Creep Behavior of Oxide/Oxide Composites with Monazite Fiber Coating at 1100 deg C in Air and in Steam Environments; Master's Thesis

摘要

The creep behavior of six oxide-oxide ceramic-matrix composites (CMCs) was investigated at 1100C in air and in steam. The six CMC systems had an alumina matrix reinforced with Nextel (TradeMark)610 fibers. The CMC systems C1, C2 and C3 were reinforced with 10 uni-directional fiber layers in a symmetric cross-ply orientation while C4, C5,and C6 were reinforced with 8 plies of fiber fabric woven. Composites C2, C3, C4, and C6 had monazite fiber coating. The tensile properties of the six CMC systems were investigated. Different methods used to apply the monazite coating to the uni-tape cross-ply composites, and the woven composites were the likely cause of reduced strength of the woven CMCs. Creep performance of all six CMC systems was noticeably degraded in steam. Creep run-out was achieved for only composites C4 and C6 in air. Results reveal that for a given fiber architecture and fiber coating method, the use of the monazite coating resulted in considerable improvement in creep resistance. Composite microstructure, as well as damage and failure mechanisms were investigated.