Electrochemical Corrosion Behavior of Nanocrystalline β-Ta Coating for Biomedical Applications

Abstract

To explore its potential as a highly corrosionresistant coating for biomedical titanium alloys, a novel β-Ta nanocrystalline coating, composed of equiaxed β-Ta grains with an average grain size ∼22 nm, was deposited onto Ti-6Al-4V substrate using a double glow discharge plasma technique. The newly developed coating exhibited an extremely dense and homogeneous microstructure, exhibiting a strong (002) preferred orientation. The electrochemical behavior and semiconducting properties, such as donor density, flat-band potential, and diffusivity of point defects (D o ), of the passive film formed on the β-Ta coating were compared to those for both uncoated Ti-6Al-4V and commercially pure Ta in Ringer's physiological solution at 37 °C, using an array of complementary electrochemical techniques. The results showed that the β-Ta coating not only provided Ti-6Al-4V with good corrosion protection but also endowed a higher resistance to corrosive attack than commercially pure Ta in Ringer's physiological solution at 37 °C. Mott−Schottky analysis revealed that the passive film formed on the β-Ta coating had a lower donor density and flat-band potential than commercially pure Ta. The calculated values of D o for the β-Ta coating (1.45 × 10 −16 cm 2 /s) are comparable to that for commercially pure Ta (1.13 × 10 −16 cm 2 /s), both of which are 1 order of magnitude lower than that for uncoated Ti-6Al-4V (2.73 × 10 −15 cm 2 /s). Compared with commercially pure Ta, the higher corrosion resistance of the β-Ta coating results from its nanosized grains and crystallographic orientation, which promotes the rapid formation of a robust passive film with a more compact structure.

Electrochemical Corrosion Behavior of Ta2N Nanoceramic Coating in Simulated Body Fluid

“…Such two linear regions located at low and high potentials have also been reported for other metal oxides in different media [46,47,48]. This phenomenon was attributed to a transition of passive film character from semiconducting behavior to dielectric behavior, as discussed in our recent work [49]. Furthermore, it can be seen from Figure 13 that the magnitude of C sc −2 and the slopes of C sc −2 vs. E increase with increasing the E f , denoting that the donor densities ( N d ) decrease with an increase in E f .…”

Nanocrystalline β-Ta Coating Enhances the Longevity and Bioactivity of Medical Titanium Alloys

“…In the present study, the linear region at low potential was chosen to calculate the semiconductor property parameters of the passive films formed on the tested samples. It is worth noting that there is a linear region with negative slope observed on the Mott-Schottky plot of commercially pure Ta, which is related to the formation of an inversion layer as a result of an increasing hole concentration in the valence band, as discussed elsewhere [48].…”

Standardization, Calibration, and Evaluation of Tantalum-Nano rGO-SnO2 Composite as a Possible Candidate Material in Humidity Sensors

“…These methods tend to be interactive in a number of cases due to random operation cost effects. Alternative cost-effective materials like tantalum exhibit an excellent dielectric constant, high capacitive behavior, and enhanced corrosion resistance to moisture and aqueous solutions [16]. Hence, tantalum is an ideal candidate for the base substrate material for humidity sensor applications.…”