Metal anodes oxidation rate forecasted by results of electrolysis

Studies on the oxidation rate of metallic inert anodes by measuring the oxygen evolved in low-temperature aluminium electrolysis

“…Here, V OX (cm year -1 ) was calculated on the basis of the c i and q of the substrate alloy. Satisfactory agreement is observed between the data on the oxidation rate V OX (cm year -1 ) for the alloy wt%: Cu-Ni(5)-Fe(5)-Al(8) based on the oxygen measurement in short-term electrolysis tests and that presented in a previous article [2]. The best fitting of the data presented in Fig.…”

“…For all cases, the dynamics of the anode's oxidation rate in the galvanostatic experiments at the potentials of oxygen evolution are almost the same as those observed in potentiostatic electrolysis without gassing at potentials below the point of oxygen evolution. The i OX À s data can be compared with that presented in a previous article, which were obtained from the changes of the thickness of the metallic (nonoxidised) part of the alloy anode in a series of long-term electrolysis tests (3-72 h) [2]. To compare the oxidation rates obtained by two methods, i OX (A cm -2 ) must be transformed to V OX (cm year -1 ):…”

“…Low-melting systems based on KF instead of a conventional electrolyte decrease the working temperature by 100-150°C. These systems could lead to substantially prolonged lifetimes of the anode because of the significant reduction of the oxidation rate [1][2][3]. Towards this end, we report here our investigation of the oxidation rate of metallic anodes in the course of low-temperature aluminium electrolysis.…”

“…The general oxidation rate of the metal substrate can be estimated from the changes in the thickness of its metal (non-oxidised) part [1,2,9] and also from the metal oxidation current at potentials less than that required for oxygen evolution [9,10]. These methods, however, exhibit some principal disadvantages.…”

“…The first method, which is supplemented with the analysis of the anode oxidation products and those dissolved in the melt, is considered to be the most exact method, but it requires long-term electrolysis tests, on the order of tens of hours [2], at a given current density. It does not allow the oxidation rate as a function of current density (or potential) to be determined in a single experiment.…”