Computation Assisted Materials Development for Improved Corrosion Resistance: On-Demand Oral Presentations
Program Organizers: Rishi Pillai, Oak Ridge National Laboratory; Laurence Marks, Northwestern University
Friday 8:00 AM
October 22, 2021
Room: On-Demand Room 9
Location: MS&T On Demand
Modelling Alkoxide Corrosion Initiation of Pure-aluminum in Ethanol with Integrated Simulation-based Experimental Methods: Visheet Arya1; Rüdiger Reitz1; Matthias Oechsner1; Eugen Gazenbiller1; Daniel Höche1; 1MPA-IfW TU Darmstadt
Renewable oxygenates such as Bioethanol are used increasingly as fossil fuel blends or substitutes directly influencing the occurrence of alkoxide corrosion in fuel-carrying vehicle components at elevated temperatures. Due to the spontaneous character and the tremendously high material degradation rate after alkoxide corrosion initiation, new approaches capable of localized and detailed measurements are needed with respective high-resolution test equipment. This work showcases a novel high pressure-temperature micro-reactor which is able to conduct measurements with high sensitivity in order to assess exact corrosion initiation times and reaction rates at elevated temperatures. A study on the corrosion reaction of commercially pure aluminium in anhydrous ethanol has been conducted using the new device. The distribution of the thermally induced chaotic pit initiation is evaluated statistically described by lognormal distribution density functions to develop a statistic-based simulation model which effectively replicates experimental results and therefore implies the ability for improvement by considering further factors.
Morphological Stability of Electrostrictive Thin Films: Jin Zhang1; Peter Voorhees1; 1Northwestern University
A large electric field is typically present in anodic or passive oxide films. Stresses due to lattice misfit are coupled with those induced by the electric field, including Maxwell and electrostrictive stresses. Understanding the electromechanical coupling in thin-film growth is essential for improving corrosion resistance. Here, a model that incorporates the lattice misfit and electric field-induced stresses is developed. We perform a linear stability analysis of the fully coupled model and show that the electrostrictive effect can dominate the stability behavior of thin films, especially under a large electric field. It is shown that the misfit and electrostatic induced morphological instabilities are obtained as the limiting cases of our model, respectively. The effect of material parameters and film thickness on the instability is studied.
Modelling Microstructural Evolution of Aluminide Coatings on Ni-based Superalloys: Wencai Leng1; Dmitry Naumenko1; Rishi Pillai2; 1Forschungszentrum Jülich GmbH; 2Oak Ridge National Laboratory
Aluminide coatings enhance the oxidation resistance of Ni-based alloys used in aero-engine and power-generating gas turbines. The degradation of aluminized Ni-based superalloys was investigated during cyclic oxidation in air at temperatures of 950 - 1100 °C. A thorough analysis of the coating microstructures in the as-manufactured condition and after thermal cycling was performed using SEM / EDX / WDX / EBSD. A coupled thermodynamic-kinetic model was used to predict the coating microstructural changes simultaneously considering oxidation and interdiffusion processes. Excellent agreement was observed between experimental and modelling results, which correctly predicted transformation of NiAl into Ni3Al and γ-Ni, overall Al-depletion, and precipitation and dissolution of TCP phases, carbides and borides in the coating. The composition of the substrate alloy was found to have a major impact on the coating systems by influencing not only Al loss due to interdiffusion but, after long exposure time, also the oxidation behavior.
Modeling of High-temperature Corrosion of Zirconium Alloys Using the eXtended Finite Element Method (X-FEM): Louis Bailly-Salins1; Léo Borrel1; Wen Jiang2; Benjamin Spencer2; Koroush Shirvan3; Adrien Couet1; 1University of Wisconsin - Madison; 2Idaho National Laboratory; 3Massachusetts Institute of Technology
A physically based zirconium alloy corrosion model called the Coupled-Current Charge Compensation (C4) model has been updated to include high-temperature corrosion in order to provide additional critical information (e.g., oxygen concentration profile) under loss-of-coolant accident (LOCA) conditions. The C4 model was implemented in the MOOSE finite-element framework developed at Idaho National Laboratory, enabling it to be coupled with mechanics in the BISON nuclear fuel performance code. The eXtended Finite Element Method (X-FEM) was applied in MOOSE to precisely track the different interfaces. The C4 model implemented with X-FEM in MOOSE now has the capability to accurately predict oxide, oxygen-stabilized α, and prior β phase layer growth kinetics under isothermal exposure at high temperature (1000–1500°C). It can predict the oxygen concentration profile evolution through the whole cladding, enabling evaluation of the remaining ductile thickness—a crucial variable for modeling the mechanical behavior of the fuel cladding under LOCA.
First Steps Towards a Coupled Thermodynamic-kinetic Model to Predict Sulfate Deposit Induced Hot Corrosion of Aluminized Ni-based Superalloys: Yaping Wang1; Rishi Pillai2; Elena Yazhenskikh1; Michael Müller1; Dmitry Naumenko1; 1Forschungszentrum jülich; 2Oak Ridge National Laboratory
Engine components, e.g. turbine blades and vanes undergo acute hot corrosion attack during service, which limits their lifespan. The hot corrosion kinetics of Ni-based superalloys and coatings exposed to multicomponent sulphate systems are difficult to model due to the complexity of the problem. In the present work, various alkali and alkaline earth sulphate mixtures were applied to the surface of an aluminized Ni-based superalloy. The hot corrosion tests were carried out at 600-1000 °C in air + 300 ppm SO2. A thermodynamic database of Na2SO4-K2SO4-MgSO4-CaSO4-NiSO4 system was developed using CALPHAD method and important transitions were validated by thermal analysis. The phase equilibria of the sub-systems of interest were assessed using the optimized database. Based on that, the metal loss rate was predicted by a simplified kinetic model. The modelling results were compared with the experimental results.