Influence of fiber orientation and matrix processing on the tensile and creep performance of Nextel 610 reinforced polymer derived ceramic matrix composites

Kurzfassung

The tensile and creep performance of two Nextels 610(N610) reinforced polymer derived ceramic composites (UMOX™, OXIPOL) is studied up to 1200C. Independent of the fiber orientation(45 or 0/90deg) all samples exhibit a segment where the strain rate was constant. The creep performance in 45deg is matrix dominated and shows a more pronounced primary creep regime, due to changes within the matrix. The following creep regime with a constant strain rate might be attributed to viscous flow of the SiOC within the matrix based on activation energy(283kJ/mol) and stress exponent (0.6). In0/90 deg orientation the creep and tensile performance is independent of oxidation, but directly influenced by grain structure of the fiber. The coarser and non-uniform microstructure of the fibers in UMOX™ decreases the stationary creep rates and changes the diffusiona lcreep mechanism. The possibility to modify the microstructure of the fiber during the manufacturing process might be used to adjust e.g. the strength and creep stability of these materials related to the desired applications.