Continuous mullite fibers with ultrafine diameters and good thermal stability are an ideal candidate to be used to prepare ceramic-based aerogels, sponges, or composites. In the present work, boron-containing mullite micro/nanofibers with the molar ratio of Al/Si/B = 3/1/1 were fabricated using monophasic precursor sols with different concentrations (15–37.5%) by electrospinning. Basic aluminum acetate (BAA) and tetraethyl orthosilicate (TEOS) were used as the raw materials. It was found that with increasing sol concentration, the reaction rates of hydrolysis and polymerization were reduced, and the chemical homogeneity of the precursor sols decreased. Besides, the viscosities of the spinning solutions increased, which was assigned to be the determining factor that led to the increasingly thicker precursor fibers. Meanwhile, the crystallization temperatures decreased and the grain sizes increased for the sintered fibers. The main reason for this was that amorphous SiO₂, which could delay the reaction between Al₂O₃ and B₂O₃ and hinder the movement of grain boundaries, was distributed more evenly.

Graphical abstract

中文翻译：

---

单相溶胶电纺含硼莫来石微/纳米纤维：溶胶浓度对形貌和微观结构的影响

具有超细直径和良好热稳定性的连续莫来石纤维是制备陶瓷基气凝胶、海绵或复合材料的理想候选材料。在目前的工作中，使用不同浓度（15-37.5％）的单相前体溶胶通过静电纺丝制备摩尔比为 Al/Si/B = 3/1/1 的含硼莫来石微/纳米纤维。以碱式醋酸铝（BAA）和原硅酸四乙酯（TEOS）为原料。结果发现，随着溶胶浓度的增加，水解和聚合反应速率降低，前体溶胶的化学均匀性降低。此外，纺丝溶液的粘度增加，这被认为是导致前体纤维越来越粗的决定因素。同时，烧结纤维的结晶温度降低，晶粒尺寸增加。主要原因是无定形 SiO₂可以延缓Al ₂ O ₃和B ₂ O ₃之间的反应，阻碍晶界的移动，分布更均匀。

图形概要