화학공학소재연구정보센터
홈 로그인 로그아웃 연락처 사이트맵
HWAHAK KONGHAK, Vol.37, No.3, 355-363, June, 1999
Export Citation
졸-겔법에 의한 구형 mullite 전미분체의 제조 및 mullite화 공정기구의 해석; I. 졸-겔 공정변수가 mullite 전미분체의 제조와 mullite화에 미치는 영향
Synthesis of Spherical Pre-mullite Particles by Sol-Gel Method and Mullitization Mechanism of Pre mullite
황운연, 이승구, 구기갑, 박형상, 유승준, 윤호성
초록
본 연구는 두 알콕시드의 반응속도 차이를 조절하기 위한 부분 가수 분해법과 용매에 대한 복합 알콕시드의 용해도 차이를 이용한 혼합용매법을 사용하여 구형 mullite 전미분체를 제조하였다. TEOS=0.0333 mol/ι, ASB=0.1 mol/ι, 물농도 0.5 mol/ι, 아세토니트릴 40 vol% 및 HPC 0.1 g/ι 반응 조건에서 입도 분포가 좋은 구형 mullite 전미분체가 제조되었으며, [Al2O3] : [SiO2]의 비는 3 : 2였다. 그리고 mullite 전미분체는 990℃ 부근의 하소에 의하여 스피넬상 생성에 기인한 발열 반응이 일어났으며, 1,100℃ 및 1,250℃부근의 하소공정에 의하여 각각 T-mullite와 O-mullite로 상전이가 일어났다. 또한 TEOS의 부분가수분해 반응에 첨가된 [H2O]/[Si-alkoxide]비가 mullite 전미분체의 mullti화 공정에 많은 영향을 미침을 확인하였으며, 이 비가 1일 때 가장 균일하면서 Si-O-Al결합을 많이 갖고 있는 mullite 전미분체가 제조되었으며, 다른 조건에서 제조된 시료에 비하여 낮은 1224.43℃에서의 하소에 의하여 O-mullite가 생성되었다.
In this study, spherical fine pre-mullite particles were prepared by partial hydrolysis method to control the reaction rate difference of two alkoxides and by mixed solvent methodd to control the particle shape. The optimum conditions for preparing spherical pre-mullite particles were; ([TEOS] = 0.0333 mol/ι, [ASB] = 0.1 mo1/ι, [H2O] = 0.5 mol/ι, [acetonitrile] = 40 vol%, [HPC] 0.1 g/ι). A12O3 : SiO2 molar ratio or pre-mullite Particles determined by XRF analysis was about 3 : 2. Mullitization reactions were studied by DTA, XRD, and FT-lR analysis. Pre-mullite particles were determined amorphous by HRD analysis, and all pre-mullite powders showed an exothermic peak around 990℃ on DTA analysis associated with crystallization to spinel phase. The samples passing through the spinel phase were transformed into the T-mullite at around 1,100℃ and the transformation to O-mullite took place about 1,250 ℃. [H2O]/[Si-alkoxide] molar ratio added in the partial hydrolysis reaction had an important effect upon the mullitization of pre-mullite powder, the pre-mullite particles of the highest degree of Si-O-Al bonding were obtained when [H2O]/[Si-alkoxide] was 1 and the particles crystallized to O-mullite at low temperature (1224.43℃) than other particles.
Keywords:Mullite;Mullitization;Sol-Gel Process;Mixed Solvent;Partial Hydrolysis
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