mechanical milling process. The initial coarse TiC powders with an average diameter of 9.3 ${\mu}m$ were milled for 5, 20, 60 and 120 mins through the conventional low energy mechanical milling (LEMM, 22G) and specially designed high energy mechanical milling (HEMM, 65G). TiC powders with angular shape became spherical one and their sizes decreased as the milling time increased, irrespective of milling energy. Based upon the FE-SEM and BET results of milled powders, it was found initial coarse TiC powders readily became much finer near 100 nm within 60 min under HEMM, while their sizes were over 200 nm under LEMM, despite the long milling time of up to 120 min. Particularly, ultra-fine TiC powders with an average diameter of 77 nm were fabricated within 60 min in the presence of toluene under HEMM.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.887-890
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• 2001

In end milling process the underformed chip thickness and the cutting force components very periodically with phase change of the tool. In this study, up end milling process is transformed to the equivalent oblique cutting. The varying underformed chip thickness and the cutting force components in end milling process are replaced with the equivalent average ones. Then it can be possible to analyze the chip-tool friction and shear process in the shear plane of the end milling process by the equivalent oblique cutting mode. According to this analysis, when cutting Inconel 718.61% of the total energy is consumed in the shear process and the balance is consumed in the friction process.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.902-906
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• 2000

In end milling process the undeformed chip thickness and the cutting force components vary periodically with phase change of the tool. In this study, up end milling process is transformed to the equivalent oblique cutting. The varying undeformed chip thickness and the cutting force components in end milling process are replaced with the equivalent average ones. Then it can be possible to analyze the chip-tool friction and shear process in the shear plane of the end milling process by the equivalent oblique cutting model. According to this analysis, when cutting SM45C steel. 82% of the total energy is consumed in the shear process and the balance is consumed in the friction process.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.724-729
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• 2000

In end milling process the undeformed chip thickness and the cutting force components vary periodically with phase change of the tool. In this study, up end milling process is transformed to the equivalent oblique cutting. The varying undeformed chip thickness and the cutting force components in end milling process are replaced with the equivalent average ones. Then it can be possible to analyze the chip-tool friction and shear process in the shear plane of the end milling process by the equivalent oblique cutting model. According to this analysis, when cutting SM45C steel, 72% of the total energy is consumed in the shear process and the balance is consumed in the friction process.