Few in-situ corrosion monitoring techniques are available to use in high pressure and high temperature (HPHT) environments. This paper presents the outcome of the development of a technique based on optical ellipsometry that may be used to measure oxide film thickness growth in real time to better understand material degradation. Ellipsometry is an optical technique where the light from a laser is reflected off the specimen surface into a sensor to measure the polarization change (phase and amplitude changes). While this technique is used at ambient pressure and temperature, it is rarely used at HPHT. In this study, the laser light was radiated through a HPHT window attached on an autoclave. This technique was used to measure nanometer to micrometer changes in thickness of an oxide film in supercritical CO2. The oxide film thickness measurements were compared to measurements of the thicknesses using scanning electron microscope imaging of the cross section and to data found in the literature.

Subject
Scanning electron microscopy, Materials, Stainless alloys, Oxides, Nickel based alloys, Autoclaves, Thickness measurement, Oxide films, Oxide surfaces, Lasers, Stainless steel, Polarization, Ellipsometry
Keywords:
in-situ techniques, supercritical CO2, oxide film, optical ellipsometry
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2022
Association for Materials Protection and Performance (AMPP)
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