Conception, développement et validation d'alliages métalliques dégradables utilisés en chirurgie endovasculaire
|Advisor:||Mantovani, D.; Dubé, Dominique|
|Abstract:||This doctoral project permitted for the first time to design, develop and study metallic alloys as degradable biomaterials. Between 2001 and 2003, commercially pure iron and magnesium alloys were evaluated for their possibility to become degradable biomaterials. In those studies, it was found that their mechanical property and degradation behaviour were not clinically well suited. In this context, a series of Fe–Mn alloys was produced with the objective to obtain physical and mechanical properties similar to those of stainless steel 316L (SS316L) and degradation behaviour more suited in human physiological environment than pure iron and magnesium alloys. Four alloys with manganese content ranging between 20 and 35 wt% were prepared via a powder metallurgy route followed by a series of cold rolling and resintering cycles. Results showed that their microstructure was mainly composed of austenitic phase with the trace of martensitic phase in alloys having lower manganese content. This microstructure resulted into a nonmagnetic behaviour of the alloys with magnetic susceptibility lower than that of SS316L. In contrast to SS316L, this magnetic susceptibility remained constant after having plastic deformation. The alloys showed mechanical property approached to that of SS316L. As manganese content increased, the yield strength decreased from 420 to 210 MPa and the elongation increased from 5 to 32%. The alloys degraded in simulated coronary artery conditions by the mechanism of corrosion. Their average corrosion rate was faster than that of pure iron and slower than magnesium alloys. The degradation products constituted of iron hydroxides and calcium/phosphorus containing layers which adhered onto the substrate. The release of iron and manganese ions into the solution was limited by the insoluble degradation layer. The cell viability assays showed that the Fe–Mn alloys possess a low inhibition effect to fibroblast cells metabolic activities demonstrating their potentiality to be a biocompatible degradable biomaterial.|
|Document Type:||Thèse de doctorat|
|Open Access Date:||16 April 2018|
|Collection:||Thèses et mémoires|
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