Production of titanium nitride coatings by physical vapor deposition in titanium alloys obtained by powder metallurgy

Abstract

Titanium alloys are attractive materials for the manufacture of implants for medical and dental applications due to their superior biocompatibility and outstanding corrosion resistance compared with other conventional metallic materials. Commercially pure titanium and Ti-6Al-4V alloy are the most used materials for the manufacture of implants. Due to the controversy concerning potential toxic effects of vanadium compounds, V-free alloys have been recently developed for biomedical applications. Powder metallurgy (PM) of titanium and Ti-based alloys may lead to the obtainment of components having weak-to-absent textures, uniform grain structure and higher homogeneity compared with conventional wrought products. Also, new PM-based manufacturing techniques, including near-net-shape consolidation and metal injection molding (MIM) offer an increasing potential for the application of titanium and its alloys. Within this scenario, the production of the titanium alloy by PM starting from blended elemental (BE) powders might be a cost-effective route considering its lower costs (a necessary prerequisite to expand the use of titanium and its alloys), versatility and also for allowing the manufacture of complex parts.An important obstacle for the wide application of titanium in surgical implants is its low wear resistance. A way to increase the wear tolerance of titanium alloys is by the production of titanium nitride (TiN) coatings from physical vapor deposition (PVD). The Materials Division (CTA/AMR) is a reference center in titanium research. In this direction, throughout some years, diverse equipments had been acquired. Amongst them, a uniaxial hot press is an important equipment in the current researches, acting in the sintering and densification of the materials in inert atmosphere or vacuum.This way, it was showed the importance of the technological development in order to produce TiN coatings in titanium alloys obtained by powder metallurgy (P/M). The present work has for objective the development of TiN coatings obtained by physical vapor deposition (PVD) via an electron bean furnace in titanium alloys produced by P/M for surgical implants (used as substratum), including microstructural characterization and study of the film stability and the interactions in the ceramic/metal interface, using wear and adesion tests. To reach these objectives is necessary to modernize the press and to use it as a more efficient instrument in the temperature control and materials densification, aiming the effective production of titanium alloys for surgical implants. (AU)