Changes in the composition and corrosion-electrochemical properties of the chromium-nickel steel 03Cr18Ni11 during implantation of argon, oxygen and nitrogen ions

Abstract

The effect of implantation of argon, oxygen and nitrogen ions on the physicochemical structure of the surface and the corrosion-electrochemical behavior of chromium-nickel steel 03Cr18Ni11has been studied. Methods of electrochemical polarization (EP), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) were used. Ion implantation of argon, oxygen and nitrogen leads to an increase in the corrosion resistance of steel 03Cr18Ni11 both in a neutral environment and in the presence of a corrosion activator (chloride anions), while irradiation with argon ions is most effective. It was found that after implantation of argon ions, a partial etching of the steel surface occurs, i.e. an increase in the true surface. This, in turn, facilitates the onset of the passive state. At the same time, the use of oxygen and nitrogen ions leads to smoothing of the surface. AFM data indicate that the studied steel treated with argon ions exhibits the greatest resistance to local corrosion. The implantation of oxygen and argon ions reduces the overall corrosion to the greatest extent. It is important to note that deep craters and traces of pitting corrosion do not form on the surface of the steel. The XPS data show that after ion implantation, there was a change in the concentration of the elements that make up the steel in the near-surface layers of the material in the depth of the implanted layer compared with the non-irradiated sample. It is established that the surface layers of steel are enriched with chromium atoms during ion implantation. This process occurs most intensively when samples are treated with argon ions. In this case, mixed chromium and iron oxides are formed, contributing to the passivation of the steel surface. Also, the process of ion implantation is accompanied by oxidation of the surface of the steel under study. This is confirmed by an increase in the oxygen content in the surface layers. To the greatest extent, this process occurs during implantation of oxygen ions. After corrosion tests, an increased chromium content is also observed on the surface of steel treated with Ar+ ions, which confirms the formation in this case of strong chromium oxides that remain on the surface during the corrosion of steel. The analysis of the fine structure of the XPS spectra showed that under the action of argon ions, the oxygen of surface oxides is redistributed in favor of chromium atoms and the formation of strong mixed iron and chromium oxides of the spinel type, including Fe2+, Fe3+, Cr3+ and Cr6+ compounds. It is important to note that although chromium oxides are also formed during oxygen implantation and in the same quantities as during argon implantation, the protective properties of the resulting compounds are noticeably lower. Therefore, not only the chemical composition is important, but also the structure of the resulting layers. It can be assumed that the high kinetic energy of heavy argon ions affects both the formation of a developed surface relief and the formation of strong mixed iron and chromium oxides of the spinel type.