bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synergetic Properties of Some Polymers with Antiscaling and Anticorrosive Action for Industrial Cooling Water Systems Protection
Authors: Branzoi Florina , Branzoi Viorel 
Published: February 2020

In this study, to examine synergistic effect of various combinations of the following polymers: PSO-1 (an oligomer phosphinosuccinic in neutralized state) and PMA-M1 (mixture by weight ratio 1/1 from 2-phosphonobutane-1-2, 4 tricarboxilic acid with polymaleic acid) were investigated as corrosion inhibitors for carbon steel of type OL 37, OLC 45 and for copper and brass. Using the microwaves energy, new polymers with antiscaling and anticorrosive properties were synthesized in microwaves field. These new polymers were obtained by radical polymerization of acrylic and/or acrylsulfonate water-soluble monomers in presence of microwaves field chain transfer agents, under the action of peroxidic initiators. The inhibitive properties of these organic compounds were analyzed by electrochemical measurements, FT-IR spectroscopy and by scanning electron microscopy (SEM) of the electrode surface. Also, a variety of short-time corrosion tests on laboratory scale were used to determine the performance and application parameters under different environmental conditions. The metallographic micrographies and scanning electron microscopy made before and after the potentiodynamic polarizations pointed out the evolution of the corrosion process.
The inhibition activity analysis of the organic compounds was made by assuming that, the mechanism of inhibition by organic molecules is chemisorption and that the energetic of the corrosion process per se is unaffected by the addition of substituients on the parent compound. We presume that, these organic compounds inhibit corrosion of these materials by a protective mechanism, forming insoluble complexes and repairing the porous oxide layer. The addition of these new organic polymers offers protection by forming an adsorption organic barrier film at the electrode surface. The corrosion parameters obtained from polarization curves and from EIS spectra are in good concordance and point out the inhibitory action of these new organic polymers.
The addition of the organic inhibitors led in all the cases to inhibition of the corrosion rate. The organic compounds used are adsorbed on the electrode surface according to a Langmuir isotherm. The inhibition process was attributed to the formation of the adsorbed film on the metal surface that protects the metal against corrosive agents. The EIS measurements have confirmed this protection and pointed out the formation of adsorption layers on the electrode surface
The negative value of thermodynamic parameter like Gibbs free energy of adsorption indicates the spontaneity of adsorption process. Moreover, characterization utilizing FT-IR confirms the adsorption of inhibitors and the constitution of corrosion products on the materials surface. EIS and potentiodynamic polarization results demonstrate its corrosion protection capacity
A Novel Inhibitor for L921A alloy Steel in a 3.5 % NaCl Solution
Authors: Yong Xingyue , Chen Zhenglin , Zhou Lin , Jiang Lin , Chen Rihui 
Published: February 2020

Corrosion inhibitors, acting as an effective method at lower operating cost, are often used to protect metallic materials from corrosion. Although many kinds of corrosion inhibitors have been used in circulating cooling water systems, a few papers have been published for introducing the applications of corrosion inhibitors in chloride media. By comparison, it is difficult to develop a novel inhibitor for alloy steels in chloride solutions or sea water.
In this paper, a novel corrosion inhibitor for L921A alloy steel in a 3.5% NaCl solution was formulated by weight loss in conjunction with orthogonal tests. The inhibitory efficiency of this novel inhibitor was over 95.0%. It was found by electrochemical polarization that this novel inhibitor was a mixed type of inhibitor which had an ability to improve the pitting corrosion resistance of L921A alloy steel in a 3.5% NaCl solution. EIS spectra showed that L921A alloy steel in a 3.5% NaCl solution was subjected to pitting corrosion, due to that EIS spectrum with two time constants of L921A alloy steel in a 3.5% NaCl solution was composed of a capacitive loop at high frequency region and an inductive loop at low frequency region. However, EIS spectrum with two time constants consisted of a capacitive loop at high frequency region and a Warburg line at low frequency region when the novel inhibitor was added into a 3.5% NaCl solution. The thickness of inhibitory film increased with increasing immersion time, resulting in the increment of the electrochemical impedance of corrosion process of L921A alloy steel in a 3.5% NaCl solution. Finally, the formation of the inhibitory film was further studied by EDX and XPS technology.

