Computation Assisted Materials Development for Improved Corrosion Resistance: B: High Temperature Corrosion
Program Organizers: Rishi Pillai, Oak Ridge National Laboratory; Laurence Marks, Northwestern University
Wednesday 2:00 PM
October 20, 2021
Room: A222
Location: Greater Columbus Convention Center
Session Chair: David Shifler, Office of Naval Research
2:00 PM Introductory Comments
2:05 PM
Hydrothermal Corrosion of Silicon Carbide: Jianqi Xi1; Dane Morgan1; Izabela Szlufarska1; 1University of Wisconsin-Madison
Silicon carbide (SiC) has been recognized for its potential as a cladding material in the advanced light water reactors. However, one of the remaining issues that can limit its application is the hydrothermal corrosion. In this talk, I will discuss our recent theoretical studies revealing corrosion mechanisms of SiC exposed to the hydrothermal environment. I will first discuss the elementary interfacial reactions driving corrosion, including a discovery of the unexpected hydrogen scission reaction that plays a key role in surface degradation. Our kinetic studies reveal that SiC is dissolved directly into the water without forming the silica layer, although the reactions are analogous to those observed during dissolution of silica. Secondly, I will discuss the surface orientation effect on SiC corrosion, which could provide strategies for the material design to suppress SiC corrosion. Finally, I will discuss the influence of irradiation-induced segregation on the hydrothermal corrosion of this material.
2:25 PM
Solubility Based Prediction of Corrosion in Molten Chloride Salts: Cory Parker1; Rishi Pillai1; Dino Sulejmanovic1; Bruce Pint1; 1Oak Ridge National Laboratory
Much data exists for the diffusion and solubility of chromium in molten fluoride salts, originally gathered during the Aircraft Nuclear Reactor Experiment. Such data does not exist for molten chloride salts considered for thermal solar applications. Pure Cr, Fe, and Ni as well as FeNiCr and NiCr model alloys were exposed to KCl, MgCl2, and KCl:MgCl2 salts at temperatures of 700, 800, 850, and 900°C for times up to equilibration. The salt after exposure was then analyzed using ICP-OES to determine elemental content and solubility limits. EDS analyses was performed on the model alloys to determine dissolution profiles of each element and compared to calculations made using activity values and estimated diffusion coefficients.Research funded by US Department of Energy Nuclear Energy Molten Salt Reactor campaign.
2:45 PM
Understanding and Reducing Bias in Machine Learning to Enhance Its Predictive and Extrapolative Capabilities: Application to the Oxidation Kinetics and Spallation Behavior of High-temperature NiCr-based Alloys: Marie Romedenne1; Rishi Pillai1; Jian Peng1; Bruce Pint1; Allen Haynes1; Govindarajan Muralidharan1; Dongwon Shin1; 1Oak Ridge National Laboratory
The development of new materials used in extreme environments needs a more profound understanding of the degradation of alloys in high-temperature oxidation environments. Combining modeling and experimental approaches such as machine learning (ML) with sufficient experimental data can accelerate the development of new materials while limiting their cost. In the current work, the role of the data distribution in the experimental dataset (data analytics), alloy composition, and chosen oxidation models (a simple parabolic law and a statistical cyclic-oxidation model) on the performance of ML models was evaluated. Potential strategies to improve the predictions and enhance the extrapolative capability of the previously trained model will be investigated. This research was sponsored by the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, and the U. S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Office, Propulsion Materials Program.