Electrophoretic Deposition of Multi-Walled Carbon Nanotube Coatings on CoCrMo Alloy for Biomedical Applications

Abstract

Carbon nanotubes are a promising material for use in innovative biomedical solutions due to their unique chemical, mechanical, electrical, and magnetic properties. This work provides a method for the development of ultrasonically assisted electrophoretic deposition of multi-walled carbon nanotubes on a CoCrMo dental alloy. Functionalization of multi-walled carbon nanotubes was carried out by chemical oxidation in a mixture of nitric and sulfuric acids. The modified and unmodified multi-walled carbon nanotubes were anaphoretically deposited on the CoCrMo alloy in an aqueous solution. Chemical composition was studied by Fourier transform infrared spectroscopy. Surface morphology was examined by scanning electron microscopy. The mechanism and kinetics of the electrochemical corrosion of the obtained coatings in artificial saliva at 37 °C were determined using the open-circuit potential method, electrochemical impedance spectroscopy, and anodic polarization curves. The capacitive behavior and high corrosion resistance of the tested electrodes were revealed. It was found that the kinetics of electrochemical corrosion of the CoCrMo electrode significantly decreased in the presence of the functionalized multi-walled carbon nanotube coating. Electrophoretic deposition was shown to be an effective, low-cost, and fast method of producing nanotubes with controlled thickness, homogeneity, and packing density.

Effect of Artificial Saliva Modification on the Corrosion Resistance and Electronic Properties of Bego Wirobond® C Dental Alloys

“…To determine the mechanism and kinetics of electrochemical corrosion occurring on After approximately 7200 s, the ion-electron equilibrium was established at the interface between the surface of the tested electrode and all the electrolytes used, resulting in a stabilized E OC value. The most negative E OC value of −317(63) mV was recorded for the CoCrMo alloy in an (1) artificial saliva solution with pH = 7.4 [30], the lowest corrosion resistance of the tested alloy. In an (2) artificial saliva solution with pH = 5.5, which simulates the inflammation of the body, the E OC value increased more than threefold, and in a physiological (7) saline solution with pH = 7.4, it increased more than one and a half times compared to the (1) artificial saliva solution with a physiological pH.…”

“…The corrosion potential (E cor ) of the tested electrode and the corresponding corrosion current density (j cor ) vary depending on the environment used. The most negative (cathodic) value was shown by CoCrMo in the (1) artificial saliva solution with pH = 7.4 (E cor = −365 mV, j cor = 1.25 × 10 −8 A cm −2 ) [30]. A strongly cathodic value of the corrosion potential was also observed in (7) saline at pH = 7.4 (E cor = −237 mV, j cor = 2.27 × 10 −9 A cm −2 ).…”

“…The phase angle shift value provides important information about the mechanism and kinetics of the ongoing corrosion processes. Obtaining the shape of Bode diagrams in the form Φ = f(logf), as shown in Figure 6, is characteristic of pitting corrosion that occurs on the passivated material [5,8,13,30]. An increase in the phase angle shift value is proportional to the increase in the corrosion resistance of the material.…”

“…(1) saliva with pH = 7.4 [30] 11.72(92) 0.74(9) × 10 The R ct parameter was characterized by the highest value of 1.59(16) × 10 6 Ω cm 2 for the electrode in the environment of artificial saliva with the addition of Listerine ® mouthwash (5), which has the strongest protective properties (Table 4). The corrosion resistance decreased successively, but it is of the same order of 10 6 in saline (7), and saliva with pH = 7.4 following the addition of Meridol ® mouthwash (6).…”