Key words: alloy steel; chloride solution, inhibitor; EIS, XPS; inhibitory mechanism
Investigation of Pit Initiations on Copper during Anodic Polarization By Real-Time Surface Observation System with Channel Flow Double Electrode
Authors: Hoshi Yoshinao , Oda Tomohiko , Shitanda Isao , Itagaki Masayuki 
Published: February 2020

A pitting corrosion on copper tube is a serious problem because it may lead to a leak accident. Though the conditions related to the pit initiations on copper were reported 1, 2, the mechanisms associated with the pit initiations on copper have not been clarified yet.
In order to investigate pit initiations on copper, we previously developed a real-time surface observation system with a channel flow double electrode (CFDE) 3. Our group 4-7 applied the CFDE to investigation of anodic dissolution mechanisms of metals and alloys because metallic ions dissolved from working electrode (WE) can be detected by arranging a detecting electrode (DE) downstream of the WE. The developed system enables us the in-situ surface observation of copper during anodic polarization since a video recording can be carried out during the measurement. In the present study, the pit initiations on coper during anodic polarization was discussed based on the results of the dissolution currents of cupric or cuprous ions and in-situ surface observation of copper surface.
References

H. S. Campbell, J. Inst. Metals, 77, 345 (1950).

R. May, J. Inst. Metals, 82, 65 (1953).

Y. Hoshi, T. Oda, I. Shitanda and M. Itagaki, J. Electrochem. Soc., 164, C450 (2017).

M. Itagaki, M. Tagaki, T. Mori and K. Watanabe, Corros. Sci., 38, 601 (1996).

M. Itagaki, M. Tagaki and K. Watanabe, Corros. Sci., 38, 1109 (1996).

M. Itagaki, T. Mori and K. Watanabe, Corros. Sci., 41, 1955 (1999).

Y. Hoshi, M. Itagaki, K. Tabei and I. Shitanda, J. Solid State Electrochem., 19, 3551 (2015).
Impedance Analysis of Ti-Based Porous Alloy
Authors: Sancy Mamié , Guerra Carolina , Silva Daniela , Walczak Magdalena , Aguilar Claudio 
Published: February 2020

Ti-based alloys as porous materials with low elastic modulus has been recently developed due to the evident need to avoid the stress shielding problems related to stiffness mismatch related to human bone. In this work, Ti-30Nb-13Ta-2Mn alloy as porous material was obtained by powder metallurgy using (NH4)2(CO3) as space-holder. Powders and space-holder were mixed together and compacted with 400 MPa stress. (NH4)2(CO3) particles were removed from the compacts during sintering at 1250 °C for 3 h in Ar atmosphere. The porosity and active area of the porous electrode were estimated by using Archimedes methods and BET analysis. In addition, the surface analysis was carried out by SEM and XRD. Finally, electrochemical measurements such as open circuit potential curves, polarization curves and electrochemical impedance spectroscopy were carried out in a simulated blood plasma fluid called Ringer’s solution at 37 ºC. Results revealed foams with heterogeneous pore distribution in diameter as well as length. The electrochemical results showed that the corrosion potential was shifted to more negative values and the anodic and cathodic current were increased as a function of exposure time. On the other hand, impedance analysis displayed an impedance of the de Levie associated to the anodic response in parallel with an interfacial impedance attributed to cathodic response. Additionally, an evolution of the passive oxide layer as a function of exposure time was observed, which was mainly formed at the pore walls and, the cathodic reaction related to the oxygen reduction reaction took place mainly outside the pore.
Reference

E. Orazem and B. Tribollet, Electrochemical Impedance Spectroscopy, 2nd Edition, John Wiley & Sons, Inc. Hoboken, New Jersey (2017) 322-332.

