bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of Passive Layers Formed on Alloy 600 in Zinc Containing High Temperature Primary Water
Authors: Jiang Yifan , Devine Thomas 
Published: February 2020

Nickel-based Cr-Fe alloys have been found to show very low corrosion rates in extreme environments and thus have been extensively used in industries, such as in nuclear power plants. One of the reasons that Ni-Cr-Fe alloys show good corrosion resistance is that there are oxides that prevent the bare metal from general corrosion. However, Pressurized Water Reactors (PWRs) have experienced stress corrosion cracking (SCC) on the primary side of the Alloy 600 (Ni-15Cr-9Fe) steam generator tubing. It is believed that passive layer formed on Alloy 600 is crucial for SCC initiation. Zn ions are added to primary water in industry in order to reduce SCC initiation. However, the mechanism of SCC suppression with Zn is not yet fully understood. The Zn incorporation process is of great importance in the way that it can help understand the mechanism of SCC initiation. Our research aims to understand the influence of surface oxides of Alloy 600 on SCC in primary water of PWR, focusing on the effect of Zn ions during short period of time (less than 100 hours) at different potentials.
The present research examined the effect of Zn ions on the passive layer using in-situ electrochemical method as well as ex-situ characterization method. We constructed a system simulating the high temperature primary water with 100ppb Zn addition and operated the system at 320 C and 1800psi. The sample was oxidized in the autoclave for up to 48 hours at different potentials. During the oxidation period, electrochemical impedance spectroscopy (EIS) was applied at different oxide forming potentials in order to get information of how the alloy performs at different potentials. Ex-situscanning electron microscopy (SEM), transmission electron microscopy (TEM), and electron dispersive spectroscopy (EDS) were also performed on the samples to determine the morphology and chemical profiles of the passive layer.
Our EIS study indicated that there was likely a change in oxide property on Alloy 600, likely related to the incorporation of Zn ion, at different potentials for short time oxidation. It was found from the ex-situ experiments that with potential changes, both the thickness and the morphology of the passive layer changes, which agreed with the changes in the impedance results. Figure 1 shows the changes on surface morphology on Alloy 600 samples polarized at different potentials for up to 40 hours. It is indicated that both the distribution and the size of oxide particles changes with polarizing potentials. Zn was found to incorporate into the passive layer of the oxide, substituting some of the Ni content in the passive layer. As potential increased, the content of Zn incorporation changed.

Figure 1
High Temperature Corrosion in Molten Salts in Solar Power Concentration Plants: Dynamic and Static Corrosion Test
Authors: Perez Trujillo Francisco Javier , Lasanta Maria Isabel , Garcia Martin Gustavo , de Miguel Maria Teresa , Encinas Sánchez Víctor 
Published: February 2020

The solar power concentration plants (CSP) are at the present time operating in the heat storage and transfer fluids with binary molten nitrates mixtures.Those mixtres at hgh temperature are dealing with hot corrosion processes in the metallic materials that compose those technologies. In order to determine the corrosion processes in storage tanks and piping, the corrosion test have to be perfomed under static and dynamic conditions. In order to determine the dynamic conditions a new molten salts dynamic loop have been develop and patented (PCT) by the UCM research team. Comparison between dynamic and static results will be provided and a comprehensive mechanism in both conditions will be provided.
The high temperature corrosion test in molten salts will be performed in different steels, in oder to analyze the salt effect,and also the influence of impurities in the salt content.
A complete review of the state of the art will be provided.
Self-Organized TiO2 Nanotube Arrays: Latest Features and Applications
Authors: Schmuki Patrik 
Published: February 2020

