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Oxidation Kinetics and Mechanisms of Hot‐Pressed TiB 2 –MoSi 2 Composites

2008; Wiley; Volume: 91; Issue: 10 Linguagem: Inglês

10.1111/j.1551-2916.2008.02656.x

1551-2916

Brahma Raju Golla, Bikramjit Basu, A.K. Suri,

Intermetallics and Advanced Alloy Properties

The densification of titanium diboride (TiB 2 ) at lower sintering temperature requires the use of sinter‐aid. However, from the high temperature application point of view, it is important to assess whether the presence of sinter‐aid degrades the material properties, including the oxidation resistance. In the present work, the isothermal oxidation behavior of TiB 2 ‐ x wt% MoSi 2 ( x =0, 2.5, and 10) composites was carried out using thermogravimetric analyzer in order to study the effect of MoSi 2 content on the oxidation kinetics of TiB 2 at 1200°C for a duration of 12 h. The oxidized surface of monolithic TiB 2 composed of highly textured rod‐like rutile (TiO 2 ) crystals. In contrast, the oxide scales on TiB 2 –MoSi 2 materials consist of a thin layer of SiO 2 along with TiO 2 . Interestingly, the analysis of the continuous measurements of the weight gain reveals parabolic rate law of oxidation for all the investigated ceramics. However, the oxidation kinetics is slower for the TiB 2 ‐10 wt% MoSi 2 , probably due to the presence of SiO 2 in the oxide scale.