Thermodynamic Analysis on Complex Oxides Formed by Aerodynamic Heating for Ultrahigh-Temperature Ceramic Matrix Composites

The oxidation and recession of carbon-fiber-reinforced ultrahigh-temperature ceramic matrix composites (C/UHTCMCs) fabricated via reactive melt infiltration (RMI) using Zr-Ti alloys with three different compositions are evaluated via an arc-jet tunnel test at temperatures above 2000 °C for 60 s. Thermodynamic evaluations show that the recession of the UHTCMCs is prevented by the formation of a solid solution of ZrTiO4 on their exposed surface. Because an increase in the Zr content increases the melting temperature of ZrTiO4, the recession of the composites increases as the Zr content in the infiltrated alloys decreases. UHTCMCs fabricated with Zr-20at%Ti showed the least recession (<5%).