The Oxidation of TiB2 Ceramics Containing Cr and Fe

The oxidation behavior of TiB₂, TiB₂–0.5 wt.% Cr–0.5 wt.% Fe and TiB₂–1 wt.% Cr–1 wt.% Fe was studied at 800, 900, and 1000°C in static air. These ceramics oxidized rather rapidly and formed thick oxide scales. The oxidation rates of TiB₂-base ceramics were comparable to TiO₂ formation on pure titanium. The scale formed on TiB₂ consisted of TiO₂ and B₂O₃. For TiB–Cr–Fe ceramics, a small amount of Cr- and Fe-oxides was additionally formed. B₂O₃ formed during oxidation tended to evaporate because of its high vapor pressure, making oxide scales porous and fragile. The oxidation of the TiB₂-base ceramics appeared to be governed by the inward transport of oxygen via the highly porous oxide scale. The oxidation resistance of TiB₂–Cr–Fe ceramics was similar to or better than that of TiB₂.