bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Advanced Experimental and Modelling Approaches to Understand and Predict Better Corrosion of Metals
Authors: Terryn Herman Albert
Published: December 2020

In the advanced materials industry, there is a clear trend towards more sustainable concepts, and this is certainly also the case for metals. They take a prominent position in the materials market thanks to their multifunctionality and structural and mechanical properties. However, metals are prone to corrosion, and therefore often organic coatings are applied to extend their lifetime. The search for organic coated metals with higher multifunctionality and extended lifetime goes together with the search for more sustainable material concepts in the context of the REACH regulation.

Nowadays, materials are developed for providing components with a lifetime ranging from 10 to 25 years. The lifetime of a material highly depends on its exposure to the environment inducing ageing processes. In the current state of the art, lifetime and ageing assessment are performed by means of experiments, combining accelerated and field testing. The limitation of the first is that the conditions of the accelerated tests are not representative for the real environmental conditions and that there is no proven relationship between accelerated laboratory tests and field performance data. The limitation of the second is that it takes several years (5 to 10 years).

The only way to realise a substantial decrease in the development time of new materials is to introduce modelling in the design cycle. What is needed to realize a breakthrough in this field is a tool that can predict quantitatively and dynamically the corrosion behaviour of (organic coated ) metals. The long term scientific motivation of our research is to build a knowledge and technology platform to enable the prediction of durability behaviour and the estimation of lifetime of (organic coated) metals under long-term environmental ageing and corrosion conditions. This requires advanced research because corrosion of a (organic coated) metal is the result of an intense interplay between several physical phenomena that need to be characterized in real conditions and modelled. Within VUB and TUDelft research we try to focus on both aspects bringing in new advanced combined electrochemical & in situ surface analysis, advanced finite element electrochemical modelling and more recently quantum chemical modelling. During the lecture an overview will be given on our state of the art in the different domains, emphasizing some success but also bringing bottlenecks when it really comes to predictions of corrosion.

Acknowledgements: all VUB-SURF and TUDELFT-CTE colleagues for the excellent collaborations.
(Invited) Measurement of Passivation on Fe-6Cr Using an Ellipso-Microscope Combined with a Channel Flow Electrode Method
Authors: Fujimura Akihiro , Kitagawa Yuichi , Hasegawa Yasuchika , Doi Takashi , Fushimi Koji
Published: December 2020

An electrochemical ellipso-microscopy cell was expanded by combination with a channel flow electrode method. Fe-6 wt% Cr was potentio-dynamically polarized to passive region in acidic 0.15 M Na2SO4 solution. During the polarization, the electrolyte solution was flowed at various flow rates under laminar flow condition, and the Fe-6Cr sample surface was monitored by the ellipso-microscope. Simultaneously, two detector electrodes in the solution downstream were potentio-statically polarized to detect Fe and Cr species dissolved from the sample. Dissolution rates of Fe and Cr species in active region were depended on the flow rate. When AES analysis was conducted after the polarization of Fe-6Cr, depth profiles revealed that Cr enrichment in the outermost layer of passive film. Cr ratio in metal cations on the passive film increased with increaseing in flow rate. These behaviors implied that the corrosion resistance of passive film formed under solution convection was improved by oxidized products generated in active region. In the presentation, Fe-6Cr anodic dissolution behavior and enrichment of Cr species are discussed.
(Invited) In-Situ Spectroelectrochemical Evaluation of Stress Corrosion Cracking of Carbon Steel in H2s/CO2 Environment in Presence of H2s Scavenger
Authors: Ynciarte Leiva Vinicio , Caseres Leonardo , Dante James , Rincon Troconis Brendy Carolina
Published: December 2020

Injecting H2S scavenger is a common practice to reduce H2S. However, failures in the form of SCC of steel pipes have been reported. There is no knowledge about the effects of this chemistry on the corrosion and cracking mechanism of carbon steel. Based on literature related to corrosion in bicarbonate containing environments and the results of this work, it is suggested that SCC is governed by a possible transition from passive to active kinetics. This transition is a complicated function of gas concentration and amine adsorption. In this work, in-situ Raman spectroscopy was used to identify the chemical species present in the test solution prior to and following the scavenging process. In-situ surface enhanced Raman spectroscopy was utilized to measure specific adsorption of amine by-products on the steel, as well as, changes in the surface film composition. Electrochemical techniques (linear polarization resistance, potentiodynamic polarization, and electrochemical impedance spectroscopy) were performed to understand the corrosion mechanism. Finally, slow strain rate tensile testing was performed to evaluate SCC susceptibility.
(Invited) In-Situ Observation of Dynamic Electrochemical Interfacial Phenomena
Authors: Matsushima Hisayoshi
Published: December 2020

Electrochemical interfacial phenomena play important roles for developing advanced nano-materials such as actuators, MEMS and catalyst. For advanced control, metal nucleation by electrodeposition is one of key technology, while the research for high durability of the nanomaterials will be an important issue in the future. It is necessary to understand the corrosion in the fine region. These processes are electrochemical-deposition and dissolution reactions of metals. Thus, the reaction is too fast to observe in real time. In this presentation, I would like to introduce some recent research on dynamic electrochemical interface phenomena using a high-speed probe microscope [1, 2] and a holographic interferometric microscopy [3, 4].

