Oxidation of HIPed TiC Ceramics in Dry O2, Wet O2, and H2O Atmospheres

Isothermal oxidation of dense TiC ceramics, fabricated by hot‐isostatic pressing at 1630°C and 195 MPa, was performed in Ar/O 2 (dry oxidation), Ar/O 2 /H 2 O (wet oxidation), and Ar/H 2 O (H 2 O oxidation) at 900°–1200°C. The weight change measurements of the TiC specimen showed that the dry, wet, and H 2 O oxidation at 850°–1000°C is represented by a one‐dimensional parabolic rate equation, while the oxidation in the three atmospheres at 1100° and 1200°C proceeds linearly. Cross‐sectional observation showed that the dry oxidation produces a lamellar TiO 2 scale consisting of many thin layers, about 5 μm thick, containing many pores and large cracks, while H 2 O‐containing oxidation decreases pores in number and diminishes cracks in scales. Gas evolution of CO 2 and H 2 with weight change measurement was simultaneously followed by heating the TiC to 1400°C in the three atmospheres. Cracking in the TiO 2 scale accompanied CO 2 evolution, and the H 2 O‐containing oxidation produced a small amount of H 2 . A piece of single crystal TiC was oxidized in 16 O 2 /H 2 18 O to reveal the contribution of O from H 2 O to the oxidation of TiC by secondary ion mass spectrometry.