bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydrogen Entry into Pure Iron Treated By Plasma Nitriding
Authors: Sugawara Yu , Muto Izumi , Hara Nobuyoshi 
Published: February 2020

In order to prevent hydrogen embrittlement of steels, it is effective to decrease the amount of hydrogen entry into steel matrix under atmospheric corrosion environments. In this study, the nitrided layer was formed in the surface of pure iron by plasma nitriding to inhibit the hydrogen entry, and the hydrogen permeation tests were conducted to clarify the barrier effect of nitrided layer on the hydrogen entry into pure iron.
Pure iron sheets of 1 mm thickness with 99.99 mass% purity were used as the specimens. The specimens were heat-treated at 1173 K for 18 ks and then furnace-cooled. The surfaces of the specimens were polished with diamond paste down to 1 μm. Plasma nitriding was performed in a nitrogen-hydrogen atmosphere composed of 75 % N2 and 25 % H2 for 3.6 ks at 673 K and at 600 Pa. The one side of the specimens was nitrided by masking another side. Figure 1a shows the cross-sectional image of the specimen etched with 3 % nital solution after the plasma nitriding. The layer with a different etching behavior from the matrix was observed in the surface region. The thickness of the surface layer was ca. 2.8 μm. Figure 1b shows the XRD patterns of the plasma-nitrided specimen. The peaks assigned to ε-Fe2-3N and γ
’-Fe4N were detected. The peaks of ε-Fe2-3N were larger than that of γ
’-Fe4N, suggesting that the surface layer was mainly composed of ε-Fe2-3N phase.
In order to investigate the property of hydrogen entry in the surface of the nitrided specimen, the hydrogen permeation tests using the Devanathan-Stachurski cell1 were carried out. The hydrogen entry was conducted by galvanostatic polarization at −100 μA (i
c) in deaerated boric-borate buffer solution with 0.01 M NaCl (pH 8.45) for 10.8 ks. The Pd-coated surface of the specimens in the hydrogen detection side was polarized at 0.2 V vs. SHE in deaerated 0.1 M NaOH solution. Figure 1c and 1d show time variation of the potential on the hydrogen entry side and the hydrogen permeation current density (i
p), respectively. In the initial 30 s, the potential of both the untreated and the nitrided specimen drastically decreased to approximately the same value (ca. −0.75 V vs. SHE). In the case of the untreated specimen, the permeation current drastically increased to ca. 300 nAcm-2 in the period from 0.5 to 1.0 ks. After that, it gradually increased and reached to 450 nAcm-2 at 10.8 ks. On the other hand, the permeation current of the nitrided specimen slightly increased to 10 nAcm-2 in the period from 1.6 to 4.0 ks and stayed at ca. 10 nAcm-2 from 4.0 to 10.8 ks. The hydrogen permeation test revealed that the plasma nitriding treatment strongly inhibited the hydrogen entry into pure iron under the cathodic polarization.
1. M. A. V. Devanathan, and A. Stachurski, Proc. Roy. Soc. A, 270, 90 (1962).

Figure 1
Evaluating Coating Degradation of Ballast Tank By Electrochemical Impedance Spectroscopy
Authors: Hayashibara Hitoshi , Tada Eiji , Nishikata Atsushi 
Published: February 2020