TiO2 nanomaterials have over the last 30 years attracted tremendous scientific and technological interest. Main research direction using TiO2 in functional applications are still the use in photocatalysis e.g. for the direct splitting of water into H2 and O2 to generate the potential fuel of the future, hydrogen, or the use in Grätzel type solar cells. In order to achieve a maximum turn-over rate (by creating a high surface area), usually nanoparticles are used either suspended or compacted to a photoelectrode. Over the past decades various 1D and highly defined TiO2 morphologies were explored for the replacement of nanoparticle networks and were found in many cases superior to nanoparticles. Nanotubes or wires can be grown by hydrothermal or template methods, or even more elegantly, by self-organizing anodic oxidation. The latter is not limited to TiO2 but to a full range of other functional oxide structures on various metals and alloys can be formed. These advanced and doped morphologies can be grown on conductive substrates as ordered layers and therefore can be directly used as functional electrodes (e.g. photo-anodes). The presentation will focus on these highly ordered nanotube arrays of TiO2 and discuss most recent progress in synthesis, modification and applications.
Literature: (review):
1. P. Roy, S. Berger, P. Schmuki, Angew. Chem. Int. Ed. (2011), 2904
2. K. Lee, A. Mazare, P. Schmuki, CHEMICAL REVIEWS, 114 (2014) 9385
(Invited) Stress-Assisted Formation of Self-Organized Porous Anodic Oxides
Authors: Hebert Kurt , Mishra Pratyush , Capraz Omer , Shrotriya Pranav 
Published: February 2020

Porous anodic oxide (PAO) films are grown by electrochemical polarization of Al, Ti, and other metals in baths that dissolve the oxide. Procedures to grow films with highly ordered and controllable arrangements of nanoscale pores have led to the extensive use of PAO films in nanofunctional devices. Experiments and calculations show that transport in the oxide occurs by electrical migration coupled with plastic flow driven by mechanical stress in the oxide, and suggest that flow may play a role in formation of self-ordered PAO (1-3). Pores initiate by a morphological instability at the oxide-solution interface when the initially formed barrier oxide reaches a critical thickness (4).
Herein is reported a combined experimental and modeling investigation of the formation and self-ordering of PAO. Experiments were carried out to identify stress generation mechanisms during galvanostatic formation of Al barrier films in 0.4 M H3PO­4. Stress distributions in these films were measured by monitoring stress-induced sample curvature changes during oxide formation followed by open circuit dissolution of the films (5). Elevated compressive stress reaching several GPa was found to build up within a few nanometers of the oxide-solution interface, coinciding with high phosphorus contamination in the same layer revealed by GDOES (6). The compressive surface stress is likely due to electric field-induced phosphate incorporation.
The experimentally characterized surface stress was incorporated in our anodizing model based on transport by coupled viscous flow and electrical migration (2). Morphological stability analysis of the model reveals pattern formation consistent with the well-established characteristic pore spacing to voltage relationship of PAO (7). Pore formation is governed by competition between stabilizing oxide formation at the solution interface and destabilizing flow driven by gradients of anion incorporation-induced surface stress. The model successfully predicts the critical threshold electric field and the narrow ranges of anodizing efficiency characterizing PAO formation on many metals (3,4). A compelling analogy exists between the mechanisms of PAO ordering and formation of hexagonally-ordered Marangoni patterns in thin liquid films.

References

1. S. J. Garcia-Vergara, et al., Electrochim. Acta.
52, 681 (2006).
2. J. E. Houser and K. R. Hebert, Nature Mater.
8, 415 (2009).
3. J. Oh and C. V. Thompson, Electrochim. Acta,
56, 4044 (2011).
4. K. R. Hebert et al., Nature Mater.
11, 162 (2012).
5. Ö. Ö. Çapraz, P. Shrotriya, and K. R. Hebert, J. Electrochem. Soc
161, D256 (2014).

6. Ö. Ö. Çapraz, et al., Electrochim. Acta
167, 404-411 (2015).

