• 한국분말재료학회지
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• 제4권3호
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• pp.179-187
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• 1997

Milling media of steel and zirconia were used to produce $MoSi_2$ by mechanical alloying (MA) of Mo and Si powders. The effect of milling media on MA of Mo-65.8at%Si powder mixture has been investigated by SEM, XRD, DTh and in-situ thermal analysis. The powders mechanically alloyed by milling medium of steel for 8 hours showed the structure of fine mixture of Mo and Si, and those mechanically alloyed by milling medium of zirconia for longer milling time showed the structure of fine mixture of Mo and Si. The tetragonal $\alpha$-$MoSi_2$ Phase and the tetragonal $Mo_5Si_3$ phase appeared with small Mo peaks in the powders milled by milling medium of steel for 4 and 8 hours. The $\alpha$-$MoSi_2$ phase and the hexagonal $\beta$-$MoSi_2$ phase were formed after longer milling time. The $\alpha$-$MoSi_2$ phase appeared with large Mo peaks in the powders milled by milling medium of zirconia for 4 hours. The phases, $\alpha$-$MoSi_2$ and $\beta$-$MoSi_2$. were formed in the powders milled for longer milling time. DTA and annealing results showed that Mo and Si were transformed into $\alpha$-$MoSi_2$ and $Mo_5Si_3$, while $\beta$-$MoSi_2$ into $\alpha$-$MoSi_2$. In-situ thermal analysis results demonstrated that there were a sudden temperature rise at 212 min and a gradual increase in temperature in case of milling media of steel and zirconia, respectively. The results indicate that MA can be influenced by materials of milling medium which can give either impact energy on powders or thermal energy accumulated in vial.

• 한국분말재료학회지
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• 제4권4호
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• pp.298-303
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• 1997

The activated sintering behavior of $MoSi_2$ powder compacts with addition of 0.5 and 1.0 wt.%Ni during the sintering under As atmosphere was studied. The shrinkage was measured and the microstructures were observed by SEM (scanning electron microscopy) and BEI (backscattered electron image) along with the phase analysis by EDS during heating up to 155$0^{\circ}C$ and holding for various time at 155$0^{\circ}C$. The most of shrinkage occurred upon heating and 92% of theoretical density was attained after sintering for 1 hr at 155$0^{\circ}C$. However, little shrinkage ensued even for prolonged sintering over 1 hr at 155$0^{\circ}C$. A liquid film formed at about 135$0^{\circ}C$ along necks and grain boundaries. The polyhedral grain structure composed of $(Mo,Ni)_5Si_3$and $Ni_2Si$ across the $MoSi_2$ grain boundary developed at 155$0^{\circ}C$. It was concluded that the activated sintering of $MoSi_2$ powder by Ni led to the diffusion of Si into Ni decreasing the liquidus temperature and the enhanced diffusion of Mo and Si through such a liquid phase and/or interboundary of $(Mo,Ni)_5Si_3$.

• 한국세라믹학회지
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• 제41권1호
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• pp.62-68
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• 2004

본 연구에서는 SHS 공정에 의하여 기공의 크기를 조절함으로서 전기저항 발열 특성을 가지는 다공성 $MoSi_2$를 제조하는 공정에 관하여 연구하였다. 결함이 억제된 다공질 재료를 제조하기 위하여 Si 함량 변화 및 예열 공정을 실시하였으며, 성형체 제조에 사용되는 Mo 분말의 크기 변화에 따른 가공 형성 거동에 대하여 연구하였다. 실험 결과 합성된 $MoSi_2$ 입자의 크기는 Mo 입자의 크기와는 관계없이 연소 합성시 발열되는 발열양에 의해 좌우되었으며, 기공의 크기는 Mo 입자의 크기에 따라 결정되었다. 또한 가공 경사 $MoSi_2$ 다공질 재료를 만들기 위하여 150-300${\mu}m$ Mo 분말과 4-5${\mu}m$ Mo 분말을 단계별로 5층으로 혼합하여 합성한 결과 거시적으로 순차적인 기공 크기 분포를 나타내었으며, 이를 통하여 포집 효율등이 우수한 다공성 발열체 재료의 제조가 가능하였다.

• 한국해양공학회지
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• 제13권4호통권35호
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• pp.37-44
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• 1999

Hardness characteristics and microstructures of $Nb/MoSi_2$ laminate composites were evaluated from the variation of fabricating conditions such as preparation temperature, applied pressure and pressure holding time. $Nb/MoSi_2$ laminate composites composed of $MoSi_2$ powder and Nb sheets were fabricated by the hot press. From experimental results, it was found that the lamination from Nb sheet and $MoSi_2$ powder was an excellent strategy to improve hardness characteristics of monolithic $MoSi_2$. However, interfacial reaction products like(Nb, Mo)$SiO_2\;and\;Nb2Si_3$ formed at the interface of $Nb/MoSi_2$ and increased with fabricating temperature.

• 한국분말재료학회지
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• 제5권4호
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• pp.241-249
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• 1998

Sintering kinetics of ball-milled $MoSi_2$ was studied with the addition of Ni. $MoSi_2$ powder with the average particle size of 1 $\mu\textrm{m}$ was obtained from ball-milling of 10 $\mu\textrm{m}$ powder. Small amount of Ni was added to the ball-milled $MoSi_2$ powder by salt solution and reduction method. The powder was compacted into cylindrical shape at 200 MPa and isothermally sintered in a $H_2$ atmosphere at the temperature range of 1100~$1400^{\circ}C$ for 3~600 minutes. The changes of linear shrinkage and sintered density were monitored as a function of sintering time. The microstructure was observed by using optical microscopy and scanning electron microscopy. Phases were identified by X-ray diffratometer and electro-probe micro analysis. Sintering kinetics of Ni-added powder was compared to as-milled powder and the apparent activation energy was calculated from Arrhenius plot.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2000년도 춘계학술강연 및 발표대회 강연 및 발표논문 초록집
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• pp.25-25
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• 2000

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 1998년도 춘계학술대회 및 발표대회 강연 및 발표논문 초록집
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• pp.22-22
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• 1998

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 1998년도 춘계학술대회 및 발표대회 강연 및 발표논문 초록집
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• pp.9-9
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• 1998

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 1999년도 춘계학술대회 및 발표대회 강연 및 발표논문 초록집
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• pp.21-21
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• 1999

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 1996년도 추계학술강연 및 발표대회 강연 및 발표논문 초록집
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• pp.21-22
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• 1996