纤维氧化处理对SiC_(sf)/SiC复合材料力学性能的影响

EFFECTS OF OXIDATION TREATMENT OF SiC FIBERS ON MECHANICAL PROPERTIES OF COMPOSITE SiC_(sf)/SiC

以Y2O3、Al2O3为烧结助剂,采用无压烧结法制备短碳化硅纤维(2～4mm)增强碳化硅(ShortSiCfiberreinforcedSiCcomposite,SiCsf/SiC)复合材料,研究了纤维氧化处理对SiCsf/SiC复合材料结构及力学性能的影响。采用X射线衍射(XRD)、扫描电镜(SEM)以及力学性能试验机对材料进行结构表征和力学性能测试。结果表明:纤维氧化处理后,复合材料的弯曲强度和断裂韧性均有大幅提高。当纤维含量达到5wt%时,复合材料断裂韧性为5.41MPa.m1/2,与原始纤维增强SiC样品相比,提高了6.5%;与无纤维增强SiC样品相比,提高了27%。扫描电镜显示纤维氧化处理后,纤维与基体结合紧密。

SiCsf/SiC（Short SiC fiber reinforced SiC） composites were fabricated by pressless sintering with Y2O3 and Al2O3 as the additives.The effect of oxidation treatment of SiC fibers on the microstructure and mechanical properties were investigated by X-ray diffraction（XRD）,scanning electron microscopy（SEM） and the measurement of fracture strength and fracture toughness.The results show that after oxidation treatment,the fracture strength and fracture toughness of the composites increased.Composites with 5wt% treated SiC fibers obtained the highest fracture toughness,5.41MPa·m1/2,which is an increase of 6.5% compared with those with untreated fiber reinforced SiC,a further increase of 27% over those monolithic SiC samples.The combination of fiber and matrix is found to be compact by SEM photographs.