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Matls 701/702: Elliott Asare, PhD Candidate

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MS Teams - team code ffuvgr3

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materials@mcmaster.ca

Effect of Cr-based Coating on Corrosion Control of SS409 in Hydrothermal Aqueous Solutions

Overview

Surface coating modification is proven to significantly improve the corrosion resistance of Fe-based alloys in subcritical and supercritical water environments. Surface coatings are currently considered to improve the corrosion control of candidate structural alloys in hydrothermal liquefaction (HTL) biomass conversion processes. Current candidate alloys for this application require suitable resistance to both general corrosion and stress corrosion cracking modes to withstand the HTL process conditions (250-374°C and 4-22 MPa). The objective of this study is to determine the relative extent to which chromium-based coatings can improve general corrosion control. The Cr-based coatings considered include chromized and electroplated Cr; application of these coatings are considered to improve the corrosion control of substrate Type 409 stainless steel (Fe-11Cr) relative to a mechanically-ground surface baseline condition. Samples are immersed in a simulated aqueous biomass conversion product mixture (KCl (aq) + K2CO3 (aq)) at 310 °C and 10 MPa for 10 days using a static autoclave test system.

Evaluation of corrosion extent will be conducted through analysis of pre- and post-exposure samples using various surface characterization techniques. The Cr coatings substantially reduced weight change after exposure and showed little evidence of corrosion compared to the mechanically ground baseline.