Corrosion behaviour of the porous iron scaffold in simulated body fluid for biodegradable implant application.

The presented work aims to evaluate the effect of porosity on the corrosion behaviour of porous iron scaffold for biodegradable implant application. Two different types of iron scaffold samples were prepared using a newly developed process based on the amalgamation of 3D printing and pressureless microwave sintering. Random porous iron scaffold (RPIS) sample having only random microporous structure and topologically ordered porous iron scaffold (TOPIS) sample having designed interconnected macroporous structure were investigated. Dense iron sample was also prepared for comparison purpose. Microstructural and morphological characterization of the prepared iron scaffold samples were performed using scanning electron microscopy and micro-computed tomography. Three different types of pore characteristics namely large sized interconnected micropores, small sized isolated micropores and designed interconnected macropores were obtained and analyzed. The corrosion properties were assessed in simulated body fluid solution at 37 °C using polarization curves and EIS measurements. Corrosion mechanisms were established using suitable circuit models. Impedance results showed that the corrosion of porous iron scaffold samples was mainly governed by the diffusion process. Electrochemical results indicated that an increase in random microporosity and reduction in designed macroporosity resulted in an increased corrosion rate of iron scaffold.