Sandia Labs FY22 Laboratory Directed Research & Development Annual Report

REVEALING THE KINETICS OF ATMOSPHERIC CORROSION DAMAGE THROUGH IN-SITU X-RAY COMPUTED TOMOGRAPHY AND MACHINE VISION.

Atmospheric corrosion is a critical materials degradation problem, yet the ability to predict its kinetics remains elusive. Conventional approaches provide no information about how localized damage evolves, giving limited predictive capabilities in common scenarios. The goal of this Sandia LDRD team was to employ in-situ X-ray computed tomography to directly observe how corrosion damage evolves, enabling the mechanistic relationships between environmental drivers, microstructural triggers, and the kinetics of atmospheric corrosion to be uncovered. To exploit the insights held within hundreds of 3D datasets, custom machine-vision algorithms were developed to automatically identify critical features.

Ohio State University conducted electrochemical experiments to unravel these relationships and revealed that corrosion rates are closely tied to the evolution of the electrolyte and the local microstructure, enabling the development of predictive tools for Sandia missions. Other academic collaborators who contributed to this work were Sandia Alliance partners Georgia Tech and the University of Texas at Austin. This work has resulted in five journal publications including one in npj Materials Degradation , one in Corrosion – The Journal of Science & Engineering , and two in Journal of The Electrochemical Society , and four presentations. (PI: Philip Noell)

In-situ XCT enables both the growth rate and morphology (yellow) of pits to be directly characterized in relationship to the evolving electrolyte (blue) and prior stages of pit morphology (black).

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LABORATORY DIRECTED RESEARCH & DEVELOPMENT