纳米SiO2对先驱体浸渍裂解法制备SiCf/SiC复合材料力学性能的影响

以纳米SiO2为填料,采用先驱体浸渍裂解法制备2.5D-SiCf/SiC（D为维数,SiCf为SiC纤维）复合材料,研究了前驱液中纳米SiO2含量对复合材料力学性能的影响。结果表明,纳米SiO2的添加能有效抑制先驱体裂解过程中的体积收缩,提高致密度,但过量引入易导致浸渍液黏度过高,浸渍效率降低。纳米SiO2含量对材料力学性能有较大影响,添加纳米SiO2后材料的抗弯强度和断裂韧性均高于没有添加的样品,材料抗弯强度随纳米SiO2含量的增加先增大后降低。当浸渍液中纳米SiO2含量为6%时,复合材料具有优异的力学性能,抗弯强度达到211.1MPa。

Effect of Nano-SiO_2 on Mechanical Properties of SiC_f/SiC Composites Fabricated via Precursor Infiltration Pyrolysis Process

The 2.5-dimensional silicon carbide fiber reinforced silicon carbide (2.5D-SiC f /SiC) composites were fabricated via a pre- cursor infiltration pyrolysis (PIP) process with a nano-sized silica powder as a filler. The influence of nano-SiO2 content in the pre- cursor solution on the mechanical properties of the as-received SiCf /SiC composites was investigated. The results show that the intro- duction of nano-SiO2 can restrain the shrinkage upon the pyrolysis and densify the composites efficiently. However, the excessive amount of SiO2 could cause a high viscosity of impregnation solution, resulting in the lower infiltration efficiency. The content of nano-sized SiO2 had an influence on the mechanical properties of the composites. The flexural strength and fracture toughness of the composites with the nano-sized SiO2 filler both were better than those without the nano-sized SiO2 filler. The flexural strength of the composites firstly increased and then decreased with the increase of nano-sized SiO2 content. The superior mechanical properties could be obtained, i.e., the flexural strength could reach 211.1 MPa, when the nano-sized SiO2 content was 6%.