bluuebunny/crossref_metadata_2025_split huggingface dataset:
High-Resolution Studies of Crevice Corrosion of Nickel and Aluminum with Real Time Multiple Beam Interferometry and Microscopy
Authors: Merola Claudia , Shrestha Buddha Ratna , Valtiner Markus 
Published: February 2020

Crevice corrosion (CC) of engineering metals remains a serious concern for structural materials. Yet combining both, a real-time and high-resolution in-situ visualization of corrosion within confined geometries remains very challenging. In this contribution, we will discuss how multiple-beam interferometry (MBI) and simultaneous microscopy can be utilized to directly visualize corrosion processes in real-time and with Ångstrom resolution within well-defined confinement geometries. Here we will directly compare results of accelerated corrosion tests of confined Aluminum and Nickel surfaces in a modified surface forces apparatus1.
With MBI, we can detect and track active sites of aluminum corrosion in NaCl solution within confined geometries in real time. We find that CC of aluminum randomly initiates in the confined crevice mouth, where the distance between apposing surfaces is between 20-300 nm. We can directly track oxide dissolution/formation, and corrosion-rates as well as their retardation due to sodium vanadate inhibitors present in solution. Formation of a compacted oxide layer effectively inhibits CC in 5 mM NaCl solutions with 2.5 mM of added NaVO3, while inhibition rapidly breaks down at chloride concentrations above 50 mM. Breakdown of the inhibition-layers is initiated by rapid dissolution of the protective oxide within the confined zone.
Interestingly, Nickel CC shows distinctly different and unexpected corrosion mechanism depending on the NaCl concentration. We find that low Chloride concentration lead to “preferential pitting corrosion” inside of confined zones, while high Chloride concentrations lead to “crevice corrosion in the crevice mouth”. We will discuss these surprising results and we will show real time high-resolution videos of CC in confined geometries that detail this behavior.

Literature

1. Shrestha, B. R.; Hu, Q.; Baimpos, T.; Kristiansen, K.; Israelachvili, J. N.; Valtiner, M., Real-Time Monitoring of Aluminum Crevice Corrosion and Its Inhibition by Vanadates with Multiple Beam Interferometry in a Surface Forces Apparatus. Journal of the Electrochemical Society 162 2015, C327-C332
Corrosion and Surface Modification of Ti-6Al-4V Implant Alloy Under Various Simulated Biological Environments
Authors: Virtanen Sannakaisa 
Published: February 2020

Ti and its alloys, for instance Ti-6Al-4V, are generally considered as highly corrosion resistant, due to the very stable passivity. These materials are widely used in biomedical applications for permanent implants, and they have an excellent reputation for biocompatibility. Some problems related to the chemical stability of Ti-based implants exist in the practical application, mainly due to the conjoint action of chemical and mechanical attack, i.e. fretting corrosion. This can lead to release and accumulation of Ti in tissue adjacent to titanium implants. However, it is also known that depassivation of Ti can take place under deaerated acidic conditions. Even though the typical chemistry in a "bulk" biological environment is pH-neutral (buffered to pH 7.4), under certain conditions, for instance in crevices, much more aggressive environments can be present. Local acidification is possible not only due to metal cation hydrolysis reactions, but in addition by possible inflammation reactions (such as following a surgery). Inflammation conditions also lead to presence of H2O2 in the surrounding. This is noteworthy in view of corrosion of Ti alloys, as H2O2 is known to complex Ti cations and hence acceleration of dissolution in possible.
This presentation will discuss dissolution of the Ti-6Al-4V implant alloy under different simulated biological environments, including simulation of inflammation conditions (pH decrease, presence of H2O2). Electrochemical measurements and metal release indicate drastically increased dissolution rates under simulated inflammation conditions. In addition, selective phase etching is observed. Various surface modification treatments for improved performance are being explored, such as anodization or TiO2 nanoparticle coating. In addition to corrosion studies, bioactivity of the surfaces in view of Ca-phosphate precipitation is being investigated.
Effects of Reclaimed Water Blending on the Pipe Corrosion in an Irrigation System
Authors: Woo Dalsik , Shin Taesub , Lee Jaekyeong , Shin Sunghoon , Lee Haksoo 
Published: February 2020

