Electrochemical Properties of Niobium Coating for Biomedical Application

Abstract

The preparation of the Nb coating was performed on the bare Ti–6Al–4V alloy using the double glow discharge plasma technique. It was characterized that the Nb coating exhibited a face centered cubic (fcc) crystal structure and a pronounced (200) preferred orientation. The SEM micrograph of the cross section for the coating displayed dense microstructure with a thickness of approximately 18 µm. The critical load (Lc) of the coating was determined to be about 83.5 N by the scratch tests. The electrochemical corrosion resistance of the coating was examined in Ringer’s solution at 37 °C by a series of electrochemical techniques, including open-circuit potential (OCP), potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and a Mott–Schottky analysis. As the result of the potentiodynamic polarization, the Nb coating possessed a more positive corrosion potential and lower corrosion current density than the Ti–6Al–4V substrate. EIS fitting date showed that the Nb coating always possessed a higher value of impedance and lower effective capacitance than those of the substrate during the five days of immersion testing. The main component of the passive film developed on the Nb coating was Nb2O5, confirmed by an X-ray photoelectron spectroscopy (XPS) analysis. A Mott–Schottky analysis demonstrated typical n-type semiconductor characteristics of the Nb coating, and both the donor density and flat band potential of the coating were lower than those of the substrate at all the given formation potential. These investigations demonstrate that the Nb coating can significantly improve the corrosion protection of uncoated Ti–6Al–4V and is thus a promising coating for the surface protection of bioimplants.

Progress in Niobium Oxide-Containing Coatings for Biomedical Applications: A Critical Review

“…Nb falls under the category of transition metals, crystallizing in a body-centered cubic (BCC) crystal lattice. 75 − 79 Table 1 lists some of the physical properties of the Nb.…”

“…Niobium (Nb) is a refractory metal, possessing high thermal stability, erosion-resistant properties, low vapor pressure, good chemical stability in a variety of hostile environments, excellent corrosion resistance, suitable tribomechanical properties, e.g., high wear resistance, excellent ductility at room temperature, favorable biocompatibility, and low thermal expansion. Nb falls under the category of transition metals, crystallizing in a body-centered cubic (BCC) crystal lattice. − Table lists some of the physical properties of the Nb.…”

Structure and Properties of DLC Films Deposited on Mg Alloy at Different C2H2 Flows of Magnetron Sputtering Process

“…Figure 4b presents the Nyquist plots of the samples. The Nyquist plots of the DLC films possess similar behavior, that the curves exhibit a single capacitive loop, indicating a typical capacitive response of the passive film [28]. The shape and diameter of the curves reflect the charge-transfer process and the corrosion resistance of the samples, respectively.…”

Biocompatible Ti 3 Au–Ag/Cu thin film coatings with enhanced mechanical and antimicrobial functionality

“…For the Nyquist plots (Fig. 13 a and c), a convenient and scientifically proven way to explain the electrochemical corrosion resistance of the thin film samples is to examine the diameters of the capacitive loops (semicircles), where a larger diameter signifies higher corrosion resistance [ 69 ] As can be seen, all samples exhibit a single capacitive loop, indicating a typical capacitive response of the passive thin films [ 70 ]. The diameters of the semicircles for the Ag and Cu doped films are larger than that for the standard Ti 3 Au thin film and increase with decreasing Ag (S Ag3 to S Ag1 ) and increasing Cu (S Cu1 to S Cu3 ) content in the film, denoting an improvement in corrosion stability, which is accordant with the potentiodynamic polarization results in Table 3 .…”