Magnesium Technology: Surface Protection, Corrosion and Degradation
Sponsored by: TMS Light Metals Division, TMS: Magnesium Committee
Program Organizers: Petra Maier, University of Applied Sciences Stralsund; Steven Barela, Terves, Inc; Victoria Miller, University of Florida; Neale Neelameggham, IND LLC
Thursday 8:30 AM
March 3, 2022
Room: 210A
Location: Anaheim Convention Center
Session Chair: Kiran Solanki, Arizona State University
8:30 AM
Flexible Surface Treatment Technology to Enable Temporary SCC Prevention for Mg Dissolvable Alloys: Lei Zhao1; Wenhan Yue1; Jiaxiang Ren1; Tim Dunne1; Peng Cheng1; Huailiang Liu1; 1CNPC USA
Massive quantities of Mg alloys are needed from oil and gas industry to manufacture “dissolving plugs”. Given its poor resistance to stress corrosion cracking (SCC), SCC is rarely reported from field operations despite their broad usage. Plugs are stressed for only short periods of time (<8 hrs), with most oil-well temperature <100℃, preventing SCC from fully developing. As a pioneer in developing HT wells (>140℃), we began to witness catastrophic failure caused by SCC. In this work, SCC resistance of dissolvable Mg alloy is found inversely related to its mechanical strength, which cannot be compromised, especially at HT. To address this dilemma, we successfully developed a flexible surface treatment technology that “temporarily” prevent SCC during operation, and a model is also proposed to explain its work mechanism. It is the first time of industry to report “temporary SCC prevention” of dissolvable plugs at extremely high temperature.
8:50 AM
Enhanced Corrosion Resistance of an AZ31 Magnesium Alloy through Shear Extrusion: Vikrant Beura1; Vineet Joshi2; Kiran Solanki1; 1Arizona State University; 2Pacific Northwest National Laboratory
Magnesium alloys with a better corrosion resistance are in high demand in the field of aerospace and automotive sectors to improve fuel efficiency and reduce carbon footprint. In this work, the AZ31B magnesium has been processed through the friction extrusion processing technique to improve the corrosion resistance. The friction extrusion processed AZ31B sample microstructure consists of equiaxed grains, fragmented and homogenously distributed Al8Mn5 cathodic phases, and a tilted basal texture. The corrosion behavior of the friction extrusion processed alloys was analyzed and compared to the feed extruded and cast AZ31B alloys. A reduced anodic reaction rate with noble breakdown potential was observed in the friction extrusion processed alloy through the potentiodynamic polarization test. Moreover, a protective and coherent protective film was characterized through electrochemical impedance spectroscopy measurement (EIS) and X-ray photoelectron spectroscopy technique (XPS). Post-corrosion microstructures were analyzed to elucidate the underlying corrosion mechanism.
9:10 AM
Active Corrosion Protection Surfaces Based on Layered Double Hydroxides Nanocontainers: A Computational Study: Xuejiao Li1; Christian Feiler1; Tim Würger2; Robert Meißner2; Daniel Höche1; Mikhail Zheludkevich1; 1Helmholtz-Zentrum Hereon; 2Hamburg University of Technology
Effective protective coatings are an essential component of magnesium-based engineering materials. Layered double hydroxides (LDHs) depict a promising approach to realize an active corrosion protection of Mg alloys as they can act as nanocontainers for corrosion inhibitors whereas the anion-exchange of intercalated inhibitors and the simultaneous uptake of aggressive anions (like chloride) is key to inhibit corrosion.[1,2] Although LDHs have been extensively characterized experimentally [1,3,4,5], some mechanistic details still have to be elucidated. Towards this end, we present a computational investigation by a combination of density functional theory and molecular dynamics simulations to unravel details for various Al-Mg-LDH systems that are not accessible by experiments. We investigate the hydration state of LDHs as this property directly affects the anion-exchange behavior. Naturally, understanding these dynamic phenomena for different LDHs is a crucial step towards the prediction of their anion-exchange capacities, unlocking pathways to select effective corrosion inhibitors.
9:30 AM Invited
Novel Laboratory-scale In Situ Methods for Studying Mg Alloy Degradation: Dmytro Orlov1; 1Lund University
Magnesium alloys are among most exciting lightweight environment-friendly materials offering plenty of opportunities for tailoring structural and degradation properties. Extensive studies over the last two decades paved a rather clear way for controlling the former. However, significant gaps remain in controlling the latter due to the multi-dimensional nature of Mg degradation involving besides the material itself various gaseous and aqueous media dynamically changing over time. Most of the remaining gaps cannot be revealed by existing experimental methods due to principal limitations. We work on developing new in situ methods for understating Mg alloy degradation and interaction with hydrogen. Our laboratory-scale instrument combining isothermal calorimetry with pressure measurements allows quantitative analysis of the process thermodynamics. Complementary studies at large-scale facilities using quantitative neutron imaging allow further understanding of the kinetics of degradation products formation. Our latest achievements in studying model Mg alloys for biomedical applications will be discussed in this talk.