Water ballast tank (WBT) of commercial cargo ships is exposed to severe corrosive environment. In WBT, high significant coating degradation was observed at the part exposed to high temperature [1]. Corrosion of WBT steel causes the deterioration of structure’s strength. Therefore it is important to evaluate the protective performance of WBT coating. The inspection is usually carried out by visual observation, but more powerful toll is necessary to detect the coating degradation at earlier stage. Electrochemical impedance spectroscopy (EIS) is one of useful method to evaluate coating degradation. In the application, coating resistance was usually used as an index of the coating degradation. On the other hand, thick heavy-duty coatings like WBT coating have too high coating resistance to measure in applicable frequency range. Some studies proposed the evaluation methods by coating capacitance or constant phase element (CPE) [2,3].
In the present study, blast-processed steel panels applied with commercial epoxy paint of approximately 200 micro-meter thickness were used as specimen. The specimens were kept in the humid air (RH = 100%) at 343 K for 246 days and subsequent immersion in 0.05M NaCl solution at 343K for 79 days (total 325 days). Before the test and at 80th, 190th, 246th, 325th days after the test, EIS was measured in the frequency of 1 k to 1 mHz in 0.01M LiCl (water activity, aw = 1 ). After that, the solution was changed to 10M LiCl solution (aw = 0.3) and the coating capacitance was monitored by continuous measurements of impedance at 1 kHz to evaluate the change of water uptake in the coating due to the degradation. The EIS measurements were carried out at room temperature. The coating resistance decreased and the coating capacitance increased in the test. It was also confirmed absorbed water calculated by Brasher and Kingsbury’s equation [4] increased. Pull off test and SEM observation of the coating cross section after the corrosion test indicated the coating degradation and a trace amount of corrosion of the underlying steel. EIS will be useful for evaluating coating degradation of thick-coated steel at early stage.
Acknowledgement
This work was supported by JSPS KAKENHI Grant Number 25820427.
References
[1] H. Emi, M. Yuasa, A. Kumano, N. Yamamoto, T. Arima, M. Umino: J. Soc. Nav. Arch. Jpn., 174(1993), 735.
[2] L. Vallentinelli, J. Vogelsang, H. Ochs and L. Fedrizzi: Prog. Org. Coat., 45(2002), 405.
[3] E. P. M. van Westing, G. M. Ferrari and J. H. W. de Wit: Corros. Sci., 36(1994), 979.
[4] D. M. Brasher and A. H. Kingsbury: J. Appl. Chem., 4(1954), 62.
Virtual Design of Green Primers
Authors: Cole Ivan Stuart , Sapper Erik , Breedon Michael , Chu Clement , Chen Fiona 
Published: February 2020

The paper reports on a collaboration between BOEING and CSIRO that aims to dramatically cut the time required to develop aircraft materials . At present the time required to develop material can be excess of 15 years, much longer than that required to develop a new craft .. One way to cut the time for materials development is design materials virtually. This virtual design does not eliminate the need for actual materials design and certification but it allows this process to focus only on material designs with a high probability of fulfilling their design function. Virtual design requires a platform that links models from the molecular scale to the engineered object scale. The project has two typical components
1. Developing a platform that permits models to be linked
2. Selection and/or development of models across the relevant platform scales
The models developed include
a) Molecular scale models to define corrosion inhibitor and surface interactions
b) Molecular and continuum models to define inhibitor movement through a polymer and to a defect
c) Models of pit initiation and propagation on structural aluminium
d) Scenario builder to define the location and activity of an aircraft
e) Microclimate models defining the conditions within and exterior to an aircraft in service and on the ground
f) Damage accumulator that keeps track of the accumulation of damage
The models have been linked through the platform and the life of a range of primers with different inhibitors calculated for different flight patterns
Current and future activities consist of validating the models at each scale and validating the complete model by assessing how will it predicts the life in neutral salt spray tests. Future work will look at validating the model against life of components on actual aircraft and extending the model to composites.
Effect of Temperature on Behavior of Oxygen Transport through Solution Layer Formed on Metals
Authors: Sakairi Masatoshi , Sakaki Ryota 
Published: February 2020

It is very important for investigate environmental corrosion behavior of steels to maintain and safely use of the steels structures. To understand environmental corrosion behavior of steels, environmental factors such as temperature, relative humidity, amounts of airborne salinity, SOx, and transport behavior of oxygen in thin water layer formed on the steels are also important. Therefore, exposure tests and measurement of some of the environmental factors were carried out in three counties, Japan, Vietnam and Thailand, under "Corrosion Mapping of Structural Materials in Asian Area with Understanding Effects of Environmental Factors, e-Asia Project". The corrosion results showed that the corrosion rate in heavy snow and cold region such as Hokkaido is higher than that expected from temperature. To clarify the unexpected corrosion rate in Hokkaido, transport behavior of oxygen in thin water layer formed on the metals at low temperature was examined.
The zinc and iron sheets were used for specimens, and specimens temperature was controlled by Peltier device form 298 K to 273 K. Three different solutions, 0.1 kmol/m3 NaCl, 1 kmol/m3 NaCl, and 1 kmol/m3 NaCl + 0.5 kmol m-3 H3BO3 / 0.05 kmol m-3 Na2B4O7 were used to form thin solution layers. The thickness of the solution layers were controlled by plastic tape from 200 µm to 1 mm. A Pt and AgCl coated Ag wires were used as counter electrode and reference electrode. The cathodic polarization curves were measured to obtain limiting current of oxygen with scanning rate of 20 mV/min. Before the polarization measurements, immersion potential was measured. In order to ensure the reproducibility, more than three times of electrochemical tests were carried out as same conditions.
The measured rest potential of both zinc and iron were strongly depends on concentration of used solution, while slightly change of the rest potential was observe by the thickness of the solution layers. A clear limiting current of oxygen was observed in every solution and it increased with increasing invers of the solution thickness. The clear increase was observed with thin solution layer at low specimen temperatures.
Corrosion Behavior of Al 6063 in Qatar's Desert and Marine Environments
Authors: Abdullah Aboubakr Moustafa , Sliem Mostafa H , Mohamed Adel M 
Published: February 2020

