Magnesium Technology 2023: Corrosion and Coatings
Sponsored by: TMS Light Metals Division, TMS: Magnesium Committee
Program Organizers: Steven Barela, Terves, Inc; Aeriel Murphy-Leonard, Ohio State University; Petra Maier, University of Applied Sciences Stralsund; Neale Neelameggham, IND LLC; Suveen Mathaudhu, Colorado School of Mines; Victoria Miller, University of Florida
Tuesday 8:00 AM
March 21, 2023
Room: 30C
Location: SDCC
Session Chair: Petra Maier, Stralsund University of Applied Sciences; Josh Caris, Terves, Inc.
8:00 AM
Open-air Plasma Assisted Si-O-C Layer Deposition on AZ91D Mg Alloy for Corrosion Mitigation: Jiheon Jun1; Yong Chae Lim1; Yi-Feng Su1; Daphne Pappas2; Andrew Sy2; Ryan Robinson2; 1Oak Ridge National Laboratory; 2Plasmatreat USA
Use of Mg alloy structural parts can enable lightweight automobiles for improved energy efficiency. High corrosion susceptibility of Mg alloys, however, remains as a technical challenge against their application in vehicle-structures. This work investigated open-air plasma assisted Si-O-C coating as a corrosion barrier for AZ91D Mg alloy. The open-air plasma coating does not involve wet chemical process and is amenable to the industries experienced in other plasma-based processes. As-deposited coatings on AZ91D substrates were characterized by advanced microscopic characterization techniques, including SEM, STEM and EDS. Corrosion evaluation was performed using electrochemical impedance spectroscopy, polarization and H2 collection measurements in 3.5 wt.% NaCl solution. Post-immersion AZ91D samples, that were uncoated or Si-O-C coated condition, were also characterized by SEM, STEM and EDS. The results indicated that plasma-assisted Si-O-C coating delayed the initiation of corrosion and the progression of corrosion attack.
8:20 AM
Integrating Multimodal Corrosion with Correlative Microscopy Across Multiple Length Scales: Sridhar Niverty1; Rajib Kalsar1; Lyndi Strange1; Venkateshkumar Prabhakaran1; Vineet Joshi1; 1Pacific Northwest National Laboratory
The corrosion behavior of light metal alloys is complex due to the simultaneous interaction of variables such as processing history, microstructure, corrosive environment, and temperature. Each of these factors contribute to corrosion damage at multiple length scales. This talk will focus on the combination of multimodal corrosion with multiscale imaging to probe the corrosion behavior of light metal alloys. This unique approach involves the simultaneous application of electrochemical methods such as Scanning Electrochemical Cell Microscopy (SECCM), in situ / ex situ imaging and hydrogen collection. It is particularly beneficial to the study of complex heterogenous microstructures (varying grain size, chemical composition, porosity, nature of oxide film) obtained during processes such as Friction Stir Processing and surface plasma treatment. Employing this approach correlatively over multiple length scales has aided in the identification of microstructural features that contribute to local and global corrosion damage.
8:40 AM
Protective Micro-arc Oxidation Surface Coating on AZ80 Forged Magnesium Alloy: Xin Pang1; Yuna Xue2; Hamid Jahed3; 1CanmetMATERIALS, Natural Resources Canada; 2Xi'an Shiyou University; 3University of Waterloo
Magnesium alloys, with a high weight-to-strength ratio, have attracted considerable attention for lightweight applications, especially in automotive industry. However, their inferior corrosion properties when in contact with aqueous solutions, salt, and other metals have become a significantly hindrance to more widespread use of magnesium alloys. Surface coating has be considered an economic and effective strategy for corrosion protection of magnesium alloys. In this work, the corrosion behavior of uncoated and micro-arc oxidation (MAO) coated cast, extruded, and forged AZ80 magnesium alloys, has been studied using salt fog corrosion chamber test and microscopic characterization techniques. The influence of the forging process and MAO surface treatment on the corrosion properties of the AZ80 magnesium alloys was investigated. The experimental results showed that the low forging temperature of 250 °C led to fine grain size and uniform distribution of secondary phase in the magnesium alloy, resulting in higher corrosion resistance. The MAO coating provided significant corrosion protection of the AZ80 magnesium alloy substrates in the aggressive continuous salt fog environment.
9:00 AM
Effect of Deformation Speed on Stress Corrosion and Fracture Toughness of Extruded Mg10Dy and Mg10Dy1Nd using C-ring Tests: Petra Maier1; Benjamin Clausius1; Norbert Hort2; 1University of Applied Sciences Stralsund; 2Helmholtz-Zentrum Hereon
The influence of the deformation speed in C-ring tests in Ringer's solution on crack initiation and propagation of extruded Mg10Dy and Mg10Dy1Nd is investigated. Deformation speeds varying from 4 to 0.012 mm/min allow corrosion times from a few minutes to hours. Both the crack initiation force (higher for Mg10Dy1Nd) and displacement (higher for Mg10Dy) increase with decreasing deformation speed up to a corrosion time of 1 hour and then decrease, more for Mg10Dy1Nd and slightly more for the displacement compared to the force at higher corrosion times. The decrease is associated with the higher corrosion times - corrosion pits become visible at a test time of 1 hour on the tensile side. In Mg10Dy1Nd the fracture toughness increases with decreasing deformation speed, no clear picture is seen for Mg10Dy. Sub-cracks often initiate at corrosion pits, which show a correlation to twinned grains at the tensile side – increasing fracture toughness.
