• Title, Summary, Keyword: $CaCO_3$ 제조

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The effect of $Co_{3}O_{4}$ substitution on properties of Ni-Zn Ferrite (Ni-Zn 페라이트 물성의 $Co_{3}O_{4}$ 치환효과)

  • An, Yong-Woon;Kim, Jong-Ryung;Oh, Young-Woo;Kim, Hyun-Sik;Lee, Hae-Yun
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.92-95
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    • 2003
  • 전력선 통신용 LC 공진필터에 사용되는 Ni-Zn 페라이트를 제조하기 위해 $Ni_{0.8}Zn_{0.2}Fe_{2}O_{4}$를 기본조성으로 첨가제 $Bi_{2}O_{3}$, CaO와 x (co mol 비)를 변화시켜 전자기적 특성을 조사하였다. $Bi_{2}O_{3}$ CaO가 첨가됨으로써 균일한 입자성장과 입계에 고저항층이 형성되어 주파수 손실이 감소하였으며, $Ni_{0.8-x}Zn_{0.2}Co_{x}Fe_{2}O_{\delta}$의 기본조성에 Co의 함량을 증가시키면 x = 0.05에서 투자율 75, 공진주파수 20MHz의 특성을 나타내고 결정 입자 크기와 같은 구조적 특성에는 영향을 거의 미치지 않지만 전자기적 특성에는 영향을 미친다. 또한, $Ni_{0.75}Zn_{0.2}Co_{0.05}Fe_{2}O_{4.017}$ 조성의 페라이트 코어의 발열량은 큐리온도 이하에서 일어난다.

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Fabrication of Magnesium Alloy Foam Through $TiH_2$ and $CaCO_3$ ($TiH_2$$CaCO_3$를 이용한 마그네슘 합금의 제조)

  • Seo, Chang-Hwan;Seong, Hwan-Goo;Yang, Dong-Hui;Park, Soo-Han;Hur, Bo-Young
    • Journal of Korea Foundry Society
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    • v.26 no.6
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    • pp.267-271
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    • 2006
  • Metal foam is a class of attractive materials, which exhibits unique combinations of physical, mechanical, thermal, electrical and acoustic properties. In particular, it is light and good at absorbing energy, which makes it attractive in automotive and aerospace applications weight is critical. In this paper, the Mg alloy foam was prepared by melt foaming method by addition of calcium as thickening agent, and $TiH_2$ or $CaCO_3$ powder as blowing agent. The macrostructural observation of foamed Mg showed that the pore structures of Mg alloy foam made by $CaCO_3$ as blowing agent were much better than that of foams made by $TiH_2$ as blowing agent. In addition, this paper showed the possible reason of fabrication magnesium alloy foam in proportion to blowing agent and the porosity range was about 40 to 76% as results value.

Fabrication of $Er^{3+}/Yb_3$ co-doped Soda-lime Glass Thin Films using Radio Frequency Magnetron Sputtering Method and Optical Property Characterization (RF 마그네트론 스퍼터에 의해 제조된 $Er^{3+}/Yb_3$ 도핑된 소다 라임 유리 박막의 제조 및 광학적 특성평가)

  • 임종모;김미옥;이병택;문종하;김진혁
    • Proceedings of the Optical Society of Korea Conference
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    • pp.42-43
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    • 2002
  • 고상 소결법으로 715iO$_2$+11$Na_2$O+10CaO+3Er$_2$O$_3$+5Yb$_2$O$_3$(all wt%) 조성의 스퍼터용 유리 타겟을 제조하여, RF 마그네트론 스퍼터에 의해 희토류 원소가 첨가된 광증폭기용 다성분계 sodium calcium silicate 유리박막을 제조하였다. 최적의 공정조건을 얻기 위해 RF-power, 공정압력, 기판온도를 변화시키면서 박막을 제조하여 RF-power 150W, 공정압력 4mtorr, 기판온도 50$0^{\circ}C$, 타겟-기판 거리 6cm에서 타겟의 손상이 심하지 않으면서, 1.4$mu extrm{m}$/h의 최고 증착율을 가지는 양질의 박막을 제조하였다. (중략)

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Fabrication of Porous Calcium Phosphate by Using a Pre-Form of Nature Material (자연물의 미세구조를 활용한 다공성 인산칼슘 제조)

  • Lee, Sang-Jin;Lee, Hoon-Cheol
    • Journal of the Korean Ceramic Society
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    • v.47 no.3
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    • pp.244-248
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    • 2010
  • Porous calcium phosphates were successfully fabricated by using a cuttlefish bone. The cuttlefish bone, which is composed of $CaCO_3$, showed a special porous microstructure containing uniform-sized voids. In this study, the pre-forms infiltrated distilled phosphoric acid were sintered at $1200^{\circ}C$ in an air atmosphere. The porous microstructure of the pre-forms was kept their original pattern after sintering with a synthesis of calcium phosphate. The obtained porous calcium phosphate, sintered at $1200^{\circ}C$ for 3 h at 17% concentration of phosphoric acid, showed uniform open pores of 150 ${\mu}m$ in size and $\beta$-TCP phase in the XRD patterns. Above 16% concentration, CaO phase, derived from the decomposition of $CaCO_3$, decreased gradually in the sintered samples, and the measured Ca/P ratios of the samples prepared from 16% and 18% concentration were 1.67 and 1.43, which are close to stoichiometric HA (1.66) and $\beta$-TCP (1.50).

