Institute of Solid State Physics


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Joining of tantalum titanium by electron beam technique for medical application
P. Christoefl
Institute of Materials Science and Welding, Graz University of Technology, Graz, Austria
15:00 - 17:00 Monday 28 September 2015 Foyer Alte Technik

Titanium and titanium alloys play an essential role as biomaterials to replace bone tissue that has become diseased or damaged. Although there are good experiences with the use of titanium, an aseptic loosening of the prostheses can be observed – under certain circumstances – shortly after the implantation. This is due to the relative movements between hard tissue/bone cement and implant that provoke the formation of abrasion debris on the implant surface. The use of a coated layer can improve these properties at the surface.
The present work investigates the joining of dissimilar metals for further applications in joint-implants (i.e. joint knee, shoulder joint). A thin film of pure Tantalum in a commercial pure Titanium is welded by electron beam technique (EBW) to develop a layer, which shows improved wear resistance and fatigue strength. The electron beam is deflecting and heating on the Tantalum foil (0.05mm thickness), producing a localized melting on the surface of pure titanium. The variation of the voltage, current, frequency and time of exposition of the beam (process parameters) as well as the beam focusing on the surface and different deflection figures influence the size and the depth of the molten zone. The focused beam on the surface with high energy produces a coating layer of titanium tantalum alloy with heterogeneities in the chemical composition due to the process parameters. The use of an unfocused beam near to the surface with moderate input energy produces a thin welded layer between the titanium and tantalum foil. Cracks have been observed due to internal stresses which are generated during cooling and produce partial debonding on the joining. Moreover, the use of a raster deflection figure produces a smooth surface, thanks to a regularly energy input on the surface.