Comparison in Foreign Object Damage between SiC/SiC and Oxide/Oxide Ceramic Matrix Composites

摘要

Foreign object damage (FOD) of two different ceramic matrix composites (CMCs), melt-infiltrated (MI) SiC/SiC and oxide/oxide, was assessed via impact testing at ambient temperature using impact velocities ranging from 100 to 400 m/s by 1.59mm-diameter steel ball projectiles. The extent of impact damage as well as post-impact strength degradation of both CMCs increased with increasing impact velocity. The degree of relative post-impact strength degradation of the MI SiC/SiC composite was similar to that of the oxide/oxide counterpart. Both of the CMCs were able to survive a very high impact velocity of 400 m/s, without complete structural failure, which is in a notable contrast with gas-turbine grade monolithic silicon nitrides. The damage of the oxide/oxide was characterized with its unique compaction/densification of the material just beneath the impact sites, attributed to the material's soft and open structure. Prediction of quasi-static impact force was made based on the static indentation data and was in reasonable agreement with the experimental data for the oxide/oxide composite.