Electrodeposited anodic oxide coatings were produced on Ti-6Al-4V substrates using aqueous electrolytes containing dissolved calcium and phosphorus. Different coatings were produced by varying the time periods. The coatings contained TiO as the major phase and contained very small quantities of calcium and phosphorus. All the coatings were less than 200 nm thick. A point defect model is obeyed by all the coatings. © Springer 2005.

Suresh Krishnamoorthy Seshadri

calcium

corrosion

Electrodeposition

Electrolytes

Oxides

Phosphorus

Point defects

ANODIC OXIDE COATINGS

POINT DEFECT MODEL

Thickness

Ti-6Al-4V

Coatings

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Journal of Applied Electrochemistry

Oxide coatings were produced on Ti-6Al-4V alloy by anodization process using two different aqueous electrolytes. The electrolytes contained calcium and phosphorus in the molar ratios of 5 and 15, respectively. Coatings were obtained by applying 250 and 300 V and were characterized by XRD and TEM. Properties like chemical composition, thickness and surface roughness were obtained. All the coatings contained TiO2 along with calcium and phosphorus. Electrochemical polarization and AC impedance studies were done in Simulated Body Fluid medium. The coating obtained by oxidation at 250 V from the bath maintained at Ca/P ratio of 5 had better corrosion properties. Improvement in corrosion resistance was attributed to the presence of phosphorus in the coatings. © 2018, The Indian Institute of Metals - IIM.

Transactions of the Indian Institute of Metals

Structure and Corrosion of High Voltage Anodic Oxide Coatings on Ti6Al4V Biomaterial

In this study, TiO2 nanotubes were fabricated using anodic oxidation in fluoride containing weak organic acid for different durations (0.5 h, 1 h, 2 h and 3 h). Scanning electron microscope (SEM) micrographs reveal that the morphology of titanium oxide varies with anodization time. Raman spectroscopy and X-ray diffraction (XRD) results indicate that the as-formed oxide nanotubes were amorphous in nature, yet transform into crystalline phases (anatase and rutile) upon annealing at 600 °C. Wettability measurements show that both as-formed and annealed nanotubes exhibited hydrophilic behavior. The electrochemical behavior was ascertained by DC polarization and AC electrochemical impedance spectroscopy (EIS) measurements in 0.9% NaCl solution. The results suggest that the annealed nanotubes showed higher impedance (105-106 Ω cm2) and lower passive current density (10- 7 A cm- 2) than the as-formed nanotubes. In addition, we investigated the influence of post heat treatment on the semiconducting properties of the oxides by capacitance measurements. In vitro bioactivity test in simulated body fluid (SBF) showed that precipitation of Ca/P is easier in crystallized nanotubes than the amorphous structure. Our study uses a simple strategy to prepare nano-structured titania films and hints the feasibility of tailoring the oxide properties by thermal treatment, producing surfaces with better bioactivity. © 2015 Elsevier B.V. All rights reserved.

Materials Science and Engineering C

Titania nanotubes from weak organic acid electrolyte: Fabrication, characterization and oxide film properties

Anodic TiO coatings were produced on Ti-6Al-4V substrates using aqueous electrolytes containing dissolved calcium and phosphorus. Two baths containing Ca and P compounds, in the molar ratios 5 and 15 were used. Different coatings were produced by electrolysis for 3 and 10 h at a constant current density of 10 mA/cm2. X-ray diffraction and X-ray fluorescence were used to identify the phases and chemical composition respectively. Thickness of the coatings was measured using ellipsometry. Electrochemical polarization and AC impedance studies were performed on the coatings by exposing them to simulated body fluid (SBF) for a period of 1 week. The coating produced by 10-h electrolysis from bath of Ca/P ratio 15 showed low corrosion current and high impedance to the week-long attack of SBF. © 2007 Wiley Periodicals, Inc.

Journal of Biomedical Materials Research - Part A

Corrosion of anodic TiO coatings on Ti-6Al-4V in simulated body fluid

TiO2 coating offers excellent corrosion resistance and the bone mineral hydroxyapatite (HA) offers very good biocompatibility. A suitable combination of these coatings is expected to produce good corrosion resistance as well as biocompatibility of an implant. Functionally graded coatings containing TiO2 and HA were produced on Ti-6Al-4V. Three sets of coatings were produced. The bare alloy is heated for 2 h at 800 °C to get TiO2 layer to get the first coating. The next coating consists of two layers, namely, (a) TiO2 produced by heat-treatment and (b) a second layer containing 50% TiO2 and 50% HA. The third sample contains three layers, namely, (a) TiO2 produced by heat-treatment as the first layer, followed by (b) a layer containing 50% TiO2 and 50% HA and (c) third layer of HA electrochemically deposited above the second layer. These three samples were subjected to corrosion tests in Simulated Body Fluid (SBF). It was found that coating 1 containing the oxide alone had the highest corrosion resistance followed by coatings 2 and 3. Coating 2 provides corrosion resistance and will show better implant-bone bonding. © 2007 Elsevier B.V. All rights reserved.

Materials Chemistry and Physics

Synthesis and corrosion of functionally gradient TiO2 and hydroxyapatite coatings on Ti-6Al-4V

Materials Letters

Deposition of calcium phosphate coating on nanotubular anodized titanium

Journal of the American Chemical Society

CRC Handbook of Chemistry and Physics:  A Ready-Reference of Chemical and Physical Data, 85th ed Edited by David R. Lide (National Institute of Standards and Technology). CRC Press LLC:  Boca Raton, FL. 2004. 2712 pp. $139.99. ISBN 0-8493-0485-7.

Corrosion Science

Crystallization of anodic titania on titanium and its alloys

Biomaterials

The influence of niobium and vanadium on passivity of titanium-based implants in physiological solution

Surface and Coatings Technology

Promoted calcium-phosphate precipitation from solution on titanium for improved biocompatibility by ion implantation

Anodic oxide coatings on Ti-6Al-4V produced from electrolyte containing Ca and P - Corrosion aspects

Journal	Journal of Applied Electrochemistry
ISSN	0021891X
Open Access	No