• Title/Summary/Keyword: carbon ceramic

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Effects of Carbon Fiber on Mechanical Behaviour of Al2O3 Porous Ceramics

  • Basnet, Bijay;Lim, Hyung Mi;Lee, Kee Sung;Kim, Ik Jin
    • Journal of the Korean Ceramic Society
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    • v.56 no.5
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    • pp.513-520
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    • 2019
  • This study reports the improvement of mechanical properties of Al2O3 porous ceramics from colloidal suspension with the addition of carbon fiber by direct foaming. The initial colloidal suspension of Al2O3 was partially hydrophobized by surfactant to stabilize wet foam with the addition of carbon fiber from 2 to 8 wt% as stabilizer. The influence of carbon fiber on the air content, bubble size, pore size and pore distribution in terms of wet foam stability and physical properties of porous ceramics were discussed. The viscosity of the colloidal suspension was increased giving solid like properties with the increased in carbon fiber content. The mechanical properties of the sintered porous samples were investigated by Hertzian indentation test. The results show the wet foam stability of more than 90% corresponds to compressive loading of 156.48 N and elastic modulus of 57.44 MPa of sintered sample with 8 wt% of carbon fiber content.

Mechanical Behavior of Indentation Stress in Carbon Fiber Reinforced Silicon Carbide Composites with Different Densities (서로 다른 밀도를 갖는 탄소섬유강화 탄화규소 복합재료의 압흔응력에 의한 기계적 거동)

  • Lee, Kee-Sung;Kim, Il-Kyum;Kim, Tae-Woo;Kim, Se-Young;Han, In-Sub;Woo, Sang-Kuk
    • Journal of the Korean Ceramic Society
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    • v.48 no.4
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    • pp.288-292
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    • 2011
  • In this study, we investigated the mechanical behavior of carbon fiber reinforced silicon carbide composites by indentation stress. Relatively porous and dense fiber reinforced ceramic composites were fabricated by liquid silicon infiltration (LSI) process. Densification of fiber composite was controlled by hardening temperature of preform and consecutive LSI process. Load-displacement curves were obtained during indentation of WC sphere on the carbon fiber reinforced silicon carbide composites. The indentation damages at various loads were observed, and the elastic modulus were predicted from unloading curve of load-displacement curve.

An Experimental Study on Bacterial Adhesion onto Activated Carbon and Ceramic (활성탄 및 세라믹 재질에의 세균 부착성에 대한 연구)

  • Kwon Sung-Hyun;Cho Dae-Chul;Rhee In-Hyoung
    • Journal of Environmental Science International
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    • v.14 no.12
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    • pp.1163-1170
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    • 2005
  • The microbial adsorption characteristics of two different media for biological treatment were studied using attached diverse microbes onto activated carbon and ceramic. The results in the experiments of the characteristics of physical adhesion on two different media with addition of high and low concentrated substrate in the culture were observed that the efficient of adhesion onto F-400 activated carbon was higher over that of ceramic due to the surface area of media. The irradiation treatment by ultrasonication with 400 W power and 3 min retention time on the media without addition substrate conditions and subsequent mixing throughly the culture showed the highest efficiency of cell detachment on the media. Three different microbes, P. ovalis, A calcoaceticus, and B. subtillis were used for the study of the characteristics of microbial adhesion on the media. p ovalis showed the highest adhesion capability while B. subtillis showed the lowest capability adhesion onto media either addition of substrate in the culture. The mixed bacterial culture showed $10\%$ lower removal efficiency of DOC in the low concentrated substrate culture compared to the single pure culture. Whileas, it did not show significant difference between two cultures at high concentrated substrate. It was also observed same population density of microorganism by counting of microbes adhered to microbial media with an ultrasound treatment.