7. A. P. Li et al., J. Appl. Phys.,
84, 6023 (1998).
Pitting Corrosion of Copper Tubes for Drinking Water Applications Due to Silicate Films
Authors: Feser Ralf , Schewe Sven 
Published: February 2020

Water installations are often constructed from copper tubes. Copper is a well-established material for water transport. Sometimes pitting corrosion could appear. In the last few years some serious failures in cold water tubes in one special region in Germany have been observed. Some influencing factors are well known (sulfates, chlorides and hydrogen carbonate), in detail some knowledge about the mechanism is missing. Beginning with a detailed failure analysis some possible factors have been identified. Especially the appearance of silicate films at the metal surface has been detected. Laboratory investigations have been performed in an electrolyte which simulates a drinking water. The experiments have been performed to study the mechanism of pitting corrosion. Measurements with the Scanning Kelvin Probe and Scanning Vibrating Electrode do show the existence of local anodes under artificially prepared silicate films on copper. At the phase boundary between the silicate film and the untreated copper surface, the free corrosion potential shows the most negative value. Interestingly this anode is surrounded by the cathode formed by the free copper surface and also by a cathodic area represented by the complete silicate covered copper surface. Polarization curves do show that the cathodic oxygen reduction is increased by the appearance of silicate films. Polarization curves and galvanostatic investigations do show that the mechanism of copper dissolution is changed. The formation of Cu2+ -ions is hindered, only Cu+ ions can be formed under thick silicate films. Moreover the existence of the silicate film hinders the copper to form a protective oxide film. The copper dissolution is higher than without a silicate film. Without a silicate film at the surface, the copper dissolution decreases with exposition time. This is the first time that the mechanism of pitting corrosion of copper in cold water due to the formation of silicate films has been proofed.
Therefore the mechanism of pitting corrosion of copper in drinking water with a sufficient amount of silicate is quite clear. First a silicate film is formed at the fresh copper surface. A local anode is established under the silicate film. A passivation of copper is hindered due to the existing silicate film. The local cathode surrounds the anode. The electrochemical reactions are increased due to the hindered oxidation of the copper surface by silicate layers.
Results of the experiments will be presented as well as the explanation of the model.
Microelectrode Test Configurations for Measurement of Galvanic Current Under Saline Drops in Simulated Atmospheric Conditions
Authors: Hangarter Carlos , Policastro Steven 
Published: February 2020

Atmospheric corrosion is characterized by thin film and discontinuous electrolytes that behave in fundamentally different ways than bulk electrolytes. These differences arise due to their finite volumes that limit availability of ionic species and permit the accumulation of corrosion products that can then impact reaction kinetics. To explore these differences between bulk and droplet electrolytes, two different cells were conceived, tested, and used to study galvanic couples in atmospheric environments. The first examined galvanic kinetics of droplets with two discrete half cells. This configuration, shown in Figure 1, allows the time resolved galvanic current and potential of the zero-resistance-ammeter (ZRA) connected anode and cathode to be examined during humidity cycling in the absence of reaction product cross-talk. The galvanic corrosion current and potential were examined during humidity cycling between 95% and 20%. This test configuration was shown to be sensitive to the deliquescence/efflorescence points.
The second galvanic atmospheric corrosion cell is that depicted in Figure 2. In this configuration the anode and cathode are brought into intimate contact with a single microliter droplet, in which the droplet is placed on the cathode and the anode is polished to a fine tip. The anode is then translated to pierce the droplet surface with a three axis micromanipulator and the aid of a microscope camera. This configuration differentiates itself from Figure 3 in that a fixed quantity of electrolyte utilized in this system and reaction products from both electrodes are free to interact with one another and either electrode.
The galvanic corrosion test cell from Figure 2 displayed a precipitous decay in corrosion current that was found to be dependent upon electrolyte composition. ZRA measurements were compared with SEM and EDS mapping of corrosion products and electrolyte residue to understand the conditions that diminish the galvanic current. These results support significant anion consumption; Cl-, in this case; with a clear dependence on pH that suggests ambient CO2 plays a role as well. This talk will also discuss how the two test configurations compare with one another and use polarization curves to understand the information they provide in a broader context and how they should be applied.

