Vida Khalili; Jafar Khalil Allafi; Hosein Maleki Ghaleh
Volume 6, Issue 1 , June 2012, , Pages 9-15
Abstract
NiTi shape memory alloy cannot provide all the clinical requirements of an implant due to the high nickel content and bio-inert surface. Thus, its surface is coated by bio-ceramics such as hydroxyapatite (HA) in different methods in order to improve biocompatibility and bioactivity. In the present ...
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NiTi shape memory alloy cannot provide all the clinical requirements of an implant due to the high nickel content and bio-inert surface. Thus, its surface is coated by bio-ceramics such as hydroxyapatite (HA) in different methods in order to improve biocompatibility and bioactivity. In the present study, a bio-active coating of HA using electrophoretic deposition technique was created on the surface of NiTi alloy to act as a barrier and prevent the diffusion of nickel ions in to the body fluid. A suspension was prepared by n-butanol as solvent and triethylenamine as dispersant. Coatings were deposited at different voltage of 40, 60 and 80 V for duration of 120s on the cathode. Then coated samples were sintered at 800 °C under argon atmosphere for 2 hrs. Evaluation of coatings was performed by X-ray diffraction techniques (XRD), scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX). Bioactivity and corrosion behavior of HA coatings was studied within simulated body fluid (SBF) environment. The results showed, the sample coated at 60 V is dense, uniform, owing proper corrosion resistant, and also the ability for nucleation and growth of apatite layer in SBF.
Vida Khalili; Jafar Khalil Allafi; Hosein Maleki Ghaleh
Volume 6, Issue 3 , June 2012, , Pages 231-238
Abstract
In this study, a hydroxyapatite/carbon nanotubes composite was coated at room temperature on NiTi shape memory alloy (SMA) through electrochemical deposition using stable suspension which was prepared by adding 4 g natural hydroxyapatite powder and 1 wt. % CNTs to 50 ml n-butanol. Suspension was stabilized ...
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In this study, a hydroxyapatite/carbon nanotubes composite was coated at room temperature on NiTi shape memory alloy (SMA) through electrochemical deposition using stable suspension which was prepared by adding 4 g natural hydroxyapatite powder and 1 wt. % CNTs to 50 ml n-butanol. Suspension was stabilized using triethylenamine as dispersant. Surface characteristics, adhesion strength, stability and bioactivity of the composite coating were subsequently studied. EDX examination of the composite coating surface revealed homogeneous dispersion of carbon nanotubes all over coating. Also, the bonding strength of composite coating was found to be about 24 MPa. Compared to NiTi sample coated with hydroxyapatite and coated with hydroxyapatite/carbon nanotubes, the bode and nyquist plots of NiTi samples with hydroxyapatite/carbon nanotubes composite coating suggested that the composite coating was chemically more stable and provided corrosion resistance for NiTi SMA. In-vitro bioactivity test in SBF showed that the presence of CNTs in HA/CNTs composite coating does not have negative effect on ability of apatite formation.
