ゾル-ゲル法によるムライト繊維の合成

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Mullite fibers were prepared by a new sol-gel Method from Al(OPr^i)_3-Al(NO_3)_3-TEOS-H_2O system. In this system, the spinnable range varied depending on solution preparation procedures. When TEOS and Al(OPr^i)_3 were added simultaneously to an Al(NO_3)_3 aqueous solution, precursor fibers could be obtained from solutions in a compositional range of H_2O mol/(Al + Si)mol = 20/1-200/1 and Al(OPr^i)_3 mol/Al(NO_3)_3 mol≤6/1. On the other hand, the spinnable range was narrow, when TEOS was added to the solution of Al(OPr^i)_3 in an aqueous Al(NO_3)_3. When Al(OPr^i)_3 was added after TEOS was dissolved in an Al(NO_3)_3 aqueous solution, no spinnable solutions were obtained. Aluminoxane polymer, oligomer of siloxane or that containing Si-O-Al bond, Al-O dimer, Si(OH)_3-O-Si(OH)_3 and [AI(H_2O)_6]^<3+> were observed by <27>^Al-and <29>^Si-NMR spectroscopy of the spinnable solutions. To the contrary, the unspinnable solutions contained Al_<13>^<7+> polycation and three-dimensional polymer having Al-O bonds. The existence of aluminoxane-polymer, Al and Si atomic scale component was deemed necessary for the appearance of spinnability. The DTA curves of all precursor fibers showed a unique and sharp ex-othermic peak at 1000℃, while those of gels obtained from unspinnable solutions showed only small peaks. The X-ray diffraction analysis revealed that the precursor fiber crystallizes directly from amorphous to mullite at temperature as low as 600℃. It was deduced that structure which has a similar composition to mullite exists in precursor fibers.
社団法人日本セラミックス協会の論文
1991-08-01

ゾル-ゲル法によるムライト繊維の合成

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