Study on the influence of porosity and medium flow on the corrosion behavior of sheet-gyroid porous structures formed by LPBF

In this paper, the corrosion resistance of sheet-gyroid porous structures with different porosities formed by LPBF under static and dynamic conditions was studied, and the mechanism of influence of medium flow on corrosion resistance was explored based on CFD simulation. It was found that the corrosion resistance of porous structures decreased with the increase in porosity in static and dynamic environments, which was mainly related to the increase in forming defects and the decrease in forming quality as the wall thickness of porous structures decreased with the increase in porosity. Under dynamic electrolyte conditions, the wall shear stress generated by the flowing medium on the surface of the porous structures will reduce the stability of the oxide film and increase the corrosion rate. The porous structures exhibited greater corrosion damage in the dynamic electrolyte solution. Based on CFD simulation analysis, it was found that with the increase in porosity, the channel size of porous structures increased, the curvature decreased, the average wall shear stress decreased, and the influence of medium flow on the corrosion rate of porous structure gradually decreased. The relationship model between average wall shear stress and corrosion rate growth rate was established, which provided data support for the subsequent design of porous structures for bone implantation. During the corrosion process, α-Ti and Ti₂Cu phase form micro-galvanic corrosion, and the preferential dissolution of Ti₂Cu phase leads to the gradual release of Cu²⁺, which is conducive to improving the antibacterial performance of Ti–Cu implants.