A new type of fiber-bonded-ceramic material synthesized from pre-oxidized Si-Ti-C-O fiber

Abstract

Two types of fiber-bonded-ceramic material (FBC2123 or FBC1873) were synthesized from preoxidized Si-Ti-C-O fibers with oxide layers of 150 to 500 nm in thickness at 2123 K or 1873 K under 50 to 70 MPa. The interstices in both types of the materials were packed by an oxide material, which had existed on the surface of the pre-oxidized Si-Ti-C-O fiber. So, the dense, fiber-bonded-ceramic materials with small amount of the oxide matrix were obtained. During hot-pressing, carbon in excess of the non-stoichiometric ratio was released from the fiber and formed an interfacial layer on the surface of the fiber, beneath the pre-existing oxide material. Both FBC2123 and FBC1873 showed fibrous fracture patterns with high fracture energies at temperatures up to 1573 K and 1773 K, respectively. FBC2123 exhibited some plasticity in air at a temperature of 1673 K or over, due to the existence of amorphous silica in the matrix, and then a reduction in bending strength was observed at 1773 K in air. On the other hand, FBC1873 maintained its initial bending strength up to 1773 K in air, which is attributed to reduced crystallization of Si-Ti-C-O fiber and to the formation of cristobalite in the matrix.