Aluminum and its alloys have been widely used outdoors, especially in construction, electrical engineering and other applications, due to their high corrosion resistance, thermal and electrical conductivity and relatively low cost. The corrosion behavior of aluminum alloys indoor was significantly investigated compared to the outdoor studies. In addition, there is no investigation so far regarding atmospheric corrosion either in marine or desert areas in Qatar.
The aim of this article is to investigate the atmospheric corrosion behavior for different exposure times (six and twelve months) of welded and non-welded Al 6063 alloy with and without crevices at seven different sites in Qatar State that represent desert, industrial, coastal and marine environments. Avergae pit densities, pit depths, pit mouth areas and aspect ratios, pitting factor and corrosion rates for the alloy at each location were measured. In addition, electrochemical characterization techniques were used in non aggressive for the collected coupons to examine the effect of exposure on the naturally formed oxide layer. Furthermore, scanning electron microscope (SEM) coupled with energy dispersive X-ray (EDX) was used to study the susceptibility of studied alloys to intergranular corrosion (IGC) and the effect of sulfur compounds and chloride ions concentration on the suceptibility for this type of corrosion. The results showed that the number, the size and the depth of pits depend on the aggressiveness of the site environment. In addition, Al 6063 alloy has the tendency for IGC at the different environments. Chloride ions were responsible for the pitting initiation while, sulfur compounds were responsible for IGC propagation. The rate of corrosion for Al 6063 alloy specimens from different sites follows the following order: North field (marine) > Ras Laffan (on shore) > Seaside Mesaieed (on shore) > Halul Island (on Shore) > Industrial Mesaieed > Dukhan (on shore) > Desert.

Figure 1
Role of the Size of Iron- and Silicon-Rich Particles in the Atmospheric Corrosion Performance of Al-Mg-Si Alloys
Authors: Esmaily Mohsen , Svensson Jan-Erik , Johansson Lars-Gunnar 
Published: February 2020

Aluminum-magnesium-silicon (Al-Mg-Si) alloys are vital lightweight materials partly owing to their excellent corrosion properties. While there is a wealth of knowledge in the literature on effect of chemical composition of second phase particles and constituents on their anodic/cathodic activity, there is little known on the influence of particles’ size on the corrosion behavior of Al alloys. Using friction stir welding/processing (FSW/P), which was combined with quantitative microstructural analyses, we were able to clearly uncover this previously less-recognized effect of intermetallic particles in an extruded Al-Mg-Si alloy. The exposures were performed at ambient temperature and in the presence of 95% relative humidity (RH) and 400 ppm CO2 for a time interval of 200-3200 hours. Prior to the exposures, samples were contaminated with 200 μg/cm2 NaCl, mimicking the environment that exists in marine atmospheres. The results showed that the size of the particles in the alloy microstructure plays extremely important role in the overall corrosion performance of the processed/welded materials. Thus, it was demonstrated that the extent of corrosion attack in the heat affected zone (HAZ) of the welded/processed alloys directly depends on the size of particles in the processed regions (a macro-galvanic corrosion process). In addition, using local corrosion analysis, it was clearly noted that the cathodic activity of intermetallic particles in this family of Al alloys is size-dependent.
Uncoupling the Mechanisms behind Tribocorrosion in Chloride Containing Media Using Spatially Resolved Friction and Electrochemical Measurements
Authors: Shockley J. Michael , Horton Derek John , Policastro Steven , Wahl Kathryn J. 
Published: February 2020

