Fabrication and corrosion behavior of Si/HA nano-composite coatings on biodegradable Mg-Zn-Mn-Ca alloy
In this study, nano-silicon (Si) thin films were deposited on biodegradable Mg-6Zn-0.8Mn-3Ca substrates by physical vapor deposition (PVD) method. Subsequently, nano-hydroxyapatite (HA) was coated as a second layer on the nano-Si film using electrochemical deposition (ED). The surface morphology and...
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Main Authors: | , , , , |
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Format: | Article |
Published: |
Elsevier B.V.
2014
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Subjects: | |
Online Access: | http://eprints.utm.my/id/eprint/52843/ http://dx.doi.org/10.1016/j.surfcoat.2014.07.025 |
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Summary: | In this study, nano-silicon (Si) thin films were deposited on biodegradable Mg-6Zn-0.8Mn-3Ca substrates by physical vapor deposition (PVD) method. Subsequently, nano-hydroxyapatite (HA) was coated as a second layer on the nano-Si film using electrochemical deposition (ED). The surface morphology and the corrosion behavior of the composite coatings were evaluated using scanning electron microscope, X-ray diffraction, Fourier-transform infrared spectroscopy, transmission electron microscopy, potentiodynamic polarization tests and immersion tests. The Si/HA nano-composite coating, with an average particle size of 72. nm, represented a uniform and dense film consisting of HA as the outer layer (8-10. μm) and Si as the inner layer (1.5-2. μm). However, some micropores and microflaws were observed in the Si thin film. The polarization test indicated that Si/HA coating could efficiently reduce the corrosion rate of Mg alloy in simulated body fluid from 2.57 to 0.12. mm/year. However, only moderate reduction in corrosion rate was observed in the case of single layer nano-Si coating. Hydrogen evolution studies showed greater reduction in degradation rate of Si/HA and Si coated samples, compared to uncoated alloy. Immersion test showed the formation of apatite layer on the surface of Si/HA film after immersion in SBF that resulted in noticeable improvement of bioactivity. |
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