Surface modifications of Ti6Al4V by a picosecond Nd:YAG laser

Abstract

AbstractInteraction of a Nd:YAG laser, operating at wavelengths of 1064 nm (23.6 J cm−2 fluence) or 532 nm (25.9 J cm−2 fluence), and pulse duration of 40 ps, with a titanium-based medical implant Ti6Al4V alloy was studied. Surface damage thresholds were estimated to be 0.9 J cm−2 and 0.25 J cm−2 at laser wavelengths 1064 nm and 532 nm, respectively. At both laser wavelengths, the energy absorbed was mostly converted into thermal energy, forming craters, albeit about 50 times deeper at 1064 nm than at 532 nm. Periodic surface structures (PSS) were also formed with both laser wavelengths, concentric, and radial at micrometer scale (3 µm to 15 µm period), parallel at nanometer scale (800 nm period with the 1064 nm laser, 400 nm with the 532 nm laser). In the case of the 532 nm laser, the concentric structures enlarge their period with accumulating laser pulse count. These features can help roughening of the implant surface and improve bio-compatibility.