O.E. Barcia, E. D’Elia, I. Frateur, O.R. Mattos, N. Pébère, B. Tribollet, Application of the impedance model of de Levie for the characterization of porous electrodes, Electrochimica Acta 47 (2002) 2109-2126.
(Invited) High Temperature Corrosion of Chromia-Forming Alloys By CO2: Effects of H2o and so2
Authors: Xie Yun , Yu Chun , Nguyen Thuan Dinh , Zhang Jianqiang , Young David John 
Published: February 2020

Hot CO2 gas is surprisingly corrosive to chromia forming alloys as a result of internal carburisation, which decreases the ability of an alloy to form a protective Cr-rich oxide scale. Comparison of Fe- and Ni- base alloys reacted with Ar-20CO2 shows that the latter can provide superior performance, by virtue of their better resistance to carburisation. Experiments with model Fe-Cr and Ni-Cr alloys at 650oC show that addition of water vapour to the gas is detrimental to the performance of Fe-based alloys: chromia grains are refined, leading to enhanced diffusion and accelerated scale growth; large chromia platelets grow from the scale, generating stress and leading to premature failure; the nucleation and growth of Fe-rich nodules leads to breakaway corrosion. Nickel-base alloys of marginal chromium content undergo internal oxidation in dry CO2, accompanied by buckling of surface regions in wet CO2.
Addition of 0.5% SO2 to Ar-20CO2 is mildly detrimental to the performance of Fe-Cr alloys, causing a slight acceleration in the nucleation and growth of Fe-rich oxide nodules. The addition of 20% water vapour to Ar-20CO2 is also detrimental, promoting Fe-rich oxide growth and breakaway corrosion. However, the simultaneous addition of H2O and SO2 to Ar-20CO2 leads to complete passivation of the alloy surface by a slow growing Cr2O3 scale. These effects are discussed in terms of grain boundary segregation and diffusion of impurity species within the chromium oxide.
Influence of Ni and Cu on Oxide-Scale Structure of Steel
Authors: Harashima Aya , Kondo Yasumitsu 
Published: February 2020

In steel products, high surface quality is required in addition to characteristics corresponding to intended use. For improving surface quality of steel products, it is important to control structure of oxide scales. In hot rolling process, heterogeneous structure of oxide scales, such as uneven scale/steel interface, causes surface defects. For steels containing Ni, it has been reported that structure of oxide scales at the scale/steel interface is characteristic and complicated. Consequently, in this report, Ni and Cu, which are nobler than Fe, are focused on, and the effects of these elements on structure of oxide scales of steels are investigated. Fe-10mass%Ni and Fe-10mass%Cu alloys were oxidized at 1000°C or 1200°C in an atmosphere of 10%O2+20%H2O+70%N2 for 1800s.
In all cases, uneven scale/steel interfaces are observed (see Fig.1). In case of Fe-Ni alloy, Ni-enriched metal phase of complicated form is observed in oxide scales. Concentration of Ni in metal phase increases as it approaches the surface. On the other hand, in case of Fe-Cu alloy, precipitation of Cu phase is observed. Cu precipitates as particles in oxide scale at 1000°C, while it precipitates as a layer at the scale/steel interface under oxide scale at 1200°C.
With regard to the uneven scale/steel interface, it should be caused by the property that both Ni and Cu are nobler than Fe. The mechanism can be explained as follows: first, selective oxidation of Fe proceeds, and Ni or Cu enriches at the scale/steel interface. Then, internal oxides of Fe precipitate and Ni or Cu enriches around them. Finally, with proceeding of such heterogeneous oxidation, internal oxides of Fe and those locally Ni- or Cu-enriched area are simultaneously occluded into the scale/steel interface, and therefore uneven scale/steel interface forms.
With regard to the different structure of oxide scales at the scale/steel interface in Fe-Ni and Fe-Cu alloys, that is, enrichment of Ni and precipitation of Cu, it should be caused by the difference of the solid solubility limit of Ni and Cu to austenite. According to the phase diagram of Fe-Ni alloy, Ni dissolves in austenite completely at both 1000°C and 1200°C. On the other hand, according to the phase diagram of Fe-Cu alloy, Cu dissolves in austenite partly at both 1000°C and 1200°C. Because the solid solubility limit of Cu to austenite is just about 10% at 1200°C, Cu which exceeds its solid solubility limit with proceeding of oxidation of Fe should precipitate as liquid phase at the scale/steel interface. Although both Ni and Cu are nobler than Fe, different structure of oxide scales forms at the scale/steel interface in Fe-Ni and Fe-Cu alloys corresponding to the solid solubility limit to austenite.

