Contact electroresistance method for in situ investigation of metal surface in electrolytes

A new contact electroresistance (CER) method is developed for studying in situ the electroresistance of films on metals and its dependence upon the electrolyte composition and potential. The method consists of measuring the CER between two identical metallic specimens, periodically contacted in electrolyte under potentiostatic control, in particular, between the walls of a fatigue crack in a sample cyclically loaded below the corrosion fatigue crack growth threshold. The sensitivity of the method is 10−9 Ω and its measuring capability comprises CER values from 10−9 to 105 Ω. The CER method can be used for all conducting materials in any electrolyte at ambient and high temperatures and pressures in a wide region of potentials including the potentials of intensive evolution of hydrogen or oxygen. The method allows one to determine the electroresistance of films on metals at very early stages of water and anion adsorption, formation and destruction of hydride and oxide films, electrochemical incorporation of cations, electrodeposition of metals and, also to study the kinetics of these processes. Application of the CER method for investigating some current problems of the surface electrochemistry (hydrophilicity of metals, hydroxide ion adsorption, connection of the latter with electrocatalysis, charge transfer during anion adsorption and others) are discussed with reference to current literature.