• Title, Summary, Keyword: Greenbody

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Effect of Graphite Powder Addition on the Mechanical Properties of Carbon/Carbon Composites (흑연분말의 첨가가 탄소/탄소 복합재료의 물성에 미치는 영향)

  • 신준혁;황성덕;강태진
    • Composites Research
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    • v.13 no.2
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    • pp.72-80
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    • 2000
  • Effect of graphite powder addition on the mechanical properties of carbon fiber reinforced carbon composites (C/C composites) was investigated. Greenbody (G/B) with 0~30wt.% graphite powder addition to phenol resin was prepared and carbonized at $1000^{\circ}C$ to make C/C composites. Flexural strengths of 20wt.% graphite powder additions showed maximum values in the both case of G/B and C/C composites. But, at the graphite addition over 20wt.%, there was negative effect due to the matrix inhomogeneity. Flexural strength of cured resin without graphite Powder was higher than that with graphite. However, flexural strength of carbonized resin with graphite increased three times as much as that of carbonized resin without graphite. Because the addition of graphite powder effects the restraint of shrinkage after carbonization and the deflection of crack path. In Mode II ENF test, energy release rates($G_{II}$) of G/B and C/C composites with the 20w1.% addition of graphite were both increased. But, the addition of graphite was more effective to the increase of $G_{II}$ in C/C composites than that in G/B.

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Effect of Chemical Parameters on Aqueous Acrylamide Gelcasting (수용성 Acrylamide 겔캐스팅에 대한 화학적 변수의 영향)

  • Yun, Seog-Eun;Woo, Sang-Kuk;Bae, Kang;Kim, Dong-Pyo
    • Applied Chemistry for Engineering
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    • v.10 no.5
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    • pp.748-753
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    • 1999
  • In gelcasting process of the Si powder slurry mixed with acrylamide monomers, it was characterized the effects of chemical parameters such as monomers and additives(polymerization initiator, catalyst and dispersant), Si powder and humidity at drying on processing parameters such as viscosity and idle time as well as on shrinkage and mechanical strength of green bodies. Generally, idle time decreased as initiator and catalyst amounts were increased, but rather depended on initiator. Idle times of the slurries greatly decreased to less than 1/2 time of the premix solutions in which gelation was delayed at higher MBAM portion as a crosslinking monomer. And fluidity of the slurries became worse at greater than 0.6 wt % dispersant. The green bodies showed only less than 7% of linear shrinkage without crack and distortion when dried for longer than 300 hrs under 98% humidity. Typically, the dried bodies containing 40, 50 vol % of Si powder displayed 64 and 36 Mpa in average, respectively.

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Development of Porous Support with Mine Waste Materials (광산 폐기물을 활용한 다공성 담체 개발)

  • 정문영;정명채;최연왕
    • Economic and Environmental Geology
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    • v.37 no.1
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    • pp.143-151
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    • 2004
  • This study focused on examining the possibility of recycling mine solid waste as environmental materials, especially for porous media. Basic properties including mineralogical compositions, chemical compositions, and particle size distribution of the tailings from the Sangdong W mine were checked. The mineralogical and chemical compositions of the tailings samples were not much different in depth. According to Korean Standard Leaching Test for Wastes(KSLT), concentrations of heavy metals leached from the tailings were below the standard values. As a result of particle size analysis, the median diameter (d$_{50}$) of the tailings was in the range of 10 to 30 ${\mu}{\textrm}{m}$. The stable tailings slurry made up of 3 ${\mu}{\textrm}{m}$ in d$_{50}$ was prepared using Attrition Mill. The milling condition was 40 vol% in slurry concentration, 700 rpm in stirring speed, and 1 hour in milling time. PEI was added as dispersing agent. Concentrated slurry was extended to 3 times by foaming method. In the case of 3 times foamed slurry, the total and open porosity of ceramic supports sintered at 1,075$^{\circ}C$ for 90 minutes was about 80% and 72%, respectively. Pore size was in the range of 30∼350${\mu}{\textrm}{m}$. Therefore, the tailings could be recycled starting material for environmental materials such as macroporous ceramic support.