Corrosion properties of Fe–24Cr stainless alloy modified by plasma immersion ion implantation in 0.5 M sulfuric acid solution

Ruthenium (Ru) and mixed Ru–Ti ions were implanted respectively into ferritic Fe–24Cr alloy using the plasma immersion ion implantation (PI3) technique. Potentiodynamic and potential-time response measurements were used to characterize the corrosion behavior of Fe–24Cr alloy exposed to a deaerated sulfuric acid solution. The results showed that the ferritic alloy does not passivate in dilute sulfuric acid. However, plasma-implanted Ru ions can induce spontaneous passivation of the alloy exposed to a sulfuric acid solution. X-ray photoelectron spectroscopy (XPS) analysis showed that Ru is incorporated as Ru4+ species in the hydrated chromium oxyhydroxide passive film formed on the Ru-implanted Fe–24Cr alloy.