• 제목/요약/키워드: Pore shape

검색결과 301건 처리시간 0.02초

Fabrication and Pore Properties of SUS316L Membrane with Double-Layered Pore Structures by Wet Powder Spraying

  • Min-Jeong Lee;Hyeon-Ju Kim;Manho Park;Jung-Yeul Yun
    • Archives of Metallurgy and Materials
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    • 제67권4호
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    • pp.1531-1534
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    • 2022
  • In this study, a SUS316L membrane having double layered pore structures was fabricated, and the pore characteristics were analyzed after coating with a spherical powder and a flake-shaped powder on a disk-shaped SUS316L support using a wet powder spraying process. The thickness of the coated layer was checked using an optical microscope, and air permeability was measured using a capillary flow porometer. When the coating amount was similar, the fine porous layer prepared using flake powder was thicker and showed higher porosity. In the case of a similar thickness, the case of using flake powder was half of the amount of spherical powder used. Therefore, it was confirmed that it is possible to manufacture a metal membrane having a high filter efficiency even with a small coating amount when using the flake powder.

Camphor-Naphthalene 동결제 조성이 Cu-Ni 다공체의 기공구조에 미치는 영향 (Effect of Sublimable Vehicle Compositions in the Camphor-Naphthalene System on the Pore Structure of Porous Cu-Ni)

  • 권나연;석명진;오승탁
    • 한국분말재료학회지
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    • 제22권5호
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    • pp.362-366
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    • 2015
  • The effect of sublimable vehicle composition in the camphor-naphthalene system on the pore structure of porous Cu-Ni alloy is investigated. The CuO-NiO mixed slurries with hypoeutectic, eutectic and hypereutectic compositions are frozen into a mold at $-25^{\circ}C$. Pores are generated by sublimation of the vehicles at room temperature. After hydrogen reduction at $300^{\circ}C$ and sintering at $850^{\circ}C$ for 1 h, the green body of CuO-NiO is completely converted to porous Cu-Ni alloy with various pore structures. The sintered samples show large pores which are aligned parallel to the sublimable vehicle growth direction. The pore size and porosity decrease with increase in powder content due to the degree of powder rearrangement in slurry. In the hypoeutectic composition slurry, small pores with dendritic morphology are observed in the sintered Cu-Ni, whereas the specimen of hypereutectic composition shows pore structure of plate shape. The change of pore structure is explained by growth behavior of primary camphor and naphthalene crystals during solidification of camphor-naphthalene alloys.

실리카에어로겔의 상압합성 및 특성연구(I) (Syunthesis of Silica Aerogel at Ambient Pressure and Characterization (I))

  • 강신규;최세영
    • 한국세라믹학회지
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    • 제33권12호
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    • pp.1394-1402
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    • 1996
  • The Silica gel with the density of 0.2g/cm3 and porosity of 90% was synthesized. The silica wet gel was dried and heat-treated under the ambient pressure after modification of the wet gel surface by TMCS. Specific surface area total pore volume and mean pore radius of dried gel were all increased with increasing heat treatment temperature and confirmed about 1400m2/g, 4.5cc/g and 8 nm respectively after heat treatment above 25$0^{\circ}C$. But the pore size distribution of dried gel was in the range of 1-100nm and was almost indepen-dent of temperature. As the result of external shape pore characteristics and microstructure of gel using SEM similar properties were observed between the silica gel synthesized in this study and the silica aerogel through the super critical drying.

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Microstructural Changes of AlOOH Doped $UO_2$ Pellet during the Annealing Process

  • Hosik Yoo;Lee, Shinyoung;Lee, Seungjae;Kwenho Kang;Kim, Hyoungsu
    • The Korean Journal of Ceramics
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    • 제6권3호
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    • pp.209-213
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    • 2000
  • Microstructural changes of AlOOH doped UO$_2$pellet after annealing up to 216h have been observed and they were compared with those of the standard pellet. Grain and pore size of UO$_2$pellet increased with the addition of AlOOH and its effect was still validated during annealing. Densification rate was reduced by the addition of AlOOH and it was attributed to coarsened pores with spherical shape. Grain and pore growth was stopped and density increase was the least after 144h of annealing. The variation of pore size resulting from annealing has a linear relationship with that of grain size.

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다공성 핵연료 소결체의 유효열전도율의 수치적 해석 (A numerical analysis of effective thermal conductivity of a porous nuclear fuel)

  • 주영철;박권현
    • 대한기계학회논문집
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    • 제11권3호
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    • pp.368-375
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    • 1987
  • 본 연구에서는 이러한 기하형태의 불규칙성을 쉽게 고려할 수 있는 윤곽좌표계 (body fitted coordinate systems)를 이용하여 다공성 물질의 유효열전도율을 결정하 는 방법을 제시하였다.기공의 형상을 원형으로 가정하고 기공율과 기공 내부기체와 고체의 열전도율비 등의 변수가 유효열전도율과 이들 변수의 상관관계식을 제안하였으 며, 또한 핵연료 소결체와 같은 실제적인 다공성 물질의 유효열전도율을 해석하는데 좀 더 타당한 타원형 형상의 기공 가정방법을 제시하였다.

