Biotribological behavior of Ag–ZrCxN1−x coatings against UHMWPE for joint prostheses devices

Abstract

This study aims to evaluate the structural, mechanical and tribological properties of zirconium carbonitrides (ZrCxN1-x) coatings with embedded silver nanoparticles, produced with the intention of achieving a material with enhanced multi-functional properties, including mechanical strength, corrosion resistance, tribological performance and antibacterial behavior suitable for their use in joint prostheses. The coatings were deposited by direct current (DC) reactive magnetron sputtering onto 316 L stainless steel, changing the silver content from 0 to 20 at% by modifying the current density applied to the targets. Different nitrogen and acetylene gas fluxes were used as reactive gases. The coatings revealed different mixtures of crystalline ZrCxN1-x, silver nanoparticles and amorphous carbon phases. The hardness of the films was found to be mainly controlled by the ratio between the hard (ZrCxN1-x) and soft (Ag and amorphous carbon) phases in the films, fluctuating between 7.4 and 20.4 GPa. The coefficient of friction, measured against ultra-high molecular weight polyethylene (UHMWPE) in Hank's balanced salt solution with 10 gL(-1) albumin, is governed by the surface roughness and hardness. The UHMWPE wear rates were in the same order of magnitude (between 1.4 and 2.0 × 10(-6)mm(3)N(-1)m(-1)), justified by the effect of the protective layer of albumin formed during the tests. The small differences were due to the hydrophobic/hydrophilic character of the surface, as well as to the silver content.

Functional properties of ceramic-Ag nanocomposite coatings produced by magnetron sputtering

“…7a and b. As the silver content increases, the columnar growth is gradually destroyed, and a granular aspect is achieved [2,3,40,73,83,84,90,128,130], as shown in Fig. 8.…”

“…Conversely, when the matrix is composed of a mixture of crystalline and amorphous phases (i.e., MeCN or MeC), a synergetic effect between the silver nanoparticles and the amorphous phases (mainly a-C) contributes to reducing the grain size of the crystalline part of the ceramic matrix. The C phase increases the nucleation rate of the ceramic phase (MeC(N)) and prevents its grain growth [4,26,40,42,81,83,90,88,130,131]. In Zr-C-N-Ag coatings, for instance, amorphous carbon phases have a higher impact on the reduction of the grain sizes due to their ability to encapsulate both silver nanoparticles and ZrCN grains [126], as shown in Fig.…”

“…The analysis of hardness for MeCN-Ag films is more complex because when silver is added to MeCN matrices, an amorphous carbon phase can form [4,26,42,90,130], as previously discussed. Therefore, a mixture of crystalline MeCN, amorphous carbon and silver nanocrystalline phases is created, each with specific mechanical properties that determine the final hardness of the system.…”

Wear Performance of UHMWPE and Reinforced UHMWPE Composites in Arthroplasty Applications: A Review

“…They are used popularly to enhance the performance of biomaterials. A range of properties can be improved including osteoinductive properties [93], hydrophilicity [94], mechanical and biological properties [95,96], surface properties (e.g., surface free energy) [97], and biotribological properties [94]. Surface coating by adding materials on the top surface will be briefly reviewed in the next paragraph.…”

“…More recently, nylon coating [95] on UHMWPE was reported to achieve lower cytotoxicity, less wear debris-induced osteolysis, and superior mechanical properties compared to neat UHMWPE. Zirconium carbon nitrides (ZrCxN1-x) coatings with embedded silver nanoparticles [94] were used as a surface modification option for multifunctional purposes including antimicrobial effect, corrosion resistance and maintaining or even improving their mechanical and tribological performance. Hydrogenated diamond like carbon (DLCH) coating has been also tested on UHMWPE with a good performance on the wear resistance, hardness and biocompatibility [99].…”