scholarly journals Effect of pH and Al Cations on Chromate Inhibition of Galvanic-Induced Corrosion of AA7050-T7451 Macro-Coupled to 316SS

2021 ◽  
Author(s):  
Utibe-Eno Charles-Granville ◽  
Carol Glover ◽  
John R Scully ◽  
Robert Kelly
Keyword(s):  
Surface Characterization ◽  
Reduction Reaction ◽  
High Rate ◽  
Buffer Effect ◽  
Galvanic Coupling ◽  
Damage Initiation ◽  
Damage Propagation ◽  
Bimetallic Systems ◽  
Coupling Behavior ◽  
Influence Of Ph

Abstract The performance of chromate in protecting AA7050-T7451 coupled to 316SS in simulated fastener environments, including those representative of the boldly exposed surfaces and downhole conditions, was investigated utilizing a number of electrochemical and surface characterization techniques. The influence of pH and Al3+ on the galvanic coupling behavior and damage evolution on AA7050 as a function of chromate concentration were assessed. The degree of chromate inhibition was observed to decrease as pH decreased, owing to chromate speciation and reduced capacity to suppress the hydrogen evolution reaction (HER) compared to the oxygen reduction reaction (ORR). The addition of 0.1 M Al3+ significantly increased HER kinetics and produced a large buffer effect which overwhelmed the ability of chromate to slow damage propagation on AA7050. Assessment of cathodes indicated that Cu was more important than 316SS in driving damage initiation, but less active than 316SS in supporting high-rate damage propagation in simulated crevice environments. The implications of this study for actual bimetallic systems are discussed.

scholarly journals In situ damage assessment using synchrotron X-rays in materials loaded by a Hopkinson bar

2014 ◽  
Vol 372 (2015) ◽  
pp. 20130191 ◽  
Author(s):  
Weinong W. Chen ◽  
Matthew C. Hudspeth ◽  
Ben Claus ◽  
Niranjan D. Parab ◽  
John T. Black ◽  
...  
Keyword(s):  
High Speed ◽  
Particle Interaction ◽  
Tensile Failure ◽  
High Rate ◽  
X Rays ◽  
Contrast Imaging ◽  
X Ray ◽  
Damage Initiation ◽  
Dynamic Experiments

Split Hopkinson or Kolsky bars are common high-rate characterization tools for dynamic mechanical behaviour of materials. Stress–strain responses averaged over specimen volume are obtained as a function of strain rate. Specimen deformation histories can be monitored by high-speed imaging on the surface. It has not been possible to track the damage initiation and evolution during the dynamic deformation inside specimens except for a few transparent materials. In this study, we integrated Hopkinson compression/tension bars with high-speed X-ray imaging capabilities. The damage history in a dynamically deforming specimen was monitored in situ using synchrotron radiation via X-ray phase contrast imaging. The effectiveness of the novel union between these two powerful techniques, which opens a new angle for data acquisition in dynamic experiments, is demonstrated by a series of dynamic experiments on a variety of material systems, including particle interaction in granular materials, glass impact cracking, single crystal silicon tensile failure and ligament–bone junction damage.

scholarly journals Сitric acid influence on electroreduction processes in low concentrated Cu(NO3)2 solutions

2017 ◽  
Vol 5 (2) ◽  
pp. 136-143
Author(s):  
Alla Pravda ◽  
Vasil Larin
Keyword(s):  
Citric Acid ◽  
Ph Value ◽  
Reduction Reaction ◽  
Copper Electrodeposition ◽  
Nitrate Ions ◽  
Low Concentrations ◽  
Physico Chemical ◽  
Influence Of Ph ◽  
Kinetics Of ◽  
Cathode Reduction

Physico-chemical regularities citric acid influence on processes of copper and nitrate-ions reduction in low concentrated nitrate solutions were established. An influence of pH value on inhibitor action of low concentrations of the additive according to cathode reduction reaction of nitrate-ions, on kinetics of copper electrodeposition, on structure of the precipitates obtained was shown. Polarization measurements show us changes of copper electrodeposition at introduction of citric acid in Cu(NO3)2 solution. By the methods of traced elements and extraction into aqueous phase the reversible inclusion complexes into electrolytic copper, was established that proves participation of complexes in cathode process.

