• 한국분말재료학회지
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• 제9권5호
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• pp.365-369
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• 2002

Silica hydrogel was synthesized by the reaction of liquid sodium silicate with sulfuric acid. The condensation polymerization of the synthesized hydrogel was carried out via an aging process under the acidic or alkaline conditions. Nano porous silica with the pore size below 3 nm and surface area of $715m^2/g$, was obtained by the above processes in acidic ranges(pH : 3~5). The pore size and surface area of the silica varied with pH, and in alkaline ranges(pH : 8~10), those were 21 nm and $300m^2/g$ respectively. The characteristics of the silica varied with the thermal treatment which caused the change of surface area, pore volume and pore diameter.

• 한국세라믹학회지
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• 제39권12호
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• pp.1177-1182
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• 2002

인산염 용액과의 반응으로 패각의 표면에 고 비표면적의 다공성 수산화아파타이트 층이 생성되는 거동을 정성적으로 관찰하였다. 수산화아파타이트의 생성기구는 패각 표면을 핵으로하는 용해-석출 반응으로 보이며 층의 생성은 다음의 과정에 의하였다. 1. 고상 표면 상의 고밀도 핵생성 및 성장 2. 결정의 접촉과 엉킴에 의한 미세 다공성 층의 형성 3. 층을 통한 용액의 확산과 내측으로의 층 두께의 성장

• 한국세라믹학회지
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• 제28권1호
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• pp.29-36
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• 1991

Microporous glasses in the system TiO2-SiO2-Al2O3-B2O3-CaO-Na2O were prepared by the phase-separation technique. Morphology and distribution of pore and specific surface area of glasses heated and leached out at various conditions were investigated by SEM and Porosimeter. Crystallization of glasses heated above transition temperature was also inspected by X-ray diffraction method. When the heating temperature and time increased, the pore size and volume increased, but the specific surface area decreased above the critical temperature. The phase-separation, specific surface area and pore size showed more sensitive change on the variation of heating temperature than of heating time. The specific surface area and micropore volume of porous glasses prepared in this study were about 120-330$m^2$/g and 0.001-0.01cc/g, respectively. Mean pore size of porous glasses were about 20-90$\AA$. Anatase phases was deposited when the parent glass was heat-treated at 75$0^{\circ}C$ for 6hrs.

• Korean Chemical Engineering Research
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• 제53권4호
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• pp.425-430
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• 2015

고분자 복제방법을 이용하여 제조한 폼 형태의 다공성 탄화규소 표면에 수열 합성 방법을 적용하여 ZSM-5를 합성하였다. 다공성 탄화규소 표면으로부터 ZSM-5가 합성될 수 있도록 유도하기 위하여 합성단계에 앞서 탄화규소 표면에 산화 층을 형성하였다. 수열합성 반응은 산화처리 된 다공성 탄화규소와 TEOS, $Al(NO_3){\cdot}9H_2O$ 및 TPAOH를 원료로 사용하여 $150^{\circ}C$에서 7시간 진행하였다. XRD 및 SEM 분석을 통하여 $1{\sim}3{\mu}m$ 크기의 ZSM-5가 다공성 탄화규소 표면에 코팅되어 성장하였음을 확인하였다. BET 분석결과 ZSM-5 합성 후에 $10{\AA}$이하의 미세기공이 급격히 증가하였으며, 비표면적이 $0.83m^2/g$에서 $30.75m^2/g$으로 급격히 증가되었음을 알 수 있었다.

• 한국결정성장학회지
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• 제25권5호
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• pp.218-224
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• 2015

최근 세라믹 다공체를 이용하여 적조 생물을 여과, 제거하려는 연구가 시도되고 있다. 하지만 해양 환경에서 1개월 이상이 경과하면 다공체 표면에 해양 생물 오손(biofouling)이 발생하여 기능이 저하되는 문제가 나타난다. 본 논문에서는 세라믹 다공체의 특성 변화 또는 표면 개질을 통하여 해양 생물 오손을 억제하는 방법에 대하여 연구하였다. 6 종류의 세라믹 다공체를 시험한 결과, 기공율과 흡수율이 낮을수록 생물 오손량이 낮게 나타났다. 또한 다공체 표면에 실리카 입자를 결합시켜 표면 거칠기를 증가시키면, 따개비 등의 대형 해양 생물로 인한 오손량을 감소시킬 수 있었다. 한편 세라믹 다공체 표면에 유리분말을 융착 코팅시키면 오히려 생물 오손량이 증가하였는데, 이는 유리에서 용출되어 나오는 무기질 성분 이온들이 미생물의 생육을 촉진했기 때문이다. 본 연구로부터 세라믹 다공체의 물리적 성질 및 표면 거칠기를 제어하면 위험 물질을 사용하지 않고도 친환경적으로 해양 생물 오손량을 줄일 수 있음을 확인하였으며, 따라서 본 결과를 향후 해양 구조물 등에 적용할 수 있을 것으로 기대된다.

