低氧含量SiC纤维在模拟航空发动机环境中结构和性能

Microstructure and Mechanical Properties of Low Oxygen Content SiC Fibers in Simulated Aeroengine Circumstance

一种低氧含量碳化硅纤维在:P_(H_2O):P_(O_2):P_(Ar)=14 kPa:8 kPa:78 kPa的模拟航空发动机环境中1200℃保温1~50 h,利用元素分析,XRD和SEM以及强度测试表征碳化硅纤维结构和性能的变化。结果表明:与干燥空气环境相比,在模拟环境中高温处理后的纤维氧含量更高、氧化层厚度更大,强度更低;氧化膜中更容易出现α-SiO_2结晶和裂纹;模拟环境中水蒸气能加速纤维氧化和氧化膜破裂。

The low oxygen content SiC fibers were exposed in simulated aeroengine circumstance of PH2O：PO2：Par=14kPa：8kPa：78kPa at 1200 ℃ for 1-50 h. Performances and structure of the fibers were characterized by element analysis, XRD,SEM and tensile test. The results show that the fibers have higher oxygen content, thicker oxide layer, lower strength compared with the fibers treated in dry air. Cracks and α-SiO2 crystal are more likely to occur in silica layer. The steam in the simulated circumstance can accelerate oxidation and crack formation in silica film.