Abstract
Abstract The open circuit behavior of hafnium at different surface film thicknesses, immersed in 0.5N H2SO4 has been investigated using potential and impedance measurements. When the anodic current is interrupted, a decrease in oxide film thickness (thinning) was attributed mainly to chemical dissolution of the barrier film. A full inertness of the surface is attained when the polarization potential reaches around 25 V (NHE) where the surface film becomes insoluble in the surrounding electrolyte. It was found also that with gradual accumulation of the oxide layer, a pronounced increase of the open circuit potential was observed. At the thickness corresponding to the polarization potential 25 V (NHE), the rate of increase of open circuit potential after cessation of the current becomes very much reduced and thus a perfect, compact, and continuous oxide film was assumed to be formed on the metal surface.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
