The Effect of Acetonitrile Additives to Tetraborate Electrolyte on the Composition and Morphology of PEO Layers on Titanium

Abstract

The effect of the CH₃CN acetonitrile additives to a tetraborate electrolyte on the composition and morphology of oxide layers on titanium formed by the method of plasma electrolytic oxidation has been studied. The composition and morphology of the coatings have been investigated by means of scanning electron microscopy and energy-dispersive and X-ray diffraction analysis. The addition of 3 vol % acetonitrile to the tetraborate electrolyte’s composition without modifying of electrical parameters of the process has resulted in a decrease of the coatings’ porosity and incorporation in them of up to 20 at % of nitrogen. Oxide layers with low manganese content and the absence of nitrogen have been formed upon the acetonitrile addition to a tetraborate electrolyte with manganese acetate. The surface of the Mn-containing oxide layers is heterogeneous. On the surface, there are separate areas that are “leaf-like” structures with a high content of manganese.