Boron mullite: Formation and basic characterization
Boron mullite: Formation and basic characterization
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DOI：
10.1016/j.materresbull.2012.08.064
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发表时间：
2012-12
影响因子：
5.4
通讯作者：
H. Lührs;R. Fischer;H. Schneider
中科院分区：
文献类型：
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作者：
H. Lührs;R. Fischer;H. Schneider
从3：2莫来石组合物开始，由具有基于Si被B 1：1同晶取代的初始组成的单相凝胶制备一系列硼掺杂莫来石（B-莫来石）（Al4.5Si1.5O9.75）。高含量的硼（> 10摩尔%）可以结合到莫来石的晶体结构中，其中它最有可能取代Si。用高温X射线衍射和热分析研究了B-莫来石的原位相形成。随着硼含量的增加，B-莫来石的形成温度降低。随着硼含量的增加，晶格参数B和c显著降低，而没有观察到a的系统演化。在1400°C下长时间退火导致B-莫来石分解为无硼莫来石和α-氧化铝。在800°C下，B-莫来石似乎在至少12天的时间内是稳定的。平均热膨胀系数降低了15%后，结合硼，这使得该材料的技术感兴趣。
A series of boron doped mullites (B-mullite) was prepared from single-phase gels with initial compositions based on a 1:1 isomorphous substitution of Si by B, starting from a 3:2 mullite composition (Al4.5Si1.5O9.75). A high amount of boron (>10mol.%) can be incorporated into the crystal structure of mullite where it most likely replaces Si. In situ phase formation of B-mullites was studied with high temperature X-ray diffraction and thermal analysis. A decrease of the formation temperature for B-mullite with increasing boron content was observed. With increasing boron content lattice parameters b and c significantly decrease, while no systematic evolution of a is observed. Long annealing at 1400°C results in decomposition of B-mullite to boron free mullite and α-alumina. At 800°C B-mullite appears to be stable over a period of at least 12 days. The mean thermal expansion coefficient was reduced by 15% upon incorporation of boron which makes the material technologically interesting.