Study on behaviour and mechanism of Cu2+ ion release from Cu bearing antibacterial stainless steel
Cu bearing stainless steels (Cu SS) possess antibacterial ability due to the release of Cu<sup>2+</sup> ions. However, the release mechanism of Cu<sup>2+</sup> ions from the steel is still unclear. Therefore, the passive film on the surface of Cu SS, the reason of Cu<sup>2+</sup> ions release and chemical reactions during Cu<sup>2+</sup> ions release were studied by means of X-ray photoelectron spectroscopy analysis and electrochemical measurements. According to the results, the release mechanism of Cu<sup>2+</sup> ions release from the Cu SS can be proposed as following: Cu rich phases in the steel promote the segregation of surrounding C and Cr to form Cr<inf>23</inf>C<inf>6</inf>, which affects the integrity and stability of the Cr<inf>2</inf>O<inf>3</inf> passive film surrounding themselves. Thus, the Cu rich phases are easy to be attacked as weak points in the corrosive media, which led to serial chemical reactions occurring while promoting the releases of Cu<sup>2+</sup> ions and playing the antibacterial role.