Stabilization mechanisms of calcium aluminate fibers made by the inviscid melt-spinning technique 机翻标题: 暂无翻译,请尝试点击翻译按钮。

作者
Fondeur, Fernando;
摘要
An eutectic composition (43.5:53.7 wt%) of calcium aluminate was analyzed for its reactivity towards carbon and its response to stress during solidification from the melt. Propane pyrolysis over calcium aluminate melts showed that aluminum carbides and carbide oxides were formed early in the reaction as a result of carbon interactions with the melt. Carbide oxides formed before carbides. Carbon monoxide formation was seen along with the carbide formation. It was not possible to observe calcium carbide formation. Accompanying aluminum carbide oxides and carbides formation, there was a significant increase in the population of tetrahedrally coordinated aluminum atoms. Depth profiling of calcium aluminate fibers formed by Inviscid Melt Spinning showed an excess of tetrahedrally-coordinated aluminum atoms as well as carbonates. It is proposed that this effect is what increases the surface viscosity and stabilizes calcium aluminate fibers. Ethers, ester and carboxylates were also seen at the surface propane stabilized calcia-alumina fibers which suggests that carbon monoxide may be reacting with carbon to form these species. It is postulated that polymerization rather than particle filler effects is responsible for the viscosity build-up in the formation of calcium aluminate fibers by IMS. Further, the fragility of calcia-alumina melt structures in the presence of stress, in particularly of different quenching methods, was demonstrated. Depending of the type of stress, deformed or undeformed tetrahedrally coordinated aluminum atoms can be increased and frozen in with simultaneous heat withdrawal. It was possible to delineate the melting behavior of (47.5:53.5) calcium aluminate samples. De-condensation of some tetrahedral aluminum atoms and the formation of pentahedrally coordinated aluminum atoms was seen with increasing temperature. Further, it was possible to make IR assignment of pentahedrally coordinated aluminum atoms at the 771 cm$\sp{-1}$ region for the calcium aluminate melt.
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关键词/主题词
Chemical engineering;Chemistry
页数
117
出版日期
2020-09-25
学位授予单位
Tulane University
学位年度
1998
学位
Ph.D.
院系
Chemical engineeringChemistry
导师
Mitchell, Brian S.
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