Effects of varying electrodeposition voltages on surface morphology and corrosion behavior of multi-walled carbon nanotube coated on porous Ti-30 at.%-Ta shape memory alloys

Abstract

The protection of the human muscle-skeletal system from the rapid degradation needs high corrosion resistance biocompatible scaffold materials. Based on this factor, this paper reports the surface morphology, structure and corrosion resistive traits of some multi-walled carbon nanotubes (MWCNTs) coated porous Ti-30 at.%-Ta shape memory alloys (hereafter coded as MWCNT-TTSMAs). The electrophoretic deposition (EPD) technique at various applied voltages was used to coat these alloys with MWCNTs. The structures and morphologies of the prepared samples were characterized at room temperature using the X-ray Diffraction (XRD), energy dispersive spectroscopy (EDS), Raman spectroscopy, Scanning Electron Microscope (SEM), Atomic Force Microscopy (AFM) and Transmission Electron Microscope (TEM) measurements. In addition, the corrosion resistance of the coated alloys was assessed via electrochemical impedance spectroscopy (EIS) in the simulated body fluid (SBF) solution. The thickness (increased from 10.05 to 25.93 μm), surface roughness (increased from 1.38 to 1.95 μm) and homogeneity of the coating was significantly affected by the increase in the applied voltages (0 to 50 V). The corrosion rate of the optimum coated specimens was 10 fold lower (0.0966 mm/year) compared to the uncoated one (0.9403 mm/year). The hydrophilic nature of the proposed MWCNT-TTSMAs affirmed their osseointegration potential to support the cell attachments. The mean water contact angle (WCA) of the coated samples indicated a hydrophilic surface with a value of 22° ± 6 compared to the uncoated sample that exhibited a hydrophobic surface with the WCA value of 96°. Thus, the surface of the MWCNTs tends to be hydrophilic, resulting in an improved surface wettability. Antibacterial activity test exhibited that TTSMAs presented minimal inhibition area toward Escherichia coli (E. coli), in contrast, using the MWCNT has shown an improvement in antibacterial performance.