Effects of porosity on the corrosion behaviour of PM-fabricated titanium foams for biomedical applications.
Makena, Isaac M. Shongwe, Mxolisi B.
Makena, Isaac M.
Shongwe, Mxolisi B.
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Abstract
Titanium foams of varying porosities were fabricated from a mixture of Ti powder, sodium chloride (NaCl), and liquid polyethylene glycol by spark plasma sintering technique at a temperature of 650℃. This paper aims to study the effects of porosity on the corrosion behaviour of Ti foams. Different porosities were achieved through varying the NaCl content between 0 – 70 vol%. The specimens were thereafter prepared for optical microscopy and XRD phase analysis. Details on the foam pore characteristics were further acquired using a 3D X-ray micro CT scanner. Electrochemical tests consisting of open-circuit potential stabilization, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) measurements were then conducted in a 0.9 wt% NaCl solution at T = 37℃. A near-complete pore interconnectivity was achieved with samples of 60 % porosity and above. The highest open circuit potential of +0.17 V (vs. SSC) was recorded with the 70 % porosity sample. The current density and corrosion rate significantly increased with an introduction of pores to values as high as ±1.87E–05A/cm2 and ±0.16210 mm/year, respectively. Porosity renders the protective oxide layer less resistant to corrosion attack. The overall surface resistance was reduced from values as high as ±78903Ω for 0 % porous sample to ±1369Ω when pores were introduced.
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Date
2024-02-02
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Elsevier
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Keywords
Porous titanium, Micro-CT images, Potentiodynamic polarization, EIS