• 한국세라믹학회지
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• 제27권7호
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• pp.851-860
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• 1990

The hydrolysis-precipitation reaction of mixed aluminum salt solutions of aluminum sulfate, aluminum nitrate, and urea has been investigated to obtain narrow-sized and unagglomerated fine spherical precipitates of aluminum hydroxide required for coating core particles. The hydrolysis-precipitatin reaction could be controlled to be appropriate to coating processes by usign urea as a pH control-agent. As the concetration of total Al3+ ion and the molar ratio of SO42-/Al3+ in starting solutions became smaller and also as the vol. ratio of water/solution for hydrolyzing mixed aluminum salt solution became larger, the morphology of precipitates tended to be more unagglomerated and spherical, while their size(0.5longrightarrow0.05${\mu}{\textrm}{m}$) to be smaller. The optimum hydrolysis condition for coating processes was to hydrolyze the mixed aluminum salt solution, in which the molar ratio of SO42-/Al3+ was 0.75, while the amount of water corresponding to the vol. ratio of water/solution of 15. The precipitate was the aluminum hydroxide which sulfate ions were strongly adsorbed on and the maximum yield in the hydrolysis-precipitation reaction was about 20%.

• 한국분말재료학회지
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• 제12권3호
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• pp.186-191
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• 2005

A formation of aluminum hydroxide by hydrolysis of nano and micro aluminum powder has been studied. The nano aluminum powder of 80 to 100 nm in diameter was fabricated by a pulsed wire evaporation (PWE) method. The micro powder was commercial product with more than $10\;{\mu}m$ in diameter. The hydroxide type and morphology depending on size of the aluminum powder were examined by several analyses such as XRD, TEM, and BET. The hydrolysis procedure of micro aluminum powder was different from that of nano aluminum powder. The nano aluminum powder after immersing in the water was transformed rapidly to a nano fibrous boehmite, accompanying with a remarkable temperature increase, and then further transformed slowly to a stable bayerite. However, the micro powder was changed to the stable bayerite slowly and directly. The formation of fibrous aluminum hydroxide from nano aluminum powder might be due to the fine cracks which were formed by hydrogen gas pressure on the surface hydroxide layer during hydrolysis. The nano powder with large specific surface area and small size reacted more actively and faster than the micro powder, and transformed to meta-stable hydroxide in relatively short reaction time. Therefore, the formation of fibrous boehmite is special characteristic of hydrolysis of nano aluminum powder.

• 한국세라믹학회지
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• 제32권12호
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• pp.1401-1407
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• 1995

Zirconia powder coated with alumina was prepared by hydrolysis of alumina butoxide. The coated powder was obtained by a hydrolysis reaction between the adsorbed water on the surface of zirconia particles and aluminum sec-butoxide. Amorphous aluminum hydroxide was uniformly coated on the surface of zirconia particles with the thickness of about 30 nm. The shape and distribution of aluminum hydroxide was varied with an existence of surfactant. The coated layer of aluminum hydroxide consists of the fine particle size, and the zirconia powder coated by alumina hydroxide have the large specific surface area of 120 $m^2$/g, compared with that of starting zirconia powder.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 C
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• pp.1216-1218
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• 1997

Hydrolysis of BTDA-ODA: MPDA, PMDA-ODA, PIQ polyimides were investigated by FT-IR. The results showed that hydrolysis depends on structure of polyimide and that polyimide obtains hydrolytic stability by curing. Polyimide-aluminum interfaces were characterized by RAIR. It was concluded that imidization of the polyamic acid to polyimde was inhibited by interaction of acid groups with substrate to form aluminum carboxylate.

• 한국수소및신에너지학회논문집
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• 제22권1호
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• pp.29-34
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• 2011

This study examined the effect of environmental variables, such as the NaOH concentration and solution temperature, on the rate of hydrogen generation from NaOH solutions through the corrosion of used aluminum cans as a potential candidate material for the safe and economic production of hydrogen. Corrosion of the used aluminum cans was promoted by increasing the NaOH concentration and solution temperature because of the loss of aluminum passivity. The measured rate of hydrogen generation from the NaOH solutions increased with increasing NaOH concentration due to the catalytic activity of NaOH in the hydrolysis process. However, at higher solution temperatures, the rate of hydrogen generation rate was less affected by the NaOH concentration than that at lower temperature.

• 한국분말재료학회지
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• 제11권2호
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• pp.118-123
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• 2004

A formation of aluminum hydroxide by hydrolysis reaction in the water has been studied by using nano aluminum powder fabricated by pulsed wire evaporation(PWE) method. The hydroxide type and morphology depending on temperature and pH were examined by structural analysis. The Boehmite($Al_2O_3$.$H_2O$ or AIO(OH)) was predominantly formed in high temperature region over 4$0^{\circ}C$, while the Bayerite($Al_2O_3$.$H_2O$ or $Al(OH)_3$) below $30^{\circ}C$ of hydrolysis temperature. The Boehmite formation was preferred to the Bayerite in acidic solution in the same hydrolysis temperature. The slowly formed Bayerite phase showed facet crystalline structure, while the fast formed Boehmite was fine fiber with a large aspect ratio of several nm in diameter and several hundred nm in length, and with much larger specific surface area(SSA) than that of Bayerite. The highest SSA was about $420m^2$/g.

