Carbon nitride thin films as protective coatings for biomaterials: Synthesis, mechanical and biocompatibility characterizations

Amorphous carbon nitride thin films have been deposited on Ti6Al4V by radiofrequency magnetron sputtering and by plasma immersion ion implantation (PIII). The aim of this study is to identify deposition conditions for which the mechanical and biological properties of deposited films can lead to application in biocompatible protective coatings. In magnetron sputtering, the target is made of graphite and the plasma is a mixture of argon and nitrogen. In PIII process, the deposition mechanism is a combination of an implantation-diffusion process and a chemical vapor deposition using a CH4 and N-2 plasma. The process has been shown to lead to the deposition of a carbon nitride coating. The mechanical properties have been investigated using in situ tensile tests performed in a scanning electron microscope. The study focussed particularly on the first steps of the damage process. The surface energy has been assessed by the drop contact angle measurements and surface is shown to be hydrophilic. This explains the good biological behavior determined by in vitro cell adhesion kinetics. (C) 2002 Elsevier Science B.V. All rights reserved.