Advances in Inorganic Fibers

Creep of Hi-Nicalon S Ceramic Fiber Tows at 800 deg C in Air and in Silicic Acid-Saturated Steam

“…For example, the Young's modulus of these fibers was approximately half that of bulk SiC (~400 GPa, 58 msi) [19,20]. Strength and creep resistance where not as expected either.…”

“…Whereas oxide fibers are much more resistant to oxidizing and corrosive environments than non- Table 2. Characteristics of Ceramic Matrix Composites, reproduced from [15] oxide fibers, non-oxide fibers tend to have better strength and creep characteristics and better thermal conductivity, especially at high temperatures [19,20]. Examples of oxide fibers are silica (SiO 2 ) and alumina (Al 2 O 3 ).…”

“…Hi-Nicalon T M S is a silicon carbide fiber with very low oxygen content, consisting of approximately 69% Si, 31% C, and 0.2% O by weight [19,20]. Each tow consists of approximately 500 fibers with an average fiber diameter of 12 µm.…”

“…Carbon/Carbon, C/SiC and SiC/SiC CMCs have been extensively studied and reported on in the literature [19,20,. These non-oxide CMCs have excellent high-temperature mechanical properties and retain these properties well, for the most part.…”

“…As such, many efforts have been and continue to be made to overcome the oxidation problem. This has lead to the development of self-healing matrix materials [85][86][87][88][89][90][91], fiber coatings that shield the fiber from the oxidizing environment [47,92], and improvements in SiC fibers to reduce oxygen content and achieve near-stoichiometric fibers [19,20,93].…”