• 한국수소및신에너지학회논문집
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• 제9권2호
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• pp.85-92
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• 1998

The hydrogenation behavior of $Mg_2Ni$ powder prepared by ball milling has been studied. Ball milled $Mg_2Ni$ was transformed to an amorphous-like state after 200hr ballmilling, and crystallized to $Mg_2NiH_x$ by hydrogenation at got. The hydrogen storage capacity gradually increased as a function of ball milling time. $Mg_2Ni$ by 400hr ballmilling shows higher hydrogen storage capacity (3H/M) than $Mg_2Ni$ by VIM(Vacuum Induction Melting).

• 한국수소및신에너지학회논문집
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• 제10권1호
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• pp.49-57
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• 1999

In order to study the effect of high energy ball milling on the $Mg_2Ni+Ni$, $Mg_2Ni+0.5Ni+0.5Al$ powders, we have investigated on the discharge properties, microstructures. The powder size of samples decreased as ball milling time. From the XRD results, the crystal structure of $Mg_2Ni+Ni$ mixed powders were changed to amorphous or nano-structure after 60hr ball milling. The discharge capacities of both $Mg_2Ni+Ni$ and $Mg_2Ni+0.5Ni+0.5Al$ powders increased, with increasing ballmilling time, the maximum capacity(342mAh/g) was shown for the 60 hrs ballmilled $Mg_2Ni+Ni$ sample. The capacity decreased drastically after a few charge-discharge cycles.

• 한국세라믹학회지
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• 제11권3호
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• pp.33-38
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• 1974

The possibility of the sources for the manufacture of mullite-rich refractories from the modified domestic alunite was studied. The modifying method of alunite studied were performed by calcination, wet ballmilling, and washing with water. For synthesis of mullite-rich refractories, the modified alunite with the addition of alumina and Fe2O3 as mineralizer was fired at 1350$^{\circ}$-155$0^{\circ}C$, and the following results were obtained: 1) The suitable firing temperature range was 1450$^{\circ}$-150$0^{\circ}C$, and adequate amounts of Al2O3 and Fe2O3 were below 30% and 3~4%, respectively. 2) Thermal expansion coefficient proportional to heating temperature was about 5$\times$10-6~10$\times$10-6cm/cm.deg. 3) The mineralogical compositions of the sintered specimens were found as mainly mullite and corundum.

• 한국분말재료학회지
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• 제16권6호
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• pp.424-430
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• 2009

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 $Fe_{73}Si_{16}B_7Nb_{3}Cu_1$ 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.

• 한국세라믹학회지
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• 제15권1호
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• pp.9-15
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• 1978

The possiblity of mullitization from the domestic alunite by adding of $Fe_2O_3-MnO_2$, $Fe_2O_3-MnO_2-TiO_2$, $Fe_2O_3-MnO_2-CaF_2$, and $Fe_2O_3-MnO_2-CaF_2-TiO_2$ mixtures as mineralizers was studied at the temperature range between $1, 250^{\circ}C$~$1, 430^{\circ}C$. The modifying method of domestic alunite was performed by calcination, wet ballmilling, and washing with water. The following results were obtained; 1) When added of 3.0% $Fe_2O_3$ plus 1.0-1.5% $MnO_2$ to modified alunite, the appropriate temperature range of mullite-forming was $1, 350^{\circ}C$-$1, 400^{\circ}C$. 2) When added of $TiO_2$ as mineralizer, the mullite-forming temperature was higher than not added. 3) When added of $CaF_2$ as mineralizer, the synthesized mullite was resolve at the temperature above $1, 350^{\circ}C$.

• 한국분말재료학회지
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• 제6권1호
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• pp.42-48
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• 1999

Three mixtures of elemental powders of Al-25at.%Ti, 48at.%Ti and 70at.%Ti were offered to ball milling process for the formation of intermetallic compounds of $Al_3Ti$, AlTi and $Ti_3Al$. Ballmilling or attrition process were carried out at the condition of rotaing speed of 110 or 350 rpm at $10^{-3}$ torr vacuum or argon atmospheres. $Al_3Ti$phases were fully obtained by heat treatment for 1 hors at $600^{\circ}C$ with Al-25at.%Ti composition mixtures milled by 100 hours. The amorphous phase was completely formed at the composition of Al-48at.%Ti mixed powders by milling 100hours at the 50 to 1 weight ratio of ball to powder, and AlTi compounds were obtained by heat treament. In the case of Al-70at%Ti mixed powders milled for 100 hours, $Ti_3Al$ and $Al_3Ti$intermetallic compounds were formed by heat treatment for 1 hour at $600^{\circ}C$. By attrition milling of 350rpm for 10 hours, $Ti_3Al$ phase was formed completley after heat treatment for 1 hour at $600^{\circ}C$.

