Study Of A Microelectrode Manufactured Of A New Material - Kovar, And A Mercury-Film Electrode On The Basis Of This Material

Studies of the processes, proceeding on the surface of the 29 NK alloy in various media (H2SO4, HNO3 center dot HCl, NaOH, NH4Cl) have been carried out. It has been found that kovar is characterized by a more negative potential than pure nickel. This is due to the fact that in the 29 NK alloy, iron is potential-determining, the normal potential of which is much more negative than that of nickel (E-Fe/Fe(0) = -0.441V; E-Ni/Ni(0) = -0.250 V, respectively). The course of the potentiometric curves makes it possible to conclude that in all studied acidic solutions, corrosion proceeds according to an electrochemical mechanism, which is observed for pure nickel only in the sulfuric acid solutions.These studies have been the basis for the creation and introduction into the analytical practice of a mercury-film microelectrode based on the 29 NK alloy. In this connection, the peculiarities of the redox processes of some electropositive metals, in particular, mercury, on this indicator microelectrode have been studied.Upon the reduction of mercury two sharp waves have been detected: the first one - at the potential of 0.25 V (a pre-wave), the second one - at 0.40 V. The character of the reactions proceeding upon the cathode polarization has been determined with the help of the potentiometric studies.It has been established that the high power yields in the initial potential region are explained by the proceeding of a mercury cementation reaction due to the dissolution of the cathode material, alongside with the electrolytic reduction process.The conducted studies allow us to come to the conclusion of expediency of using the 29 NK alloy with a mercury-film coating as an indicator electrode for the electrochemical determination of metals within the potential range of 0.2 - 0.6 V in the sulfuric acid electrolyte.