Enhanced Surface Antibacterial Properties of Gray Cast Iron by Aging Precipitation of Cu Phase

This study aims to improve the antibacterial properties of Cu-containing gray cast iron materials through aging heat treatment. The research investigates the impact of varying Cu contents (1.2, 2.0, 2.8, and 3.6 wt.%) on the corrosion behavior and antibacterial activity of the cast iron materials. The findings indicate that aging heat treatment leads to the precipitation of nano-sized and dispersed Cu-rich phase (ε-Cu) primarily along the ferrite and pearlite grain boundaries. Consequently, the corrosion resistance of Cu-added gray cast iron is enhanced. (The corrosion media is NaCl aqueous solution.) Notably, the gray cast iron with a Cu content of 3.6% exhibits the maximum self-corrosion potential of − 0.574 V and the minimum self-corrosion current density of 5.394 × 10⁻⁵ A/cm⁻². Moreover, the Cu-rich phases, after aging heat treatment, release Cu ions upon contact with the bacterial solution. These Cu ions directly interact with bacteria in the environment, effectively eliminating bacteria on the material’s surface and thus improving the antibacterial properties of Cu-added gray cast iron. Additionally, all Cu-added gray cast iron samples exhibit an antibacterial rate of over 90% against Escherichia coli. Notably, for Cu contents ranging from 2.8 to 3.6 wt.%, the antibacterial rate against Escherichia coli may reach approximately 99%.