Prakt. Met. Sonderband 38 (2006) 437 
Mechanical, Tribological, and Biocompatibility Properties of ZrN- 
Ag Nanocomposite Films 
S.M. Aouadi*, Z. Kertzman*, A. Aul*, P. Basnyat*, J. Marchal****, P. Kohli**, P. Filip***, 
* Department of Physics, Southern Illinois University, Carbondale, IL 62901 
** Department of Chemistry, Southern Illinois University, Carbondale, IL 62901 
™ Center for Advanced Friction Studies, Southern Illinois University, Carbondale, IL 62901 
*** Department of Microbiology, Southern Illinois University, Carbondale, IL 62901 
Abstract 
Nanocomposite films of ZrN-Ag were produced by reactive unbalanced magnetron sputtering 
and their structural, chemical, mechanical, tribological, haemocompatibility, and anti-bacterial 
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. Films produced with optimum deposition 
conditions were worn against ball-bearing steel using a ball-on-disk tribotester in bovein 
serum and were found to have superior tribological properties compared to ZrN. 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. 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 anti-bacterial activity compared to the uncoated samples. 
1. INTRODUCTION 
In recent years, transition metal nitride (TMN) based nanocomposite films have been at the 
forefront of research in the area of protective coatings due to their superior mechanical, 
tribological, and electrochemical properties.” These enhanced properties stem from the 
ability to control phase composition, which, in turn, provides flexibility in tailoring the 
properties of the deposited materials. Such nanostructures are produced by depositing a 
multi-component film with phases that are partially or completely immiscible. Another 
advantage of multi-phase nanostructures resides in the grain refinement that results from the 
competing events of the growth of immiscible phases.’ This grain refinement hinders 
dislocation motion and crack development at interfaces and enhances ductility by grain