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|Title:||Dissolution and passivation characteristics of titanium and its alloy (VT-9) in hydrochloric acid|
|Authors:||Singh, V B|
|Abstract:||The potentiostatic technique has been used to examine the anodic behaviour preceding cathodic polarization of Ti and its alloy (VT-9) in the concentration range 1-11M of deareated hydrochloric acid solution at room temperature. Effect of temperature on the electrochemical behaviour of Ti and VT-9 has been studied for a few selected compositions of the acid solution. An active/passive transition and a large passivity range of potential are observed for all concentrations and for different temperatures. Cathodic charging of the metal and alloy resulted in a shift of the corrosion potential (Ecorr) towards more noble potentials, a decrease in the critical current density for passivity (icr) and a slight increase in the passivation current (ip). Hydrogen evolution is the most probable cathodic reaction in this medium. Titanium and VT-9 showed similar corrosion behaviour, however, the passive current density is found to be somewhat higher in case of the alloy. The film formed on the surface of the metal and alloy, after polarization under different experimental conditions, remained fairly stable in prolonged exposure of the specimens. SEM examination shows formation of uniform passive surface on both the specimens. The electrochemical impedance measurements, at different potentials, resulted in non-ideal semicircles and analysis yielded a linear relationship between reciprocal capacitance and formation potential of the passive film like other valve metals.|
|ISSN:||0975-0991 (Online); 0971-457X (Print)|
|Appears in Collections:||IJCT Vol.01(5) [September 1994]|
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