Structure and Properties of Si-Ti-C-O Fiber-Bonded Ceramics

Abstract

This paper deals with Si-Ti-C-O fiber-bonded ceramics (Tyrannohex™) produced by hot-pressing the sheets or woven cloth of pre-oxidized Si-Ti-C-O fiber covered with a surface oxide (SiO2 and TiO2) layer. Tyrannohex showed a close-packed structure with fiber volume fraction of 90%, and the interstices were perfectly filled with an oxide material, in which very fine TiC particle are uniformly dispersed. It was considered that the TiC particle was formed by the reaction between the TiO2, which was one component of the oxidized surface layer, and excess carbon in the raw fiber itself during hot-pressing. Moreover, an interfacial carbon layer (10–20 nm) was formed around all the fibers. Tyrannohex showed both high fracture energy (∼9000 J/m2) and high interlaminar shear strength (about 80 MPa). Uni-directional Tyrannohex showed elastic behavior to almost maximum load, and two-directional Tyrannohex also showed a relatively high proportional limit (∼130 MPa) up to high temperature in air. Both type of Tyrannohex showed excellent creep-resistance up to 1673 K in air. Moreover, by replacing the starting fiber with lower oxygen Tyranno fiber (Lox E), high temperature properties of Tyrannohex up to 1873 K could be improved.