The Cu dissolution was investigated by HS-AFM (High-Speed Atomic Force Microscopy). The in-situ observation was conducted using an Au(111) single in 3 mM copper sulfate solution with 50 mM sulfuric acid. The HS-AFM operating in a dynamic mode can measure surfaces at frame rates up to 10 frame s−1. In the present experiment, the scan area range was in the range of 375–1000 nm2 and the scanning speed was 1 frame s−1. The dissolution process was observed at 0.05 V vs. Cu reference. The dissolution could be occurred as soon as the electrolysis was started. The dissolution rate was independent of the edge type. At 3 s, the effects of dissolution became clear and the step lines of the nuclei became uneven. Interestingly, as dissolution progressed beyond 5 s, some clusters [indicated by arrows in Fig.1] remained on the substrate briefly. This behavior had the appearance of small water droplets drying on a flat surface. The average size of the clusters was approximately 8 nm. After the large nuclei dissolved, these small clusters gradually dissolved.

In the interferometric microscopy, the ionic mass transfer phenomenon of Al3+ in a sulfuric acid (pH 1) was investigated. The investigation revealed the refractive index profile corresponding to the Al3+ concentration profile in the electrolyte. The thickness of the diffusion layer was proportional to the square root of time, which supported the reaction dominated by the mass transportation. The Al3+ surface concentration started to decrease at 20 s after starting electrolysis, probably because the Al dissolution reaction was hindered and the Al oxide layer formation progressed. This in-situ research might be a steppingstone in order to understand the mechanism of anodization of Al.

References

[1] T. Yoshioka et al., Electrochim. Acta, 302, 422 (2019).

[2]H. Matsushima et al., Faraday Discuss., 193, 171 (2016).

[3] A. Miki et al., J. Electrochem. Soc., 167, 062501 (2020).

[4] K. Nishikawa et al., Electrochim. Acta, 297, 1104 (2019).

Figure 1
(Invited) Investigation of Corrosion Inhibitor Adsorption on Mild Steel By Electrochemical Atomic Force Microscopy
Authors: Wang Huiru , Pailleret Alain , Brown Bruce N , Nesic Srdjan
Published: December 2020

Mild steel has wide application in oil and gas industry due to its excellent mechanical properties and low costs. However, it is susceptible to corrosion attack in a typical water-containing service environment. Organic corrosion inhibitors can adsorb on steel surfaces to form protective layers even when added in a small amount. As conceptualized in the literature, the decrease in corrosion rates due to addition of inhibitor should be directly related to their surface coverage. However, studies have so far not provided any direct evidence of such a link, primarily due to limitations of conventional electrochemical analysis that have been used to investigate them. In the present work, a specially designed holder for electrochemical atomic force microscopy (EC-AFM) has been used to study the influence of a tetra-decyl-dimethyl-benzyl-ammonium inhibitor model compound on mitigation of corrosion. AFM results shows that when the bulk solution inhibitor concentration was at 0.5 CMC, partial coverage of the surface by the inhibitor film and patchy corrosion (which could lead to localized attack) of the UNS G1018 steel surface were observed by contact mode AFM imaging. When inhibitor bulk concentration was above the surface saturation value (1 CMC), full surface protection was indicated by the almost unchanged AFM topography images from 10 minutes to 4 hours exposure to the inhibited solution. The LPR results obtained with EC-AFM showed that the corrosion rates of this steel decreased as the bulk solution concentration of inhibitor in separate tests was increased from 0, 0.5 CMC to 1 CMC, while further increase of concentrations (from 1 CMC to 2 CMC) didn’t lead to any apparent reduction of general corrosion rate. Although the LPR corrosion rates at 1 CMC and 2 CMC were extremely low (0.05 - 0.1 mm/year), the values didn’t reduce to 0 under these full coverage conditions. Additional AFM tapping mode imaging results on mica indicated the formation of a porous film (a layer with ‘holes’) which is used to explain the types of adsorption layers possible and their probable influence on corrosion.
(Invited) High Precision Corrosion Measurements from Flow Type Scanning Droplet Microscopy with Downstream Analysis By Inductively Coupled Optical Emission Spectroscopy or Inductively Coupled Mass Spectrometry
Authors: Hassel Achim Walter , Mardare Andrei Ionut , Mardare Cezarina Cela , Kollender Jan Philipp
Published: December 2020

The oxide formation on valve metals such as Al, Nb, Ti, Ta has been studied for a long time. However one major drawback was always the unrealiability of the coulometric data. While the electrochemical current and thus the charge can be measured with very precision, it was simply not clear which reaction is actually consuming the charge or with which share are contributing concurrend reactions. The assumption of an almost complete consumption of the charge for oxide formation has often been read in papers. But especially the small losses which are usually neglected tell us a lot about the mechanism of oxide formation and lead to a modern basic understanding of the concurrent reactions.