동결건조 공정에서 동결제의 응고조건이 기공특성에 미치는 영향 (Effect of Solidification Condition of Sublimable Vehicles on the Pore Characteristics in Freeze Drying Process)

  • 석명진;김지순;오승탁
    • 한국분말재료학회지
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    • 제21권5호
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    • pp.366-370
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    • 2014
  • The present study demonstrates the effect of solidification condition on the pore structure in freeze drying process using the slurries of CuO/sublimable vehicles. Camphene and Camphor-45 wt% naphthalene based slurries with 14 vol% CuO powder were frozen into a mold at $-25^{\circ}C$, followed by sublimation at room temperature. The green bodies were hydrogen-reduced and sintered at $500^{\circ}C$ for 1 h. The porous Cu specimen, frozen the CuO/camphene slurry into the heated mold of the upper part, showed large pores with unidirectional pore channels and small pores in their internal wall. Also, it was observed that the size of large pores was decreasing near the bottom part of specimen. The change of pore structure depending on the freezing condition was explained by the nucleation behavior of camphene crystals and rearrangement of solid powders during solidification. In case of porous Cu prepared from CuO/Camphor-naphthalene system, the pore structure exhibited plate shape as a replica of the original structure of crystallized vehicles with hypereutectic composition.

다층 기공구조를 갖는 다공성 반응소결 탄화규소 다공체 제조 (Fabrication of Porous Reaction Bonded Silicon Carbide with Multi-Layered Pore Structures)

  • 조경선;김규미;박상환
    • 한국세라믹학회지
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    • 제46권5호
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    • pp.534-539
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    • 2009
  • Reaction Bonded Silicon Carbide(RBSC) has been used for engineering ceramics due to low-temperature fabrication and near-net shape products with excellent structural properties such as thermal shock resistance, corrosion resistance and mechanical strength. Recently, attempts have been made to develop hot gas filter with gradient pore structure by RBSC to overcome weakness of commercial clay-bonded SiC filter such as low fracture toughness and low reliability. In this study a fabrication process of porous RBSC with multi-layer pore structure with gradient pore size was developed. The support layer of the RBSC with multi-layer pore structure was fabricated by conventional Si infiltration process. The intermediate and filter layers consisted of phenolic resin and fine SiC powder were prepared by dip-coating of the support RBSC in slurry of SiC and phenol resin. The temperature of $1550^{\circ}C$ to make Si left in RBSC support layer infiltrate into dip-coated layer to produce SiC by reacting with pyro-carbon from phenol resin.

Alkoxide 법으로 합성한 알루미나의 동공구조에 미치는 가수분해 온도의 영향 (Effect of Hydrolytic Temperature on Pore Structure of Alkoxide-derived Aluminas)

  • 조정미;정필조
    • 한국세라믹학회지
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    • 제25권3호
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    • pp.217-224
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    • 1988
  • Alkoxide 법으로 합성한 알루미나의 동공 구조를 BET 법으로 구한 흡 탈착 등온선의 hysteresis loop와 동공 분포로부터 고찰하였다. 알루미나는 aluminum isopropoxide를 화학량의 물로 가수분해하여 제조하였고, 가수분해 온도는 3$^{\circ}C$와 8$0^{\circ}C$에서 수행하였다. 이어 20$0^{\circ}C$부터 50$0^{\circ}C$까지 단계적으로 승온시키며 일정시간 열처리하였다. 3$^{\circ}C$ 가수분해 시료의 동공부피는 열처리 온도에 비례하여 증가하였으며, 동공크기는 쌍입분포(twin peaked pore size distribution)형으로 나타났다. 그러나 8$0^{\circ}C$ 가수분해 시료는 열처리에 의하여 동공부피가 감소하고, 동공크기는 단입분포(single peaked pore size distribution)로 나타났다. 이러한 관찰 결과로부터 전자의 동공형태는 slit형, 후자는 ink-bottle형을 하고 있는 것으로 추정되었다. 이와 같이 가수분해 온도는 동공 형태를 결정하는 중요한 인자일 뿐만 아니라, 층상 알루미나의 구조수 일탈 거동을 결정하는데 중요하다. 열처리 효과는 단지 최종 제품의 동공 분포를 결정하는데 영향을 주고 있는 것으로 해석되었다.

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