• 한국수소및신에너지학회논문집
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• 제18권1호
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• pp.52-59
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• 2007

We investigated the effects of the addition of Mn and $AB_5$ type alloy on the electrochemical characteristics of Ti-Cr-V BCC type alloys as anode materials for Ni-MH battery. The activation behavior and discharge capacity of the BCC type alloys were significantly improved by ball-milling with the $LmNi_{4.1}Al_{0.25}Mn_{0.3}Co_{0.65}$ alloy, because the $AB_5$ type alloy acted as hydrogen path on the surface of the BCC type alloy. Among the Mn substituted alloys($Mn=0.03%{\sim}0.08%$), the $Ti_{0.32}Cr_{0.38}Mn_{0.05}V_{0.25}$ alloy ball-milled with $AB_5$ type alloy exhibited the greatest discharge capacity of $336\;mAh{\cdot}g^{-1}$. In addition, Mn substituted alloys exhibited the lower plateau pressure in P-C- T curve, the better hydrogen storage capacity and faster surface activation compared with the alloy without Mn.

• Carbon letters
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• 제11권4호
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• pp.293-297
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• 2010

To investigate new potential application of a clay material for C/C composites, illite added C/C composites were prepared with various illite contents. The improvement of filler effect by illite size reduction was also investigated using wet ballmilling by evaluating illite/phenolic resin infiltration using bulk density and porosity measurements, chemical structural changes of the composites using XRD, and thermal oxidation stability in air of the composites using TGA. The size reduction of illite resulted in narrower particle size distribution and improved illite infiltration into carbon preform. And the resultant C/C composites prepared with illite had even more improved thermal oxidation stability in air, showing more increased IDTs up to $100^{\circ}C$, compared to those of the C/C composites with pristine illite, due to the SiC formation through carbothermal reduction between illite and carbon materials. The illite induced delay in oxidation of the illite-C/C composites was also observed and the delayed oxidation behavior was attributed to the layered structure of illite, which improved illite/phenol resin infiltration. Therefore, the potential use of illite as filler to improve oxidation stability of C/C composite can be promising. And the size reduction of illite can improve its effect on the desired properties of illite-C/C composites even more.

• 한국자기학회지
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• 제14권1호
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• pp.18-24
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• 2004

Fe(N $O_3$)$_3$$.$9$H_2O$, Ni(N $O_3$)$_2$.6$H_2O$, Zn(N $O_3$)$_2$$.$6$H_2O$와 같은 질산금속염들을 습식법의 일종인 습식 직접 합성법을 이용하여 Ni-Zn ferrite 분말로 합성하였다. 분말의 화학조성은(N $i_{0.284}$F $e_{0.053}$Z $n_{0.663}$)F $e_2$ $O_4$로 하였으며, 고투자율 재료의 영역에 목표를 두었다. 습식 직접 합성법으로 시편을 제조하기 위하여 측량된 질산금속염들을 반응 용기 내에서 NaOH로 침전시키면서 9$0^{\circ}C$의 합성온도로 8시간 동안 교반.합성하였다. 가소 온도는 $700^{\circ}C$로 하여 2시간 유지시켰고, 소결온도는 11$50^{\circ}C$-12$50^{\circ}C$의 범위에서 각각 2시간 유지시켰다. 또 금속산화물을 출발물질로 하여 동일한 조성을 가지는 분말을 습식볼밀링하여 제조하였으며, 두 가지의 공정으로 합성된 분말의 특성과 소결체의 전자기적 특성을 비교.연구하였다. 동일 조건일 경우, 습식 직접 합성법으로 제조하면 입도분포가 좁고, 고순도이며, 미분말인 페라이트 분말을 얻을 수 있었으며 소결체의 특성 또한 비교적 높은 투자율과 자화 값을 나타내었다.