Influence of the Silver Content on Mechanical Properties of Ti-Cu-Ag Thin Films

Abstract

In this work, the ternary titanium, copper, and silver (Ti-Cu-Ag) system is investigated as a potential candidate for the production of mechanically robust biomedical thin films. The coatings are produced by physical vapor deposition—magnetron sputtering (MS-PVD). The composite thin films are deposited on a silicon (100) substrate. The ratio between Ti and Cu was approximately kept one, with the variation of the Ag content between 10 and 35 at.%, while the power on the targets is changed during each deposition to get the desired Ag content. Thin film characterization is performed by X-ray diffraction (XRD), nanoindentation (modulus and hardness), to quantitatively evaluate the scratch adhesion, and atomic force microscopy to determine the surface topography. The residual stresses are measured by focused ion beam and digital image correlation method (FIB-DIC). The produced Ti-Cu-Ag thin films appear to be smooth, uniformly thick, and exhibit amorphous structure for the Ag contents lower than 25 at.%, with a transition to partially crystalline structure for higher Ag concentrations. The Ti-Cu control film shows higher values of 124.5 GPa and 7.85 GPa for modulus and hardness, respectively. There is a clear trend of continuous decrease in the modulus and hardness with the increase of Ag content, as lowest value of 105.5 GPa and 6 GPa for 35 at.% Ag containing thin films. In particular, a transition from the compressive (−36.5 MPa) to tensile residual stresses between 229 MPa and 288 MPa are observed with an increasing Ag content. The obtained results suggest that the Ag concentration should not exceed 25 at.%, in order to avoid an excessive reduction of the modulus and hardness with maintaining (at the same time) the potential for an increase of the antibacterial properties. In summary, Ti-Cu-Ag thin films shows characteristic mechanical properties that can be used to improve the properties of biomedical implants such as Ti-alloys and stainless steel.

Biocompatibility and antibacterial properties of TiCu(Ag) thin films produced by physical vapor deposition magnetron sputtering

“…After the flame sterilization test, no change was observed in the mechanical properties of thin film, consistent with a previous report [33]. All the samples were analyzed by XPS spectroscopy before and after flaming with alcohol (flamed samples will be labelled (F) in the following text).…”

“…As we can observe in Figure 3A and 3B, the addition of Ag into the TiCu(Ag) thin films induced a decrease of both modulus and hardness, with the lowest values of modulus (109.25 GPa) and hardness (6.45 GPa) observed in the sample containing 30% of Ag. The very good adhesion of the coating layer has been addressed in a previous article [33].…”

A state-of-the-art review of the fabrication and characteristics of titanium and its alloys for biomedical applications

“…One of the techniques for surface modification to improve the biocompatibility and antimicrobial properties of titanium is silver coating by PVD. Several researches have been conducted to develop antimicrobial coatings with titanium and silver using PVD [ 162 , 163 ]. Some of the recent studies investigated the mixed system of anodization and PVD to improve the titanium/silver coating, and the results showed the deposition of Ag 2 O on the edges of highly ordered TiO 2 nanotubular arrays (schematic shown in Fig.…”

Synthesis, Characterisation and Antibacterial Properties of Silicone–Silver Thin Film for the Potential of Medical Device Applications

“…According to the tensile test, crystallite grains or interconnection between the grains could play a major role in the tensile properties [86,87]. Although crystalline materials are stiffer due to grain-boundary-related hardening, other factors such as larger-sized of grains could lead to greater collisions between particles and consequently the breaking point [88]. Moreover, Kong et al [89] asserted that the stress-concentration phenomena of Si films caused by the lack of particle or matrix adhesion of Ag could lead to reductions of elongation and tensile stress.…”