Corrosion and wear damage are persistent, unavoidable problems in marine environments and are significant contributors to maintenance costs. When coupled, system or component lifetime can be severely decreased by the deleterious synergistic contributions between tribological and corrosion stresses applied to the contacting surfaces and protective oxide films. For example, material choices that separately meet standards for wear or corrosion resistance may, when exposed to marine environments, suffer from unexplained accelerated degradation.
This study focuses on understanding the mechanisms of the coupled damage process through spatially resolved measurements of friction and electrochemical response and correlation of behavior to the underlying microstructure features and properties. The repeated loss of passivity under wear conditions likely causes increased material loss due to an effective increased corrosion rate required to repassivate the metal surface, but also can cause an acceleration of wear by producing wear debris and changing the surface state of the underlying metal through dissolution of a hardened, plastically deformed area, among other mechanisms.
A common duplex stainless steel was used to study the role of multiple phases, composition segregation, grain boundaries and other microstructural features as initiation sites for the tribocorrosion process. This alloy system enabled controlled microstructural changes: varied grain size in a two phase field of austenite and ferrite, precipitation of sigma phase at the grain boundaries, and formation of nitrides and carbides. Using this approach each microstructural feature could be controlled and examined. An in situ tribometer was developed that enabled simultaneous friction and electrochemical measurements capable of resolving micron sized spatial features. Loss of passivity as a driving mechanism for tribocorrosion behavior was studied using simultaneous friction and electrochemical measurements at a high sampling rate that could then be correlated to specific microstructural features. Complementary analysis, performed ex situ, enables correlation of microstructure electrochemical properties to characteristic friction and wear behavior using analytical tools such as surface potential measurements (SKP) and electrochemical behavior (SECM, EIS).
The Influence of Non-Passivating and Passivating Alloys on the Galvanic and Local Corrosion Rates of 6061-T6 Al
Authors: Quiambao Kathleen , Hihara Lloyd H. 
Published: February 2020

Galvanic corrosion of 6061-T6 aluminum-coupled metals was studied in marine, volcanic, and rainforest environments. In addition to outdoor exposure, the galvanic couples were subjected to the chloride-containing GM 9540 accelerated corrosion test. The galvanic couple types included 6061-T6 Al paired with Ti-6Al-4V, 316 stainless steel, silver, copper, 1018 steel, or Mg AZ31B using fiberglass-epoxy fasteners.
In this experiment, galvanic corrosion currents were measured through portable data loggers connected to each metal in the aluminum-coupled specimens. The total corrosion on the 6061-T6 Al in the galvanic couple resulted from the galvanic corrosion between the 6061-T6 Al anode and the cathode plus additional simultaneous local corrosion on the 6061-T6 Al caused by local cathodic reactions occurring on the 6061-T6 Al. The value of the total corrosion rate (i.e., local corrosion plus galvanic corrosion) was determined by mass loss of the galvanically coupled aluminum coupons. The local corrosion rate was determined using the difference between the total corrosion rate and the galvanic corrosion rate, as determined from the galvanic current data and Faraday’s law. The corrosion rates of the coupled 6061-T6 Al coupons were up to approximately 20 times greater than the uncoupled 6061-T6 Al coupons. Interestingly, less than 30% of the mass loss of the coupled 6061-T6 Al was directly due to the galvanic current, and accordingly 70% or more was due to local corrosion on the 6061-T6 Al. This implied that corrosion-product contaminants from the cathodic coupons (i.e., Ti-6Al-4V, 316 stainless steel, silver, copper, and 1018 steel) or byproducts such as excess H+ on the anodic 6061-T6 Al and excess OH- on the adjacent cathode may have had a major influence on the local corrosion of the 6061-T6 Al. In some cases, the type of cathodic coupon (i.e., Ti-6Al-4V, 316 stainless steel, silver, copper, and 1018 steel) made a significant difference on the corrosion rates of the 6061-T6 Al. Potentiodynamic polarization experiments were also conducted to study the mechanisms of galvanic corrosion for the couples described above.
Predictive Engineering of Coating Adhesion on a Molecular Basis
Authors: Utzig Thomas , Stock Philipp , Valtiner Markus 
Published: February 2020

