Investigation of Biodegradability of Wrought Mg-Ca-Mn Alloy as a Potential Material for Urological Applications

After numerous surgeries in the urinary system, stenting is often required to ensure complete urine discharge, prevent urine from flowing back into the kidneys, and maintain proper urine flow to avoid renal failure. The stents currently used in medical centers are primarily polymeric. Over time, the surface of these stents becomes covered with a crystalline layer and bacterial colonies, which, without secondary care, leads to reduced mechanical properties and potential infection. To address these issues, biodegradable stents have been introduced as an alternative. This research investigates the magnesium alloy, specifically the Mg-Ca-Mn alloy, as a biodegradable material for this purpose. Given the limited formability of magnesium alloys, rolling was selected as the fabrication method for the stents. Samples were rolled from an initial thickness of 5.0 mm down to 0.4 mm with a preheating duration of 10 minutes. The grain size of the specimens after rolling was significantly reduced from 200 ± 30 µm to 17 ± 5 µm. This reduction in grain size resulted in a notable increase in yield and ultimate tensile strength, from 108.30 ± 3.60 MPa to 231.45 ± 17.17 MPa. The microstructure and texture of the material were evaluated using optical microscopy, X-ray diffraction, and electron backscatter diffraction. The results indicate a significant reduction in grain size following rolling, along with changes in dislocation density and texture, as revealed by EBSD data. These factors contribute to a higher surface potential, leading to a higher corrosion rate in the initial seconds of the corrosion process. Nevertheless, a protective layer forms rapidly, thereby controlling the corrosion rate sooner and resulting in lower rates over time. The average corrosion rates calculated from hydrogen evolution and weight loss studies in artificial urine over 14 days, and from polarization assessments, were 0.889 mm/y, 1.616 mm/y, and 2.402 mm/y, respectively. Consequently, the stent produced through this process is expected to fully degrade within 10-12 weeks.