• 한국분말재료학회지
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• 제9권5호
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• pp.315-321
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• 2002

Pure tantalum powder has been produced by combining Na as a reducing agent, $K_2TaF_{7}$ as feed material, KCl and KF as a diluent in a stainless steel(SUS) bomb, using the method of metallothermic reduction. The present study investigated the effect of the amount of the diluent and reaction temperature on the characteristics of tantalum powder in the production process. The temperature applied in this study $850^{\circ}C$ and the amount of the additional reductant from +5% of the theoretical amount used for the reduction of the entire $K_2TaF_{7}$. The results showed that as the amount of the diluent increased, the reaction temperature became lower because the diluent prevented a temperature rise. Also, according to the mixture ratio of the feed materials and the diluent changed from 1 : 0.25 to 1 : 2, the particle size decreased from $5\mutextrm{m}$ to $1\mutextrm{m}$ and a particle size distribution which is below 325 mesh in fined powder increases from 71% to 83%. The average size of Tantalum powder, $2-4\mutextrm{m}$, was close to that of the commercial powders($2-5\mutextrm{m}$). Also under this condition, impurities contained in the powder were within the range allowed for the commercial Ta powders.

• 한국재료학회지
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• 제12권9호
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• pp.706-711
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• 2002

High-pure tantalum powder was fabricated through Na reduction process and has been produced by using $K_2$TaF$_{7}$, and KCI, KF for raw material and diluent, respectively. A raw material and diluent were charged at the hestalloy bomb by the weight rate of 1:2, 1:1, 1:0.5 and 1:0.25 each other, investigated properties of morphology, chemical composition and yield and particle size after reduced. Ta metal has been achieved by reduction of $K_2$$TaF_{7}$ 500g with 1% sodium in excess of stoichiometric amount in the charge at a reduction temperature of $850^{\circ}C$ for 3hours. According to amount of the diluent, a formation of the powder doesn't have an effect. The diluent prevented the temperature rising caused from the heat of reaction and it maintained the speed of reducing reaction. But in the mixture ratio of raw material and diluent in the 1 : 2 and 1 : 0.25, an oxide and partially not reacted K were detected. As the amount of diluent increased, the size of tantalum powder decreased. According as raw material and the mixture ratio of diluent change from 1:0.25 to 1:2, the size is decreased from 5$\mu\textrm{m}$ to 1$\mu\textrm{m}$, and a particle size distribution which is below 325 mesh in fined powder increases from 71% to 83%. In the case of average size of Tantalum powder which is the mixture ratio (1:0.5), we would get the Ta powder with grain size about 3$\mu\textrm{m}$, which come close to the average size (2~4$\mu\textrm{m}$) of tantalum powder which is used commonly in the present is Ta powder about 3$\mu\textrm{m}$.

• 한국세라믹학회지
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• 제39권8호
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• pp.764-768
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• 2002

산화물의 금속 전구체인 $Ce(OH)_4$를 희석제인 NaCl과 함께 기계적으로 분쇄하여 나노 크기의 일차입자를 제조하고, 분쇄한 전구체 분말은 희석제와 함께 열처리를 하여 나노 결정립의 $CeO_2$를 합성하였다. 희석제는 전구체의 분쇄시 분말의 재응집을 억제하여 분쇄효율을 증진시켰을 뿐만 아니라 열처리 중에는 일차입자 성장과 응집을 억제하여 열처리 온도와 시간에 따라 일차입자의 크기 뿐만 아니라 응집체으 크기도 제어할 수 있었다. 열처리 중 희석제는 고온에서 전구체 표면에서 치밀화 되어 일차입자 성장과 응집체 형성의 확산장벽으로 작용하는 것으로 판단되며 열처리 후 증류수에 쉽게 용해되어 $CeO_2$ 나노 입자 제조에 효과적이었다. 일차입자와 응집체의 크기 및 결정성은 희석제의 농도, 열처리 온도와 시간에 의존하는 것으로 확인 되었다.

• 한국세라믹학회지
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• 제33권9호
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• pp.961-968
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• 1996

The aluminum nitride was synthesized by the self-propagating high-temperature synthesis(SHS). The synthe-sis was used aluminum powder mixed with AlN powder as reactant and the control factors affected to synthesis were considered compact density pressure of reaction gas AlN diluent content and aluminum powder size. The SHS reaction conducted with a reactant containing 50% AlN diluent under 0.8MPa nitrogen gas pressure yielded a complete conversion of aluminum powder to AlN powders. The size and purity of AlN produced were found to be comparable with that of AlN produced by the carbothermal nitrogen method.

• 한국표면공학회지
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• 제42권5호
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• pp.227-231
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• 2009

The niobium capacitor showed somewhat more unstable characteristics than the commercial tantalum capacitors, but is nonetheless considered applicable as a future substitute for tantalum capacitors. In this study, niobium powder was fabricated by metallothermic reduction process using $K_2NbF_7$ as the raw materials, KCl and KF as the diluents and Na as the reducing agent. The niobium particle size greatly decreased from 0.7um to 0.2 um as the amount of diluent increased. However if a higher surface area of powder is required, more diluents need to be used in the said method in order to produce niobium powder. The niobium powder morphology and particle size are very sensitive to a amount of sodium excess. The particle size of niobium powder increased with a increasing amount of sodium excess. When more diluent and sodium are used, the niobium powder will be contaminated with more impurities such as Fe, Cr, Ni so on.