High purity valve metals namely Al, Hf, Nb, Ta, Ti, Zr were anodised in voltage step experiments, in cyclic voltammetry or galvanostatically using a flow type scanning droplet cell microscope (FT-SDCM) with an ultra trace analytical downstream electrolyte analysis using an inductively coupled mass spectrometer. Experiments reveal that even the most corrosion stable element tantalum undergoes a measurable dissolution during anodisation which clearly scales with the field strength in the oxide and in the interface between oxide and electrolyte. This dissolution is roughly 10 times higher for niobium and 100 times for titanium. A comparison of the electrochemical current during titanium anodisation and the corresponding chemical current proves that the onset of oxygen evolution at some 3.5 V SHE is definitely not an ionic but an electronic current. However this electronic current can be driven only under high field conditions in which a significant number of ionic charge carriers act as stepping stones for electron movement in the oxide.

Spatial resolution and time resolution for these experiments are being analysed to put these method in the context of other corrosion evaluation tools. In particular when studying material libraries of laterally graded materials the spatial resolution of the FT-SDCM is of importance as it alloys allows adressing specific compositions.
(Invited) Investigating Galvanic Corrosion at a through-Coating Defect on Cu-Coated Carbon Steel Using X-Ray Micro Computed Tomography (μ-CT)
Authors: Standish Thalia E. , Keech Peter G , Behazin Mehran , Ramamurthy Sridhar , Zagidulin Dmitrij , Sarazen Rebecca , Shoesmith David W. , Noel James
Published: December 2020

The Nuclear Waste Management Organization (NWMO) is preparing to implement the safe long-term disposal of Canada’s used nuclear fuel in robust, corrosion-resistant used fuel containers (UFC). The current UFC design employs a strong carbon steel vessel, coated with copper for corrosion protection. This project explores corrosion processes that could happen on the surface of a container with a through-coating defect that exposes a small area of the underlying carbon steel, in contact with the copper coating, which corrosion scientists would consider a risk for galvanic (dissimilar metal) corrosion. High resolution ex situ and operando observations of Cu-coated carbon steel specimens with an artificial defect penetrating the copper to the steel, exposed to saline solutions with and without dissolved oxygen, have been made using X-ray micro computed tomography (μ-CT) to reveal the three-dimensional form of the corrosion damage and follow its progression with time (as shown for example in Figure 1). These measurements have shown that the form of the corrosion damage is dependent on both the type of additive manufacturing procedure used to create the Cu coating (electrodeposition or cold spray deposition) and the quality of the Cu/steel interface. In the presence of oxygen, the volume of corrosion damage increases linearly with time, independent of the type of coating, but with a rate dependent on the availability of oxygen. In the absence of oxygen, the corrosion rate is low and decreases with time. Post-experiment characterization of corrosion products by Raman spectroscopy indicated the presence of akageneite (β-FeOOH) and lepidocrocite (γ-FeOOH), depending on the solution conditions within the corroding defect.

Figure 1
(Invited) Analysis By Electrochemical Impedance Spectroscopy of Passive Film Properties of Additive Manufactured 17-4PH Stainless Steel
Authors: Barroux Adrien , Ducommun Nadège , Nivet Eric , Delgado Julien , Tribollet Bernard , Orazem Mark , Laffont Lydia , Blanc Christine
Published: December 2020

Additive manufacturing is currently one of the most innovative processes to build metallic components, in particular because it allows to manufacture parts with new design out of reach of conventional processes. Among the various additive manufacturing processes, power bed technologies such as laser beam melting (LBM), also called selective laser melting (SLM), are certainly the most common and developed process at this time. The specific microstructures generated by LBM and the associated mechanical properties of the final parts have been well discussed in the literature for many types of materials. Nevertheless, these peculiarities can also affect the durability of such parts and specifically their corrosion behaviour.

The main goal of this work was to analyse the electrochemical impedance measurements performed on a 17-4PH martensitic stainless steel (MSS) manufactured by LBM. In this framework, LBM parts were built from 17-4PH MSS powder, using optimised machine parameters. Samples machined from a wrought cylindrical bar were studied as references. Differences between the impedance of the LBM samples and the references samples were observed; they appeared as a small shift in frequency on the Bode plots. The impedance of the passive layer was analysed in detail by using the Young impedance model; in this model it is also necessary to take into account the ohmic impedance [1] to perform the analysis in the entire frequency range. In agreement with TEM observations, an increase of about 40% of the film thickness was obtained for the LBM samples; but, for both samples the resistivity distribution was similar. In conclusion, electrochemical impedance spectroscopy appears as a powerful method to study passive film and better understand the corrosion behaviour of LBM 17-4PH stainless steel.

