The actual challenge in the orthopaedic surgery is to obtain orthopaedic implants with good mechanical, physical, chemical and surface compatibility with the bone. But the difficulties are remarkable, because these characteristics fail in time and, in general, it is difficult for a single material to have all the required properties.
The main goal of the present project is to give innovative solutions to increase the service life of load bearing implants by:
• Preparation in a levitation melting furnace of a novel type of alloy consisting of only biocompatible elements (Ti, Zr, Nb), in order to replace Ti6Al4V, the most popular alloy in the present, but which consists of elements (Al, V) causing cytotoxic and allergic reactions. The novel alloy is I nsystem Ti-Zr-Nb. It is expected that an optimum Nb content in the alloy composition will be found, for achieving a Young’s modulus close to that of the bone, which was an important target for the researchers in the last two decades.
• Preparation of novel types of osteoconductive coatings, by magnetron sputtering method,as follows:
- osteoconductive coatings in mono (type 1) and bilayer (type 2) structures, in order to enhance the osteoconductive capability of the TiZr30Nbx alloy:
• type 1: MeC+IA (Me-metal, C-carbon, IA-inorganic additive), by addition in the MeC film composition (Me = Ti, Zr, Nb) of small amounts of various IA (Ca3(PO4)2, TiSi);
• type 2: MeC/(IA + TiO2), where IA is Ca3(PO4)2 and MeC is the bottom layer and (IA+TiO2) is the top layer. It is expected that such structures will reveal an optimum combination of the coating microhardness, adhesion, residual stress, toughness, friction, corrosion-wear resistance, osteoconduction and biocompatibility. The MeC films are produced to enhance the adhesion of the osteoconductive coatings to metallic substrates, because the films consist of elements which are found in the bioalloy composition.
- use of a complex magnetron set-up, containing a high vacuum system and equipped with 5 different cathodes made of pure metallic or alloyed targets, able to work simultaneously or alternatively.