Transient stage oxidation behavior of Mo76Si14B10 alloy at 1150 °C

The transient stage during isothermal oxidation of Mo76Si14B10 has been studied at 1150 °C. The maximum mass loss is found to occur by volatilization of MoO3 within the first 480 s of exposure, which is considered to be the transient period. Scanning electron microscopic studies have revealed that a glassy borosilicate layer flows to cover the top surface, and thereby it acts as a protective coating. The thickness of the borosilicate layer increases with exposure time following a parabolic relationship. The mechanism of oxidation during transient period has been discussed with the help of an analytical model.

► MoO3 evaporates during oxidation of Mo76Si14B10 at 1150 °C, thus mass loss occurs.
► The transient period during oxidation is confined within 480 s of exposure.
► The growth of protective borosilicate layer follows a parabolic rate law.
► An analytical model is proposed to explain the mechanism of protection.