High temperature oxidation of some MSi2-type silicides

In order to determine oxidation properties of refractory-metal silicides, oxidation tests of MoSi2, WSi2, NbSi2, and TaSi2 were carried out. In the isothermal oxidation behaviors at 1773 K determined by applying an extremely rapid heating procedure, the weight changes of MoSi2 and WSi2 were negligibly small as a result of the formation of a glass-like protective SiO2 layer. On the other hand, such protective oxide layer was not formed on NbSi2 and TaSi2. In addition, the oxidation behaviors of the silicides during heating at a relatively slow rate to 1473 K were also determined. When this heating procedure was applied, a pronounced increase in weight was observed in the silicides except for MoSi2. Furthermore, the effect of the dissolution of WSi2 upon the oxidation behavior of MoSi2.