• Title/Summary/Keyword: 분산입도

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The Effect of Reactant Composition on the Synthesis of Resole-Type Phenolic Bead (레졸형 구형 페놀입자의 합성에서 반응물의 조성이 입자 형성에 미치는 영향)

  • Hahn, Dongseok;Kim, Hongkyeong
    • Korean Chemical Engineering Research
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    • v.52 no.1
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    • pp.63-67
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    • 2014
  • The effects of reactant composition on the particle size distribution, synthetic yield, and density of Phenol-formaldehyde bead were examined in the synthesis of resol-type phenolic resin. Decrease of the content of DI water as dispersion media can increase the viscosity of suspension, which may cause the difference of particle size distribution and aggregation. The average particle size of synthesized beads was also decreased with the increasing content of stabilizer which can affect the interfacial area. The amount of crosslinking agent showed no effect on the size distribution and synthetic yield, but it made a decrease in the density of synthesized bead due to the macropore in the bead.

A Study on the Explosion Riskiness with Flying of Activated Carbon (활성탄의 부유중 폭발 위험성에 관한 연구)

  • 김정환;현성호;이창우;함영민
    • Fire Science and Engineering
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    • v.12 no.3
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    • pp.3-9
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    • 1998
  • We investigated the weight loss according to temperature using TGA in order to find the thermal hazard of brand-new activated-carbon and disused activated-carbon dusts, and the properties of dust explosion in variation of the specific surface area of their dust with the same particle size. Using hartman's dust explosion apparatus which estimate dust explosion by electric ignition after making dust disperse by compressed air, dust explosion experiments have been conducted by varying concentration and size of activated carbon dust. The explosion pressure of both activated carbon increased as the specipic surface area increased. The results indicated that brand-new activated-carbon of which specific surface area was larger three to four times than that of disused activated-carbon was much easier of dust explosion.

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Mineralogy of Size Fractions in Sancheong Kaolin and Its Origin (산청고령토 입도분리시료들의 광물조성 변화와 그 원인)

  • Jeong, Gi-Young;Kim, Soo-Jin
    • Journal of the Mineralogical Society of Korea
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    • v.5 no.1
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    • pp.22-31
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    • 1992
  • The Sancheong kaolin was fractionated into 9 size fractions by wet sieving, sedimentation, and centrifugation. The systematic X-ray diffraction combined with electron microscopy shows that the clay mineral composition of each size fraction is related to the original fabric of kaolin. Minerals such as halloysite (10${\AA}$), kaolinite, illite, and goethite which were formed by procipitation from solution are generally concentrated in the finer fractions, whereas verniculite which was formed by pseudomorphic transformation from other primary minerals are concentrated in the coarser factions. Kaolinits of various types which were formed by precipitation or transformation show a wide size range but they are generally concentrated in the coarser fractions. Halloysite or halloysite-kaolinite clusters in coarse fractions are the fragmentation products of the walls of original boxwork clusters in coarse fractions are the fragmentation products of the walls of original boxwork kaolin which escaped the complete dispersion even through the grinding, ultrasonic agitation, and chemical treatment. Separation of fully hydrated halloysite and kaolinite was possible by systematic wet size fractionation. The coarse-grained minerals such as vermiculite and kaolinite are usually removed during the preparation of clay fraction smaller than 2${\mu}m$, whereas the fine-grained minerals such as illite and goethite are overlooked in X-ray diffraction of the bulk samples because of their minor contents. The systematic wet size fractionation is needed for understanding of the exact mineralogy of kaolin of weathering origin.

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FeO, $TiH_2$, Carbon 원료분말을 이용한 Fe-TiC 나노 복합분말 제조 및 소결