Fabrication of Macro-porous Carbon Foams from Spherical Phenolic Resin Powder and Furfuryl Alcohol by Casting Molding (구상 페놀수지 분말과 푸르프릴 알코올로부터 주형성형에 의한 매크로 다공성 카본 폼의 제조)

  • Jeong, Hyeondeok;Kim, Seiki
    • Journal of Powder Materials
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    • v.26 no.6
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    • pp.502-507
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    • 2019
  • Macro-porous carbon foams are fabricated using cured spherical phenolic resin particles as a matrix and furfuryl alcohol as a binder through a simple casting molding. Different sizes of the phenolic resin particles from 100-450 ㎛ are used to control the pore size and structure. Ethylene glycol is additionally added as a pore-forming agent and oxalic acid is used as an initiator for polymerization of furfuryl alcohol. The polymerization is performed in two steps; at 80℃ and 200℃ in an ambient atmosphere. The carbonization of the cured body is performed under Nitrogen gas flow (0.8 L/min) at 800℃ for 1 h. Shrinkage rate and residual carbon content are measured by size and weight change after carbonization. The pore structures are observed by both electron and optical microscope and compared with the porosity results achieved by the Archimedes method. The porosity is similar regardless of the size of the phenolic resin particles. On the other hand, the pore size increases in proportion to the phenol resin size, which indicates that the pore structure can be controlled by changing the raw material particle size.

FRICTION AND WEAR AT SLIDING CERAMIC SURFACES

  • Kong, Hosung
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 1992.06a
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    • pp.1-20
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    • 1992
  • 1. Ceramics as engineering Materials Ceramic \ulcorner :'material based on inorganic non-metallic compounds' Oxygen, Carbon, Nitrogen with metal (Al, Si) -cheap, plentiful and widespread element in the Earth -dirt: ceramic

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Electrochemical Characteristics of the MFCs using the Ceramic Membrane as a Separator (세라믹막을 이용한 미생물연료전지의 전기화학적 특성 연구)

  • Lim, Ji-Young;Park, Dae-Seok;Kim, Jin-Han
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.8
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    • pp.5728-5735
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    • 2015
  • This study attempts to verify the applicability of ceramic membrane as a separator by comparing the power generation characteristics in single-chamber MFCs using ceramic membranes to those in the MFCs using nafion membrane. The generated power in MFCs by using acetate as a substrate was more stable than that by using formate, propionate and butyrate, respectively. It was shown that the generated power by using formate substrate in MFCs was unstable and a little higher than that by using acetate, and the power generated by using propionate and butyrate were lower than that by using acetate. In order to find out the Pt catalyst effect, it was compared the power generated in MFCs using Pt-coated carbon cloth as electrode to that power using normal carbon cloth. The power generated in MFCs using Pt-coated carbon cloth as electrode was 1.2 times higher than that using normal carbon cloth. The Pt-coated carbon cloth was about 5 times more expensive than normal carbon cloth. It is suggested that both power generation efficiency and cost together should be considered in selecting electrodes of MFCs. It was found that the ceramic membrane was superior to nafion membrane by comparing to the power generation characteristics obtained. It was shown that average voltage values were $523.67mV{\pm}49.41mV$ by using synthetic wastewater, in MFCs of ceramic membrane as a separator. While average voltage values were $424.09mV{\pm}79.95mV$ by using synthetic wastewater, in MFCs of nafion membrane as a separator. The organic removal efficiency, 41.7% by using ceramic membrane was a little bit higher than 40.8% by using nafion membrane. This research implies ceramic membrane can be a valid alternative to nafion membrane as a separator when considering the power generation and the efficiency of organics removal.

Powder Characteristics of Fly Ash Beneficiated by Cold Plasma and Heat Treatment

  • Lee, Seung-Heun;Cho, Un-Jin;Kwon, Sung-Ku
    • Journal of the Korean Ceramic Society
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    • v.53 no.1
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    • pp.93-98
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    • 2016
  • Cold plasma and heat treatment were selected as technologies to reduce unburned carbon in fly ash to less than 1.0%. Both cold plasma and heat treatment made it possible to eliminate unburned carbon to less than 1.0%. In the case of fly ash, which almost entirely eliminated unburned carbon with an ignition loss of 0.5%, heat treatment caused adhesion among particles and the BET specific surface area rapidly decreased as the mean particle size increased. On the other hand, with cold plasma, unburned carbon elimination caused the BET specific surface area to decrease and, as no adhesion occurred among particles, the mean particle size became small. Also, cold plasma treatment allowed small spherical particles confined within the unburned carbon particles to be released with the elimination of the unburned carbon frame, so that the quantity of fine particles had a tendency to slightly increase.