Mechanical Behavior of Bi-Layer and Dispersion Coatings Composed of Several Nanostructures on Ti13Nb13Zr Alloy

Abstract

Titanium implants are commonly used because of several advantages, but their surface modification is necessary to enhance bioactivity. Recently, their surface coatings were developed to induce local antibacterial properties. The aim of this research was to investigate and compare mechanical properties of three coatings: multi-wall carbon nanotubes (MWCNTs), bi-layer composed of an inner MWCNTs layer and an outer TiO2 layer, and dispersion coatings comprised of simultaneously deposited MWCNTs and nanoCu, each electrophoretically deposited on the Ti13Nb13Zr alloy. Optical microscopy, scanning electron microscopy, X-ray electron diffraction spectroscopy, and nanoindentation technique were applied to study topography, chemical composition, hardness, plastic and elastic properties. The results demonstrate that the addition of nanocopper or titanium dioxide to MWCNTs coating increases hardness, lowers Young’s modulus, improves plastic and elastic properties, wear resistance under deflection, and plastic deformation resistance. The results can be attributed to different properties, structure and geometry of applied particles, various deposition techniques, and the possible appearance of porous structures. These innovative coatings of simultaneously high strength and elasticity are promising to apply for deposition on long-term titanium implants.

Mechanical Behavior of Bi-Layer and Dispersion Coatings Composed of Several Nanostructures on Ti Substrate

“…The hybrid and composite coatings have higher hardness and Young's modulus, and lower maximum indent depth compared to the reference MWCNTs coating, as the addition of nanoceramics and nanometals, in general, improves mechanical properties. However, we can observe the nanohardness increase when Young's modulus decreases (regarding the reference MWCNTs coating), differently than in our previous research [47], in which the same coatings have been deposited on Ti alloy substrate. The mechanical properties of the MWCNTs_Cu coating are pretty close to the reference sample, except plastic and elastic properties, while different for the MWCNTs/TiO 2 coating.…”

“…The MWCNTs/TiO 2 contains uniformly positioned angular particles of TiO 2 , which adhere to the surface of the MWCNTs coating, while the Cu agglomerates in the MWCNTs_Cu coating are built into the MWCNTs structure. Therefore, they are almost invisible, but nevertheless influence mechanical properties of the coating, as previously observed in [47]. The areas, where the SEM image of the MWCNTs_Cu coating is blurred, are probably spaces in which the cracks of the MWCNTs coating occur.…”

“…Young's modulus (E) parameter was estimated based on the reduced Young's modulus (Er) parameter and the Poisson's ratio (v). Assuming the MWCNTs/TiO 2 and MWCNTs_Cu coatings as unidirectional composite materials, the values of v, E, and H parameters were calculated from the Halpin-Tsai (H-P) model, explained in our previous publication [47]. The volume fraction was calculated according to [48] and assuming densities of 2.10 g/cm 3 [49], 4.23 g/cm 3 [50], and 8.94 g/cm 3 [51] for MWCNTs, TiO 2 , and nanoCu, respectively.…”

“…It could be observed that the S a parameter is higher for all surfaces when using the atomic force microscopy, which could be attributed to the use of the non-contact mode AFM and thus lower accuracy. values of v, E, and H parameters were calculated from the Halpin-Tsai (H-P) model, explained in our previous publication [47]. The volume fraction was calculated according to [48] and assuming densities of 2.10 g/cm 3 [49], 4.23 g/cm 3 [50], and 8.94 g/cm 3 [51] for MWCNTs, TiO2, and nanoCu, respectively.…”

Mechanical Properties and Residual Stress Measurements of Grade IV Titanium and Ti-6Al-4V and Ti-13Nb-13Zr Titanium Alloys after Laser Treatment

“…The Ti-13Nb-13Zr alloy is an innovative material with zero toxicity to human tissues, unlike Ti-6Al-4V which contains aluminum and vanadium [ 20 , 21 , 22 , 23 ]. The advantages of this alloy include good mechanical properties, with relatively low density, excellent biocompatibility and good abrasion resistance.…”