• 한국가축번식학회지
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• 제20권2호
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• pp.101-109
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• 1996

본 연구는 돼지 액상정액을 인공수정용 100ml 플라스틱 병에 보존하면서 Lactose-Egg yolk 희석액과 B tschwiler 희석액 간에 보존 온도별 차이를 조사하고, Lactose-Egg yolk 희석액에서의 글리세롤 농도의 효과를 조사하여 돼지 액상정액을 좀더 장기간 사용할 수 있는 방법을 찾고자 실시하였다. 돼지 액상정액을 5$^{\circ}C$ 냉장고에 보존하면서조사한 바에 의하면, 37$^{\circ}C$에서 0.5 및 2시간 배양 후의 정자 운동성은 전체 보존기간동안 Lactose-Egg yolk 희석액이 B tschwiler 희석액보다 유의하게 (P,0.05) 높게 나타났고, 정상첨체비율은 두 희석액간에 차이가 없었다. 돼지 액상정액을 15$^{\circ}C$에 보존하면서 조사한 바에 의하면, 3일부터 7일 보존시까지 정자 운동성과 정상첨체비율에 있어서 B tschwiler 희석액이 Lactose-Egg yolk 희석액보다 유의하데 높게 나타났다. Lactose-Egg yolk 희석액을 이용한 돼지 액상정액의 글리세롤 농도의 효과에 있어서는 최종 글리세롤 농도가 0, 1, 3 및 5%보다 2%일 때 가장 높은 정자 운동성과 정상첨체비유을 나타내었다. 분만율, 복당 생존자돈수 그리고 출생시 평균 생시체중은 Lactose-Egg yolk 희석액과 B tschwiler 희석액간에 차이가 없었다. 이상의 연구 결과를 종합해 볼 때 Lactose-Egg yolk 희석액은 5$^{\circ}C$에서 B tschwiler 희석액은 15$^{\circ}C$에서 6~7일 동안 돼지 액상정액을 보존할 수 있었다.

• 한국분말재료학회지
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• 제10권5호
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• pp.349-352
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• 2003

This study examined the correlation of various operational factors including reaction temperature and the quantity of reductant and diluent with the characteristics of powder using $K_2$ TaF$_{7}$ as feed materials, Na as a reductant and KCl/KF as a diluent. Also to control the particle size and shape, external supply system developed, it can provide a feed material and a reductant at a fixed quantity and evaluated the characteristics of tantalum powder. When the external supply system was applied instead of the batch type process that charges feed material, reductant and diluent at the same time, it was possible to induce regular reduction reaction between feed material and reductant, which increased the recovery rate and reduced the mixture of impurities. In particular, the application of the external supply system enabled the control of reaction temperature and reaction speed according to the feeding rate of feed material during reduced reaction, and resultantly it enabled the manufacturing of granular-shaped powder with a regular granularity of 2∼3 ${\mu}{\textrm}{m}$ and purity of 99.5%.

• 한국세라믹학회지
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• 제42권1호
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• pp.69-75
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• 2005

고온자전연소법에 의한 질화알루미늄 합성에 있어서, 반응물(Al) 형상과 희석제(AlN) 입도 등의 형상학적 조건이 반응생성물에 미치는 영향을 조사하였다. 평균 입경(34$\mu$m)이 같은 두 종류의 Al 분말(입상, 편상)과 평균입경이 다른 4종류의 AM분말을 희석제로 사웅하여 반응 성형체를 준비하였다. 반응성형체의 충진밀도는 이론밀도의 $35\%로 고정하였고, 초기 질소압은 $1\~10MPa$, 희석을은 $0.4\~0.7$로 변화시키면서 반응을 실시하였다. 반응물과 희석제의 입도를 비슷하게 조절함으로써, 상대적으로 질소압이 낮은 1MPa의 조건에서도 순도 $98\% 이상, 입경 수십 $\mu$m의 AlN 합성이 가능함을 확인하였다. 이러한 고순도, 고입경화는 연소파 진행 후, 성형체 내부로 질소가스 투입 용이성의 차이에 의한 현상이라고 판단된다.

• 공업화학
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• 제7권4호
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• pp.777-786
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• 1996

Seed 중합 방법에 의하여 단분산성 다공의 폴리아크릴로니트릴-에틸렌글리콜 디메타크릴레이트 (PAN) 고분자 마이크로 겔이 제조되었다. PAN 마이크로 겔의 물리적인 특성을 모노머/seed와 희석제/모노머의 비율, 가교제의 농도 및 희석제의 종류에 따라 연구하였다. PAN 마이크로 겔의 입도 분포는 모노머/seed의 비율이 50 이하 일 때 단분산성을 나타냈으며, 가교제의 농도가 증가할수록 입자 내부의 미소 구체 (microsphere)의 크기가 작아져 더욱 밀집된 형태를 나타내기 때문에 입자의 비표면적이 증대되었다. 또한 희석제로 톨루엔을 사용하고 희석제/모노머의 비율이 1.0일 때 입자표면의 세공이 가장 발달되었다.

• 한국분말재료학회지
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• 제14권3호
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• pp.190-196
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• 2007

A process known as the MR and EMR combination process is able to overcome the shortcomings of the MR (metallothermic reduction) and EMR (electronically mediated reaction) process. The effects of $K_2TaF_7$ as the raw material, sodium as the reducing agent and KCl/KF as the diluent on the characteristics of tantalum powder are investigated. In this study, a MR-EMR combination process has been employed to tantalum powder on the location of reductant. The excess of reductant were varied from 25, 50 to 75 wt%. The total charge and external circuit decreases as the amount of reductant increases. The average particle size increases with increasing the amount of reductant.