Global climate change is a change in the statistical distribution of weather patterns when that change lasts for an extended period of time. Nowadays, this change has been affect to water source shortage. Usage of reclaimed water is one of the most important solutions for this problem. There are a lot of methodologies for using reclaimed water instead of fresh water. Especially, agriculture field uses a lot of water to grow crops. Many countries water usage amount in agriculture is to 40~60% of their total water capacity. Therefore, usage of reclaimed water is one of solutions for supplement water shortage. There are several efforts to saving and improving water usage in agricultural field.
In pipeline irrigation system, pipes were made of metallic or non-metallic materials. Depending on the case, the metallic pipes are used for following; large diameter, high pressure or loading. Because of the corrosion problem of metallic pipes by water, non-metallic pipes also used if there is concern about corrosion. There are various techniques in order to prevent corrosion. In these methods, sacrificial anode method and pipe lining are useful method for irrigation pipeline. For the effective application of corrosion prevention for usage of reclaimed water, it is necessary that the evaluation of corrosion pipes with various type of water blending (reclaimed water, surface water, etc.).
In this study, we evaluated about corrosion index for blending effect of surface water and reclaimed water in metallic pipeline. Based on blending ratio, pH, alkalinity, conductivity, hardness, nitrate, nitrite, phosphate, ammonium were measured and evaluated in batch reactor. Based on this research, it is expected that the usage of this data can be useful for usage of various type of water in agriculture field and many engineers related corrosion field can apply this data for their works.
Acknowledgement
This research was supported by a grant (12-TI-C01) from Advanced Water Management Research Program funded by Ministry of Land, Infrastructure and Transport of Korean government
The Effect of Plasma Electrolytic Oxidation Parameters on Coating Morphology and Corrosion Behavior
Authors: Cengiz Sezgin , Uzunoglu Aytekin , Tarakci Mehmet , Gencer Yucel , Stanciu Lia 
Published: February 2020

Zirconium (Zr) and Zr-based materials have been widely used in biomedical and dental applications. Although these materials have better chemical and mechanical properties compared to titanium-based implants for biomedical applications, their poor bioactivity is still a challenge that needs to be overcome in order to increase the cell attachment properties [1-3]. In this study, the surface of Zr substrates was modified by plasma electrolytic oxidation (PEO) to induce a significant changing the surface chemistry and topology and thus increase bioactivity. The PEO processes were conducted at different current frequencies ranging from 80 to 420 Hz in a 30 g/l calcium acetate monohydrate (CA), 8 g/l β-glycerophosphate disodium salt pentahydrate (β-GP) and 2 g/l KOH containing electrolyte solution. The phase and chemical composition, as well as the morphology of the coatings were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and optical surface profilometry (OSP) techniques. The corrosion performance of the fabricated coatings, which is also crucial for biomedical applications, were evaluated. The results revealed that the current frequency had a profound influence on the microstructure and the chemical composition of the fabricated coatings. The SEM and OSP experiments revealed that the increase in the current frequency resulted in rougher surface coatings with bigger pores. The corrosion behaviour of each samples conducted in simulated body fluid (SBF) at the temperature of 36.5 °C will be presented.

References

1- V. Sollazzo, F. Pezzetti, A. Scarano, A. Piattelli, C.A. Bignozzi, L. Massari, G. Brunelli, F. Carinci, Zirconium oxide coating improves implant osseointegration in vivo, Dent Mater, 24 (2008) 357-361.
2- P. Thomsen, C. Larsson, L.E. Ericson, L. Sennerby, J. Lausmaa, B. Kasemo, Structure of the interface between rabbit cortical bone and implants of gold, zirconium and titanium, J Mater Sci-Mater M, 8 (1997) 653-665.
3- Y.Y. Yan, Y. Han, Structure and bioactivity of micro-arc oxidized zirconia films, Surf Coat Tech, 201 (2007) 5692-5695.
Corrosion Behavior of Austenitic Stainless Steel in Supercritical CO2 Containing O2 and H2o
Authors: Teeter Lucas , Huerta Nicolas , Dogan Omer , Ziomek-Moroz Margaret , Oleksak Richard , Oryshchyn Danylo 
Published: February 2020

