Combined Galvanostatic and Potentiostatic Plasma Electrolytic Oxidation of Titanium in Different Concentrations of H2SO4

Bernd Engelkamp,Björn Fischer,Klaus Schierbaum,Mhamed El Achhab,Ülkü Kökçam-Demir

doi:10.3390/met8060386

Bernd Engelkamp, Björn Fischer + Show 3 more

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https://doi.org/10.3390/met8060386

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Journal: Metals	Publication Date: May 26, 2018
Citations: 6	License type: CC BY 4.0

Affiliation: Heinrich Heine University Düsseldorf

Abstract

We report on plasma electrolytic oxidation of titanium, employing a technique with combined potentiostatic and galvanostatic control. The effect of different H 2 SO 4 electrolyte concentrations on the titanium oxide formation was studied sytematically. The titanium oxide consisted of two distinguishable layers. The upper layer is porous, up to few micrometers thick and primarily rutile, while the interlayer is compact, comparatively thin and is associated to anatase formation. The electrolyte concentration changed substantially layer thickness, porosity and phase composition, as deduced from scanning electron microscopy, X-ray diffraction and Raman spectroscopy.

Highlights

Microstructured oxide layers on titanium, produced by plasma electrolytic oxidation (PEO), are of great interest for various applications, including bioengineering, architecture, photovoltaic and sensing technology [1,2]
We refined a PEO process for titanium, which benefits from the combination of galvanostatic and potentiostatic oxidation
scanning electron microscopy (SEM) investigations showed that the resulting oxide layer can be distinguished by a thin interlayer at the titanium substrate and a thick porous layer on-top of the interlayer

Summary

Introduction

Microstructured oxide layers on titanium, produced by plasma electrolytic oxidation (PEO), are of great interest for various applications, including bioengineering, architecture, photovoltaic and sensing technology [1,2]. Sulphuric acid is frequently used and yields porous oxide layer of certain thickness under PEO conditions [9,10,11,12,13]. Previous studies confirm the growth of a compact interlayer at the metal substrate which is thin compared to the porous layer [8,14,15]. Growth models for lightweight metals have been proposed which explain the relevant structure-determining processes and correlate them with the key influence factors, including electrolyte composition, electrical process parameters, process temperature, oxidation time and additives [16,17]. Our process employed an exceptionally high concentration of sulphuric acid of

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