Figure 1
Understanding Corrosion of Ni-Cr Alloys in Molten Chloride Salts
Authors: Raiman Stephen S , McMurray Jake , Mayes Richard , Abney Carter , Keiser James , Pint Bruce 
Published: February 2020

Molten chloride salts possess many attractive properties for use as a coolant and storage medium in advanced nuclear reactors and in concentrating solar power systems. Among the many challenges is the corrosion of salt-facing structural components. In molten halide salts, the passive films that typically form on the surface of corrosion resistant alloys either do not form, or are unstable due to the very low oxygen activities. Therefore, corrosion of materials is dependent largely on interfacial dissolution reactions between the molten salt and the bare metal surface in which alloy constituents with the most stable chlorides tend to be the most likely to dissolve.
For most common structural alloys, chromium has the most stable chloride, and thus selective dissolution of chromium from the alloy into the salt is the dominant form of material degradation in molten halides. While this fact is well known and backed-up by experimental data, the mechanism of chromium depletion from alloys is not yet known. To truly understand corrosion in molten salts, the mechanism of chromium depletion from alloys must be understood and quantified.
This talk will discuss results of a combined experimental and computational strategy aimed at fundamentally understanding corrosion of alloys in molten chloride salts. Controlled capsule tests are conducted in which model Ni-Cr alloys are exposed to molten KCl-MgCl2 at temperatures in excess of 600°C to measure degradation in molten salt. In an effort to maintain greater control of the molten salt environment, new processes to sufficiently purify salts are discussed. Quantification of salt impurities is matched to corrosion results in an effort to quantify the effect of salt impurity concentrations on corrosion rates. Traditional experimentation is coupled with x-ray spectroscopy and thermodynamic modeling to identify relevant reactions and to develop a thermodynamic description of the alloy-salt system.
This work is funded by the Laboratory Directed Research and Development Fund at Oak Ridge National Laboratory.
(Invited) Chromia Semiconducting Properties Study: A Textbook Case?
Authors: Latu-Romain Laurence , Parsa Yohan , Wouters Yves 
Published: February 2020

Chromia, Cr2O3, is the protective layer of a large family of metallic alloys denominated as chromia-formers. The chromia structure is particularly complex [1] and merits to be studied if one wants to try to improve its chemical durability.
In this work, oxidation of pure Cr is studied as a function of temperature (from 800 °C to 900 °C) and oxygen partial pressure p(O2) (from 10-14 to 10-12 atm.) Chromia semiconducting properties are investigated by photoelectrochemistry at macroscopic, mesoscopic and microscopic scales, whereas its morphological and structural properties are studied by Transmission Electron Microscopy with orientation mapping tool (called ASTAR). By associating these two techniques -which gives respectively the type of semiconduction and the oxide growth direction- it becomes possible to identify the nature of the major point defects in chromia [2].
In every case, the morphology of the oxide scale is duplex (see Fig. 1). It is revealed that the morphology is linked to the growth direction and not to the nature of the major point defect: anionic (inward) growth leads to equiaxed grains whereas cationic (outward) growth is conducive to columnar grain formation.
Finally by tuning the oxygen partial pressure, chromia semiconducting properties can be controlled. In particular when p(O2) increases from 10-14 to 10-12 atm., the type of semiconduction of the external chromia subscale changes from n-type to p-type ; and, for intermediate conditions, chromia is insulating [3]. The growth of such stoichiometric chromia layer may be helpful for the optimization of chemical durability of chromia forming alloys.
References
[1] A. Holt, P. Kofstad, Electrical conductivity and defect structure of Cr2O3. I. High temperatures ( > ~ 1000°C), Solid State Ionics, 69 (1994) 127-136.
[2] L. Latu-Romain, Y. Parsa, S. Mathieu, M. Vilasi, M. Ollivier, A. Galerie, Y. Wouters, Duplex n- and p-type chromia grown on pure chromium: a photoelectrochemical and microscopic study, Oxid. Met. 86(5) (2016) 497-509
[3] L. Latu-Romain, Y. Parsa, S. Mathieu, M. Vilasi, A. Galerie, Y. Wouters, Towards the growth of stoichiometric chromia on pure chromium by the control of temperature and oxygen partial pressure, Corros. Sci. (2017) DOI 10.1016/j.corsci.2017.07.005
Figure 1: ASTAR grain orientation maps recorded with a probe size of 1 nm and a step size of 3 nm (see color codes on the left) of Cr2O3 grown on pure Cr (a) at 800 °C during 60 min at a p(O2) of 10-14 atm, (b) at 850 °C during 30 min at a p(O2) of 10-13 atm, (c) at 900 °C during 30 min at a p(O2) of 10-12 atm. From [3].

