• 한국정보통신학회:학술대회논문집
• /
• 한국해양정보통신학회 2003년도 추계종합학술대회
• /
• pp.957-962
• /
• 2003

The preparation of $Al_2$O$_3$-SiO$_2$ thin films from less than one micron to several tens of microns in thickness had been prepared from metal alkoxide sols. Two methods, dip-withdrawal and electrophoretic deposition, were employed for thin films and sheets formation. The requirements to be satisfied by the solution for preparing uniform and strong films and by the factors affecting thickness and other properties of the films were examined. for the preparation of thin, continuous $Al_2$O$_3$-SiO$_2$ films, therefore, metal-organic-derived precursor solutions contained Si and Al in a chemically polymerized form has been developed and produced in a clear liquid state. In the process of applying to substrates, this liquid left a transparent, continuous film that could be converted to crystalline $Al_2$O$_3$-SiO$_2$ upon heating to 100$0^{\circ}C$. And, a significant change of the film density took place in the crystallization process, thus leading to the strict requirements as to the film thickness, which could survive crystallization.

• 상하수도학회지
• /
• 제31권6호
• /
• pp.577-586
• /
• 2017

One of the major sources causing eutrophication and algal blooms of lakes or streams is phosphorus which comes from point and nonpoint pollution sources. HAP (hydroxyapatite) crystallization using granular alkaline materials can achieve the decrease of phosphorus load from wastewater treatment plants and nonpoint pollution control facilities. In order to induce HAP crystal formation, continuous supply of calcium and hydroxyl ions is required. In this research, considering HAP crystallization, several types of lime-based granular alkaline materials were prepared, and the elution characteristics of calcium and hydroxyl ions of each were analyzed. Also, column tests were performed to verify phosphorus removal efficiencies of granular alkaline materials. Material_1 (gypsum+cement mixed material) achieved the highest pH values in the column tests consistently, also, Material_2 (gypsum+slag mixed material) and Material_3 (calcined limestone material) achieved over pH 9.0 for 240 hours (10 days) and proved the efficiencies of long-term ion supplier for HAP crystallization. In the column tests using Material_3, considerable pH increase and phosphorus removal were carried out according to each linear velocity and filtration depth. T-P removal efficiencies were 87.0, 84.0, 68.0% and those of PO4-P 100.0, 97.0, 80.0% for linear velocity of 1.0, 2.5, 5.0 m/hr respectively. Based on the column test results, the applicability of phosphorus removal processes for small-scale wastewater treatment plants and nonpoint pollution control facilities was found out.

• 대한금속재료학회지
• /
• 제46권6호
• /
• pp.338-344
• /
• 2008

The crystallization kinetics of the $Cu_{43}Zr_{43}Al_7Be_7$ bulk metallic glass were studied by differential scanning calorimetry(DSC) in the continuous heating and isothermal annealing modes. Only one major peak could be detected on the DSC traces of $Cu_{43}Zr_{43}Al_7Be_7$ bulk amorphous alloy, and the activation energy for crystallization corresponding to the peak determined by the Kissinger method was resulted of 239 kJ/mol. The isothermal kinetic, analyzed by the Johnson-Mehl-Avrami equation yielded values for the Avrami exponents in the range 1.69 to 2.37, which implied a crystallization governed by a three-dimensioned growth. Primary phases were essentially the cubic structure CuZr together with the $Cu_{10}Zr_7$ phase. At higher temperature, the CuZr disappeared while the $Cu_{10}Zr_7$ became predominant. After long term annealing at 731 K, the phases were $Cu_{10}Zr_7$, $Cu_2ZrAl$ and $Al_3Zr_5$.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
• /
• pp.96.2-96.2
• /
• 2010

The surface morphology and structural properties of polycrystalline silicon (poly-Si) films made in-situ aluminum induced crystallization at various substrate temperature (300~600) was investigated. Silicon films were deposited by hot-wire chemical vapor deposition (HWCVD), as the catalytic or pyrolytic decomposition of precursor gases SiH4 occurs only on the surface of the heated wire. Aluminum films were deposited by DC magnetron sputtering at room temperature. continuous poly-Si films were achieved at low temperature. from cross-section TEM analyses, It was confirmed that poly-Si above $450^{\circ}C$ was successfully grown on and poly-Si films had (111) preferred orientation. As substrate temperature increases, Si(111)/Si(220) ratio was decreased. The electrical properties of poly-Si film were investigated by Hall effect measurement. Poly-Si film was p-type by Al and resistivity and hall effect mobility was affected by substrate temperature.

• 한국산학기술학회논문지
• /
• 제7권4호
• /
• pp.709-714
• /
• 2006

본 연구는 폐기물로 발생되는 부산석회 Core를 연속식 칼럼에 적용하여 수중의 인산염을 효과적으로 제거할 수 있는 방안을 찾고자 수행되었다. 부산석회와 인산염의 칼럼 반응에서 Hydroxyapatite을 형성하여 수중의 인산염을 제거할 수 있는 것으로 나타났으며 부산석회 Core size 1, 2에서 유입수의 인산염 농도에 관계없이 초기 11시간동안 90% 이상의 높은 제거율을 보였다. 또한 부산석회 Core size와 관계없이 유입수 유량이 증가할수록 파과시간이 줄어드는 것을 알 수 있었다.

