SiCf/SiO2复合材料的制备及界面层对其力学性能的影响

Fabrication of SiCf/SiO2 composites and the Influence of Interfaces on the mechanical properties

摘要:

以碳化硅（SiC）纤维为增强体，采用真空浸渍法制备了2.5维连续SiC纤维增韧的SiO2 基(SiCf/SiO2) 复合材料，研究了SiC纤维编织体上不同的界面层对SiCf/SiO2复合材料力学性能的影响。化学气相渗透（CVI）法制备的热解碳（PyC）和PyC/SiC双层界面层分别使材料的抗弯强度由无界面层的52.2MPa提高至67.4MPa和180.3MPa，但均使材料的韧性降低。用扫描电镜观察了材料的断口形貌。结果表明，PyC和PyC/SiC层不仅提高了材料的抗弯强度，而且增加了基体同纤维间的结合力，使基体有效地将载荷传递给纤维。PyC/SiC层能有效地保护SiC纤维，防止烧结过程中释放出的结晶水对纤维的损伤，有助于提高材料的力学性能。

Abstract:

2.5-dimension continuous silicon carbide fiber reinforced silicon dioxide composites (SiCf/SiO2) was fabricated by vaccum infiltration. The effects of different interfaces on SiC fabric preform on the mechanical properties of the composites were studied. The bending strength of the composites， in which the fabric without interface，was 52.2MPa, while coating the fabric with pyrolytic carbon (PyC) and PyC/SiC multi-layer interfaces enhanced the bending strength to 67.4 and 180.3MPa. However, the interfaces also declined the toughness of SiCf/SiO2 composites. The surface morphology of fractured composites was analyzed by Scanning electron microscope. The results show that the interfaces not only increase the bending strength but also enhance the bonding between the matrix and fibers which improves the load transfer from the matrix to the fibers. The PyC/SiC interfaces protect the SiC fibers against being damaged by the water released during the processing of sintering and promote the mechanical properties of SiCf/SiO2 composite.