Oxidation Kinetics and Mechanisms of Hot‐Pressed TiB₂–MoSi₂Composites

Abstract

The densification of titanium diboride (TiB2) 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 TiB2‐x wt% MoSi2 (x=0, 2.5, and 10) composites was carried out using thermogravimetric analyzer in order to study the effect of MoSi2 content on the oxidation kinetics of TiB2 at 1200°C for a duration of 12 h. The oxidized surface of monolithic TiB2 composed of highly textured rod‐like rutile (TiO2) crystals. In contrast, the oxide scales on TiB2–MoSi2 materials consist of a thin layer of SiO2 along with TiO2. 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 TiB2‐10 wt% MoSi2, probably due to the presence of SiO2 in the oxide scale.

Review on the Development of Titanium Diboride Ceramics

“…The oxidation kinetics was slower for the TiB2-10 wt.% MoSi2 due to the presence of SiO2 in the oxide scale. The efficacy of MoSi2 in imparting enhanced oxidation resistance of TiB2 [161]. Murthy et al found a new composite of TiB2 with CrSi2 with excellent oxidation resistance [162].…”

Oxidation kinetics of overstoichiometric TiB2 thin films grown by DC magnetron sputtering

“…10(a). Although the columnar TMO 2 grains are also observed in oxidized bulk diborides [34,97], it is unknown why these grains tend to grow preferentially in one direction. We speculate this columnar growth may be attributed to the restricted TiO 2 grain coarsening in the lateral [100] direction.…”

Sintering, Mechanical and Optical Properties of TiB2 Composites with and without High-Energy Milling

“…Therefore, non-metallic additives such as carbides (B 4 C [42], SiC [43], TiC [44], TaC [45], WC [46]), nitrides (Si 3 N 4 [9], AlN [10,47], TiN [29,43]), disilicides (TiSi 2 [48], MoSi 2 [7,[49][50][51]) and borides (ZrB 2 [52]) are preferred for applications at elevated temperatures.…”