  • An, Gi-Bong;Kim, Ji-Sun
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2011.10a
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    • pp.26-26
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    • 2011
  • Fe계 TiC 합금은 미량의 합금원소를 첨가시켜 경화능, 내식성, 내마모성 성질을 개선한 특수 공구용 재료로서 현재 절삭, 내마모성, 광산, 금형재료 등의 분야에 널리 사용되고 있다. 금속과 세라믹의 복합재료인 초경합금은 비열처리용 공구강으로 WC, TiC 등의 4, 5, 6족 금속탄화물에 Co, Ni, Fe등의 철족이 결합금속으로 소결한 복합재료로 WC-Co계 초경합금이 주종을 이루고 있으나, 전략 소재로서 고가인 Co 원료를 대체하기 위한 재료로서 초경재료의 고경도와 공구강의 경제성 및 가공성의 장점을 이용한 Fe-TiC계 초경합금의 연구가 다양하게 진행되고 있다. 본 연구에서는 Fe기지에 서브마이크론 크기의 미세한 TiC 입자가 균일하게 분산된 Fe-TiC 복합분말을 경제적으로 제조하기 위해 순수한 Fe, Ti 원료분말에 비해 단가가 낮고 미세 분쇄가 용이한 FeO, $TiH_2$ 분말을 고에너지 밀링 후 반응 열처리 시키는 유사 기계화학적 공정을 시도하였다. 조성비 Fe-30wt%TiC 복합분말을 제조하기위해 마이크론(micron) 크기의 FeO, $TiH_2$, C 분말을 사용하였고, 1단계로 FeO와 C을 고에너지 밀링으로 혼합 후 반응시켜 환원시키는 공정과 2단계로 이렇게 환원된 분말과 TiH2를 고에너지 밀링으로 다시 혼합, 분쇄한 후 반응열처리 하는 두 단계 공정을 사용하였다. FeO의 환원 단계에서는 $700{\sim}1,000^{\circ}C$ 온도 범위에서 1시간 유지하였고, 고에너지 밀링 시 밀링시간, 회전속도를 변수로 두고 실험하였다. 환원된 분말은 수평관상로를 이용해 아르곤분위기에서 $1,000{\sim}1300^{\circ}C$까지 1시간 유지하여 반응열처리시켜 Fe-TiC 복합분말을 제조하였다. 준비된 복합분말을 XRD와 FE-SEM, EDS, 입도분석기 (LPSA) 등을 이용해 분말의 형태와 특성, 상, 조성, 입도, 분산도 등을 조사하였다. 제조된 Fe-TiC 나노복합분말을 방전플라즈마소결(SPS) 과 상압소결 실험을 진행하였다. Fe-TiC 복합분말 제조공정의 첫 번째 단계인 FeO의 환원반응은 $800^{\circ}C$이상의 온도에서 Fe로 환원이 진행됨을 확인하였다. 두 번째 단계인 반응열처리공정에서는 $1,000^{\circ}C$ 이상에서 TiC가 형성됨을 XRD 상분석을 통해 확인할 수 있었고, $1,100^{\circ}C$ 이상의 온도에서 반응열처리를 했을 때 XRD 분석결과와 산소 조성 분석 결과로부터 반응의 완결성과 순도에서 최적 온도 조건임을 확인하였다. 온도를 $1,300^{\circ}C$로 증가시킬 경우 반응의 완결성에 큰 변화가 없는 반면 분말입자간의 목형성이 일어나 가소결 되는 것을 FE-SEM을 통해 관찰하였다. 또한 최적조건으로 제조된 Fe-TiC 복합분말의 입도분석과 FE-SEM/EDS 관찰/분석을 시행한 결과 평균 입도 0.6 ${\mu}m$의 미세한 Fe-TiC 복합분말 내에 Fe분말 주변과 내부에 나노크기의 TiC입자가 균일하게 분산되어 존재하는 것을 확인하였다.

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Preparation and Properties of Water-borne PU Having Ionic Center onto Flexible Side Chain (유연한 곁가지 말단에 이온성 작용기를 가지는 양이온성 수분산 PU의 제조와 물성)

  • Kim, Dong-Min;Bang, Moon-Soo;Kim, Hyung-Joong
    • Journal of Adhesion and Interface
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    • v.7 no.1
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    • pp.3-9
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    • 2006
  • Three isocyanate groups of IP-$75^{(R)}$ and one hydroxyl group of various amino alcohols were applied for preparing cationic type water-borne polyurthane (PU) having ionic center onto flexible side chains. Average particle size, dispersion stability, viscosity, contact angle, surface energy, glass transition temperature ($T_g$), and adhesion strength of prepared water-borne PUs were measured and analyzed with different NCO/OH mol ratios, ionomers, and neutralizing agents. It was characterized that the prepared PU has a smaller particle size and a better dispersion stability than the conventional cationic water-borne PU containing ionic centers onto main chains.

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Improvement Particle and Physical Characteristics Applying of The Pretreatment Process System of Coal Gasification Slag and It's Verification Based on Statistical Approach (석탄 가스화 용융 슬래그의 전처리 공정 시스템 적용에 따른 입자 및 물리적 특성 개선 및 통계적 검증)

  • Kim, Jong;Han, Min-Cheol;Han, Jun-Hui
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.10 no.3
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    • pp.285-292
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    • 2022
  • The objective of this study is to investigate whether CGS generated in IGCC satisfies the fine aggregate quality items specified in KS F 2527(Concrete Aggregate) through the pretreatment process system and the quality improvement the system. The statistical significance of the pretreatment process was analyzed through Repeated Measurements ANOVA as measured values according to individually pretreatment process system. As a result of the analysis, In the case of CGS fine aggregate quality before and after the pretreatment process system, the density increased 5.2 %, the absorption rate decreased by 1.86 %, the 0.08 mm passing ratio decreased by 2.25 %, and Fineness Modulus and Particle-size Distribution were also found to be adjustable. It was found that the pretreatment process system was significant in improving the quality of CGS.

