Al粉作为活性填料对PIP法SiC_f/SiC复合材料性能的影响

Effect of Active Al Fillers on Properties of PIP-derived SiC_f/SiC Composites

利用2.5D SiC纤维预制件,通过前驱体浸渍裂解法(PIP法)制备SiC_f/SiC复合材料,通过在第一次浸渍浆料中加入活性Al粉和惰性颗粒SiC粉来提高浸渍效率.研究了活性填料的加入以及纤维表面热解碳层的厚度对材料性能的影响.结果表明,由于Al粉在热解过程中与含碳有机小分子发生化学反应生成新的物相,使得复合材料的力学性能得到了很大的提高,在1200℃经过六个周期的浸渍裂解后,复合材料的三点弯曲强度达到441MPa,比例极限应力达到380MPa.在200～500nm厚度范围内,热解碳的厚度对复合材料的抗弯强度影响不明显.复合材料的弹性模量随着热解碳层厚度的增加而降低.

SiCf/SiC composites were fabricated by a polymer infiltration and pyrolysis process using 2.5D SiC fiber preforms. In the first slurry infiltration process, active Al and inert SiC filler were introduced to enhance the infiltration efficiency. The effects of A1 filler addition and thickness of PyC as interphase on mechanical properties of the composites were characterized. The mechanical properties of the composite with active A1 as the filler are remarkably improved. The bending strength and proportional limit stress reach 441MPa and 380MPa, respectively. In the range of 200-500nm, the effect of PyC thickness on the bending strength is not noticeable. The elastic modulus of the composite slightly decreases with the increase of PyC thickness.