The Project aim The aim of this project is the development of ion-plasma synthesis processes of nanostructured coatings based on carbon and titanium nitride for medical implants. For the deposition of coatings, modern high-CVD and PVD methods will be used, particularly modified PECVD and vacuum-arc deposition of filtered plasma. They plan to determine the dependence of structural, mechanical, electrochemical and tribological characteristics of coatings on the parameters of the synthesis process. Improving the quality of coating is planned due to doping and optimizing their composition, synthesis and deposition of transition layers in the conditions of supply of high-voltage pulsed bias potential to the substrate.
The main feature of the new millennium - the growing interest in increasing the quality and length of human life. Achieving this goal requires, in particular, to provide materials for artificial organs and tissues. Many medical devices, such as hip and knee joints, coronary stents, heart valves, intraocular lenses implanted in the human body. Despite significant progress in the development of these devices, there are a number of factors, significantly reducing implant functioning life in the body. Physiological fluid represent an aggressive medium for implants. Articular implants are subjected to sliding wear. Interaction of the implants with tissues and cells, products of corrosion and wear debris may have adverse effects on the body and implants.
Prevent or ease the above problems and to prolong the service life of implants allows application to their surface the protective coatings, which may reduce the corrosion and wear. At present, the most promising coatings for these purposes are ion-plasma coatings based on nanostructured diamond-like carbon (DLC) and titanium nitride, which are successfully used for hardening of surfaces in the manufacture of cutting tools and machine parts for very long time.
It’s proved that diamond-like carbon and titanium nitride coatings are characterized by chemical inertness, corrosion and wear durability, biocompatibility as well as they have bactericidal and athrombogenic properties.There are two main directions for using such coatings in medicine. Firstly, as a barrier layer on bio-inert implants, made of materials, which can cause negative reaction in the organism. Secondly, as tribological coatings in friction pairs of joints. First of all, the reason is the recent achievements in the field of ion-plasma technology, which allow to form nanostructure coatings and acquire a unique properties that’s hardly used for medical application.
Despite the significant potential of the coatings usage in medicine their actual use in clinical practice is still quite limited. The responses are contradictory. In addition, not enough to move the technologies, developed for the problems of mechanical engineering, to medical devices. It needs the creation of deposition technology especially for medical devices where they should pay more attention to the following issues: coatings biocompatibility, increasing their corrosion durability, reduced coefficient of friction, increased wear resistance, ensure high adhesion level while applying to the alloys, which are traditionally used for implants.
An important factor is the choice of the optimal thickness of the coating, which will provide high protective properties without impairing adhesion.
There will be held tests of the model samples of friction pairs “carbon-carbon” and “carbon-nitride” on the special stands. It’s supposed to study the products of wear (wear debris) in friction pairs and investigate their cytotoxicity in vitro tests. The comparative analysis of the characteristics of carbon coatings made by different methods will be carried out. With the test results the deposition process for coating medical implants will be optimized.
Expected results and their application.
As a result, research is planned to obtain new experimental data of a world-class about the features processes obtaining and investigation the properties of nanostructured carbon coatings, nitride and oxide coatings synthesized by modified plasma CVD method and the vacuum-arc deposition of filtered vacuum-arc plasma. It is supposed to find out what the conditions of the deposition process promote synthesis of solid coatings with good adhesion and high wear resistance suitable for the manufacture of medical implants.
Scope of activities The research is planned to realize by the following steps:
- modification of installations for coatings deposition by plasma CVD method and from filtered vacuum-arc plasma;
- synthesis of nanostructured carbon coatings, nitride and oxide coatings;
- investigation of mechanical, tribotechnical properties and biocompability of nanostructured carbon coatings, nitride and oxide coatings;
- evaluation and prediction for application of nanostructured carbon coatings, nitride and oxide coatings for medical implants;
- presentation of results to the international scientific community;
- preparation of reports.
