The Effect of Nitrided Layer on Antibacterial Properties of Biomedical 316L Stainless Steel

This study investigates the effect of the nitrided layer on antibacterial properties of biomedical stainless steel, grade 316L. The surfaces were sanded #1200 mesh papers, subsequently plasma-nitrided at a temperature of 400 °C for 2 h, which resulted in a 4.5 μm thick layer. The characterization was made using optical and scanning electron (SEM) microscopies, energy dispersive spectrometry (EDS) X-ray diffraction, and Vickers hardness testing. The antibacterial characteristic of the untreated steel and the nitrided layer was evaluated using Gram-negative Escherichia coli ATCC8739, according to Japanese International Standard (JIS) no. Z2801:2000. A single γ-phase layer was formed, supersaturated in nitrogen, increasing the surface hardness significantly by 35%. The bacterial test demonstrated that the nitrided layer presented suitable antibacterial characteristics.