9:20 AM Break
9:35 AM
A Comparative Study about Hydroxyapatite Coated AZ31 and AZ91 Mg Alloys: Serkan Baslayici1; Mehmet Bugdayci2; Kagan Benzesik3; Ozan Coban4; Onuralp Yucel3; Ercan Acma3; 1Istanbul Medipol University; 2Yalova University; 3İstanbul Technical University; 4Istanbul Gedik University
Magnesium alloys are potential candidates for hard tissue replacements due to their structural and mechanical properties close to bone. Unlike conventional metallic implants, the corrosion rate of magnesium is quite high. This will be an advantage if magnesium-based materials are used as biodegradable. In this study, magnesium-based AZ31 and AZ91 magnesium alloys were coated with hydroxyapatite by plasma spray and electrostatic spray methods and their corrosion rates were compared.
9:55 AM
In Situ Study of the Degradation Behaviour Under Load of Mg1.8Y0.6Zn(1Ag) Using Synchrotron Tomography: Domonkos Tolnai1; Birte Hindenlang1; Jan Bohlen2; Joao Pereira da Silva1; Jianan Gu1; Anais Louapre1; Florian Wieland1; Fabian Wilde3; 1Institute of Metallic Biomaterials, Helmholtz-Zentrum Hereon; 2Institute of Material and Process Design, Helmholtz-Zentrum Hereon; 3Institute of Materials Physics, Helmholtz-Zentrum Hereon
The addition of Y and Zn improves the property profile of Mg by forming a Long Period Stacking Ordered (LPSO) phase. The addition of Gd, Ca or Ag can further improve the degradation- and mechanical-properties. Owing to their biocompatibility and degradation under physiological conditions, these alloys are considered for temporary implants. Mg1.8Y0.6Zn in pure condition and modified with 1.6 wt.% of Gd, 1 wt.% of Ag or 0.4 wt.% of Ca, were extruded and subjected to in situ tensile testing in air and submerged in simulated body fluid. At selected load intervals, synchrotron tomography was performed in order to follow the crack initiation and propagation in 3D. The results show the effect of corrosive media on the mechanical failure. Furthermore, the results are used to develop a computational model on stress corrosion cracking that can be applied in failure prediction of implants and designing alloys for structural and medical applications.
10:15 AM
In Vitro Degradation Assessment of Magnesium Wire in Sternal-closure-like Conditions: Adam Griebel1; Natalie Romick1; 1Fort Wayne Metals
Though minimally-invasive surgery allows for treatment of a growing set of medical conditions, often open-heart surgery is still necessary. In open-heart surgery, the sternum is bisected to allow access to the heart. After surgery, the two halves of the sternum are mechanical fixed with stainless steel wires or in some cases titanium or stainless steel cables and plates. These devices are left behind indefinitely, and can cause patient discomfort or interfere with subsequent operations. An absorbable magnesium wire could allow for sufficient mechanical support while the sternum heals while avoiding the secondary complications of permanent materials. In this study, feasibility of Mg sternal wire was assessed using patent-pending LZ21 alloy wire and a simple sternal model mimic. Baseline mechanical and microstructural properties of 0.95 mm wire with and without a MgF2 coating were established and compared to wire corroded in a modified Hank’s fluid in a variety of loading conditions.
10:35 AM
Influence of Corrosion Extent on Residual Tensile Strength and Corrosion Fatigue Properties of an Mg-Y-Nd Alloy Characterized by µCT: Benjamin Clausius1; Nils Wegner2; Sharmajeya Jeyavalan1; Hendrik Hartweg2; Frank Walther2; Petra Maier1; 1University of Applied Sciences Stralsund; 2TU Dortmund University
This study focuses on the influence of inhomogeneous corrosion on the quasi-static and cyclic properties of an Mg-Y-Nd alloy. Uniform corrosion is essential for biodegradable im-plant materials to avoid notching effects and premature failure. Previous studies on extruded Mg-3Y-3RE have shown a tendency to pitting in Ringer’s solution at 37 °C. Tensile tests on pre-corroded samples with different corrosion extents, adjusted by corrosion time, allow the correlation to residual tensile strength. Corrosion fatigue tests enable determination of the influence of the pitting factor on service life and monitoring of the evolution of pits through electrochemical parameters. µCT scanning of corroded samples before and after the tests allows identifying the weak spots. Through 3D-µCT analysis, it was possible to quantify the corrosion extent and thus conclude that the amount and size of corrosion pits is critical for shorter corrosion times, whereas the residual load-bearing area is critical for longer corrosion times.