References

[1] O. Gharbi, A. Dizon, M. Orazem, M.T.T. Tran, B. Tribollet, V. Vivier, From Frequency Dispersion to Ohmic Impedance: A New Insight on the High-Frequency Impedance Analysis of Electrochemical Systems. Electrochimica Acta, 320 (2019) 134609.
(Invited) A High Throughput Screening Approach for Corrosion-Resistant Alloys
Authors: Melia Michael Anthony , Pegues Jonathan , Summers Kodi , Jones Morgan , Nation Brendan , Chidambaram Dev , Argibay Nicolas , Kustas Andrew
Published: December 2020

Additive manufacturing (AM) is an attractive process for alloy development with some techniques having the ability to print a standalone part that spans a wide composition range. Fabricating compositionally graded parts allows spatially sensitive characterization techniques to perform property measurements across the composition gradient, providing high throughput testing of composition and phase space. This study utilizes an AM technique to make incremental additions of a single alloying element to a high entropy alloy (HEA), exploring how these alloying additions impact the HEAs microstructure and corrosion behavior. Specimens were produced with an in-house laser engineered network shaping (LENS) system capable of in-situ mixing of up to 5 metal powders. The equiatomic CoCrFeMnNi HEA is used in this study and compositionally graded with pure elements (Ti, W, and Nb). The susceptibility of the compositionally graded specimens to local corrosion initiation are tested using a micro (100 μm)-electrochemical cell and a scratch tester designed to measure repassivation kinetics. The efficacy of using this high throughput screening approach to develop alloys with superior corrosion resistance will be discussed.

SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.
(Invited) Highly-Stable Li Ion Batteries Based on Porous Si Anode and Localized High Concentration Electrolytes
Authors: Zhang Ji-Guang , Yi Ran , Chae Sujong , Li Qiuyan , Li Xiaolin , Xu Wu
Published: December 2020

Si is one of the most promising anode materials for the next generation of lithium (Li) ion batteries (LIBs). Stability of Si based anode mainly depends on two factors: one is a nano-structures Si which can tolerate large volume change during Li injection/extraction process and also have a small surface area which can minimize the side reaction between Si and electrolyte, another is a stable SEI layer formed on the surface of porous Si which are highly conductive and mechanically stable during cycling process. In this work, we report a scalable approach to prepare nano-structured Si particles in combination with a highly stable SEI layer formed in Localized High Concentration Electrolytes (LHCE) tailored for Si based LIBs. Both Si||LiCoO2 and Si||LiNi0.6Mn0.2Co0.2O2 batteries with a high-loading Si based anode developed in this work can retain more than 90% capacity after 500 cycles. Comparing with the baseline electrolyte, the new electrolytes developed in this work enabled a more then 30% increase in cycle life of Si based Li ion batteries. Therefore, the combination of the porous Si anode and the novel electrolytes developed in this work can enable long term cycling of high energy LIBs required for both electrical vehicles and consumer electronics applications.
(Invited) Current Status and Bottlenecks of the Intercalation of Mg into Spinel Oxides
Authors: Cabana Jordi
Published: December 2020

Electrochemical energy storage was an important enabler of the wireless revolution and it is touted as a key component of a society that shifts away from its dependence on fossil fuels. Li-ion batteries are the primary technology when high energy devices are required. However, despite their improved functionality over older systems (e.g. lead-acid car batteries), they do not quite yet meet the emerging energy demands in transportation and grid markets. This roadblock sparked interest in the development of batteries that utilize Mg2+ as ionic carrier. Theoretical predictions indicate that couples exist between a Mg metal negative electrode and oxide positive electrodes that could surpass the current practical limits of current devices. However, severe practical challenges have limited the study of the electrochemical properties of oxides to the simple elucidation of the viability and reversibility of the fundamental reactions of intercalation of Mg2+. Among the candidate oxides, the general family of spinel-type M2O4 (M=transition metal) are considered as leading contenders [1, 2]. In this talk, we will present the most up-to-date insight into the ability of spinel oxides to diffuse Mg2+. These observations will be paired with the outcomes of electrochemical reactions in non-aqueous electrolytes, since the use of Mg metal requires rigorously anhydrous environments. We will discuss the evidence supporting intercalation of Mg2+, and describe changes that correlate with both the identity of M and the existence of defects in the spinel structure [2, 3]. Critical to the endeavor is the ability to synthesize particles at small dimensions, as is the characterization of chemical and physical phenomena using a combination of tools providing information at different scales. The discussion will naturally lead us to reveal foundational bottlenecks that must be overcome to make Mg electrochemistry viable for energy storage.

Liu et al., Energy Environ. Sci.
2015, 8, 964.

Kim et al., Adv. Mater.
2015, 27, 3377.

Hu et al., Nanoscale
2019, 11, 639.
(Invited) Directions of High Energy Batteries and Status of Battery500 Consortium
Authors: Liu Jun , Bao Zhenan , Chueh William C. , Cui Yi , Dufek Eric J. , Goodenough John Bannister , Khalifah Peter , Liaw Boryann (Bor Yann) , Liu Ping , Manthiram Arumugam , Meng Ying Shirley , Subramanian Venkat R. , Yang Jihui , Xiao Jie , Whittingham Stan , Xu Wu , Yang Xiao-Qing , Zhang Ji-Guang
Published: December 2020

