Portal de Periódicos da CAPES

The impact of structure and temperature on the mechanical properties and radiopacity of Ta-W coatings for tiny endovascular medical implants

2023; Elsevier BV; Volume: 297; Linguagem: Inglês

10.1016/j.matchemphys.2023.127342

1879-3312

Samira Ravanbakhsh, Carlo Paternoster, P. Mengucci, Pascale Chevallier, Sofia Gambaro, Théophraste Lescot, Chiara Paoletti, Vinicius Sales de Oliveira, Marcello Cabibbo, Marc‐André Fortin, Diego Mantovani,

Advanced materials and composites

The trackability of tiny endovascular medical implants (TEMIs) during and after surgery is a crucial parameter for their accurate implantation and after surgery follow-ups. In this work, novel radiopaque Ta-W coatings were produced by magnetron sputtering deposition and further investigated with the aim to improve X-ray visibility of TEMIs under fluoroscopy imaging. Different deposition strategies, named micro-multilayer (Micro-ML), nano-multilayer (Nano-ML) and co-deposition (Co-dep), and different substrate temperatures (25 °C and 600 °C) were implemented which allowed to tune the morphology, mechanical properties and radiopacity of the coatings, while avoiding the formation of brittle phases, such as β-Ta and β-W. Ta-W coatings produced at high temperature (600 °C) contained stable phases such as α-Ta (bcc) and α-W (bcc), without brittle phases such as β-Ta and β-W. However, traces of β-W and β-Ta were detected in the group of samples produced at low substrate temperature (25 °C). The elastic modulus and the hardness of Micro-ML and Nano-ML were found to increase with increasing temperature, whereas they decreased in the case of samples produced by the Co-dep condition. The chemical state of Ta as well as the proportion of oxidized Ta (Ta-O) detected on all coatings were found to change as a function of the substrate temperature and deposition strategy. Samples with the highest amount of Ta-O at their surfaces showed the lowest corrosion potential. Finally, the samples produced by Micro-ML strategies performed on 600 °C substrates and irradiated according to radiographic imaging of conditions comparable to that of fluoroscopy, exhibited an X-ray contrast improvement of 82%/μm, which was higher than what was found in all other samples. Higher volume fractions of α-W in the coatings resulted in higher X-ray attenuation potential for photons in the energy range typical of fluoroscopy. Overall, the production of Ta-W coatings by the Micro-ML strategy and performed with a substrate temperature of 600 °C seems an optimal approach for the production of highly visible TEMIs in X-ray imaging.