• Korean Journal of Materials Research
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• v.15 no.3
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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 $409\;m^2/g$.

• Fire Science and Engineering
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• v.30 no.6
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• pp.9-13
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• 2016

Anti-oxidation and flame resistant polyurethane nanofibers were prepared by electrospinning and aluminum hydroxide addition. Electrospinning was carried out under the following procedure conditions; applied voltage, 20 kV; polymer solution feeding rate, 1.2 ml/h; collector rolling speed, 120 rpm; and tip to collector distance, 15 cm. Aluminum hydroxide was added to the prepared polymer solution for electrospinning to enhance the oxidation and flame resistant properties. The thermal properties were investigated by thermogravimetric analysis to determine the polymer decomposition temperature, integral procedure decomposition temperature, final decomposition temperature, and remaining amount after thermal decomposition. The activated energy for polymer degradation was also investigated using the Horowitz-Metzger equation. The activation energy increased to more than 50%. The thermal properties of the polyurethane nanofibers were improved by a hydration reaction during the thermal decomposition of aluminum hydroxide around $300{\sim}500^{\circ}C$.

• Resources Recycling
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• v.14 no.4 s.66
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• pp.41-46
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• 2005

Waste aluminum dross is a major waste in the aluminum scrap smelters and its major components are alumina and metallic aluminum. In this study, waste aluminum dross was leached with sodium hydroxide solution to extract the remained aluminum into the solution, and aluminum hydroxide was recovered from the leached solution. The dross residue generated at the leaching step was recycled into alumina base ceramic materials through a series of treatments such as washing, drying and roasting. Also, a pilot plant was constructed and tested to demonstrate the developed technology. Four tons of waste aluminum dross could be processed per day. From the test run of the pilot plant, it was confirmed that the developed technology could be applied to commercialization.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.389-391
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• 1995

Using as an alternate of insulating material for outdoor and cable, however, it has still many problems to be solved in the field of material such as resistances of environment and tracking. In this paper, Tracking property of PVC filled with aluminum hydroxide have been investigated by ASTM D 2303 method. It was found that time to track of PVC filled aluminum hydroxide was longer than that of unfilled PVC. Tensile strength and elongation of PVC were decreases increased with aluminum hydroxide contents. On the other hand, Thermegravimetry of PVC decreased. Therefore, the increase of time to tracking breakdown by antitracking additive can be explained by increased degradation temperature of polymer.

• Journal of Powder Materials
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• v.13 no.2 s.55
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• pp.108-111
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• 2006

Aluminum hydroxides were synthesized by a simple electrolytic reaction of aluminum plates. The aluminum hydroxide, boehmite (AlO(OH)), was predominantly formed in the application of electrical potential at and above 30V, while the mixture of bayerite ($Al(OH)_3$) and boehmite (AlO(OH)) phases were formed below 20V. The boehmite has a clear fibrous structure controlled on nanometer scale. On the contrary, the bayerite consists of the typical hourglass or semi-hourglass shaped coarse crystals as a result of aggregation of various crystals stacked together. The specific surface area of the boehmite nanofiber was markedly high, approaching at about $302\;m^2/g$.

• Journal of the Korean Ceramic Society
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• v.27 no.7
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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%.

• Archives of Pharmacal Research
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• v.3 no.2
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• pp.65-74
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• 1980

Analysis of particle size distribution of a sample of fine aluminum hydroxide powder was carried out by four different methods, i. e., conductivity, air permeability, gas-adsorption and sedimentation. Each method was reproducible. The results obtained by Coulter counter and sedimentation balance were similar, and the data obtained by Lea and Nurse permeameter and Stroehlein areameter were also similar. But the results differ considerabley between the former and the latter. The advantages and disavantages of each method were discussed briefly and a means of comparing the results with those obtianed by surface area measurements was shown.

• YAKHAK HOEJI
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• v.15 no.1
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• pp.1-7
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• 1971

When a large quantity of insoluble drugs was added into a solution containing a small amount of soluble drugs, the latter was adsorbed to the former. Their adsorption was expected to alter the drug activity. Berberine hydrochloride (BH) was selected as a soluble drug and tested with frequently combined insoluble drugs and antacids for their adsorption phenomena in prufied water, gastric and intetinal fluid test solutions, respectively. The adsorption isotherms of kaolin and natural anuminum silicate with BH in the three media fitted the Langmuir (LM) equation, and that of talc in purified water and gastric fluid fitted it, but in intestinal fluid it fitted the Freudlich quation. The adsorption isotherm of aluminum hydroxide fitted the LM equation only in intestinal fluid. The degree of adsorption of BH in purified water and gastric fluid is in the following order: magnesium trisilicate, kaolin, natural aluminum silicate and talc; in intestinal fluid: magnesium trisilicate, kaolin, talc, natural aluminum silicate and aluminum hydroxide. Magnesium stearate did not adsorb BH.

• Journal of the Korea Institute of Building Construction
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• v.13 no.5
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• pp.457-464
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• 2013

Traditionally, the material used for the form in reinforced concrete construction has been wood or steel. But recently, aluminum forms have been widely used in wall structures such as apartment buildings. Aluminum is light, easy to handle, and economically advantageous, but the hydrogen gas created due to its reaction with the alkali component in concrete gives rise to air pockets on the concrete's surface, and deteriorates the surface's finishability. In this research, to determine the influence of aluminum material on concrete, the cement paste W/C and its chemical reactivity in alkali and acid solution were analyzed. As a prevention plan, the influence of the number of applications of calcium hydroxide and various surface coating materials was analyzed. Through the analysis, it was found that the surface voids on the aluminum form are the result of the reaction of hydrogen gas with an alkali such as $Ca(OH)_2$. This can be prevented by the surface treatment of $Ca(OH)_2$, separating material and coating material. However, poor surface form and damages to the form are expected to cause quality degradation because of the aluminum-concrete interaction. Therefore, thorough surface treatment, rather than the type of separating material or coating material, is considered the most important target of management.

• Korean Journal of Materials Research
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• v.22 no.9
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• pp.445-449
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• 2012

We investigate the effects of redox reaction on preparation of high purity ${\alpha}$-alumina from selectively ground aluminum dross. Preparation procedure of the ${\alpha}$-alumina from the aluminum dross has four steps: i) selective crushing and grinding, ii) leaching process, iii) redox reaction, and iv) precipitation reaction under controlled pH. Aluminum dross supplied from a smelter was ground to separate metallic aluminum. After the separation, the recovered particles were treated with hydrochloric acid(HCl) to leach aluminum as aluminum chloride solution. Then, the aluminum chloride solution was applied to a redox reaction with hydrogen peroxide($H_2O_2$). The pH value of the solution was controlled by addition of ammonia to obtain aluminum hydroxide and to remove other impurities. Then, the obtained aluminum hydroxide was dried at $60^{\circ}C$ and heat-treated at $1300^{\circ}C$ to form ${\alpha}$-alumina. Aluminum dross was found to contain a complex mixture of aluminum metal, aluminum oxide, aluminum nitride, and spinel compounds. Regardless of introduction of the redox reaction, both of the sintered products are composed mainly of ${\alpha}$-alumina. There were fewer impurities in the solution subject to the redox reaction than there were in the solution that was not subject to the redox reaction. The impurities were precipitated by pH control with ammonia solution, and then removed. We can obtain aluminum hydroxide with high purity through control of pH after the redox reaction. Thus, pH control brings a synthesis of ${\alpha}$-alumina with fewer impurities after the redox reaction. Consequently, high purity ${\alpha}$-alumina from aluminum dross can be fabricated through the process by redox reaction.