The success in the development and commercialization of Li-ion batteries has transformation the modern society. Currently there have been intense efforts to further improve battery performances and reduce the cost with many different materials and battery concepts. Based on careful analysis of commercially available advanced electrode materials and state-of-art cell manufacturing processes, we have identified the most feasible pathways for developing high energy batteries with a specific energy much higher than 300 Wh kg−1 using Li metal anode and high capacity metal oxides or sulfur cathode materials. This talk will highlight our analysis, the strategy, and current understanding of the scientific and technological challenges, and discuss recent progresses and directions based on a high-energy cell level design, fabrication, characterization and testing. This talk will also discuss the fundamental mechanisms for premature cell failure, and present recent results for achieving long cycle life.
(Invited) Are “Beyond Li-Ion” Batteries Only a Dream?
Authors: Mohtadi Rana
Published: December 2020

Environmental pollution and resources scarcity are monumental challenges that face humankind. Indeed, rapid technical advances and industrialization of societies continue to push the boundaries of stresses that can be imposed on our planet and with these comes a realization that sustainable energy technologies produced from renewable resources and stored and harnessed in highly efficient and environmentally friendly ways are inevitable. Electrochemical energy storage devices have been and are expected to play a critical role in enabling these efforts, however they must meet a highly demanding set of performance metrics.

For over three decades, Li-ion batteries have offered a reliable and a relatively dense form of electrochemical energy storage and their enormous success is evident from their widespread use. Indeed, while these transformational technologies drove innovations in societal electrification and warranted a recent Noble Prize in Chemistry,1 the urge to enable batteries that allow for safer, cheaper, sustainable and more energy dense forms has been driving interests in batteries beyond Li-ion.2 Batteries that essentially use safer and more abundant active materials such as rechargeable magnesium batteries are in principle poised to meet these requirements.2,3 Nonetheless, despite tremendous breakthroughs that include demonstrating a rechargeable Mg battery prototype close to two decades ago, these batteries remain confined to research laboratories due to the absence of practical electrolytes and cathodes that can enable demonstrating competitive, energy dense systems.

However, over the past few years, scientific advancements have been producing more certainty in the potential of these batteries as manifested in the discovery of new classes of competent battery materials beyond classical state of the art and unraveling of associated underlying fundamental chemistries that take place; all of which have altered our understanding of these batteries and what an ideal material needs to be like. Herein, the concepts applied towards enabling a next generation Mg battery, which in its functionality mimic Li-ion, will be unveiled. This battery was made possible through coupling novel battery materials and isolating of true barriers that contributed thus far to the demise of these devices.

References

https://www.nobelprize.org/prizes/chemistry/2019/press-release/

Choi J. W. Aurbach D. Nature Reviews Materials 1, 2016, 16013, 1.

Mohtadi R., Orimo S., Nature Reviews Materials, 2016, 2,16091, 1311.

Mohtadi R., Mizuno F. Beilstein J. Nanotechnol. 2014, 5, 1291.
Effects of Applied Stress on Atmospheric Corrosion and Pitting Characteristics of 304 Stainless Steel
Authors: Plumley John Bryan , Alexander Christopher Lewis , Yu Zhenzhen , Kemp Nicholas A , Garzon Fernando H , Schindelholz Eric John , Schaller Rebecca Filardo
Published: December 2020

The effects of applied stress, ranging from tensile to compressive, on atmospheric pitting corrosion of stainless steel 304L (SS304L) were analyzed through laboratory exposure and localized corrosion experiments. Pitting characteristics, analyzed through optical profilometry, scanning electron microscopy, and electron backscatter diffraction, were obtained after exposure for 50 days of an SS304L four-point bend bar to simulated seawater conditions at 50°C and 35% RH. Additionally, localized electrochemical measurements were carried out on an unexposed SS304L four-point bend bar to analyze the effects of applied stress on the corrosion susceptibility in analogous chloride solutions. In the tested, simulated seawater environment, the applied stress showed no effect on the pitting characteristics due to the aggressivity of the 4g/m2 loading of simulated seawater. Pitting depth, surface area, roundness, and distribution were found to be largely stochastic and rely on the available cathodic area and preexisting microstructure. However, through localized corrosion experiments in more benign environments, containing lower Cl- concentrations, the effects of stress on corrosion susceptibility start to become noticeable from the open circuit potential (OCP) measurements. A measurable decrease in the OCP indicated increased susceptibility to corrosion in the region of applied tensile stress as compared to the compressively stressed region. These findings indicate that stress may be less of a contribution to corrosion susceptibility than Cl- concentration under the exposure conditions examined.

Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the US Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525. SAND2020-4490 A
(Corrosion Division H. H. Uhlig Award Address) Corrosion of (Nominally and Notionally) Reactive Engineering Alloys
Authors: Birbilis Nick
Published: December 2020

The requirement of many industries to utilise engineering alloys that are lightweight is increasing as a result of rapidly advancing technologies (such as portable electronics), and due to environmental requirements (such as the need to reduce emissions). Paradoxically, the so-called ‘light alloys’ are also amongst the most reactive of the engineering alloys. In particular, the lightest of the commodity engineering alloys, namely aluminium and magnesium alloys, continue to present significant issues with respect to corrosion. The persistence of corrosion related issues has been assured by the increasing utilisation of materials in previously unconsidered environments / scenarios, and from the timescales required to fully understand the durability of newly developed alloys. Herein, a number of ‘materials’ factors, from the microstructural to the atomic scale, that contribute to corrosion of light alloys will be presented. In particular, the development of increasingly corrosion resistant magnesium alloys will be discussed, with a view to rationalising so-called ‘dynamic passivity’ as a means for providing engineering materials with kinetic stability.
Nanoscale Thin Film Corrosion Barriers Enabled By Multilayer Polymer Clay Nanocomposites
Authors: Schindelholz Eric John , Melia Michael Anthony , Spoerke Erik , Percival Stephen , Grunlan Jaime , Alexander Christopher Lewis
Published: December 2020

