Optical reflection spectroscopy of thick corrosion layers on 304 stainless steel

Abstract

Corrosion resistant structural materials of both iron and nickel based alloys are used in the electric power industry for the construction of the coolant loops of both conventional and nuclear power generating stations. These materials, in the presence of high temperature (e.g. 287° C), high pH (e.g. 10.0 @ 20°C) water with dissolved hydrogen will oxidize and form corrosion films that are double metal oxides (or spinels) of the form AB 2 O 4. This work describes optical reflectivity techniques that have been developed to study the growth of these films in situ. The optical technique uses a dualbeam specular reflection spectrometer to measure the spectrum of reflected light in small angle (i.e. < 15°) scatter. The reflection spectra are then calibrated using a set of corrosion coupons with corrosion films that are well known. Results are compared with models based on multilayer reflection and Mie scattering from a particle size distribution. Surface roughness is found to be the dominant cause of reduced reflection as the films grow.

Magnetic and Optical Properties of Submicron-Size Hollow Spheres

“…The green dotted curve in Figure 11 (c) is the theoretical best fit to the experimental curve for the hollow spheres with the following parameters: m 1 = 1.0 (fixed), m 2 = 2.55 + 0.70i, r 1 = 285 nm (fixed), and r 2 = 325 nm (fixed). The obtained m 2 values are consistent with the reported values for bulk magnetite [ 103 , 104 , 105 ]. The theoretical curve reproduces the weak reflectance peak at around 725 nm and the higher one at 510 nm.…”

Investigation of sidewall roughness of the microgrooves manufactured with laser-induced etching technique

“…The thermophysical properties of stainless steel, assumed to be constant, are r STS = 8 g/cm 3 , C p,STS = 0.5 J/g K, k STS = 0.16 W/cm K, a STS = 0.12 Â 10 7 cm À1 , and R = 0.76 [11][12][13].…”

Linking the optical and the mechanical measurements of dimension by a Newton’s rings method

“…In most cases the complex refractive index is not known with sufficient precision as it depends on many parameters, e.g. in the case of steel, surface treatment, composition and crystallization [14]. Sufficiently precise estimation of the complex refractive index is a relatively complex task, meaning the published values significantly differ even for pure metals [15,16]; moreover, the difference between an optical estimation of surface position and an estimation made by mechanical contact will also be influenced by the surface texture, and selecting a surface texture parameter to be used for correction is not straightforward [2].…”