纳米SiO_2对先驱体浸渍裂解法制备SiC_f/SiC复合材料力学性能的影响

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

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。

The 2.5-dimensional silicon carbide fiber reinforced silicon carbide（2.5D-SiCf/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%.