scholarly journals Top Coating Anti-Erosion Performance Analysis in Wind Turbine Blades Depending on Relative Acoustic Impedance. Part 1: Modelling Approach

Coatings ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 685 ◽  
Author(s):  
Luis Domenech ◽  
Jordi Renau ◽  
Asta Šakalytė ◽  
Fernando Sánchez
Keyword(s):  
Speed Of Sound ◽  
Turbine Blades ◽  
Multilayer Coating ◽  
Material Behavior ◽  
Acoustic Properties ◽  
High Rate ◽  
Viscoelastic Materials ◽  
Transient Pressure ◽  
Damage Initiation ◽  
The Impact

Top coating are usually moulded, painted or sprayed onto the wind blade Leading-Edge surface to prevent rain erosion due to transverse repeated droplet impacts. Wear fatigue failure analysis based on Springer model has been widely referenced and validated to quantitatively predict damage initiation. The model requires liquid, coating and substrate speed of sound measurements as constant input parameters to define analytically the shockwave progression due to their relative vibro-acoustic properties. The modelling assumes a pure elastic material behavior during the impact event. Recent coating technologies applied to prevent erosion are based on viscoelastic materials and develop high-rate transient pressure build-up and a subsequent relaxation in a range of strain rates. In order to analyze the erosion performance by using Springer model, appropriate impedance characterization for such viscoelastic materials is then required and represents the main objective of this work to avoid lack of accuracy. In the first part of this research, it is proposed a modelling methodology that allows one to evaluate the frequency dependent strain-stress behavior of the multilayer coating system under single droplet impingement. The computational tool ponders the operational conditions (impact velocity, droplet size, layer thickness, etc.) with the appropriate variable working frequency range for the speed of sound measurements. The second part of this research defines in a complementary paper, the ultrasonic testing characterization of different viscoelastic coatings and the methodology validation. The modelling framework is then used to identify suitable coating and substrate combinations due to their acoustic matching optimization and to analyze the anti-erosion performance of the coating protection system.

Outermost Surface Structures and Oxygen Reduction Reaction Activities of Co/Pt(111) Bimetallic Systems Fabricated Using Molecular Beam Epitaxy

2011 ◽  
Vol 115 (38) ◽  
pp. 18589-18596 ◽  
Author(s):  
Toshimasa Wadayama ◽  
Hirosato Yoshida ◽  
Koichiro Ogawa ◽  
Naoto Todoroki ◽  
Yoshinori Yamada ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Molecular Beam ◽  
Reduction Reaction ◽  
Surface Structures ◽  
Bimetallic Systems ◽  
Outermost Surface

Facet-dependent Catalysis of CuNi Nanocatalysts toward 4–Nitrophenol Reduction Reaction

MRS Advances ◽  
2020 ◽  
Vol 5 (27-28) ◽  
pp. 1491-1496
Author(s):  
Can Li ◽  
Yiliang Luan ◽  
Bo Zhao ◽  
Amar Kumbhar ◽  
Xiaobo Chen ◽  
...  
Keyword(s):  
Sodium Borohydride ◽  
Catalytic Performance ◽  
Reduction Reaction ◽  
High Rate ◽  
Colloidal Synthesis ◽  
Pseudo First Order Reaction ◽  
Nitrophenol Reduction ◽  
Crystallographic Facets ◽  
Capping Ligands ◽  
Synthesis Approach

