316L Stainless Steel Sensitization in Carbon Nanotube CVD Growth for Bacterial Resistance

Physically altering the micro-topography of a surface can dramatically affect its capacity to support or prevent biofilm growth. Growing carbon-infiltrated carbon nanotubes on biomedical materials is one such approach which has proven effective. Unfortunately, the high temperature and carbon-rich gas exposure required for this procedure has proven to have deleterious effects. This paper proposes a kinetic model to explain the rusting phenomenon observed on 316L stainless steel substrates which have undergone the chemical vapor deposition process to grow carbon-infiltrated carbon nanotubes. The model is derived from Fick’s Second Law, and predicts the growth of chromium carbide as a function of temperature and time. Chromium carbide formation is shown to be the mechanism of corrosion, as chromium atoms are leeched from the the matrix, preventing the formation of a passivating chromium oxide layer in place of problematic iron oxide (rust) formation. The model is validated using experimental methods, which involve immersion in bacteria culture, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX).