Enhancement of the Wettability Characteristics of a Nickel-Titanium (NiTi) Medical Implant Alloy by Laser Surface Alloying with Molybdenum (Mo) and Niobium (Nb)
K.W. Ng, J. Lawrence, H.C. Man, T.M. Yue and D.G. Waugh
The factors responsible for modifications to the wettability characteristics of a nickel-titanium (NiTi) medical alloy following CO2 laser treatment were considered in this work. These modifications have been investigated in terms of the changes in the surface energy components, the surface topography and the surface chemical composition profile. Contact angles, θ, were measured by the sessile drop technique using water and diodomethane. The surface chemical profiles were determined using non-contact confocal point gauge and energy-dispersive X-ray (EDX). It was found that the surface roughness is the factor influencing the wettability characteristics, a critical point was predicted as the transition point from improving to degrading the surface energy with the increasing in surface roughness. θ measurements revealed that the laser-alloyed NiTi exhibited a considerable reduction in θ, implying that laser surface alloying technique improved the wettability characteristics of this material.
Keywords: CO2 laser, laser alloying, wettability, contact angle, surface energy, nickel-titanium (NiTi) alloy, implant