Venkateswarlu, K and Rameshbabu, N and Sreekanth, D and Bose, A C and Muthupandi, V and Babu, N K and Subramanian, S (2012) Role of electrolyte additives on in-vitro electrochemical behavior of micro arc oxidized titania films on Cp Ti. In: APPLIED SURFACE SCIENCE, 258 (18). pp. 6853-6863.
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The present work is aimed at studying the influence of electrolyte chemistry on the voltage-time (V-T) response characteristics, phase structure, surface morphology, film growth rate and corrosion properties of titania films fabricated by micro arc oxidation (MAO) on Cp Ti. The titania films were developed with a sodium phosphate based reference electrolyte comprising the additives such as sodium carbonate (Na2CO3), sodium nitrite (NaNO2) and urea (CO(NH2)(2)). The phase composition, surface morphology, elemental composition and thickness of the films were assessed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) techniques. The corrosion characteristics of the fabricated films were studied under Kokubo simulated body fluid (SBF) condition by potentiodynamic polarization, long term potential and linear polarization resistance (LPR) measurements and electrochemical impedance spectroscopy (EIS) methods. In addition, the corrosion characteristics of the grown films were analyzed by EIS curve fitting and equivalent circuit modeling. Salt spray test (SST) as per ASTM B 117 standard was also conducted to verify the corrosion resistance of the grown films. The XRD results showed that the titania films were composed of both anatase and rutile phases at different proportions. Besides, the films grown in carbonate and nitrite containing electrolyte systems showed an enhanced growth of their rutile phase in the 1 0 1] direction which could be attributed to the modifications introduced in the growth process by the abundant oxygen available during the process. The SEM-EDX and elemental mapping results showed that the respective electrolyte borne elements were incorporated and distributed uniformly in all the films. Among all the grown films under study, the film developed in carbonate containing electrolyte system exhibited considerably improved corrosion resistance due to suitable modifications in its structural and morphological characteristics. The rate of anatase to rutile phase transformation and the rutile growth direction were strongly influenced by the abundant oxidizing species available during the film growth process. (C) 2012 Elsevier B. V. All rights reserved.
|Item Type:||Journal Article|
|Additional Information:||Copyright for this article belongs to Elsevier B V|
|Keywords:||CORROSION-RESISTANCE;OXIDATION COATINGS;MAGNESIUM ALLOY; DEPENDENCE;TI-6AL-4V|
|Department/Centre:||Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)|
|Date Deposited:||17 Jul 2012 11:59|
|Last Modified:||17 Jul 2012 11:59|
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