• Journal of Powder Materials
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• v.9 no.2
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• pp.83-88
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• 2002

The mechanochemical milling of Mg and $Mg_2Ni$ alloys were carried out to examine the enhancement of hydrogen storage properties of Mg alloys. The hydroge characteristics of the ball-milled products were evaluated with a Sievert-type apparatus and electrochemical test. Various intermediate compounds were obtained by chemical reactions induced during the ball milling of Mg of $Mg_2Ni$ alloys with C, Ni, $Ni_2Cl$ and $Ca_2Cl$. The system of $Mg_2Ni$ with 10 wt% C improved markedly the kinetics of hydrogen absorption, while the hydrogen capacities were practically unchanged. The hydrogen storage alloys such as Mg-Ca can be successfully.

• Journal of the Semiconductor & Display Technology
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• v.3 no.1
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• pp.9-13
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• 2004

Carbon nanofibers (CNFs) with uniform diameter and controlled size were prepared from catalytic decomposition of $\textrm{C}_{2}\textrm{H}_{2}$ with Ni-MgO catalyst treated by mechanochemical (MC) process. The properties of Ni catalyst, such as size, distribution and morphology, can be governed by tuning grinding time in MC process. As a result, size and structure of CNFs can be tailored. The effect of grinding time to the as-grown CNFs was studied. CNFs with diameter from 10-70 nm were synthesized. CNFs with bundle formation sharing one tip and twisted CNFs were also synthesized with catalyst treated by MC process.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05a
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• pp.218-223
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• 2002

Low temperature synthesis of $LaNiO_3$ crystalline phase composited from mixtures of $La_2O_3$ and NiO via the ball mill and mechanochemical process were investigated. By the ball mill, 20% of $LaNiO_3$ crystalline phase was formed in the samples sintered at $900^{\circ}C$ due to the lack of reactivity of NiO. However, the mechanochemical process yielded about 93% of $LaNiO_3$ crystalline phase in room temperature.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.646-647
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• 2006

Nano-sized WC particles in WC/Co composite powders were synthesized by mechanochemical method. The raw powders$(WO_3,\;Co_3O_4,\;VC,\;Cr_3C_2$ and graphite) were mixed by planetary milling for 30 hours. The compositions were WC-10 and -20 wt% Co added VC and $Cr_3C_2$. The direct reduction and carburization of the mixed powders were carried at $900\;^{\circ}C$ for 1 to 3 hours under flowing Ar gas. The mean size of WC particles in WC/Co composite powders was about 16 nm. The resultant powders were compacted and sintered at $1300{\sim}1360\;^{\circ}C$ for 0.5 hour. After sintering the mean size of WC particles was about 50 nm.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.19 no.2
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• pp.255-266
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• 2021

Solid-state mechanochemical reduction combined with subsequent melting consolidation was suggested as a technical option for the oxide reduction in pyroprocessing. Ni ingot was produced from NiO as a starting material through this technique while Li metal was used as a reducing agent. To determine the technical feasibility of this approach for pyroprocessing, which handles spent nuclear fuels, thermodynamic calculations of the phase stabilities of various metal oxides of U and other fission elements were made when several alkaline and alkali-earth metals were used as reducing agents. This technique is expected to be beneficial, not only for oxide reduction but also for other unit processes involved in pyroprocessing.

• Korean Journal of Materials Research
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• v.7 no.2
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• pp.152-156
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• 1997

In this paper, I meritioned ,I study on thc rnechanochernic;~l effec ts of grountl iljckite To investigate the mechanochemical effects of ground tlickite 1,y planet,~r\- mill. a structul-ill i~nalvsis of dickite prepared with different grinding time has been made 11y X-ray diffraction and ilifierenti,~l tl~i.~-ni;~i analysis. 'l'he $SiO_{4}$ hecira was unchanged bl- milling and remained ;is the local ordering unit s t t - ~ c ~ u ~ - c ~ s in the ground dickitc samples I ) v analyzing the radial distribution function. On the other hand, with an increi~se of the grinding time a decrease of coordination number and atomic distance bet\vccn aluminum and oxygen hi1c.r l~een octurreil, and Li~~antitativcl\. coniirrned them This result corresponded to the local c,hange around aliimi~iuni I>V tliftercntii~l t1ii:rm;il ani~lysis. Therefore, the mechanochemical phenomina of ground tiickite werc3 h e to the local c~l~mge around aluminum \IT. the prolonged grinding.

