Porous mullite ceramics through diphasic gels of large boehmite and small silica particles |
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Authors: | Ladislav Pach Sridhar Komarneni Chunling Liu |
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Affiliation: | (1) Intercollege Materials Research Laboratory, The Pennsylvania State University, 16802 University Park, PA, USA |
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Abstract: | Mullite formation process has been studied in stoichiometric mullite (3Al2O3·2SiO2) diphasic gel containing large boehmite ( 1 m) and small silica ( 10 nm) particles. It has been found that initial mullitization did not take place inside the silica phase (cristobalite), but took place in the defect -alumina phase. -alumina was stabilized by silica when the temperature was below 1350°C. At temperatures above 1350°C, mullite crystallized directly. It was suggested that silica diffused into the pores (<1.8 nm) of -alumina and prevented the collapse of -alumina pore structure. On the other hand, when silica was not present, the pore structure of -alumina collapsed and -alumina crystallized at 1100°C. Porous mullite ceramics were obtained by using special diphasic gels containing large boehmite and small silica particles. |
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Keywords: | mullite diphasic gels porous mullite boehmite silica sol |
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