Citation:
V. V. Starikov, S. L. Starikova, A. G. Mamalis, S. N. Lavrynenko, J. J. Ramsden; The application of niobium and tantalum oxides for implant surface passivation. Journal of Biological Physics and Chemistry, Vol 7, No 4, Dec 2007 pp141-145
Abstract:
Despite the advantages of ceramics, with their high corrosion
stability in vivo, most medical implant constructions
are still made from metals [1]. To increase the
corrosion stability of metals, different coatings are applied
to the implant surfaces, typically such coatings are the
oxides of the metals in the implants [2].
For an oxide film to have protective properties it
must satisfy the following requirements:
• to be unbroken and pore-free;
• to have good adhesion with the metal;
• to have a thermal expansion constant near to the
value for the metal;
• to be chemically inert in different environments;
• to be hard and have minimal wear under load.
The oxides of metals such as Al, Ti, Zr, Nb and Ta
satisfy all these properties to some degree [3–5]. Indeed,
some of these metal oxides are used in medicine
independently without a metal substrate, such as implant
constructions from sapphire (a single-crystal modification
of Al2O3) [6, 7].
Titanium is the most widely used material for
medical implant manufacture [8]. Its chemical passivity is
provided by the oxide film (TiO2), covering the entire free
surface; a result of titanium contact with air. But titanium
is unable to satisfy all the requirements necessary for an
implant material because of its insufficient corrosion
stability [9–11]. The application of combined implants
consisting of a metal base and a ceramic coating also does
not give a complete solution to the problem, because of
the low adhesion strength and fragility of ceramic
coatings [12, 13].