Figure 1
(Invited) Developing Environmental Barrier Coatings Resistant to Molten Calcium-Magnesium-Aluminosilicate (CMAS)
Authors: Wiesner Valerie L , Harder Bryan J , Garg Anita , Bansal Narottam P 
Published: February 2020

In order to improve fuel efficiency in commercial aircraft engines, ceramic matrix composites (CMC) are considered a leading material system to replace metal-based turbine engine components, due to their lower density and high-temperature capabilities compared with traditional metallic structural materials. However, silicon-based CMCs are susceptible to oxidation and corrosion in the harsh combustion environment found in air-breathing turbine engines. Environmental barrier coatings (EBCs) are being developed and applied to protect and to enhance durability and service life of CMC components for application in the hot-section of engines.
The development of robust EBCs is threatened by sand, volcanic ash and other particulate debris, which are routinely ingested by aircraft engines in varying geographic regions. At temperatures >1200°C, these particulates melt, yielding molten calcium-magnesium-aluminosilicate (CMAS) deposits. These deposits can significantly reduce the durability of present and future engine component materials, particularly EBCs designed to protect silicon-based ceramic matrix composites (CMC). Near target operating temperatures (~1500°C) of future CMC-based aircraft engines, molten CMAS behaves like a viscous melt that can infiltrate and chemically interact with protective coatings, causing premature failure of the EBC system and ultimately the overall CMC engine component.
Degradation of candidate EBC materials based on rare-earth silicates by molten CMAS will be presented with a focus on recent work, as well as methods of evaluating the complex high-temperature materials interactions, accomplished at NASA Glenn Research Center.
(Invited) All-Inorganic Water-Dispersible Silicon Quantum Dots
Authors: Fujii Minoru , Sugimoto Hiroshi , Kano Shinya 
Published: February 2020

A colloidal solution of Si quantum dots (QDs) is a versatile material useful for electronics, optoelectronics and biophotonics. Recently, we have developed a new type of all-inorganic Si QDs that can be dispersed in alcohol and water almost perfectly without organic ligands. The unique property of the QDs arises from the heavily B and P codoped crystalline Si shell, which induces negative potential on the surface and prevents agglomeration of Si QDs in polar solvents. Thanks to the shell, the luminescence property is very insensitive to the environment and to the chemical treatment. To the ligand-free surface of codoped Si QDs, molecules in a solution can easily access, and thus a variety of charge-transfer-induced processes such as a photocatalytic effect are expected.
In this presentation, we first discuss the structure of codoped Si QDs based on the data obtained by atom probe tomography. We then discuss the size dependence of the HOMO and LUMO level energies measured from the vacuum level by combining photoemission yield spectroscopy and photoluminescence spectroscopy. Furthermore, we show density of state spectra of single codoped Si QDs obtained by scanning tunneling spectroscopy and discuss the size dependence of the in-gap donor and accepter states, onset of the conduction and valence band edges, and the ionization energies of dopants. From these data, we will identify the origin of the luminescence in B and P codoped Si QDs. We demonstrate that the codoped Si QDs exhibit efficient luminescence in the energy ranges below and above bulk Si band gap. The below bulk band gap luminescence opens up a new application of codoped Si QDs as a phosphor in the second biological window (1000-1300 nm). We also discuss charge transfer between Si QDs and adsorbed molecules. We show charge-transfer-induced reversible enhancement and quenching of photoluminescence of Si QDs and the photocatalytic activity to adsorbed molecules. We can produce a variety of nanocomposites composed of codoped Si QDs and noble metal (Au, Ag and Pt) nanostructures. We discuss the enhanced optical response due to the coupling with the localized surface plasmon resonances of metal nanostructures. By using the colloidal solution of codoped Si QDs, we can produce the monolayer film, the multilayer film and the dense solids. In these films, we discuss the energy transfer between QDs. Finally, we show electrical transport properties of the films and demonstrate the possible application as electronic devices.