Creep and Fatigue in Inert and Vacuum Environments of Woven Sylramic- iBN Melt-Infiltrated Composites (Preprint)

摘要

In order to better understand the effect of stressed-oxidation, the performance of woven Sylramic-iBN fiber-reinforced slurry cast melt-infiltrated (MI) composites were tested in creep and fatigue under non-oxidizing conditions. Initially creep and fatigue tests were performed at 1204 deg C in an argon atmosphere; however, it was observed that sufficient oxidizing species existed in the environment to degrade the composites in a manner similar to air environments. Therefore, creep and fatigue tests were performed at 1204 deg C in a vacuum environment which showed no evidence of oxidation and superior properties to composites subjected to stressed-oxidation conditions. The mechanical results and microscopy of the vacuum and argon are compared to the behavior of these composites tested in air. It was found that the stress rupture properties of the vacuum-tested composites could be predicted from single fiber creep rupture data assuming reasonable values for the Weibull modulus.