Influence of different modes of microarc oxidation of titanium on the electrochemical properties and surface morphology of the obtained coatings

ABSTRACT

The influence of Microarc Oxidation (MAO) modes of titanium substrate in electrolytes of the original composition is investigated. Used electrolytes no contain sodium silicate but includes nickel sulphate, sodium aluminate and alkali. The morphology and composition of the obtained coatings were studied by electron microscopy. The electrochemical behaviour was studied using polarisation curves and electrochemical impedance spectroscopy (EIS). Proposed Equivalent circuits are adequately corresponded to experimental EIS data with no more 6% error. The dependence between the elements of the Equivalent circuits and the morphological characteristics depending on the processing is considered. It is shown that MAO coatings on titanium have high corrosion resistance in an aggressive sulphuric acid. The electrochemical properties of coatings undergo irreversible changes in the direction of deterioration after anodic polarisation. It has been established that nickel doping of MAO coatings on titanium does not allow them to serve as anode materials.

KEYWORDS:

• Microarc oxidation (MAO)
• titanium
• sulphuric acid
• passivity
• electrochemical impedance spectroscopy (EIS)
• electrolytes
• coatings
• corrosion resistance

Acknowledgements

The study was supported by the Russian scientific fund (project No 21-79-30058) with using the equipment of the Collective use center of MSUT ‘STANKIN’.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by Russian scientific fund: [Grant Number 21-79-30058].