Molecular design of polymer/metal interfaces relies on understanding single molecular interactions and their scaling towards integral interactions at the meso- and macroscopic scale. Here, we will discuss how one can measure the interaction free energy of single interacting functional groups and polymers with electrified and corroding surfaces for predicting the stability of macroscopic polymer/metals bondings. In particular, we will show how single interactions scale with the number density towards the macroscopic level [1, 2], where a large number of single bonds interact simultaneously and in parallel. For this, we developed a synergistic experimental approach combining electrochemical Surface Forces Apparatus (SFA) experiments and single molecule force spectroscopy (SMFS) in an electrochemical Atomic Force Microscope.
First, in model experiments we can demonstate how macroscopic measurements scale linearly with the number density of a gold-amine bond at an electrified interface, providing gold-amine interaction energies of ~35 ± 2 kT at OCP. Using Bell-Evans theory together with non-equilibrium thermodynamics, we can show how a set of single molecule interaction forces measured by SMFS similarly converges to an interaction energy of 36 ± 3 kT. This demonstrates excellent predictive power of our newly developed scaling approach.
Second, and in addition to gold-amine interactions, we now tested a number of different bonds including hydrophobic, electro-active mussel-peptide/surface and metal/polymer [2] bonds with our model and find that our model is widely applicable, in particular also to electrified and corroding interfaces. In this context, we will discuss in detail how single molecule unbinding energy landscapes can be measured and utilized to predict scenarios where a large number of molecules simultaneously interact, giving rise to adhesive failure and coating delamination under corrosive and wet conditions. Our experimental strategy provides a unique framework for the molecular design of novel functional coatings through predicting of large-scale properties such as adhesion and molecular interactions in electrochemical systems based on experimentally determined single molecule energy landscapes.
[1] S. Raman et al. in
Nature Communications
, 5
(2014), 5539.
[2] T. Utzig et al. in Langmuir, 31(9) (2015), 2722.
A Novel, Highly Effective, Chrome-Free, Smart-Release, Economically Viable Corrosion Inhibitor- from Lab Kinetics through to Industrial Coating Incorporation
Authors: Dodds Patrick Charles , Williams Geraint , Ansell Phil , Glover Carol Frances 
Published: February 2020

Novel, smart-release in-coating corrosion-inhibiting pigments for hot dip galvanised (HDG) steel, were investigated as a low cost replacements for hexavalent chromate. Organic anions were exchanged into the smart-release divynl benzene resin based pigment, dispersed in a model coating and analysed using an in-situ scanning kelvin probe (SKP) technique, for their effectiveness at preventing cathodic delamination. SKP allows rapid screening of the inhibitor-containing pigment when dispersed in a model organic polyvinyl butyral (PVB) coating. Each experiment lasts 24 hours, enabling a larger experimental through-put in comparison to traditional screening techniques, such as EIS or salt spray (ASTM-B117). SKP gives spacially resolved corrosion potential (Ecorr) profiles enabling identification of the delamination front and subsequent measurement of its progression and rate kinetics. Figure 1 shows plots of delamination distance vs. time for the anions screened in these experiments. Results indicate that a benzotriazolate-containing pigment system is the most effective, where delamination rates were reduced by 95% and the onset of cathodic delamination was increased by ca. 2160 hours from the point of initiation with an external electrolyte. It has been reported previously that benzotriazole is an effective corrosion inhibitor for a range of metals when in solution (1-5), the divynl benzene matrix allows benzotriazolate to be stored and released only when the coating encounters a corrosive electrolyte, via ion exchange mechanisms. Open circuit potential measurements show an increase in Ecorr measurements where benzotriazole is present in the experimental electrolyte suggesting anodic inhibition. Results from salt-spray testing carried out on a commercial coil coating are also presented where benzotriazole is shown to be effective after a period of 1000 hours. The current study suggests that a benzotriazolate-containing pigment system is a strong, environmentally friendly, contender to replace chromate for the inhibition of corrosion on hot dip galvanised steel.
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2. Kosec T, Merl DK, Milošev I (2008) Corros Sci 50:1987–1997.
3. Aramaki K (2001) Corros Sci 43:1985–2000.
4. Müller B, Imblo G (1996) Corros Sci 38:293–300.
5. LEROY RL (1978) Corrosion 34:98–110.

Figure 1