2018 Volume 126 Issue 1 Pages 27-33
The low-temperature melt-infiltration method using eutectic Si alloys is a novel process of fabricating SiC fiber-reinforced SiC-based matrix composites (SiCf/SiCs) for high-temperature structural applications. SiCf/SiCs were fabricated by the melt-infiltration method using a eutectic Si–8.5 at%Hf alloy to evaluate their dry oxidation behavior at 800–1200°C for times ranging from 10–100 h. The oxidation behavior of monolithic HfSi2 (Monolith) fabricated by spark plasma sintering was also evaluated in dry air. The oxidation behavior of the composite matrix and Monolith obeyed the parabolic law in dry conditions. The steps to form the oxidation layer were expected to produce HfO2 and Si, followed by SiO2, and, finally, HfSiO4. The oxidation rate of the matrix was similar to that of Monolith and 102–104 times larger than that of Si. The oxidation activation energy employed in oxidation of HfSi2 was calculated as 258 kJ/mol in dry air.