Wang Mingjie, Liu Fu, Chen Yao, Gao Jianmin
MOE Key Laboratory of Wooden Materials Science and Application, College of Materials Science and Technology, Beijing Forestry University, Beijing 100083, China.
Materials (Basel). 2018 Nov 30;11(12):2430. doi: 10.3390/ma11122430.
The biomorphic Silicon Carbide (BioSiC) ceramic with highly interconnected porous three-dimensional (3D) structure was fabricated by utilizing balsa wood cellulose nanofibers aerogel as the biotemplate and polycarbosilane (PCS) as the preceramic precursor. Evolution of morphology, composition, and pore properties from untreated wood to porous BioSiC was investigated systemically. The shrinkage and weight gain during pyrolysis was discussed. It was found that the structure of as-synthesized BioSiC was related to the microstructure of wood aerogel template and the concentration of PCS precursor. The proper microstructure of cellulose skeleton which was essential for the infiltration process could obtained by removing lignin and hemicellulose appropriately. The optimum PCS content was 40 wt. % for easy infiltration and proper SiC content. The results revealed that the dredged skeleton of cellulose was reproduced perfectly by PCS ceramization. The obtained BioSiC presented high porosity (61.03%) and low density (0.86 g/cm³) with good Darcy permeability (19.22 mD).
以轻木纤维素纳米纤维气凝胶为生物模板、聚碳硅烷（PCS）为陶瓷前驱体，制备了具有高度互连的多孔三维（3D）结构的生物形态碳化硅（BioSiC）陶瓷。系统研究了从未处理木材到多孔BioSiC的形态、组成和孔隙性质的演变。讨论了热解过程中的收缩和重量增加情况。结果表明，合成的BioSiC结构与木材气凝胶模板的微观结构和PCS前驱体的浓度有关。通过适当去除木质素和半纤维素，可以获得对渗透过程至关重要的纤维素骨架的适当微观结构。对于易于渗透和适当的SiC含量，最佳PCS含量为40 wt.%。结果表明，PCS陶瓷化完美地再现了纤维素的疏通骨架。所制备的BioSiC具有高孔隙率（61.03%）和低密度（0.86 g/cm³），并具有良好的达西渗透率（19.22 mD）。
