Investigation of Corrosion Properties and Composition of the Surface Formed on AISI 321 Stainless Steel by Ion Implantation

Abstract

In this work, the corrosion resistance of AISI 321 stainless steel is increased through. the two-stage implantation of oxygen ions and of both aluminum and boron ions together. During ion implantation, a modified layer with a thickness of about 200 nm is formed, which affects the properties of material. The increase in corrosion resistance is confirmed by prolonged acid corrosion tests at pH 3.5 and by accelerated electrochemical tests using a potentiostat. The corrosion rate of the implanted sample is 0.708 μA/cm2, in contrast to the non-implanted sample (1.26 μA/cm2). The modified surface layer is examined using X-ray photoelectron spectroscopy (XPS), secondary-ion mass spectrometry (SIMS), and transmission electron microscopy (TEM). Aluminum and boron are implanted to a depth of more than 250 nm. It is found that the modified surface of the stainless steel substrate contains oxides of implanted ions (Al2O3) and oxides of substrate ions (Cr2O3 and NiCr2O4).