ABSTRACTWe report a facile method to fabricate CuNi nano-octahedra and nanocubes using a colloidal synthesis approach. The CuNi nanocrystals terminated with exclusive crystallographic facets were controlled and achieved by a group of synergetic capping ligands in a hot solution system. Specifically, the growth of {111}-bounded CuNi nano-octahedra is derived by a thermodynamic control, whereas the generation of {100}-terminated CuNi nanocubes is steered by a kinetic capping of chloride. Using a reduction of 4-nitrophenol with sodium borohydride as a model reaction, CuNi nano-octahedra and nanocubes demonstrated a strong facet-dependence due to their different surface energies although both exhibited remarkable catalytic activity with the high rate constant over mass (k/m). A kinetic study indicated that this is a pseudo first-order reaction with an excess of sodium borohydride. CuNi nanocubes as the catalysts showed better catalytic performance (k/m = 385 s-1•g-1) than the CuNi nano-octahedra (k/m = 120 s-1•g-1), indicating that 4-nitrophenol and hydrogen were adsorbed on the {100} facets with their molecules parallel to the surface much easier than those on {111} facets.

The influence of pH in the hydrolytic stage of anaerobic digestion of the organic fraction of urban solid waste

2003 ◽  
Vol 48 (6) ◽  
pp. 249-254 ◽  
Author(s):  
S. Dinamarca ◽  
G. Aroca ◽  
R. Chamy ◽  
L. Guerrero
Keyword(s):  
Anaerobic Digestion ◽  
Solid Waste ◽  
Volatile Fatty Acids ◽  
Organic Fraction ◽  
Buffer Effect ◽  
Two Phase ◽  
Protein Residues ◽  
Working Volume ◽  
Urban Solid Waste ◽  
Influence Of Ph

The influence of the pH in the first stage, the hydrolytic stage, of the anaerobic digestion of the organic fraction of urban solid waste in a two phase anaerobic reactor was studied. The reactor was fed with a solution of the organic fraction of urban solid residues containing 5 to 7% solids. Four reactors with a working volume of 3 L were used, the experiments were done at three controlled pHs; 6, 7, and 8, and one with free pH, the temperature was keep at 37°C in all the experiments. The higher degradation of TSS and VSS was obtained in the reactors operated at pH 7 and 8; 75% degradation of TSS and 85% degradation of VSS. The volatile fatty acids were determined at the different pH conditions, no significant differences were found, and as was expected, the acetic acid was found at the higher value among them (from 25 to 29 g/L). According to the results obtained it is possible to conclude that in the case of the hydrolytic stage of the anaerobic digestion of the organic fraction of urban solid waste it is not necessary to control the pH, the pH is kept stable by the buffer effect of the protein residues and other macromolecules present in the residue.

scholarly journals Bimetallic AgFe Systems on Mordenite: Effect of Cation Deposition Order in the NO Reduction with C3H6/CO

Catalysts ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 58 ◽  
Author(s):  
Perla Sánchez-López ◽  
Yulia Kotolevich ◽  
Serguei Miridonov ◽  
Fernando Chávez-Rivas ◽  
Sergio Fuentes ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Inductively Coupled Plasma ◽  
Active Sites ◽  
No Reduction ◽  
Optical Emission ◽  
Reduction Reaction ◽  
Exchange Method ◽  
Inductively Coupled ◽  
Preparation Conditions ◽  
Bimetallic Systems

Mono- and bimetallic systems of Ag, Fe, and Ag–Fe exchanged in sodium mordenite zeolite were studied in the reaction of NO reduction. The transition metal cations Ag and Fe were introduced by ion exchange method both at room temperature and 60 °C; modifying the order of component deposition in bimetallic systems. These materials were characterized by Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), ultraviolet-visible spectroscopy (UV-Vis), X-Ray photoelectron Spectroscopy (XPS) and High-resolution transmission electron microscopy (HR-TEM). The XPS and UV–Vis spectra of bimetallic samples revealed that under certain preparation conditions Ag+ is reduced with the participation of the Fe2+/Fe3+ ions transition and is present in the form of a Ag reduced state in different proportions of Agm clusters and Ag0 NPs, influenced by the cation deposition order. The catalytic results in the NO reduction reaction using C3H6/CO under an oxidizing atmosphere show also that the order of exchange of Ag and Fe cations in mordenite has a strong effect on catalytic active sites for the reduction of NO.

Sign in / Sign up

Export Citation Format

Share Document