The corrosion behavior of 347H stainless steel was investigated in supercritical CO2 (sCO2) containing H2O and O2 to simulate heat exchanger conditions that would exist in direct sCO2 power cycles. To understand the thermodynamic properties of oxygenated sCO2 aqueous systems related to the corrosion phenomena, thermodynamic modeling was performed using REFPROP software. Samples were exposed to oxygenated water-containing CO2, and oxygenated CO2-containing H2O. The exposure tests were carried out at a pressure of 80 bar and two temperatures, 50 °C and 248 °C. The environmental conditions were simulated by filling each 1100 ml autoclave with 400 ml of deionized water, bringing each autoclave to its respective test temperature, and then pressurizing it with a CO2:O2mixture having a molar ratio of 95:1.
The corrosion rate of each sample was determined by mass loss measurements. The surface morphology and the composition of the corrosion product layers were analyzed using surface analysis techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), wavelength dispersive spectroscopy (WDS) for oxygen and chromium, and X-ray photoelectron spectroscopy (XPS). Weight gain results reveal that the samples exposed to higher temperatures experience a significant increase in oxide growth compared to the lower temperature counterparts. XRD results confirmed this result in that corrosion products present on the samples exposed to sCO2 containing H2O and O2 and H2O containing sCO2 and O2 at 50 °C were too thin for conventional Bragg-Brentano XRD to detect anything aside from the base material. However, the samples exposed to the environments at 248 °C had sufficiently thick corrosion layers for this method. The XRD results for the corrosion products on the sample surfaces formed in the oxygenated CO2-containing H2O and water-containing CO2 environments at 248 °C revealed the presence of primarily hematite (Fe2O3) and magnetite (Fe3O4), respectively. These results indicate that the corrosion degradation mechanism for 347H in oxygenated H2O containing sCO2 is different from the mechanism in oxygenated sCO2 containing H2O at 248 °C.
Investigation, Modeling and Design of a Cathodic Protection System for Hull Structures in Marine Environment
Authors: Aksu Rauf , Uguz Refik Onur , Erdogan Metehan , Meco Halim , Karakaya Ishak 
Published: February 2020

Corrosion is a form of material deterioration process due to chemical interactions with surrounding environment. Metals must be isolated or protected to avoid corrosion. Metallic components of amphibious vehicles are exposed to aggressive conditions during their service lives. These components are coated with organic substances to isolate metal surface from corrosive species. Occasionally, protective layer on metallic components fails due to poor adhesion, chalking, peeling and delamination. Damaged areas on coated components may become exposed to seawater. Cathodic protection is an effective method to inhibit corrosion of metallic components of amphibious vehicles which are in direct contact with seawater.
Selected steel types and aluminum alloys [1], which are used in manufacturing the hulls of armored amphibious vehicles, were subjected to accelerated corrosion tests in synthetic seawater to collect data for simulation of cathodic protection. Typical Nyquist and Tafel plots are shown in Figure 1. COMSOL Multiphysics modeling software [2] was used to integrate electrochemical data obtained by both impedance spectroscopy and potentiostatic tests to simulate cathodic protection of the vehicle hulls under seawater. Potential and current density distributions in marine environment were evaluated to design the cathodic protection system that could impress the currents. The size, shape and locations of sacrificial anodes were optimized to enhance homogenous protection performance.
[1] National Research Council (U.S.). (2013). Materials for Lightweight Military Combat Vehicles: Report, Nabu Press
[2] COMSOL Multiphysics 5.1, Corrosion and Electrochemistry Modules

Figure 1
Degradation of Ir-Ta Oxide Coated Ti Anodes in Sulfuric Acid Solutions
Authors: Ma Dongni , Ngo Vanda , Raghavan Srini 
Published: February 2020

