Identification of Corrosion Minerals Using Shortwave Infrared Hyperspectral Imaging

Abstract

In this study, we propose a new method to identify corrosion minerals in carbon steel using hyperspectral imaging (HSI) in the shortwave infrared range (900–1700 nm). Seven samples were artificially corroded using a neutral salt spray test and examined using a hyperspectral camera. A normalized cross-correlation algorithm is used to identify four different corrosion minerals (goethite, magnetite, lepidocrocite and hematite), using reference spectra. A Fourier Transform Infrared spectrometer (FTIR) analysis of the scraped corrosion powders was used as a ground truth to validate the results obtained by the hyperspectral camera. This comparison shows that the HSI technique effectively detects the dominant mineral present in the samples. In addition, HSI can also accurately predict the changes in mineral composition that occur over time.

Hyperspectral imaging analysis of corrosion products on metals in the UV range

“…The SWIR spectra examined did not share many features among corroded points, as determined by human visual inspection of the spectra. However, in literature, the SWIR spectral range was successfully exploited to identify different corrosion products on steel [4]. It is possible that the spectral features identified here may be indicative of different corrosion products, but missing the chemical characterisation of these samples, it is difficult to determine whether this is the case.…”

“…In [4] the severity of corrosion was assessed based on the corrosion products present on the surface of carbon steel (s235) in the SWIR range (900 -1700 nm) and cross-correlating retrieved spectra with the pure reference spectra for products including hematite, lepidocrocite, and goethite. The results are represented as the percentage total of each corrosion mineral present in the sample, as compared with the percentages of minerals present found by the Fourier Transform Infrared (FTIR) spectroscopy ground truth.…”

Quantitative detection of corrosion minerals in carbon steel using shortwave infrared hyperspectral imaging

“…The MA-XRD measurements were performed by means of an inhouse built mobile scanner (AXIS, University of Antwerp, Belgium). The device is set-up with a low power X-ray micro source (50 W, Im S-Cu, Incoatec GmbH, Germany), which produces a monochromatic and focused X-ray beam (Cu-Ka; 8.04 keV), a more detailed description can be found elsewhere 27 [24]. A primary beam angle of incidence of 10°relative to the corroded steel samples was employed due to geometrical limitations.…”

“…Previous research by the same authors. 24 focused on the comparison between FTIR analysis and HSI measurements. However, the FTIR data were obtained with scraped corrosion products, so spatial information about where the corrosion products are present was not considered.…”

Quantitative detection of corrosion minerals in carbon steel using shortwave infrared hyperspectral imaging.

“…The MA-XRD measurements were performed by means of an inhouse built mobile scanner (AXIS, University of Antwerp, Belgium). The device is set-up with a low power X-ray micro source (50 W, IµS-Cu,Incoatec GmbH, Germany), which produces a monochromatic and focused X-ray beam (Cu-Kα ; 8.04 keV), a more detailed description can be found elsewhere 27 [24]. A primary beam angle of incidence of 10°relative to the corroded steel samples was employed due to geometrical limitations.…”