Heavy Metals in Surface Sediments from Kwangyang Bay, South Coast of Korea (광양만 표층퇴적물의 중금속 함량 및 분포)

  • Lee, Chang-Bok;Koh, Chul-Hwan;Cho, Yeong-Gil
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.5 no.2
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    • pp.131-140
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    • 2000
  • Heavy metals (Fe, Mn, Cr, Co, Cu, Ni, Zn, Pb) were determined in ninety-one surface sediments collected from Kwangyang Bay, south coast of Korea. The data show that the Fe, Cr, Ni, and Zn distribution in the bay can be described by metal vs. grain size relationship. However, the distribution pattern of Mn, Co, Cu and Pb were found to be changed because they are anthropogenically enriched to sediment. Correlation matrix and R-mode factor analyses revealed that two important factors controlling the distribution of metals in the bay are grain size and anthropogenic input.

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Integration of Kriging Algorithm and Remote Sensing Data and Uncertainty Analysis for Environmental Thematic Mapping: A Case Study of Sediment Grain Size Mapping (지표환경 주제도 작성을 위한 크리깅 기법과 원격탐사 자료의 통합 및 불확실성 분석 -입도분포지도 사례 연구-)

  • Park, No-Wook;Jang, Dong-Ho
    • Journal of the Korean Geographical Society
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    • v.44 no.3
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    • pp.395-409
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    • 2009
  • The objective of this paper is to illustrate that kriging can provide an effective framework both for integrating remote sensing data and for uncertainty modeling through a case study of sediment grain size mapping with remote sensing data. Landsat TM data which show reasonable relationships with grain size values are used as secondary information for sediment grain size mapping near the eastern part of Anmyeondo and Cheonsuman bay. The case study results showed that uncertainty attached to prediction at unsampled locations was significantly reduced by integrating remote sensing data through the analysis of conditional variance from conditional cumulative distribution functions. It is expected that the kriging-based approach presented in this paper would be efficient integration and analysis methodologies for any environmental thematic mapping using secondary information as well as sediment grain size mapping.

Dispersion Characteristics Control of $TiO_2$ Nano Particles for Electronic Paper (전자 종이 적용을 위한 $TiO_2$나노 입자의 분산 특성 제어)

  • 권순형;김세기;홍완식;안진호;김선재
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2003.03a
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    • pp.127-127
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    • 2003
  • 전자종이에 대한 관심이 높아지면서 전자잉크의 pigment 소재에 대한 연구가 최근 활발하게 이루어지고 있다. 많은 재료 중 TiO$_2$는 비표면적이 크고 열적안정성 및 명암도가 뛰어나 전자잉크 재료로 많은 장점을 지닌다. TiO$_2$ 나노 입자를 전자종이에 적용할 경우 우수한 디스플레이 구현을 위해 높은 전기영동 특성 및 분산 안정성이 요구되어진다 이를 위해 표면 개질된 나노 크기의 루틸상 TiO$_2$ 입자의 제조 및 분산에 대한 최적의 공정조건에 대해 연구하였다. 10$0^{\circ}C$ 이하의 저온에서 가열하여 균일하게 침전시키는 저온균일침전법(HPPLT)으로 루틸 결정상의 TiO$_2$ 나노입자를 제조하였다. 제조된 TiO$_2$ 나노 입자와 용매의 비중을 맞추기 위해 비중이 낮은 투명성 polymer로 코팅을 한 후 비중병을 이용해 비중을 확인하였다. 그 후 copolymer block을 가지는 분산제를 TiO$_2$ 입자 기준 0.5-5wt% 범위에서 저유전율을 가지는 다양한 유기용매에 첨가하여 최적의 분산 및 전기영동 조건을 찾았다. 실험을 통한 분산안정성 및 전기영동 특성 평가를 위해 ζ-potential analyzer와 입도 분석기를 이용하였고 코팅된 입자의 표면상태는 FT-IR을 통해 측정하였다.

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Synthesis of Diarylide Pigments and Their Dispersion Behavior by Dispersion Precursors (분산 전구체를 이용한 Diarylide계 안료의 합성 및 분산거동)

  • Kim, Song Hyuk;Kim, Jae Hwan;Yang, Seok Won;Kim, Dae-Sung;Lee, Gun-Dae;Park, Seong Soo
    • Applied Chemistry for Engineering
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    • v.25 no.6
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    • pp.586-591
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    • 2014
  • In this study, the diarylide compound pigment of high hiding power and vivid color was synthesized successfully by controlling several factors such as pH, coupler solution temperature, kind and addition amount of dispersion precursor, and crystallization temperature in the process of coupling synthesis. The properties of samples were measured by the means of FT-IR, UV-Vis spectroscopy, PSA, zeta potential, and turbiscan. It was found that the highly dispersive sample could be prepared by introducing the dispersive precursor.