Microarc oxidation in slurry electrolytes: A review

Abstract

The experience gathered from the use of plasma electrolytic methods in the context of improving the performance of valve group metals is summarized. Emphasis is placed on the formation of coatings by microarc oxidation (MAO) in slurry electrolytes containing powders with different degree of dispersion (a few nanometers to a few tens of microns) and nature (oxides, carbides, nitrides, borides, graphite, etc.). A phenomenological model of the mechanism of formation of MAO coatings in slurry electrolytes is proposed; characteristics of the electrolytes and the coatings are discussed. The results of our studies of the composition of MAO coatings carried out by nuclear backscattering (NBS) spectrum simulation are described. A significant improvement in the properties of MAO coatings formed in slurry electrolytes is registered. It is concluded that this modification can considerably extend the range of application of the MAO method not only in conventional fields of mechanical and instrument engineering but also in aerospace engineering, medicine, biology, and living systems technology.