Mechanical Properties of Carbon and BN Coated SiC Fibers

Ceramic fibers are used as reinforcements for high-performance ceramics. For these ceramic matrix composites, weak fiber-matrix interfaces which are realized by fiber coatings, are favorable because they provide damage-tolerant mechanical behavior. In this study chlorination of different SiC fibers (HiNicalon, Tyranno SA, Sylramic and Tyranno ZMI) at temperatures up to 550°C was used to produce a thin carbon coating on the fibers. The treated SiC fibers show different carbon layers as a function of temperature. The mechanical behavior at room and high temperatures was investigated and compared to the as-received fibers. This showed that the chlorination treatment does not decrease the strength and Young's modulus of the fibers. Additional tensile tests have been carried out for BN-coated Tyranno ZMI fibers at both room temperature and 1000°C to study the mechanical behavior of the coated fibers.