• Title/Summary/Keyword: Diluent size

Search Result 36, Processing Time 0.023 seconds

Characteristic of Tantalum Powder and Effect of Reaction Temperature on the amount of Diluent (희석제량에 따른 탄탈륨 분말 특성 및 반응온도의 영향)

  • 윤재식;박형호;배인성;정성만;김병일
    • Journal of Powder Materials
    • /
    • v.9 no.5
    • /
    • pp.315-321
    • /
    • 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.

Characteristics and Production of Tantalum Powder on the amount of Diluent By Na Reduction Method (Na환원법에 의한 희석제량에 따른 탄탈 분말 제조와 특성)

  • Yoon, Jae-Sik;Park, Hyeong-Ho;Bae, In-Sung;Kim, Byung-Il;Jung, Sung-Man
    • Korean Journal of Materials Research
    • /
    • v.12 no.9
    • /
    • pp.706-711
    • /
    • 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$\mu\textrm{m}$.

Diluted Synthesis of Manocrystalline CeO2 by Mechanical Milling (희석혼합체의 기계적 분쇄에 의한 나노 CeO2의 합성)

  • Lim, Geon-Ja;Kim, Tae-Eun;Lee, Jong-Ho;Lee, Hae-Weon;Rhee, Dong-Joo;Hyun, Sang-Hoon
    • Journal of the Korean Ceramic Society
    • /
    • v.39 no.8
    • /
    • pp.764-768
    • /
    • 2002
  • The nanocrystalline $CeO_2$ was synthesized by mechanical milling and subsequent heat-treatment with the mixture of $Ce(OH)_4$ precursor and diluent, NaCl. Using deionized water, the diluent, NaCl, in the mixture has been easily dissolved out. Diffusion barrier was provided by the diluent during heat-treatment, which suppressed not only the coarsening of primary particle but also the agglormeration between the particles. Crystallite and aggregate size of $CeO_2$ depended on the concentration of diluent, temperature and time of heat-treatment; increased with the temperature and time increases. In case the mixture was heat-treated at high than $600^{\circ}C$, however, the crystallite size was saturated near 20 nm, which was supposed to be due to the densification of diluent.

Fabrication of AlN Powder by Self-propagating High-temperature Synthesis I. Synthesis of AlN Powder (자전고온 반응 합성법에 의한 AlN 분말의 제조 I.AlN 분말의 제조)

  • 신재선;안도환;김석윤;김용석
    • Journal of the Korean Ceramic Society
    • /
    • v.33 no.9
    • /
    • pp.961-968
    • /
    • 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.

  • PDF

Fabrication of Niobium Powder for Solid-electrolyte Capacitors (고체 전해커패시터용 니오븀 분말제조)

  • Yoon, Jae-Sik;Hwang, Sun-Ho;Kim, Byung-Il
    • Journal of the Korean institute of surface engineering
    • /
    • v.42 no.5
    • /
    • pp.227-231
    • /
    • 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.

Comparision of Preservation of Liquid Boar Semen between Lactose-Egg Yolk and $B\ddot{u}tschwiler$ Diluents (돼지 액상정액 보존을 위한 Lactose-Egg Yolk와 $B\ddot{u}tschwiler$ 희석액의 비교)

  • Park, C.S.;Cheon, Y.M.;Xu, Z.
    • Korean Journal of Animal Reproduction
    • /
    • v.20 no.2
    • /
    • pp.101-109
    • /
    • 1996
  • This study was done to find out the methods of long-term use of liquid boar semen in 100 ml plastic bottle for artificial insemination and to investigate differences between Lactose-Egg yolk and Biitschwiler diluents according to storage temperature, and effect of final glycerol concent ration in Lactose-Egg yolk diluent. Liquid boar semen diluted with Lactose-Egg yolk diluent showed significantly higher sperm motility (p<0.05) after 0.5 and 2h incubation at 37$^{\circ}C$,than Butschwiler diluent at all storage length when it was preserved in the 5$^{\circ}C$ refrigerator. The NAR acrosome in Lactose-Egg yolk diluent a after 0.5 and 2h incubation at 37$^{\circ}C$, respectively, during preservation periods was similar to that in Biitschwiler diluent. When liquid boar semen was preserved at 15$^{\circ}C$, liquid boar semen in the Butschwiler diluent showed significantly higher percentages of sperm motility and NAR acrosome from third day to seventh than that in Lactose-Egg yolk diluent. In the effect of final glycerol concentration of liquid boar semen in the Lactose-Egg yolk diluent, the final glycerol concentration of 2% showed higer percentages of sperm motility and NAR acrosome than that of 0, 1, 3, and 5%. Farrowing rate, litter size and average pig weight at birth did not differ significantly between Lactose-Egg yolk and But schwiler diluents. As a result of this study, we found out that liquid boar semen can be stored for 6-7 days at 5$^{\circ}C$ in Lactose-Egg yolk diluent and at 15$^{\circ}C$ in Butschwiler diluent.

