Study of the Effect of Current Pulse Frequency on Ti-6Al-4V Alloy Coating Formation by Micro Arc Oxidation.

Alexander Sobolev,Alexey Kossenko,Konstantin Borodianskiy

doi:10.3390/ma12233983

Abstract

The micro arc oxidation (MAO) process has been applied to produce ceramic oxide coating on Ti-6Al-4V alloy. The MAO process was carried out at the symmetric bipolar square pulse in electrolyte containing Na2CO3 and Na2SiO3. The effect of current frequency on the surface morphology, the chemical and the phase compositions as well as the corrosion resistance was examined. Morphology and cross-sectional investigation by electron microscopy evaluated more compacted and less porous coating produced by high current frequency (1000 Hz). This alloy also exhibited a high corrosion resistance in comparison with the untreated alloy. Additionally, the alloy subjected to MAO treatment by a current frequency of 1000 Hz showed a higher corrosion resistance in comparison with alloys obtained by lower current frequencies. This behavior was attributed to more compacted and less porous morphology of the coating.

Highlights

Titanium alloys are widely applicable in marine, aerospace, chemical and biomedical industries due to their high specific strength, corrosion resistance and excellent biocompatibility [1,2,3,4]
micro arc oxidation (MAO) is an electrochemical processing of ceramic oxide coating formation on the metallic substrate by the appearance of dielectric breakdown and plasma discharges
It was found that the application of different current frequency affected the porosity and compaction of the formed oxide coating

Summary

Introduction

Titanium alloys are widely applicable in marine, aerospace, chemical and biomedical industries due to their high specific strength, corrosion resistance and excellent biocompatibility [1,2,3,4]. Their advanced properties are limited due to the lack of the protective surface properties. MAO is an electrochemical processing of ceramic oxide coating formation on the metallic substrate by the appearance of dielectric breakdown and plasma discharges. Micro-arc discharge migration points appear on the surface lead to the oxide coating formation [5,6,7,8]. MAO treatment is suitable for the enhanced mechanical properties and corrosion resistance of the alloys’ surface [9,10,11]

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