Effect of hydroxyapatite thickness on metal ion release from Ti6Al4V substrates

• Type: Article in International Scientific Journal
• Date: 1996

Authors

Sousa, SR (Author) Other; Mário Adolfo Barbosa (Author) FEUP

Journal

Title: Biomaterials

Vol. 17 No. 4

Pages: 397-404

ISSN: 0142-9612

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 82 Citations

Scopus - 85 Citations

Other information

Authenticus ID: P-001-EST

DOI: 10.1016/0142-9612(96)89655-4

Abstract (EN): The electrochemical dissolution behaviour of Ti6Al4V alloy coated with hydroxyapatite (HA) by plasma spraying was studied in Hank's balanced salt solution (HBSS) and compared with that of polished and grit-blasted passivated surfaces. Two different nominal thicknesses of HA (50 and 200 mu m) were used. Taking a polished passivated surface as reference, grit blasting of the substrate increased the electrical charge used in the oxidation of Ti6Al4V alloy at constant potential, as a result of increased surface area. However, only HA coatings with a thickness of 200 mu m were capable of reducing the charge to values lower than those measured for polished surfaces. Electrochemical impedance spectroscopy has also shown that only 200 mu m thick coatings are effective in reducing the oxidation rate of the substrate. Furthermore, in potentiostatic experiments the 50 mu m thick coating detached from the substrate, which did not occur with the 200 mu m thick coating. However, after 6 months immersion in HBSS, detachment occurred in some regions of both coatings. No titanium, aluminium or vanadium were detected in solution by electrothermal atomic absorption spectroscopy. These data indicate that HA is an effective barrier to metal ion release, even for the thinner coatings, due to formation of metal phosphates or to incorporation of metal ions in the HA structure.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 8