Figure 1
Electrochemical Evaluation of Degradation of Zn-Coated Steel Exposed to Cyclic Wet-Dry Condition
Authors: Nishikata Atsushi , Okazaki Takafumi , Tada Eiji 
Published: February 2020

The corrosion process of Zn-coated steel is divided into four stages: τ1; Zn-coating corrosion, τ2; sacrificial protection by zinc, τ3; protection by zinc corrosion products, τ4; substrate steel corrosion. To understand the degradation process, it is very important to quantitatively evaluate the corrosion behavior in each stage. In this study, the corrosion behavior of Zn-coated steel has been investigated under cyclic wet-dry condition.
An Electro-galvanized steel plate (EG, 5μm coating thickness) was used as the test sample. The surface area exposed was 10 mm in diameter and the rest was masked with tape. Solution of NaCl was placed on the surface. The mount of chloride ion placed on the sample was 3.0 g/m2. The attached salt was washed away by distilled water every week and the same amount of the fresh salt was newly placed on the surface. The six samples each metallic coating were exposed to alternate conditions of drying at 40 %RH for 2h and wetting at 95 %RH for 2h in a chamber at 25 oC. One sample was removed from the chamber every week and corrosion potential E
corr and EIS were measured using a conventional three-electrode set-up. The corrosion surface was observed with optical microscope. The remaining coating thickness was measured by an anode stripping method. All electrochemical measurements were carried out in 10 mM NaCl solution.
Optical microscopic observation showed a trace amount of red rust appeared at 1 week and increased with the cycle number. The E
corr did change so much until 3 weeks, afterward, changed drastically. The anodic stripping showed the coating layer disappeared at an early period at three weeks. From the results described above, the τ2 stage would start from the 2nd week and τ3 from the 3rd week. Zn-coated steel sample at each stage (τ1 ~ τ4) indicated characteristic EIS. It seemed that the oxide film resistance R
oxide in the high frequency region and charge transfer resistance R
ct in the low frequency would appear. The degradation stages of τ1 ~τ4 can be distinguished by the changes of both E
corr and EIS.
Corrosion Resistant and UV Durable PVDF-Co-HFP /Al2O3 Superhydrophobic Nanocomposite Coating for Aluminum
Authors: Bahgat Ahmed , Abdullah Aboubakr Moustafa , Mohamed Adel M , Almaadeed Mariam 
Published: February 2020

The interest in superhydrophobic surfaces, which demonstrate high water-repellency, have recently increased dramatically because of their wide range of applications in many fields. The two major needed conditions to get a nanostructured superhydrophobic surfaces are the optimum surface roughness and low surface energy.
In our present work, the fabrication process of a porous superhydrophobic coating on aluminum surfaces was achieved using a one-step electrospinning technique. The wettability properties of the prepared coating was inspected by measuring the water contact (WCA) and sliding angle (WCAH) before the addition of Al2O3 nanoparticles (150±2.9 and 6.25±1) while the measured WCA and WCAH after addition of nanoparticles was found to be 152±0.59 and 5±2.5, respectively. The wettability of the prepared coatings was inspected also after being irradiated with strong ultraviolet (UV) radiation of 1.5 W/m2 at a high temperature of 70 °C for 64 h. In fact no big difference was noticed after the UV test with respect to the wettability properties. The morphology of the superhydrophobic coating was studied using scanning electron microscope (SEM) coupled with energy dispersive X-ray (EDX). It shows the formation of a beaded fiber structure. Furthermore, Fourier transform infrared (FTIR) spectroscopy was used to check the nanocomposite coating before and after irradiation with UV. The surface roughness of the composite materials were measured using atomic force microscope (AFM). The corrosion behavior of the superhydrophobic nanocomposite coating was evaluated by the electrochemical impedance spectroscopy (EIS) and the potentiodynamic polarization in 3.5% NaCl. The results have shown that new nanocomposite coating exhibits a very high corrosion resistance.
An Svet Study of the Throwing Power of Smart-Release Corrosion Inhibitor Pigments in Organic Coatings
Authors: Glover Carol Frances , Williams Geraint , Ansell Phil , Dodds Patrick Charles 
Published: February 2020