Conductive ceramic oxides based onIr and Ta are commonly used in the fabrication of dimensionally stable anodes for many electrochemical systems requiring high chemical stability and electrocatalytic activity in aggressive environments. In this paper, the degradation of IrO2-Ta2O5 (35.6 wt% Ir and 26.3 wt% Ta ) coated titanium mesh anodes in 2 M sulfuric acid solutions will be discussed. The Ir-Ta oxide coated electrodes were prepared by brush coating Ti mesh samples with an organic solvent system containing H2IrCl6 and TaCl5followed by firing at approximately 450 deg. C. The thickness of the oxide coating was ~ 4.8 to 6.9 microns.
The electrochemical properties of the prepared electrodes were studied by performing galvanostatic accelerated life tests and anodic polarization. The accelerated life test consisted of subjecting the sample to a current density in the range of 0.54 to 1 A/cm2 in 2 M sulfuric acid solution in a customized flow through cell with a titanium mesh cathode for a period lasting over five hundred hours. The degradation of the coating was followed by monitoring the cell potential. A PARSTAT 2273 Potentiostat system equipped with a PowerSuite®software was used for these experiments. The acid concentration was maintained at 2M by adding the required amount of water to compensate for the decomposition of water to oxygen at the anode. The lifetime test was interrupted periodically to conduct anodic polarization experiments and determine changes in the potential for oxygen evolution. The morphology and chemical composition of the coatings at different stages of the accelerated life test were characterized by SEM and energy dispersive X-ray spectroscopy (EDS).
The as-prepared sample had numerous cracks and displayed amorphous and crystalline features. Localized thinning as well as complete removal of the oxide coating were evident in samples subjected to accelerated life testing (see Figure). EDS analysis indicated selective removal of IrO2 from the oxide coating. The presentation will discuss the results of the electrochemical and morphological investigations and propose a degradation mechanism for the Ir-Ta oxide coating in acidic environment.

Figure 1
The Utilization of Hydrophobic Coatings on Insulative Skirts to Galvanically Decouple Mechanically-Fastened Aluminum Alloy and Carbon-Fiber Reinforced Polymer-Matrix Composites
Authors: Srinivasan Raghu , Hihara Lloyd H. 
Published: February 2020

In a quest to reduce weight and improve performance, aluminum (Al) alloys have been used in conjunction with lightweight materials such as carbon-fiber reinforced (CFR) polymer-matrix composites (PMCs). The mechanical contact of CFR PMCs (which serves as cathode) with Al alloys (which serves as anode) can result in galvanic corrosion of the Al alloys in a corrosive environment. The major objective of this research was on devising corrosion control strategies for couples of 6061-T6 Al that were mechanically fastened to CFR PMCs using Ti-6Al-4V bolts.
A typical method used to mitigate galvanic corrosion when bolting Al to CFR PMCs is to insert an insulating layer (G-10 fiberglass or E-glass–reinforced PMC) between the members. Although the direct contact between the aluminum and CFR PMC is eliminated, the aluminum and the CFR PMC are still galvanically coupled through the Ti fastener, and galvanic corrosion on Al will occur if the electrolyte bridges over the insulating layer. Galvanic corrosion can be mitigated by increasing the IR loss across the skirt, which can be achieved by lengthening the skirt or breaking up the continuity of the salt bridge that forms on the skirt. The continuity of the salt bridge can be disrupted by applying hydrophobic coatings on the insulative skirt.
In this study, galvanic corrosion rates were monitored for 6061-T6 Al—CFR PMC couples (with insulating skirts) subjected to the following conditions:
1) Insulting skirts having coatings (silane-based coating, epoxy, polyurethane, or latex) of various levels of hydrophobicity
2) Salt solutions of various concentrations (0, 10, 100, 1000, 10000, and 20000 ppm of chlorides)
3) Various insulating skirt lengths (0.25 inch or 0.5 inch),
4) Various exposure conditions (controlled humidity laboratory exposure, outdoor exposure with sheltered and unsheltered conditions).
The effect on galvanic corrosion by the different coatings was studied as a function of hydrophobicity, as determined by the contact angle for wetting. The contact angle was measured on the coating surface before and after exposure to the outdoor test sites to study the effects of environmental degradation on hydrophobicity. The degradation of the coatings was also studied using other techniques such as Raman spectroscopy. The ingress of environmental constituents (i.e., chlorides, sodium ions, etc.,) towards the anode and cathode surfaces was analyzed using scanning electron microscopy (SEM) and energy dispersive-X-ray analysis (EDXA).
(Invited) High-k Materials and Embedded Nanocrystals for Electronic and Photonic Applications
Authors: Heitmann J. 
Published: February 2020