Ultrathin nanocomposite films fabricated by layer-by-layer (LbL) assembly are an emerging class of coatings with remarkable barrier performance. Here, we examine LBL polymer-clay nanocomposite (PCN) coatings that afford anti-corrosion properties comparable to those exhibited by more traditional films that are orders of magnitude thicker. PCN barrier thin films comprised of up to 40 bilayers of polyethyleneimine (PEI) and exfoliated laponite (LAP), montmorillonite (MMT), or vermiculite (VMT) clay platelets were coated onto steel plates using a scalable LBL dip-coating process. A combination of electrochemical impedance spectroscopy and ex-situ electron and vibrational spectroscopy were used to evaluate coating performance during exposure in 0.6 M NaCl for up to 7 days. A PEI/VMT crosslinked coating of only 250 nm thick slowed the corrosion rate of mild steel by three orders of magnitude (Rct = 106 vs. 103 Ω-cm2) after seven days in 0.6 M NaCl. This performance exceeded the reported performance of other LBL coatings along with much thicker multilayer composite coatings and several conventional pretreatments on mild steel under similar test conditions. The exceptional performance is attributed to the effective barrier properties imparted by a high loading (>80 wt%) of orientated, high aspect ratio (2000:1) platelet layers in a nanobrick wall morphology. Substitution of VMT with lower aspect ratio clay platelets of either MMT (400:1) or LAP (30:1) showed that coated steel corrosion rates and apparent coating permeability scales with platelet size following LAP > MMT >> VMT. Thus, this study has for the first time shown that platelet aspect ratio is a primary means of improving the performance LbL nanocomposite coatings which is in line with the expected behavior of conventional nanocomposites. Given film debonding from the substrate was observed as a common failure mode during exposure for all coating types, replacement of the PEI polymer component with a more debonding-resistant polymer may be an additional pathway to further improve LbL PCN anticorrosion performance.
Effect of Zinc Addition on Electrodeposition of Fe-W Alloys
Authors: Park Jae-Hyeok , Hagio Takeshi , Kamimoto Yuki , Ichino Ryoichi
Published: December 2020

Tungsten (W) and its alloys have been applied to various industrial fields for its excellent mechanical, tribological and chemical properties. Electrodeposition process is anticipated to be a economical and cost-effective method for preparing W-based alloys since W has the highest melting point among metals (3422 ℃). In general, electrodeposition of metal W from aqueous solution is difficult because it exists as oxyanions in a wide pH range. However, electrodeposition in the co-existence of iron group metals such as iron (Fe), nickel (Ni), and cobalt (Co), enables W to be reduced to metal state, which is so called the induced co-deposition. Recently, electrodeposited W alloys have gained increased attention due to their advanced properties such as high microhardness, thermal stability, wear resistance and corrosion resistance. Among them, binary Fe-W, Ni-W alloys have been most intensively studied. These alloys are expected to be promising substitute for hard chrome (Cr) plating due to its high hardness, abrasion resistance, heat resistance and corrosion resistance without the use of hazardous hexavalent chromium (Cr6+). Meanwhile, Ni has been reported as the one of the major elements in triggering skin allergies for humans. Therefore, we focused on Fe-W-based alloys that do not use Ni. Unfortunately, Fe-W alloys are reported to have inferior mechanical properties and corrosion resistance compared to Ni-W alloys. Thus, the addition of Zinc (Zn); an element that is widely used in anti-corrosion coatings, as a third element to the Fe-W binary alloy was considered for preparation of a ternary alloy with improved properties.

This study reports the first experimental results of electrodeposition of ternary Fe-W-Zn alloy by incorporation of Zn to Fe-W alloys. Ternary Fe-W-Zn plating was prepared in citrate-ammonia aqueous solution heated to 80℃ by potentiostatic elcecrolysis range from -1.1 to -1.4V (vs. Ag/AgCl). Ternary alloys with the compositions of Fe-(28.8 to 37.1 at.%) W-(1.7 to 6.5 at.%) Zn were obtained with maximum current efficiency of 42%. The corrosion properties of the prepared ternary alloys were compared with those of Ni-W and Fe-W platings by a potentiodynamic polarization test in deaerated 1M sulfuric acid solution and 3 mass% sodium chloride solution. Although Zn has lower potential than Fe, ternary Fe-W-Zn alloys with relatively low Zn contents of 1.7 to 2.6 at.% showed better anti-corrosion properties than Ni-20 at.%W and Fe-33 at.%W alloys in acidic media. Addition of a small amount of Zn was found to be effective in tuning properties of Fe-W alloys.

