Sinergistic effect of ion implantation as a surface modification technique to improve localised corrosion of AISI 304 austenitic stainless steel

Ion implantation allows the formation of special alloys capable of slowing down the corrosion process at the metal surface without alteration or sacrifice of the bulk properties. In this work, the effect on the corrosion behaviour of silicon, nitrogen and argon ion implantation on AISI 304 is discussed where a 1×1015 ions/cm2 implantation dose at 80 keV was used. Silicon and nitrogen, as alloying elements, are known to improve the localised corrosion resistance of austenitic stainless steels in chloride media. Their effect as implanted elements has met different degrees of success depending on the implantation conditions. Argon implantation was also carried out to confirm whether the modifications produced on the materials behaviour are mainly due to the chemical effect of the implanted element or to the physical changes produced during the implantation process. Additionally, a multiple Si+N implantation was performed in the same conditions in order to find the response of this combination in the corrosion resistance of AISI 304. Theoretical simulations using TRIM96 computer code have been performed to estimate the depth profiles of the implanted elements. The corrosion measurements were carried out in NaCl solution by using Electrochemical Impedance Spectroscopy (EIS). The experimental results show that an improvement on the corrosion behaviour of AISI 304 could be achieved in these conditions.