Heat treatment for bactericidal particulate silver plating on 316L stainless steel

Abstract

The paper presents the impact of heat treatment on the characteristics of the particulate silver plating on 316L stainless steel. Heat treatment was applied in Argon gas media at 500, 600, and 800 oC for 15 minutes. Advanced evaluation methods was applied as scanning electron microscopy (SEM) for surface morphology assessment, tape tests for adhesion determination of silver plating, atomic absorption spectroscopy (AAS) for released concentration of ions in the simulated body fluid (SBF). The antibacterial effect of the silver plating versus Escherichia coli was evaluated through inhibition of bacterial growth after 60 minutes of exposure. The SEM images indicated that there is no change on the grain boundaries after heat treatment. The adhesion of the silver plating increased while increasing temperature from 500 to 800 oC; and the released concentration of silver ion in SBF decreased. The antibacterial effect efficiency of silver plating was from 92 to 99 %. The released concentration of silver ion in SBF after 168 hours was in range of 0.012÷0.18337 μg/mL with average silver plating content was 6.0 mg, much lower in comparison with the allowed threshold of released concentration of silver ion in human body fluid (10 μg/mL).