In situ Scanning Tunneling Microscopic Study of the Corrosion of Type 304L Stainless Steel in Aqueous Chloride Media

摘要

Scanning tunneling microscopy (STM) has been finding growing application for in situ surface studies of various substrates immersed in solutions. Several reports have further demonstrated the possibility of performing the STM imaging under well-defined electro-chemical environments, such as under potentiostatic control. We have recently employed STM for in situ investigation of potential-driven phase transition on a nickel electrode in 0.5M sulfuric acid. We demonstrate here the use of STM in the in situ study of the corrosion of Type 304L stainless steel (SS) in aqueous chloride media. Such studies can provide very high resolution (ca. nm) topographic images of the corroding substrate, as well as some information about the electronic conductivity of surface phases. Note that the topography of corroding substrates can also be probed by scanning potentiometry, although at much lower resolution. We also describe the effects of an organic pitting corrosion inhibitor, e.g., N-lauroylsarcosine (NLS), chloride concentration, and pH on the STM images. Keywords: Reprints.