Acknowledgement

This work was partially supported by the JST-OPERA Program, Japan [grant number JPMJOP1843]
Observation of Wake-up Effect on Ferroelectric Y:HfO2 Thickness Scaling
Authors: Mizutani Kazuto , Lin Yu Wei , Hoshii Takuya , Wakabayashi Hitoshi , Tsutsui Kazuo , Kakushima Kuniyuki
Published: December 2020

Ferroelectric HfO2 films have attracted lots of attention because they can be applied to various devices, including memories and logics, with reduced power consumption1. Some of the issues of ferroelectric HfO2 films are the wake-up effect and the thickness scaling to the ferroelectricity. The wake-up effect is the increase in the remnant polarization (Pr
) during the cycling test, and the physical explanation in the film has been reported so far. Also, the crystal structure change after the cycling test has been detected2. The thickness scaling includes both roll-up and off of the Pr
on the film thickness. The physical phenomena are still not known, and the combination of the wake-up effect and the thickness scaling may give a clue to understanding the physics. In this study, we investigated the thickness-dependent wake-up effect of Y-doped atomic-layer-deposited (ALD) HfO2 films.

Metal-insulator-metal (MIM) capacitors with 5 mol% Y-doped-HfO2 (Y:HfO2) films were sandwiched by W electrodes. A post metallization annealing (PMA) is performed at 600oC (1 min) to crystallize the films. Figure 1 shows the initial Pr
of the capacitors on the HfO2 thickness. One can observe a peak in the Pr
at a thickness of 8 nm. The existence of a peak in Pr
on thickness is in good agreement with references3. The switching cycle dependence on the switching polarization (PSW
), the difference between positive and negative Pr
, shown in figure 2, indicates a strong wake-up effect, especially for the 8-nm-thick film. The cross-sectional transmission electron microscope (TEM) image of the 12-nm-thick capacitor, shown in figure 3, indicates the presence of an amorphous interfacial layer at Y:HfO2/W. The magnitude of the wake-up effect might be influenced by the presence of the interface layer.

This work is supported by JST-COI (JPMJCE1309).

[1] T. S. Boscke, et al., Appl. Phys. Lett., 99, 102903 (2011). [2]Y. Tashiro, et al., The JSAP Autumn Meeting, 20a-C309-5, (2019). [3]X. Tian, et al., Appl. Phys. Lett., 112, 102902 (2018).

Figure 1
Robustness of Ferroelectricity in Hafnium-Zirconium Dioxide Films Deposited By Sputtering and Chemical Solution Deposition for Ferroelectric Transistor Applications
Authors: Mohit Mohit , Migita Shinji , Ota Hiroyuki , Morita Yukinori , Tokumitsu Eisuke
Published: December 2020

Since the discovery of ferroelectricity in HfO2 in 2011, extensive work begin to burst forth on HfO2-based ferroelectric materials and devices. Orthorhombic phase is responsible for ferroelectricity in HfO2, which is usually stabilized by the dopant such as Al, Zr, Si, la and Y. In particular, Zr doped HfO2 (HZO) has large Pr around 20 µC/cm2 and ferroelectricity can be obtained in a wide range of Zr composition. The orthorhombic phase is a metastable phase and Migita et al. [1] reported that the orthorhombic phase of sputtered HZO film was transferred to monoclinic phase by further annealing. In this work, robustness of ferroelectric phase against the further annealing process has been investigated using sputtered HZO and solution-derived Y-doped HZO films [2].

Sputtered HZO films were prepared by room temperature deposition followed by 600 oC, 10 min annealing in N2. Y-doped HZO films were prepared by chemical solution deposition (CSD) by annealing the samples at 800 oC for 3 min in O2.[2] Ferroelectric properties were confirmed by polarization-electric field (P-E) and capacitance-voltage (C-V) measurements for both samples before the second time annealing. Then, both samples were further annealed in 400 and 600 oC in N2 to examine the robustness of ferroelectricity. It was found that sputtered HZO films become paraelectric and that X-ray diffraction (XRD) pattern shows diffraction peak from orthorhombic phase disappeared. On the other hand, CSD HZO films shows ferroelectric nature even after second time annealing with negligible monoclinic phase. Such a significant difference in robustness is presumably due to residual carbon in the CSD films.

In addition, In2O3/(Y-)HZO structures are also fabricated for oxide channel thin film transistor applications and characterized, which will be presented at the conference.

[1] Shinji Migita et al, Jpn. J. Appl. Phys. 58 SBBA07, 2019.