  • PDF

Production of Tantalum Powder and Characteristics by External Supply of Feed Material and Reductant (원료물질과 환원제의 외부공급에 따른 탄탈륨 분말의 제조 및 특성)

  • 윤재식;박형호;배인성;김병일
    • Journal of Powder Materials
    • /
    • v.10 no.5
    • /
    • pp.349-352
    • /
    • 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%.

Effect of Diluent Size on Aluminum Nitride Prepared by Using Self-Propagating High-Temperature Synthesis Process (희석제 입도가 고온자전연소법에 의한 질화알루미늄 합성에 미치는 영향)

  • Lee, Jae-Ryeong;Lee, Ik-Kyu;Shin, Hee-Young;Chung, Hun-Saeng
    • Journal of the Korean Ceramic Society
    • /
    • v.42 no.1
    • /
    • pp.69-75
    • /
    • 2005
  • To investigate the morphological effect on synthesis of aluminum nitride by SHS Process, two type of Al Powder (granular and flacky shape) with the mean size of 34 $\mu$m and the diluent AIN powders of four different mean sizes.0.12, 9.7, 39.3, 50.5 $\mu$m, were used to prepare green compact. The packing density was fixed to $35 TD\%. The initial pressure of $N_{2}$ and diluent fraction was varied in the range of $1\~10 MPa,\;0.4\~0.7$, respectively. AlN with high purity of $98\% or over and large particle size of about several tens fm can be synthesized by SHS reaction as a consequence of adjusting particle size of AlN dilutent similarly to that of Al reactant. This may be caused by improvement of $N_{2}$ gas permeation to compact after passing the propagation wave. In the case of flaky-shape aluminum used as reactant, instead of granular Al-powder, unstable combustion would be occurred. As the result, irregular propagation of combustion wave and falling-off of maximum temperature would be observed during the reaction.

Preparation and Characterization of Monodisperse Porous Poly(acrylonitrile-ethylene glycol dimethacrylate) Microgels (단분산성 다공의 폴리아크릴로니트릴-에틸렌 글리콜 디메타크릴레이트 마이크로 겔의 제조 및 특성)

  • Kim, Kong-Soo;Kang, Seog-Ho;Kim, Young-Sik
    • Applied Chemistry for Engineering
    • /
    • v.7 no.4
    • /
    • pp.777-786
    • /
    • 1996
  • Uniform sized-porous poly(acrylonitrile-ethylene glycol dimethacrylate) (PAN) microgels were synthesized by seed polymerization using monodisperse polystyrene seed particles. The effect of weight ratios of monomer/seed (M/S) and diluent/monomer (DIM), concentration of crosslinking agent and the type of diluent was investigated on the formation of PAN microgels. The particle size distribution of PAN microgels was found to be monodisperse in that the weight ratio of M/S is less than 50. More porous microgels were formed and the interstices between small sized interior microspheres present inside of PAN microgels were also smaller with increasing crosslinking agent concentration. Well-developed pore structure was found to be in that weight ratio of D/M is 1 and toluene is used as a diluent.

  • PDF

Characteristics of Tantalum Powder on the Location of Reductant by MR and EMR Combination Process (MR-EMR 복합제조공정에서 환원제 위치가 탄탈륨 분말 특성에 미치는 영향)

  • Park, Hyeoung-Ho;Yoon, Jae-Sik;Bae, In-Sung;Kim, Yang-Soo;Yoon, Dong-Ju;Won, Dae-Hee;Kim, Byung-Il
    • Journal of Powder Materials
    • /
    • v.14 no.3 s.62
    • /
    • pp.190-196
    • /
    • 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.