High-Temperature Oxidation of TiN-Ti5Si3 Composites Prepared by Polymer Pyrolysis

Abstract

Composites consisting of a TiN matrix containing about 32 vol.% Ti 5 Si 3 were synthesized via polymer pyrolysis, and oxidized in the temperature range of 700 to 900°C for up to 120 h in air. Oxidation occurred mainly in the TiN matrix, because Ti 5 Si 3 was resistant to oxidation. The oxidation of the TiN matrix was preceded by the outward diffusion of Ti ions to form an outer TiO 2 layer, and the inward diffusion of oxygen ions to form an inner TiO 2 layer, together with nitrogen evolution from the TiN matrix.

Interaction of Oxygen with the Stable Ti5Si3 Surface

“…It is necessary to note that Ti 5 Si 3 itself is considered a promising candidate for high temperature applications due to its high melting point (2130 • C), high strength, low density and good creep resistance [31][32][33][34][35][36]. However, the major challenges of Ti 5 Si 3 applications include the difficulty of synthesis above 1600 • C, poor high temperature oxidation resistance and low fracture toughness.…”