Enhanced Antibacterial Properties of Copper Surfaces Using Cold Spray Shot Peening

Metal surface characteristics play a significant role in interacting with their biological environment. Stainless steel is commonly used in a wide range of biomedical applications due to its good biocompatibility properties and excellent mechanical properties such as corrosion resistance. Copper surfaces also have been identified for their antimicrobial properties. Improvement of antibacterial and antiviral performances can be tailored by surface microstructure modification. Severe plastic deformation is an effective surface modification procedure to improve the mechanical performances of metal surfaces. This technique can be adapted to obtain surface grain refinement. In this work, cold spray shot peening is used to modify copper and stainless steel substrates surface and study the effects on their antiviral/antibacterial properties. To modify the grain structure of copper and stainless steel, different shot-peening parameters were examined and the microstructure of the surfaces was investigated employing optical and scanning electron microscopy. The bactericidal activity of copper and stainless steel substrates after shot peening treatment is discussed and a comparison between the bacterial load on treated and untreated surfaces is provided. Bio testing of the surfaces after their exposure to the biological environment demonstrated that the inactivation time was shorter for surfaces that had undergone grain refinement.