Degradation of biodegradable metallic intravascular stents and roughness analysis

Cardiovascular disease is the leading cause of death worldwide for both men and women. For instance, over 17 million people die of this disease every year, this is one death over four. It is also almost twice the number of people dying because of cancer. The most frequent type of heart disease is the coronary heart disease which can be remedied thanks to cardiovascular stents. In view of this, we understand why research in cardiovascular stents is crucial and meaningful. Nowadays, cardiovascular stents are mainly being made of long lasting materials such as, stainless steel, cobalt-chromium alloys and titanium~\cite{jadhav2002bioresorbable}. These materials are being used for their biocompatibility, good corrosion resistance and appropriate strength and ductility. However, this permanent implantation has some drawbacks such as thrombosis, restenosis, chronic inflammation, ect. An other issue for permanent implantation is their inability to adapt to growth of blood vessels. Furthermore, It is frequently asserted that a stent is not permanently needed\cite. Indeed thanks to the mechanical stresses generated by the stent, the arterial wall is likely to remodel. This is why the study of bio-degradable materials for stent is significant. Currently, polymer and metals are the most employed materials for biodegradable stents. For the latter the exact degradation is not always well understood and this will be the topic of this master thesis. More specifically, this work is going to focus on the study of two bio-degradable metals, pure iron and TWIP, and more concretely on there roughness behaviour through the process of degradation. A part of this work will be focusing on the data gathering. While another part is dedicated to the roughness analysis. For that purpose a step by step procedure including different software will be proposed in order to compute the roughness of the sample based on CTscan set of images.