An Experimental Study on the Properties of Chloride Binding of Mg/Al-NO3 and Ca/Al-NO3 Layered Double Hydroxides in Solution (수용액내에서 Mg/Al-NO3 및 Ca/Al-NO3 층상이중수산화물(LDHs)의 염소이온 고정화 특성에 관한 실험적 연구)

  • Lee, Seung-Yeop;Yang, Hyun-Min;Lee, Han-Seung
    • Journal of the Korea Institute of Building Construction
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    • v.16 no.3
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    • pp.219-227
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    • 2016
  • Chloride ions ingress continuously in reinforced concrete through pores of it by $Cl^-$. Finally, it causes a localized corrosion of the rebar and then it generates cracks on concrete structures. Recently, new materials removing harmful anions have been developed. Layered double hydroxides(LDHs) has an excellent ability to remove harmful anions because various anions can be adsorbed in the interlayer space between divalent and trivalent cations. Thus, LDHs has been applied in various fields. Especially, LDHs is expected to be effective adsorbent binding chloride ions. In this study, $Ca/Al-NO_3$ and $Mg/Al-NO_3$ LDHs were prepared by using a co-precipitation method. $Ca/Al-NO_3$ and $Mg/Al-NO_3$ LDHs were compared and analyzed by using XRD, SEM analysis. Many nano size hexagonal crystals were observed by SEM. Experiments for binding chloride ions of LDHs were conducted by using potentiometric method. The experimental data were measured every 15 minutes. It was observed that the chloride ion content is reduced by increasing of LDHs mass fraction and the reaction rate of $Mg/Al-NO_3$ is faster than $Ca/Al-NO_3$. In future studies, binding chloride capacity in cement materials will be evaluated based on results of this study.

The Design of Oxide Module for High Temperature Thermoelectric Power Generation (고온 발전용 산화물 열전모듈의 설계)

  • Park, Jong-Won;Yoon, Sun-Ho;Cha, Jeong-Eui;Choi, Seung-Chul
    • Journal of the Microelectronics and Packaging Society
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    • v.15 no.4
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    • pp.93-100
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    • 2008
  • The one and two pair of oxide modules for high temperature thermoelectric power generation were fabricated with $Ca_{2.7}Bi_{0.3}Co_4O_9$(p-type) and $Ca_{0.96}Bi_{0.04}Mn_{0.96}Nb_{0.04}O_3$(n-type) on $Al_2O_3$ substrate. For the optimizing of the design process, contact resistance was derived from the results of the one pair modules, and then the resistance of two pair modules were calculated to use the derived data. Those values were compared with the measured values for the optimizing of this design process. The resistance of calculated and measured two pairs modules was 0.956 $\Omega$ and 1.110 Q $\Omega$ $T_h$=833 K, respectively, the difference of resistance was about 0.15 $\Omega$. From the result, proposed design process is effective for high temperature thermoelectric oxide modules fabrication.

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Thermal Conductivity and Pore Characteristics of Low-Temperature Sintered Lightweight Aggregates Mode from Waste Glass and Bottom Ash (바텀애쉬와 폐유리를 사용하여 제조한 저온소성 경량골재의 열전도율과 기공특성)

  • Lee, Han-Baek;Ji, Suk-Won;Seo, Chee-Ho
    • Journal of the Korea Concrete Institute
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    • v.22 no.6
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    • pp.851-858
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    • 2010
  • In this study, waste glass and bottom ash were used as basic materials in order to secure a recycling technology of by-products which was mostly discarded and reclaimed. In addition, because softening point of waste glass is less than $700^{\circ}C$ and bottom ash includes combustible material, it was possible to manufacture low-temperature sintering lightweight aggregates for energy saving at $800{\sim}900^{\circ}C$ that it is as much as 20~30% lower than sintering temperature of existing lightweight aggregates. Thermal conductivity of newly-developed lightweight aggregates was 0.056~0.105W/m. K and its porosity was 40.36~84.89%. A coefficient of correlation between thermal conductivity and porosity was -0.97, it showed very high negative correlationship. With this, we were able to verify that porosity is key factor to affect thermal conductivity. Microstructure of lightweight aggregates by $CaCO_3$ content and replacement ratio of bottom ash in the variation of temperature were that $CaCO_3$ content increased along with pore size while replacement ratio of bottom ash increased as pore size decreased. Specially, most pores were open pore instead of closed pore of globular shape when replacement ratio of bottom ash was 30%, and pore size was small about 1/10~1/5 as compared with case in bottom ash 0~20%. In addition, open pore shapes were remarkably more irregular form of open pore in $900^{\circ}C$ than $700^{\circ}C$ or $800^{\circ}C$ when replacement ratio of bottom ash was 30%. We reasoned hereby that these results will influence on absorption increase, strength and thermal conductivity decrease of lightweight aggregates.

