BS in Materials Engineering
Materials Engineering Department
AZ31B was heat treated to evoke more controlled and uniform corrosion. 1/16” diameter AZ31B wire was cut into six samples each 1” long. The samples underwent heat treatments following ASTM B661-06. Samples were weighed and placed into three different in vitro environments. In the first scenario two samples of each heat treatment were individually placed in 50 ml of saline solution at 0.9% sodium, in a static test tube at 37°C temperature. Two samples were placed in 100 ml of 0.9% saline solution in a 250 ml stirring beaker with an average whirlpool depth of 1”. Two of each sample was placed into 50 ml of saline solution at 0.9% sodium at room temperature. The final experiment placed an air cooled sample in 0.9% saline solution in a 6mm tube with a flow rate of 325ml/min at 37°C. All samples were removed at a 3 day, dried, and weighed. Mass loss was recorded, and samples were returned to solution. Samples ranged from 32% mass loss in quenched samples to 17% mass loss in the control samples (as manufactured) over fifteen days. All samples failed as possible stent candidate materials do to the unpredictability of their corrosion in both rate and uniformity. Experimental data was used to create a theoretical mathematic model and COMSOL FEA model that synthesized experimental data and physiological effects such as wall shear stress to predict the corrosion rate for future testing as well as stent geometry optimization to promote vascular health and limit the restenosis event.