An SVET study of the throwing power of smart-release corrosion inhibitor pigments in organic coatings
Ion-exchanged anti-corrosion pigments phenylphosphonic acid, benzotriazole and 5-methylbenzotriazole exchanged in hydrotalcite (HT) are studied in terms of ‘throwing power’ when dispersed in a model polyvinyl-butyral (PVB) primer coating adherent to a hot dip galvanised steel substrate. The Scanning vibrating electrode technique (SVET) is used in a novel study to determine the inhibitory effects of the primer coatings when fully immersed in 5% w/v NaCl electrolyte. Samples are prepared as shown in Figure 1 where a coated sample is insulated such that only the edges of the protective coating and a defined area of bare metal are exposed to electrolyte. Current density mapping of the exposed area is carried out over a 24 h period. HT has been shown previously to reduce cathodic delamination, by moderation of under coating pH, reduce chloride activity and also release ionic inhibitors[1]. In the presence of a penetrating electrolyte, effective inhibition is achieved through the leaching of anions creating an insoluble blocking layer[2]
[3]. The current study enables the isolation of the leaching mechanism. By systematically altering distance x, the extent to which inhibitors are able to leach into the bulk electrolyte and stifle corrosion can be mapped, allowing a threshold to be determined.
Figure 1. Sample set-up showing coated hot dip galvanised steel surface with exposed scan area.
References
[1] T. T. X. Hang, N. T. Duong, T. A. Truc, T. Hoang, D. T. M. Thanh, S. Daopiset, A. Boonplean, J. Coatings Technol. Res.
2015, 12, 375.
[2] C. F. Glover, R. Subramanian, G. Williams, J. Electrochem. Soc.
2015, 162, C433.
[3] M. Finsgar, I. Milosev, Corros. Sci.
2010, 52, 2737.

Figure 1
Enhancement of Corrosion Resistance in Carbon Steels Using Fe-Based Amorphous Metallic Coatings Under High-Temperature Flowing Water
Authors: Kim Seunghyun , Kim Jeong Won , Kim Ji Hyun 
Published: February 2020

Carbon steels are the backbone material of modern industry applications owing to excellent forming, machining, and welding properties. However high-temperature flowing water condition induces complex corrosion phenomena involving destructive electrochemical reactions and mechanical wear for carbon steels thus a cost-effective countermeasure for the corrosion of carbon steels is highly required. In this study, to enhance the corrosion resistance in carbon steels under high-temperature flowing water, Fe-based amorphous metallic coatings (AMC) are deposited on carbon steels using high-velocity oxygen fuel (HVOF) technique. The Fe-based AMC gathers tremendous interests as they exhibit excellent corrosion and wear resistance thus it is expected that it provides effective corrosion protection ability for carbon steels even in severe environments including nuclear power plants. To examine the corrosion resistance of the Fe-based AMC, rotating cage corrosion (RCC) test was designed with a magnedrive-installed autoclave and recirculation loop system. The temperature for each test was 125, 150, 175, and 200 oC, respectively. To simulate power plant water chemistry, pH 9.3 ETA solution was continuously supplied. The weight loss of each specimen was measured after 2 weeks of elapsed time and the result shows that the Fe-based AMC exhibits excellent RCC resistance at all temperature and most effective at 150 oC as shown in Fig. 1. Further, while microstructure evolution of carbon steels displays the formation of porous Fe3O4 at the surface, the Fe-based AMC displays the formation of thin Cr2O3 layers meaning passivity as shown in Fig. 2.. At 200 oC, the formation of FeCr2O4 was also observable (Fig. 3) The early conjecture is that the Fe-based AMC is able to protect carbon steels by forming passive oxide layer at its surface. Previous research argued that Cr and its passive layer is the most effective RCC barrier in high-temperature. Thus, further investigation using transmission electron microscopy and X-ray photoelectron spectroscopy will be carried out to figure out their stoichiometry and detailed microstructure evolution.

Figure 1