Influence of electrolyte composition on microstructure and properties of coatings formed on pure Ti substrate by micro arc oxidation

The aim of this work is to study how electrolyte composition incorporates into the prepared micro arc oxidation (MAO) coatings on titanium in electrolytes containing K2ZrF6 or K2TiF6 and modify the surface characteristics. The microstructure of MAO coatings were characterized by scanning electron microscope (SEM), energy dispersive X-ray spectrometry (EDS) and X-Ray Diffractometer (XRD). Vickers hardness, corrosion resistance and wear resistance of these coatings were evaluated. The obtained results showed that arcing phenomenon could be affected by the electrolyte composition, and it occurred with short arc starting time and low arc starting voltage in the solution with K2TiF6 addition, resulting in an increasing growth rate of the coating. Compared with the MAO coating prepared in the base solution, the MAO coating formed in electrolyte with K2ZrF6 or K2TiF6 additives showed a self-sealing microstructure, exhibiting improved hardness. The ZrO2-modified MAO coating showed an excellent tribological behavior and the coating with K2TiF6 addition exhibited the best corrosion resistance. Furthermore, the correlation of the electrolyte composition, microstructure and properties had been revealed.