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CO₂-Laser-Assisted Surface Modification of Titanium Alloys for Biomedical Applications

S. Gräf, F. A. Müller

Friedrich-Schiller-University of Jena, Otto-Schott-Institute of Materials Research (OSIM), Löbdergraben 32, 07743 Jena, Germany

received June 24, 2014, received in revised form August 5, 2014, accepted August 23, 2014

Vol. 5, No. 4, Pages 281-286   DOI: 10.4416/JCST2014-00022

Abstract

The surface of Ti₆Al₄V alloys was activated by means of selective laser microstructuring and subsequent sintering of hydroxyapatite (HAp) nanopowders into the generated structures. For structuring, a novel Q-switched CO₂ laser with pulse durations of about 400 ns and a peak power of up to 7 kW was used. This laser system provides defined blind-holes with structural sizes in the range of 100 – 500 μm. The influence of different process gases (Ar, O₂, N₂) on the formation of titanium oxide (TiO₂) and titanium nitride (TiN) interfaces during laser structuring was investigated with glow discharge optical emission spectroscopy (GDOES). HAp nanopowders prepared via a wet-chemical synthesis route were subsequently sintered into the generated structures using a CO₂ laser with continuous radiation intensities up to 240 W/cm². The homogeneously sintered structures consist of HAp as the major phase and minor amounts of tricalcium phosphate (TCP) and tetracalcium phosphate (TTCP). The formation of TCP and TTCP during laser sintering can be minimized by adjusting sintering parameters (time, laser intensity) and by applying additional process gases (O₂, Ar).

Keywords

CO₂-laser surface structuring, titanium alloy, bioactivation, laser sintering, hydroxyapatite

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