Analysis of Corrosion by Speckle Polarimetry

One of the most common problems in material engineering is the appearance of corrosion. For this reason, numerous efforts are underway to design materials that are resistant to this damage. In the same context, the diagnosis of corrosion is also of great interest since its detection reveals the real state of a structure. This article is focused on the latter. The purpose of the presented study is to provide a simple optical methodology to analyze the corrosion process and its evolution by means of a non-destructive method based on changes in the polarization state of the speckle patterns. To carry this out, two experimental arrangements with different wavelengths are proposed: one in the far field and another in the near field. The samples are first subjected to accelerated acid corrosion in the laboratory, and then, the degree of corrosion is quantitatively analyzed using the proposed technique. Moreover, in order to ensure that the acid attack on the samples is uniform (generalized corrosion), a detailed study is performed on the specimen surfaces via Raman spectroscopy. The results obtained show the ranges of applicability of both setups and their limits for studying corrosion.