The nature of anodic gas at plasma electrolytic oxidation

The output of electro- and thermochemical reactions has been estimated quantitatively on the basis of analyses of the products obtained by plasma electrolytic oxidation (PEO) such as volume and composition of anodic gases evolved on aluminium, weight of oxide and metal passed in to solution. It was shown, that the main component of anodic gases is hydrogen (about 90 vol %). This testifies to preferential occurring of thermochemical processes such as vapor conversion of aluminium by water. Estimation of the hydrogen ‘energy yield’ has provided evidence of an excellent correlation between calculated and experimental results. The efficiency of thermal aluminium conversion in PEO processing under sparking conditions has been found to be approximately 50% and of water decomposition approximately 12%.