Determining of the Critical Passivation Potential by a Step Potentiostatic Method

Issue 4(90) 2018
Pages 36-41

A.N. Podobayev, Moscow Polytechnic University, Moscow, Russia
I.I. Reformatskaya, Academy of the State Fire Service EMERCOM of Russia, Moscow, Russia


Keywords: passivation, passivity, polarization curve, potential, stepwise change

http://www.doi.org/10.31615/j.corros.prot.2018.90.4-4

 

On the example of iron-chromium alloys the question of the correct determination of the critical passivation potential of metallic materials from the measurement of stationary potentiostatic or potentiodynamic curves is analyzed. It is shown that these methods give incorrect results due to a change in the composition of the alloy surface as a result of selective dissolution of one of its components occurring during the measurement. A new method for determining this potential is offered based on a stepwise change of the potential and an analysis of the current response to this action.