SIО₂ nanofilm growth kinetics on MOSI₂ surface during anodic polarization

Abstract

Silica film growth kinetics on MoSi₂ surface during anodic polarization is studied. MoSi₂ anodic oxidation in 3% NaCl solution is shown to be a multi-step process. It is found with Auger electron spectroscopy method that in potentials range of 1,5-2,0 V exceptionally silica grows on MoSi₂ surface, while molybdenum transfers entirely to electrolyte. SiО₂ film growths kinetics has been studied with chronoamperometry method under constant potential values. The received kinetic curves have two areas. At the first one response speed (current density) decreases on an order of magnitude in few minutes, when silica nanofilm starts forming. Then diffusion controlled process establishes which is described with parabola. The model describing formation of oxide nanofilm on molybdenum disilicide surface generally corresponds to Cabrera-Mott theory proposed earlier for high-temperature oxidation processes.