Studies on the Preparation of Precipitated Calcium Carbonate(I) : Formation and Transformation of Amorphous Calcium Carbonate (침강성탄산칼슘의 제조에 관한 연구(I) : 비정질탄산칼슘의 생성과 전이)

  • Ha, Ho;Park, Seung-Soo;Lee, Hee-Cheol
    • Applied Chemistry for Engineering
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    • v.3 no.3
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    • pp.522-526
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    • 1992
  • Carbonation process of an aqueous solution of $Ca(OH)_2$ with $CO_2$ gas at $10^{\circ}C$ has been studied to investigate the formation and transformation processes of amorphous calcium carbonate. It was suggested that the amorphous calcium carbonate consisting of spherical particles with the diameter in the range of $0.02{\sim}0.05{\mu}m$ be a non-stoichiometric $CaCO_3$ phase containing small amounts of $H_2O$ and small incorporations of $HCO^-_3$. Amorphous $CaCO_3$ is unstable in the aqueous solution and converts to calcite, and its morphology depends on the carbonate species present in the slurry such that with [$CO_3^{2-}$] prevailing, chain-like calcite composed of ultrafine colloidal particles and with [$HCO^-_3$] prevailing, rhombohedral particles of calcite are formed respectively. Therefore, morphological control of calcium carbonate crystals could be expected by the adequate controls of transformation process of the amorphous calcium carbonate.

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Preparation of Surface-Hydrolyzed Cellulose Acetate Fibers and Their Applications to LCD Rubbing Cloth (표면가수분해된 셀룰로오스 아세테이트 섬유의 제조 및 LCD 러빙포로의 응용)

  • Kim, Hyun-Sun;Kim, Young Ho
    • Polymer(Korea)
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    • v.37 no.1
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    • pp.52-60
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    • 2013
  • Partially hydrolyzed cellulose acetate (CA) fibers were prepared by treating CA fibers in aqueous $Na_2CO_3$ solutions of various concentrations. The deacetylation of CA fibers was confirmed through FTIR spectra and WAXD patterns. The hydrolysis was confined to the surface part of the CA fiber by controlling the treatment conditions. The resultant fibers had a sheath-core structure with a sheath component of regenerated cellulose and a core of non-hydrolyzed cellulose acetate. The SEM images of the surface-hydrolyzed CA fibers, the core of which was dissolved out using acetone as the solvent, showed that the sheath thickness increased with increasing alkaline concentration, indicating an increase in the hydrolyzed fiber, i.e., regenerated cellulose. Polarized FTIR analysis of the polyimide film rubbed with velvet fabrics of surface-hydrolyzed CA fibers showed that polyimide molecules were preferentially oriented to the rubbing direction.

Preparation of Urethane Nanocomposites with Inorganic Nano Fillers and Their Physical Properties (무기계 나노분말 충전 폴리우레탄 나노복합재료의 제조 및 물성)

  • Yang Yun-Kyu;Hwang Taek-Sung;Hwang Eui-Hwan
    • Polymer(Korea)
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    • v.30 no.2
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    • pp.129-134
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    • 2006
  • Nanocomposites of polyurethane were prepared from inorganic nano particles, $Na^+-montmorillonite$ (MMT), silica, $CaCO_3$, and surface modified MMT and their properties were investigated. It was shown that the molecular weight and polydispenity of nanocomposites of polyurethane were 20000 to 28000 and 1.0 to 2.0, respectively. d-Spacing for nanocomposites of MMT were increased than that of pure MMT. Initial degradation temperature of nanocomposites were 250 to $280^{\circ}C$. And also, the range of weight loss for nanocomposites were decreased and the end of thermal degradation was observed at higher temperatures about $50^{\circ}C$. The elongation at break for $CaCO_3$ filled nanocomposites were the highest among the nanocomposites used in this study. studied. It was found that the tensile strength increased with increasing the filler contents while the silica nanocomposite exhibited the lowest increase and the $CaCO_3$ nanocomposite the highest.