• 한국표면공학회지
• /
• 제37권2호
• /
• pp.80-85
• /
• 2004

Chromium-carbon (Cr-C) and chromium-carbon-phosphorus (Cr-C-P) alloy deposits using trivalent chromium sulfate baths containing potassium formate were prepared to study their current efficiency, hardness change and phase transformations behavior with heat treatment, respectively. The current efficiencies of Cr-C and Cr-C-P alloy deposits increase with increasing current density in the range of 15-35 A/dm$^2$. Carbon content of Cr-C and phosphorous of Cr-C-P layers decreases with increasing current density, whereas, the carbon content of Cr-C-P layer is almost constant with the current density. Cr-C deposit shows crystallization at $400^{\circ}C$ and has (Cr+Cr$_{ 23}$$C_{6}$) phases at $800^{\circ}C$. Cr-C-P deposit shows crystallization at $600^{\circ}C$ and has (Cr+Cr$_{23}$ $C_{6}$$+Cr_3$P) phases at $800^{\circ}C$. The hardness of Cr-C and Cr-C-P deposits after heating treatment for one hour increase up to Hv 1640 and Hv 1540 and decrease about Hv 820 and Hv 1270 with increasing annealing temperature in the range of $400～^{\circ}C$, respectively. The hardness change with annealing is due to the order of occurring of chromium crystallization, precipitation hardening effect, softening and grain growth with temperature. Less decrease of hardness of Cr-C-P deposit after annealing above $700^{\circ}C$ is related to continuous precipitation of $Cr_{23}$ $C_{6}$ and $Cr_3$P phases which retard grain growth at the temperature.

• 공업화학
• /
• 제8권6호
• /
• pp.939-944
• /
• 1997

금속 지지체 표면에 연속적인 결정화방법으로 제올라이트-X의 피막을 형성시켜 필름을 제조하였다. 금속 표면에서의 제올라이트 결정의 성장은 금속 성분에 따라 많은 차이가 있으며 본 연구에서 사용한 stainless steel 316은 표면을 산처리하여 표면의 크롬층을 파괴하여야 제올라이트 핵 형성이 용이 하였다. 연속적인 결정화 방법에 의해 제올라이트 결정 성장을 관찰하기 위해 12시간을 주기로 제올라이트-X 조성물($6.36Na_2O-Al_2O_3-5.3SiO_2-190.8H_2O$)을 계속 공급하였다. 그리고 금속 표면과 제올라이트 핵의 생성 사이의 상호 관계와 메카니즘에 대해 조사 하였다. 그 결과 겔 조성물중 $SiO_2/Al_2O_3$의 비가 높을수록 금속 표면에 제올라이트 핵 형성이 용이하였으며, 금속 표면에 부착된 제올라이트 입자는 선형 성장을 계속하고 성장된 입자간에 축합반응에 의해 서로 연결되어 하나의 결정 형태로 된다는 것을 알 수 있었다. 필름 형태로 합성된 시료를 XRD 및 SEM으로 분석한 결과 제올라이트-X임을 확인하였다.

• Korean Chemical Engineering Research
• /
• 제57권5호
• /
• pp.666-671
• /
• 2019

탄산칼슘은 칼사이트, 바테라이트, 아라고나이트 3개의 상이 있다. 칼사이트와 아라고나이트는 열역학적으로는 바테라이트 보다 안정하다. 연속식결정화기에서 탄산나트륨과 염화칼슘 용액반응으로 아라고나이트 결정 제조공정에서 온도와 혼합속도 영향에 대하여 연구하였다. 회분식결정화기에서 칼사이트는 상대적으로 낮은 온도($40^{\circ}C$ 아래)에서 생성되지만, 아라고나이트는 높은 온도에서 발견된다. 혼합속도가 100 rpm인 연속식결정화기에서, 아라고나이트는 어떤 반응온도에서도 발견할 수 없었다. 그러나 혼합속도가 300 rpm, 500 rpm으로 증가하면, 칼사이트와 아라고나이트의 비는 온도가 증가하면서 증가하였다.

• 한국세라믹학회:학술대회논문집
• /
• 한국세라믹학회 2004년도 춘계총회 및 연구발표회 초록집
• /
• pp.51.2-51.2
• /
• 2004

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
• /
• pp.245-247
• /
• 2003

We have previously shown that single-crystal Si regions on glass substrates can be obtained by crystallizing as-deposited a-Si films using a specific version of the SLS process, referred to as dot-SLS Such single-crystal islands can, for instance, be used for manufacturing of high-performance TFTs that are expected to become increasingly more relevant in the future. In this paper, we demonstrate that the dot-SLS process can be implemented using a continuous-scan SLS scheme that enables the attainment of high crystallization rates that are desired for industrial applications. We will furthermore report on recent experimental findings regarding the nature of the defects that can be created during the process.