Efeito do tratamento de superfície a laser em ligas Ni-Ti utilizadas em próteses endovasculares.

Abstract

Some materials have the ability to change shape or size, simply adding a little heat, or change from a liquid to a solid almost instantly when a magnet is near. These materials are called smart materials. Shape Memory Alloys (SMA) have the character to recover its original state after being deformed beyond its elastic limit, differing from general materials, which have permanent plastic deformation. The scientific and technological interest devoted to NiTi alloys is very high due to their unique properties such as shape memory mechanical (superelasticity associated with high pure elastic deformation), thermal shape memory (related to the shape recovery upon heating the material), pseudo-plasticity (associated with high bendability of the material, without fatigue and fracture) and biocompatibility (related to the high corrosion resistance and excellent compatibility quote. In this paper the SMA of NiTi alloy is obtained through the process PSPP (plasma skull push-pull), using small amounts of metal components quickly heated in a copper crucible in a plasma torch and injected into a rotating metal mold. The homogeneity of the EMF was obtained from five mergers and mergers before re-injection (1173 K homogenization at a level of 900 s with subsequent cooling in water). Regarding the super-elastic phase, in crystalline form, Tα varies from 45.50 º C to 90 º C, so if Tα is lower than body temperature to EMF can be used in medical applications such as vascular stents. The selected alloy (Ni-Ti Equation) were subjected to a surface treatment by Nd: YAG laser (λ = 1.064 mm) in air and under certain fluency. Samples of this alloy were characterized using optical microscopy (OM), scanning electron microscopy (SEM), x-ray diffraction (XRD), differential scanning calorimetry (DSC), rugosimetric laser (RL). The results showed that EMF had obtained a large hysteresis as a function of temperature, justifying the potential application of these alloys in intravascular devices, as well as in laser surface treatment on certain parameters of creep employees, allows these devices to maintain their biocompatibility, without change its original features.