• 설비공학논문집
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• 제29권12호
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• pp.621-627
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• 2017

Nitrogen ion with various levels of dose and irradiation energy was irradiated on aluminum surfaces. Contact angle of surface was increased and surface color was changed by nitrogen ion implantation. During steam condensation experiment using nitrogen ion implanted specimen, dropwise condensation initially occurred on specimens. However, condensation mode eventually changed into filmwise condensation. The color of the surface was also changed from yellow-brown to silver-white. This change of surface color and condensation mode were results of hydrolysis reaction between condensate and nitrogen ion implanted on aluminum surfaces.

• 한국산림과학회지
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• 제79권4호
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• pp.376-387
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• 1990

대기오염(大氣汚染)과 산성우(酸性雨)가 삼림토양(森林土壤)의 완충능(緩衝能)에 미치는 영향(影響)을 규명하기 위하여 이동오염원지역(移動汚染源地域)으로 서울지역(地域), 고정오염원지역(固定汚染源地域)으로 울산(蔚山) 및 여천지역(麗川地域) 그리고 대조지역(對照地域)으로 강원도(江原道) 평창지격(平昌地域)에서 토양시료(土壤試料)를 채취하여 인공산성우(人工酸性雨)를 처리(處理)하고 조사분석(調査分析)한 결과(結果)를 고찰(考察)해 볼 때 다음과 같았다. pH 3.0-5.7 수준(水準)의 인공산성우(人工酸性雨)에 대하여 토양용탈용액(土壤溶脫溶液)波이 나타낸 용액(溶液) pH의 수준(水準)은 강원도지역(江原道地域)에서 pH 6.2-7.1이었고, 다음이 울산(蔚山)으로 pH 3.8-6.0, 여천(麗川)은 pH 4.0-5.4, 서울이 pH 4.0-5.5로 나타나므로써 산성우(酸性雨)에 대한 토양완충능(土壤緩衝能)은 강원도(江原道)가 가장 컸으며 서울이 가장 낮았다. 그러나 pH 2.0의 산성우처리(酸性雨處理)에서는 각 지역(地域)에서 모두 토양완충능(土壤緩衝能)이 급격히 낮아졌다. 인공산성우(人工酸性雨)의 처리(處理)에 대한 토양완충능(土壤緩衝能)은 강원도지역(江原道地域)의 경우 화강암(花崗岩) 지역(地域)과 석탄암지역간(石炭岩地域間)의 유의적(有意的)인 차이(差異)를 나타냈고 서울과 울산지역(蔚山地域)의 경우 pH 3.0-5.7의 산성우(酸性雨)에 대해서는 오염원(汚染源)으로부터 거리(距離)가 멀어 질수록 토양완충능(土壤緩衝能) 유의적(有意的)으로 증가(增加)하였다. 인공산성우처리(人工酸性雨處理)에 대한 토양완충능(土壤緩衝能)의 기작(機作)은 강원도지역(江原道地域)의 경우 양(陽)이온치환(置換)이었으며, 서울지역(地域)에서는 pH 3.0 이상(以上)의 산성우(酸性雨)에 대해서는 양(陽)이온치환(置換)이 완충작용(緩衝作用)을 주도(主導)하였으나 pH 2.0에서는 Aluminum 및 Silicate hydrolysis가 주도(主導) 하였다. 울산지역(蔚山地域)의 경우 pH 3.0 이상(以上)에서는 양(陽)이온치환(置換)이, pH 4.5 이하(以下)에서는 Aluminum hydrolysis가, 그리고 pH 3.0 이하(以下)에서는 Aluminum hydrolysis 및 Silicate hydrolysis가 주도(主導)하였다. 여천지역(麗川地域)에서는 pH 4.5에서 Silicate hydrolysis가, pH 4.5 이하(以下)에서는 Aluminum hydrolysis가 주도(主導)하였다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2003년도 춘계학술강연 및 발표대회
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• pp.30-30
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• 2003

• 한국재료학회지
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• 제15권3호
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• pp.172-176
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• 2005

Formation of aluminum hydroxide by a hydrolytic reaction of nano aluminum powder synthesized by a pulsed wire evaporation (PWE) method has been studied. The type and morphology of the hydroxides were investigated with various initial temperatures and pHs. The nano fibrous boehmite (AlOOH) was formed predominantly over $40^{\circ}C$ of the hydrolytic temperature in acid solution, while the bayerite $(Al(OH)_3)$ was formed predominantly below $30^{\circ}C$ in alkali solution with a faceted crystalline structure. As a result the boehmite showed a much larger specific surface area (SSA) than that of bayerite. The highest SSA of the boehmite was about $409\;m^2/g$.