Effect of electrical parameters on morphology and in-vitro corrosion resistance of plasma electrolytic oxidized films formed on zirconium

Sandhyarani, M and Ashfaq, M and Arunnellaiappan, T and Selvan, MP and Subramanian, S and Rameshbabu, N (2015) Effect of electrical parameters on morphology and in-vitro corrosion resistance of plasma electrolytic oxidized films formed on zirconium. In: SURFACE & COATINGS TECHNOLOGY, 269 . pp. 286-294.

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Abstract

The objective of the present work is to study the effect of electrical process Parameters (duty cycle and frequency) on morphological, structural, and in-vitro corrosion characteristics of oxide films formed on zirconium by plasma electrolytic oxidation in an electrolyte system consisting of 5 g/L of trisodium orthophosphate. The oxide films fabricated on zirconium by systematically varying the duty cycle and frequency are characterized for its phase composition, surface morphology, chemical composition, roughness, wettability, surface energy, scratch resistance, corrosion resistance, apatite forming ability and osteoblast cell adhesion. X-ray diffraction pattern of all the oxide films showed the predominance of m-ZrO2 phase. Dense and uniform films with thickness varying from 9 to 15 mu m and roughness in the range of 0.62 to 1.03 mu m are formed. Porosity of oxide films is found to be increased with an increase infrequency. The water contact angle results demonstrated that the oxide films exhibited similar hydrophilicity to zirconium substrate. All oxide films showed improved corrosion resistance, as indicated by far lower corrosion current density and passive corrosion potential compared to the zirconium substrate in simulated body fluid environment, and among the four different combinations of duty cycle and frequency employed in the present study, the oxide film formed at 95% duty cycle and 50 Hz frequency (HDLF film) showed superior pitting corrosion resistance, which can be attributed to its pore free morpholOgy. Scratch test results showed that the HDLF oxide film adhered firmly to the substrate by developing a notable scratch resistance at 19.5 +/- 1.2.N. Besides the best corrosion resistance and scratch retistance, the HDLF film also showed good apatite forming ability and osteo sarcoma cell adhesion on its surface. The HDLF oxide film on zirconium with superior surface characteristics is believed to be useful for various types of implants in the dental and orthopedic fields. (C) 2015 Elsevier B.V. All rights reserved.

Item Type:	Journal Article
Publication:	SURFACE & COATINGS TECHNOLOGY
Publisher:	ELSEVIER SCIENCE SA
Additional Information:	Copyright for this article is belongs to the ELSEVIER SCIENCE SA, PO BOX 564, 1001 LAUSANNE, SWITZERLAND
Keywords:	Zirconium; Plasma electrolytic oxidation; Pulse duty; Frequency; Corrosion resistance
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	29 May 2015 06:42
Last Modified:	29 May 2015 06:42
URI:	http://eprints.iisc.ac.in/id/eprint/51622

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