SIО2 nanofilm growth kinetics on MOSI2 surface during anodic polarization

V.Lavrenko,
 
V.Lavrenko,
 
A. Chirkin,
  
A.Panasyuk
 

I. M. Frantsevich Institute for Problems of Materials Science of the NAS of Ukraine, Krzhizhanovsky str., 3, Kyiv, 03142, Ukraine
Powder Metallurgy - Kiev: Frantsevich Institute for Problems of Materials Science NASU, 2008, #01/02
http://www.materials.kiev.ua/article/696

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.


ANODIC OXIDATION, DIFFUSION, DISILICID OF MOLYBDENU, MOTT-CABRERA THEORY, PARABOLIC KINETICS, SILICA FILM