Characteristics of silver-dopped carbon nanotube coating destined for medical applications

Carbon nanotubes are materials demonstrating outstanding mechanical, chemical, and physical properties and are considered coatings of titanium implants. The present research is aimed to characterize the microstructure and properties of the multi-wall carbon nanotubes (MWCNTs) layer decorated with silver nanoparticles (Ag NPs) on the Ti13Nb13Zr alloy destined for long-term implants. The electrophoretic deposition of coatings was performed in a two-stage process, at first at 0.25 wt. pct. of MWCNTs, and next at 0.30 wt. pct. of Ag NPs content in the bath. The SEM, EDS, AFM, Raman spectroscopy, nanoindentation tests, nano-scratch test, wettability assessments, and corrosion tests were carried out. The effects of the presence of Ag NPs onto the MWCNTs coating were observed as the roughness increased to 0.380 µm and thickness to 5.26 µm, the improved adhesion and corrosion resistance, the water contact angle of 62.94°, the decreased nanohardness, Young`s modulus and resistance to plastic deformation under load, and slightly improved adhesion. The obtained results can be explained by a specific two-layer structure of the coating, in which the Ag NPs agglomerates create the coating less porous and permeable, but softer structure. Future research will focus on the improvement of the adhesion of the component coatings in different ways.