Corrosion behavior of AISI 316 L borided and non-borided steels immersed in a simulated body fluid solution

摘要

The corrosion resistance of AISI 316 L bonded and non-bonded steels was evaluated during 10 days of immersion in a simulated body fluid (Hanks' solution). The FeB/Fe2B layer was developed using the powder-pack bonding process at 1223 K and 6 h of exposure. First, the electrochemical behavior on the surface of bonded and non-bonded steels was assessed using Electrochemical Impedance Spectroscopy, EIS. After the corrosion tests, the surface of both types of samples were analyzed by Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectrometry (EDS) and X-Ray Photoelectron Spectroscopy (XPS), to establish the corrosion mechanisms, the composition and the electrochemical species developed over the surface, after 10 days in the simulated body fluid solution (SBFS), respectively. According to the electrochemical study, the AISI 316 L bonded steel provided a reasonable corrosion resistance notwithstanding, the non-bonded steel exhibited higher resistance values. Finally, it was concluded that the decrease of corrosion resistance of AISI 316 L bonded steel was caused by a rather complex combination of chemical interactions amongst boron-bearing species, sulfates and phosphates taking place initially over the bonded surface and subsequently through pits and cracks after 10 days of immersion in Hanks' solution. (C) 2015 Elsevier B.V. All rights reserved.