惰性气氛下低氧碳化硅纤维结构和性能的演变∗

摘要

将低氧碳化硅纤维( KD-II)在氩气中分别于1400、1600、1800和2000℃热处理1 h,对纤维强度和微观结构进行了测试和表征。结果表明,随着热处理温度的升高, KD-II中β-SiC晶粒不断长大,孔隙逐渐增多,强度下降。经1800℃热处理后纤维拉伸强度保持在1 GPa以上。纤维拉伸强度的下降主要是因为β-SiC晶粒的长大、 SiCx Oy相的分解和自由碳的增多。%A precursor-derived SiC fiber with low oxygen content ( KD-II) was treated respectively at 1400℃, 1600℃, 1800℃ and 2000℃ for 1 hour in flow argon. The residual strength and microstructures were characterized by XRD and SEM analysis. Results showed that with the temperature increased, the crystal size and porosity ofβ-SiC in fibers increased while the tensile strength decreased. The strength of fiber could remain over 1 GPa after heat treatment at 1800℃. The strength decrease of the fiber was caused by the growth of β-SiC crystal, decomposition of SiCxOy phase and the increase of the free carbon.