• 대한기계학회논문집B
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• 제30권7호
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• pp.646-655
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• 2006

The present research is an experimental study on characteristics of cooling behavior for the adjacent copper blocks with surface roughness or micro-porous coated surface. The experiments were carried out at saturation state or within subcooled states of PF5060. The effects of heater orientation and the intervals between heating surfaces or substrates were investigated under various heat flux conditions. The boiling performance of copper block with micro-porous coated surface was better than that of copper block with surface roughness. It is understood that the bubble sweeping enhances boiling performance for the heaters with inclinations of $\theta=45^{\circ}\;and\;\theta=90^{\circ}$, where as the bubble flattening decreases boiling performance for the heaters with inclinations of $\theta=135^{\circ}\;and\;\theta=180^{\circ}$. In comparison to upper heater and below heater with orientation, the upper heater has lower superheat temperature than the below heater due to the bubble sweeping. It is also found that boiling performance decreases in the case of adjacent double heaters with only 0.2cm substrate interval.

• JSTS:Journal of Semiconductor Technology and Science
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• 제15권4호
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• pp.454-461
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• 2015

Light enhancement of GaN based light emitting diodes (LEDs) have been investigated by texturing the top p-GaN surface. Nano-textured LEDs have been fabricated using self-assembled Ni nano mask during dry etching process. Experimental results were further compared with simulation data. Three types of LEDs were fabricated: Conventional (planar LED), Surface nano-porous (porous LED) and Surface nano-cluster (cluster LED). Compared to planar LED there were about 100% and 54% enhancement of light output power for porous and cluster LED respectively at an injection current of 20 mA. Moreover, simulation result showed consistency with experimental result. The increased probability of light scattering at the nano-textured GaN-air interface is the major reason for increasing the light extraction efficiency.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.160-160
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• 2011

In the present work, $TiO_2$ fiilms supported by porous silica gel with high surface area synthesized by atomic layer deposition(ALD). Porous structure of silica substrate could be maintained even after deposit large amount of $TiO_2$ (500 cycles of ALD process), suggesting the differential growth mode of $TiO_2$ on top surface and inside the pore. All the $TiO_2$-covered silica samples showed improved MB adsorption abilities, comparing to bare one. In addition, when silica surface was covered with $TiO_2$ films, MB adsorption capacity was almost fully recovered by re-annealing process (500$^{\circ}C$, for 1 hr, in ambient pressure), whereas MB adsorption capacity of bare silica was decreased after re-heaing process. FT-IR study demonstrated that $TiO_2$ film could prevent deposition of surface-bound intermediate species during thermal decomposition of adsorbed MB molecules. Photocatalytic activity of $TiO_2$/silica sample was also investigated.

• Journal of Electrochemical Science and Technology
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• 제1권2호
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• pp.117-120
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• 2010

Materials used as fuel cell electrode should be light, high conductive, high surface area for reaction, catalytic surface and uniformity of porous structure. Nickel is widely used in electrode materials because it itself has catalytic properties. When used as electrode materials, nickel of only a few im on the surface may be sufficient to conduct the catalytic role. To manufacture the nickel with porous structure, Electroless nickel plating on carbon fiber be conducted. Because electroless nickel plating is possible to do uniform coating on the surface of substrate with complex shape. Acidic bath and alkaline bathe were used in electroless nickel plating bath, and pH and temperature of bath were controlled. The rate of electroless plating in alkaline bath was faster than that in acidic bath. As increasing pH and temperature, the rate of electrolee plating was increased. The content of phosphorous in nickel deposit was higher in acidic bath than that in alkaline bath. As a result, the uniform nickel deposit on porous carbon fiber was conducted.

• 한국정밀공학회지
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• 제14권6호
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• pp.44-51
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• 1997

Crinding of stainless steel, aluminium alloy, copper alloy, and titanium alloy are difficult to obtain high quality finish, because they have the mechanical properties such as low hardness, high toughness. The low hardness and the high toughness result in the loading of wheel and the poor surface finish. In order to perform the grinding operations for these sorts of materials easily, the discontinuous grinding wheel wiht multi-porous grooves has been newly developed. The multi-porous grooves inthe discontinuous grinding wheel were formed during grinding wheel manufacturing process. In this paper, discontinuous grinding wheels having intermittent ratio 0.66, 0.81 and number of grooves 18,32 have been manufactured and grinding surface characteristics of these grinding wheels for SUS304 have been analyzed. Discontinuous grinding temperature according to intermittent ratiohas been also estimated by simulation. The discontinuous grinding wheels increase the grinding performance considerably. It is desirable to use the discontinuous grinding wheel in grinding the materials with high efficiency and accuracy.