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- 저자 : Chikara Ohtsuki Sung-Baek Cho(조성백) (검색결과 2 건)
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졸 겔 법을 이용한 Cao-SiO<sub>2</sub>계 겔의 합성 및 구조분석
이태형,이수정,황연,김일용,조성백,Lee, Tae-Hyung,Lee, Su-Jeong,Hwang, Yeon,Kim, Ill-Young,Ohtsuki, Chikara,Cho, Sung-Baek 한국세라믹학회 2008 한국세라믹학회지 Vol.45 No.10
It has been proposed that the Cao-$SiO_2$ binary system can be good basic composition of bioactive glasses and glass-ceramics. In the present study, various kinds of Cao-$SiO_2$ gels were prepared by sol-gel method in order to control the microstructure which are related to their dissolution rate, induction period of apatite formation in body environment. Characterization of the gels were done by wet chemical analysis, SEM observation, FT-IR spectroscopy and XRD. The gelation time decreased with CaO content. However, the volume of all the dried gel decreased to 50% of the wet gels irrespective of increasement of CaO content. All the Cao-$SiO_2$ gels were amorphous and contained a large amount of silanol groups on their surfaces after heat treatment up to $800^{\circ}C$. The interconnected structure of the gel changed to agglomerated spherical powders when Ca content exceed to 20 mol%. Most of the Cao-$SiO_2$ gel showed amorphous when heat-treated up to $900^{\circ}C$. However, quartz and cristobalite was produced when heat-treated at $1000^{\circ}C$ and resultant microstructure of the gel contained microporous structure.
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알루미늄 블랙 드로스로부터 산화 환원반응을 이용한 고순도 알파 알루미나의 제조
신의섭,안응모,이수정,오오츠키 치카라,김윤종,조성백,Shin, Eui-Sup,An, Eung-Mo,Lee, Su-Jeong,Ohtsuki, Chikara,Kim, Yun-Jong,Cho, Sung-Baek 한국재료학회 2012 한국재료학회지 Vol.22 No.9
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.
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