• Journal of Powder Materials
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• v.13 no.4 s.57
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• pp.243-249
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• 2006

Yttrium aluminum garnet (YAG) powders were synthesized via mechanochemical solid reaction using $Y_2O_3$ with three types of aluminum compounds. $Y_2O_3$ reacted mechanochemically with all A1 compounds and formed YAM (yttrium aluminum monoclinic), YAG and YAP (yttrium aluminum perovskite) phases depending on the starting materials. The ground samples containing ${\gamma}-A1_2O_3$ showed the best reactivity, whereas the ground sample containing A100H, which had the largest surface area, exhibited pure YAG after calcination at $1200^{\circ}C$. The sample containing Al had the least reactivity, producing YAP along with YAG at $1200^{\circ}C$. The types and grinding characteristics of the starting materials and grinding time are believed to be important factors in the mechanochemical synthesis of YAG.

• Journal of Powder Materials
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• v.9 no.3
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• pp.167-173
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• 2002

A new approach to produce nanostructured WC/Co composite powders by a mechanochemical process was made to improve the mechanical properties of advanced hardmetals. Homogeneous spherical W-Co salt powders were made by spray drying of aqueous solution from ammonium metatungstate($(NH_4)_6(H_2W_{12}O_{40})\cdo4H_2O$,AMT) and cobalt nitrate hexahydrate (Co(NO$_3$)$_2$.6$H_2O$). spray dried W-Co salt powders were calcined for 1 hr at $700^{\circ}C$ in atmosphere of air. The oxide powder was mixed with carbon black by ball milling and this mixture was heated with various temperatures and times in $H_2$. The $WO_3/CoWO_4$ composite oxide powders were obtained by calcinations at $700^{\circ}C$. The primary particle size of W/Co composite oxide powders by SEM was 100 nm. The reduction/carburization time decreased with increasing temperatures and carbon additions. The average size of WC particle carburized at $800^{\circ}C$ by TEM was smaller than 50 nm.

• Journal of Korean Society for Atmospheric Environment
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• v.33 no.4
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• pp.297-305
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• 2017

In this study, the activity and structural properties of catalysts prepared by mechanochemical method under dry condition were studied. A dry milling was used as a mechanochemical method. The precursors of vanadium were $NH_4VO_3$ and $V_2O_5$. The activity and characterization of the catalysts prepared by dry milling were compared with those prepared by impregnation. In addition, the correlation between the catalytic activity and the structural characteristics was observed through XRD, Raman, and $H_2$-TPR analysis. As a result, the monomeric vanadate species exhibited excellent redox characteristics, which were confirmed to be related to the catalytic activity.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.469-471
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• 2001

Dry grinding of a mixture of CaCO$_3$ and Ca(H$_2$PO$_4$)$_2$.$H_2O$ was conducted using a planetary ball mill in order to investigate solid state reaction for a synthesis of hydroxyapatite(Ca$_{10}$(PO$_4$)$_{6}$(OH)$_2$, HAp) through mechanochemical treatment method. The raw materials, which are composed of waste oyster and calcium biphosphate Ca(H$_2$PO$_4$)$_2$.$H_2O$, were mixed and then treated mechanochemically. The synthesis of hydroxyapatite(Ca$_{10}$(PO$_4$)$_{6}$(OH)$_2$, HAp) from the mixture was almost completed by about 60 minute grinding. The formation of HAp monophase in the ground mixture was characterized through X-ray diffraction (XRD) analysis. Moreover, the formation of HAp monophase depending on the grinding time was improved by increasing the grinding time.ime.ime.