Mechanical, tribological, and biocompatibility properties of ZrN‐Ag nanocomposite films

Abstract

Nanocomposite films of ZrN-Ag were produced by reactive unbalanced magnetron sputtering, and their structural, chemical, mechanical, tribological, haemocompatibility, and antibacterial properties were studied as a function of film composition. The films formed a dense and homogeneous microstructure whereby nanocrystals of Ag are distributed evenly throughout the ZrN matrix. For small additions of silver, the hardness was found to increase, whereas the elastic modulus was found to decrease drastically. In the process of optimizing the deposition conditions, three kinds of coatings were prepared on 316 L surgical steel and tested by accelerated electrochemical polarization tests in order to detect the influence of Ag and the value of the bias potential on the corrosion performance of the system. Films produced under the optimum deposition conditions were, subsequently, deposited on medical grade Ti-Al-V and worn against ball-bearing steel using a ball-on-disk tribotester in bovine serum and were found to have superior tribological properties compared with single-phase ZrN coatings. The haemocompatibility of the films was assessed by investigating the adsorption of human serum albumin and fibrinogen on samples with different phase compositions. Quantification of the protein adsorption was carried out using spectroscopic ellipsometry, which confirmed the haemocompatibility of the films. Antibiotic activity of the films was quantified by incubating the films in bacterial cultures, namely, Staphylococcus epidermis, Staphylococcus aureus, and Escherichia coli. Films with a silver content > 10% exhibited superior antibacterial activity compared with the uncoated samples.

Ceramics and ceramic coatings in orthopaedics

“…Other hard ceramic coatings were subsequently introduced, including zirconium nitride (ZrN) on a cobalt chromium (CoCr) substrate [134] and titanium niobium nitride (TiNbN) also on CoCr [135,136]. These single or mixed nitride coatings are nano-crystalline and have thicknesses in the range of 1 m to 15 m. All have been shown to be biocompatible [123][124][125][126][127][136][137][138][139], and they are currently used or considered for use as hip resurfacing implants, for total hip arthroplasty, or as femoral knee components. In 1997 another new metal-ceramic composite was introduced via clinical trials [140,141].…”

Accelerated bacterial reduction on Ag–TaN compared with Ag–ZrN and Ag–TiN surfaces

“…Due to the similar radii, it is possible to discard nitride cation size considerations to rationalize the observed effect. But there is a significant difference in the potentials of TaN undergoing Ta 5+ /Ta 6+ redox reactions compared to TiN and ZrN undergoing M 3+ /M 4+ redox reactions [23][24][25][26][27][28][29][30][31][32][33][34]29]. The oxidation-reduction potential values for the Ta, Ti and Zr depend heavily on the nature of the composite compound they are found.…”

“…For this reason we investigate in the present study the bacterial reduction by Ag-TaN nanoparticulate films. The bacterial reduction performance is presented for Ag-TaN and compared to Ag-TiN [20][21][22][23][24][25] and Ag-ZrN [26] films. The films prepared in our laboratory were performed under similar experimental conditions [20,26].…”

Electronic and crystal structure and bonding in Ti-based ternary solid solution nitrides and Ti–Cu–N nanocomposite films

“…a single-phase compound) or as nanocomposites (i.e. consisting of at least two phases), consisting of at least one transition metal, such as: 1) blending two IVb-Vb-VIb metals and nitrogen to form solid solution nitride compounds (with Ti x Zr 1 − x N being the most widely studied) in an effort to improve further their properties [17][18][19][20][21][22][23][24][25][26][27][28][29][30], 2) blending one IVb-Vb-VIb metal, one noble metal (or Ni) and nitrogen to form nanocomposites consisting of a metallic and a ceramic phase [31][32][33][34][35][36][37][38][39][40][41][42][43], 3) blending one IVb-Vb-VIb metal, one group IIIa-IVa (Al, B, Si) element and nitrogen to form either a metastable solid solution nitride phase in a limited compositional range, or superhard nanocomposites consisting of two ceramic phases, which are not topologically compatible, such as nc-TiN/a-SiN x , [1,2,[44][45][46][47][48][49][50][51][52][53][54][55][56][57]…”