• Title/Summary/Keyword: Solid-state reaction

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Surface Potential Behavior of Nano $CeO_2$ Particles in Aqueous Media (수계분산매체에서 나노 $CeO_2$ 입자의 계면전위 거동)

  • 이태원;백운규;최성철;이상훈;임형섭;김철진
    • Journal of the Korean Ceramic Society
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    • v.37 no.7
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    • pp.721-725
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    • 2000
  • In this study, the dispersion stability of nano-sized CeO2 particles, synthesized by hydrothermal method in aqueous was evaluated from observing the surface potential behavior of CeO2 particle synthesized by solid state reaction. The isoelectric point(IEP) of nano-sized CeO2 synthesized by hydrothermal synthesis was found to be pH 9 contrary to the isoelectric point of micro-sized CeO2 synthesized by solid state reaction at pH 6.7. IEP was shifted to pH 2.0 as the addition of D-3019 from 0.1 to 1.0 wt%. The surface potential of CeO2 particles synthesized by hydrothermal synthesis was reduced as the addition of B-1001 used as a binder without change of IEP because the absorption of B-1001 polymer on the CeO2 particles shifted the shear plane of CeO2 particles outward away from the surface. This surface potential behavior was well correlated with the dispersion stability of slurry.

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Phase Distribution and Interface Chemistry by Solid State SiC/Ni Reaction

  • Lim, Chang-Sung;Shim, Kwang-Bo;Shin, Dong-Woo;Auh, Keun-Ho
    • The Korean Journal of Ceramics
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    • v.2 no.1
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    • pp.19-24
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    • 1996
  • The phase distribution and interface chemistry by the solid-state reaction between SiC and nickel were studied at temperatures between $550 \;and\; 1250^{\circ}C$ for 0.5-100 h. The reaction with the formation of silicides and carbon was first observed above $650^{\circ}C$. At $750^{\circ}C$, as the reaction proceeded, the initially, formed $Ni_3Si_2$ layer was converted to $Ni_2$Si. The thin nickel film reacted completely with SiC after annealing at $950^{\circ}C$ for 2 h. The thermodynamically stable $Ni_2$Si is the only obsrved silicide in the reaction zone up to $1050^{\circ}C$. The formation of $Ni_2$Si layers with carbon precipitates alternated periodically with the carbon free layers. At temperatures between $950^{\circ}C$ and $1050^{\circ}C$, the typical layer sequences in the reaction zone is determined by quantitative microanalysis to be $SiC/Ni_2$$Si+C/Ni_2$$Si/Ni_2$$Si+C/…Ni_2$Si/Ni(Si)/Ni. The mechanism of the periodic band structure formation with the carbon precipitation behaviour was discussed in terms of reaction kinetics and thermodynamic considerations. The reaction kinetics is proposed to estimate the effective reaction constant from the parabolic growth of the reaction zone.

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Characterization of Poly(vinyl phosphate-b-styrene) by Solid-State $^{31}P$ NMR and Titration

  • Li, Guang-Hua;Kim, Sang-Hun;Cho, Chang-Gi;Park, Tae-Joon;Kim, Yong-Ae
    • Macromolecular Research
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    • v.14 no.5
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    • pp.504-509
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    • 2006
  • Poly(vinyl phosphate-b-styrene) (PVPP-b-PS) block copolymers were synthesized successfully from poly(vinyl alcohol-b-styrene) (PVA-b-PS) by reaction with phosphorus oxychloride and subsequent hydrolysis. The obtained block copolymers were slightly crosslinked, and were characterized by various analytical techniques. The total phosphorus content and the ratio of the differently bound phosphorus were obtained by both solid-state $^{31}P$ NMR and pH titration, but the results differed slightly. Characterization by energy dispersion X-ray analysis (EDS) or Rutherford back scattering (RBS), on the other hand, determined the total phosphorus contents, but the results were quite different from those by solid-state $^{31}P$ NMR.

Investigating the Leaching Rate of TiTe3O8 Towards a Potential Ceramic Solid Waste Form

  • Noh, Hye Ran;Lee, Dong Woo;Suh, Kyungwon;Lee, Jeongmook;Kim, Tae-Hyeong;Bae, Sang-Eun;Kim, Jong-Yun;Lim, Sang Ho
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.18 no.4
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    • pp.509-516
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    • 2020
  • An important property of glass and ceramic solid waste forms is processability. Tellurite materials with low melting temperatures and high halite solubilities have potential as solid waste forms. Crystalline TiTe3O8 was synthesized through a solid-state reaction between stoichiometric amounts of TiO2 and TeO2 powder. The resultant TiTe3O8 crystal had a three-dimensional (3D) structure consisting of TiO6 octahedra and asymmetric TeO4 seesaw moiety groups. The melting temperature of the TiTe3O8 powder was 820℃, and the constituent TeO2 began to evaporate selectively from TiTe3O8 above around 840℃. The leaching rate, as determined using the modified American Society of Testing and Materials static leach test method, of Ti in the TiTe3O8 crystal was less than the order of 10-4 g·m-2·d-1 at 90℃ for durations of 14 d over a pH range of 2-12. The chemical durability of the TiTe3O8 crystal, even under highly acidic and alkaline conditions, was comparable to that of other well-known Ti-based solid waste forms.

Liquid-phase Thermal Degradation Properties of Waste Plastic Film (폐플라스틱 필름의 액상 열분해 특성에 관한 연구)

  • Hwang, T.S.;Kim, Y.S.;Kang, T.W.;Hwang, E.H.
    • Proceedings of the Korean Institute of Resources Recycling Conference
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    • 2003.10a
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    • pp.116-121
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    • 2003
  • In this study, the thermal degradation process has been investigated at various reaction temperature$(350{\sim}400^{\circ}C)$ and times$(30{\sim}120\;min)$ in order to recycle waste plastic films as solid state wax. Waste plastic films were easily melted by adding a small amount of waxes. The effects of wax addition and nitrogen flow rate on their thermal degradation properties were investigated. FT-IR, GPC and viscometer were used to analyze properties of the solid wax including the structure, molicular weight distribution and melt viscosity. The average molecular weight of solid wax was decreased with increasing the reaction time, temperature and amount of wax added, Also, the viscosity of solid wax decreased with increasing the stirring speed at a constant reaction temperature and time, and its viscosity got close to zero above $390^{\circ}C$.

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