Self-Organization Kinetics of Microarc Oxidation: Nonequilibrium-State Electrode Reaction Kinetics

Abstract

Here, we present a new method for studying and gaining new insights into microarc oxidation (MAO) and its corresponding nonequilibrium-state electrode reaction kinetics. We observed that the fundamental condition of microdischarge formation was the resistance nonequilibrium in the oxide film caused by the existence of a defective region. Specifically, the current always first passed through a path with the lowest resistance. After the first discharge, a ceramic phase (e.g., α-Al2O3) was formed, which changed the conductive properties of the defective region, and the resistance in the defective region was subsequently increased, which sent feedback to the next current distribution. This fundamental and inherent law rendered controlling and predicting the microarc system kinetics by the external environment difficult. Therefore, we developed a microarc algorithm and proposed a feedback coefficient k, which determines whether the anode current distribution is inclined to or deviates from the equilibrium state. Finally, we analyzed the k-frequency relationship and used frequency to experimentally describe various kinetic behaviors of MAO.

Commercial preparation of hybrid carbon filler/HDPE composite electrodes for lead methanesulfonate flow batteries

“…But for the positive electrode reaction, oxygen evolution is an inevitable competing reaction during the oxidation of Pb 2+ to PbO 2 [24]. There must be the electrolysis of water to produce oxygen on the electrode surface area where the current is large due to its high conductivity [25]. It could be active to combine with the graphite or other carbon-based materials.…”

The role of cathodic current in plasma electrolytic oxidation of aluminium: current density ‘scanning waves’ on complex-shape substrates

“…Besides, it is worth noting that the scanning phenomena considered above should be clearly distinguished from the known feature of some PEO processes, where discharges do not occupy the whole sample surface, but form some sort of aggregated group acting only within the surface part. Usually, the collective behaviour of discharges is accompanied by gradual migration within the sample [21][22][23][24][25]. Such behaviour is thought to be attributed to thermal effects of the discharges, promoting predictable ignition of the following discharges, rather than with switching between positive and negative polarity.…”