[2] Mohit et al, Jpn. J. Appl. Phys. 59 SMMB02, 2020.
Conformal and Smooth TiN Film Growth By Using ALD Method
Authors: Cho Hyunchol , Jung Sung-Hoon , Nie Ben , Nair Anu , Chen Zhigang , Rathi Somilkumar , Mukherjee Niloy
Published: December 2020

As the generation of memory devices evolve, the successful fabrication of high aspect ratio (HAR) features becomes more and more challenging. Apart from the traditional patterning, deposition and etch related issues, conformal film deposition onto these HAR structures becomes a critical parameter in determining the overall device yields. It is well established now that compared to conventional deposition techniques such as chemical vapor deposition (CVD) and physical vapor deposition (PVD), atomic layer deposition (ALD) offers a pathway to highest conformality and step-coverage. On the other hand, film conformality, especially roughness property has trade-off relationship to step-coverage property. High-pressure process is appropriate to obtain high step-coverage performance in short ALD cycle time process, but roughness value becomes worse due to higher chance of crystalline film growth at high-pressure process condition. High roughness causes local variations in step-coverage and poses problems for deposition of subsequent layers and device performance.

In the present study, we report that it is possible to obtain conformal and smooth TiN film by using low/high pressure two-step growth, initially low-pressure TiN growth, and secondly high-pressure TiN growth on the non-pattern and HAR pattern wafers. Eugenus’s versatile 300mm mini-batch system and HAR structures with approximately 120:1 (Dimension of bottom opening, and total height are approximately 17nm and 2μm, respectively) were used in this research, respectively. TiCl4 and NH3 were used as the precursors for TiN film deposition and grown TiN films were analyzed by using ellipsometry, atomic force microscopy (AFM) and transmission electron microscopy (TEM) to study the film properties and step-coverages. In addition, reactor-scale computational fluid dynamics (CFD) simulations were performed and correlated to on-wafer experimental results and utilized as a predictive tool.

It was found that TiN film grown at low-pressure condition was more conformal and smoother than that grown at high-pressure condition, although step coverage value grown at low-pressure condition was worse than that grown at high-pressure condition. By optimizing low/high pressure two-step TiN growth condition, it was achieved that not only better roughness than that of pure high-pressure TiN, but also, better step coverage value than that of pure low-pressure TiN as well as than that of pure high-pressure TiN (Figure 1).

Figure 1
Silicene Growth through Island Migration and Coalescence
Authors: Cherukara Mathew Joseph , Narayanan Badri , Chan Henry , Sankaranarayanan Subramanian K. R. S.
Published: December 2020

Silicene, the Si based counterpart to graphene is predicted to demonstrate similar desirable features to graphene, possessing a Dirac cone in the band-structure and Fermi velocities comparable to graphene. It has also been predicted to demonstrate several exotic properties such as the quantum spin Hall effect, chiral superconductivity and giant magnetoresistance. It has the added benefit of being easy to integrate into current industrial device engineering processes. Silicene monolayers have been grown on Ag (111) and Ir (111) substrates and recently a working field-effect transistor has been demonstrated at room temperature. While it is possible to characterize the final monolayer structure, it is impossible to probe experimentally the evolving atomic structure during growth.

We perform massively-parallel molecular dynamics (MD) simulations to study long time monolayer silicene growth on an Ir (111) surface. We observe an intricate multi-stage growth process driven by atomic and cluster migration on the surface. Initial growth involves formation of sub-nanometer clusters via adatom surface diffusion. Subsequently, these clusters rearrange spontaneously with each additional Si atom, forming clusters containing 4–7 member rings. Growth of each cluster through adatom adhesion is accompanied by the formation of larger islands through cluster migration and coalescence. Coalescence of smaller, more mobile islands into larger clusters is aided by the internal rearrangement of rings within each cluster. This flexibility, both of clusters and their constituent atoms, allows the impinging clusters to reorient after first contact and form a more perfect union. We also report on the effect of temperature and flux on the growth process and the final nanostructure. Our study provides atomistic insights into the early stage growth mechanisms of silicene which can be significant for controlled synthesis of its 2D monolayers.

Reference:

Cherukara, M. J., Narayanan, B., Chan, H., & Sankaranarayanan, S. K. (2017). Silicene growth through island migration and coalescence. Nanoscale, 9(29), 10186-10192.

Figure 1
Microwave Photon Detection Using a Topological Josephson Junction
Authors: Pan Wei
Published: December 2020

Single photon detection (SPD) has found increasingly important applications in many forefront areas of fundamental science and advanced engineering applications, ranging from studying the galaxy formation though cosmic infrared background to entanglement of superconducting qubits, single molecular spectroscopy, and remote sensing. In recent years, the rapid developments in superconducting quantum computation, high fidelity quantum measurement, quantum key distribution, and quantum network call for SPD in the microwave frequency range.

In this talk, I will first present our recent experimental work on topological Josephson junctions in Dirac semimetal Cd3As2. In high quality aluminum-Cd3As2-aluminum Josephson junctions, we observe both π and 4π periodic supercurrents. The π period is manifested by both the magnetic-field dependence of the critical supercurrent and the appearance of half-integer Shapiro steps in the ac Josephson effect. Our simulation by a resistively shunted junction model suggests that the π period arises from interference between the induced bulk superconductivity and the induced Fermi-arc surface superconductivity. In the second part of the talk, I will discuss microwave photon detection using these topological Josephson junctions. The temperature dependence and microwave power dependence of the junction resistance are studied. It is observed the effective temperature of the junction device under microwave radiation increases with microwave power, suggesting a promising potential for photon number-resolving capability.

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under Contract No. DE-NA-0003525.