High-k materials play a major role in semiconductor research and development. Semiconductor industry made a step towards high-k dielectrics like Al2O3, HfO2 and ZrO2 for MIM capacitors in DRAM and rf applications [1], as well as for gate dielectrics for sub 45 nm devices or in high electron mobility transistor in GaN based hetero structures. Implementing high-K materials into the process flow of a GaN based high electron mobility transistor needs to adapt the whole process sequence, like thermal budget of electrode formation etc. [2]. Furthermore, in solar industry the high-k material Al2O3 is discussed to replace SiN passivation layer for the newest PERC concept [3,4].
Beyond the already established applications routes high-k materials show superior properties as matrix material for semiconductor quantum dots – rare earth element alloys to enhance their optical and electrical properties. Embedded group IV nanocrystals like Si and Ge show superior charge storage properties in high-K matrix materials deposited via rf-magnetron sputtering. Ge nanocrystals embedded in an amorphous TaZrOx matrix as blocking oxide implemented in a metal-insulator-semiconductor capacitor show a voltage hysteresis in a capacitance-voltage slope of 5 V and a programming voltage – hysteresis voltage slope of nearly 1 [5]. In case of embedded Au nanoparticles in sol gel deposited Er doped ZrO2 films a temperature stability of the Au nanoparticle related surface plasmon resonance up to 1000°C annealing temperature could be shown [6].
In this contribution we will review our efforts to realize optimized properties of the high-K materials for the needs of the different applications as matrix material for nanocrystalline semiconductors for optical and electrical applications and as passivation layer for Si photovoltaics or nitride electronics.
[1] J. Heitmann, A. Avellan, T. Boescke, E. Erben, B. Hintze, S. Jakschik, S. Kudelka, and U. Schroeder, HfAlO and HfSiO Based Dielectrics for Future DRAM Application, ECS. Trans. 2 (2006) 217.
[2] Schmid, A.; Schröter, Ch.; Otto, R.; Schuster, M.; Klemm, V.; Rafaja, D.; Heitmann, J., Appl. Phys. Lett. 106, 053509 (2015)
[3] Benick et al. Applied Physics Letters 2008; 92; 253504
[4] F. Kersten, A. Schmid, S. Bordihn, J. W. Müller, J. Heitmann, Energy Procedia, 38, p. 843, (2013)
[5] D. Lehninger, P. Seidel, M. Geyer, F. Schneider, V. Klemm, D. Rafaja, J. von Borany, J. Heitmann, Appl. Phys. Lett. 106, 023116 (2015)
[6] S. Seidel, A. Sabelfeld, R. Strohmeyer, G. Schreiber, V. Klemm, D. Rafaja, Y. Joseph, and J. Heitmann, J. of Appl. Phys., submitted for publication.
Effect of Cu Drift on Dielectric Breakdown for Porous Low Dielectric Constant Film under Static and Dynamic Stress
Authors: Cheng Yi-Lung , Huang Yao-Liang , Sun Chung-Ren , Lee Wen-Hsi , Chen Giin-Shan , Fang Jau-Shiung 
Published: February 2020

Cu-ion-migration-induced the porous low-k dielectric breakdown was studied in alternating polarity-bias conditions using a metal–insulator–metal (MIM) structure with Cu as a top electrode. The experimental results indicated that Cu ions migrate into a dielectric film under a positive polarity stress, leading to a shorter time to failure (TTF). Additionally, the TTF obtained in the alternating-polarity test increased with decreasing the stressing frequency, indicating that the backward migration of Cu ions during the reverse-bias stress. Meanwhile, this Cu backward migration effect is effective as the stressing time of a negative polarity stress is larger than 0.1 s. When the frequency is decreased to 10-2 Hz, the measured TTFs were higher as compared to a direct-current (DC) stress condition. Finally, the electric-field acceleration factor of porous low-k dielectric breakdown became larger under Cu-ion-migration case.