scholarly journals Inhibition of copper corrosion in chloride solution by caffeine isolated from black tea

2014 ◽  
Vol 33 (1) ◽  
pp. 13 ◽  
Author(s):  
Senka Gudić ◽  
Emeka Emanuel Oguzie ◽  
Ani Radonić ◽  
Ladislav Vrsalović ◽  
Ivana Smoljko ◽  
...  
Keyword(s):  
Chloride Solution ◽  
Electrochemical Impedance ◽  
Black Tea ◽  
Copper Surface ◽  
Uv Spectrophotometry ◽  
Copper Corrosion ◽  
Corrosion Reaction ◽  
Inhibition Performance ◽  
Dynamics Simulations ◽  
Experimental Findings

<p>Caffeine (1,3,7-trimethylxanthine) was isolated from black tea and characterized using different physical methods (determination of melting point, thin layer chromatography, FTIR spectroscopy and UV spectrophotometry). The corrosion inhibition performance of the caffeine isolate on copper corrosion in neutral 0.5 mol L-1 NaCl solution was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy measurements. The obtained results show that caffeine effectively inhibited the corrosion reaction in the chloride solution with inhibition efficiency up to » 92 %. Furthermore, caffeine was found to function essentially as a cathodic inhibitor by adsorption on the copper surface according to the Langmuir adsorption isotherm. The adsorption free energy of » –37 kJ mol<sup>-1</sup> indicates strong adsorption of the caffeine on the metal surface. Quantum chemical computations and molecular dynamics simulations were adapted to understudy the adsorption of a single caffeine molecule as well as a polymeric cluster of caffeine molecules on a model Cu surface at a molecular level and show good agreement with the experimental findings.</p>

scholarly journals Modification of Cu(111) Surface with Alkylphosphonic Acids in Aqueous and Ethanol Solution. An Experimental and Theoretical Study

Electrochem ◽  
2022 ◽  
Vol 3 (1) ◽  
pp. 58-69
Author(s):  
Valbonë Mehmeti ◽  
Fetah Podvorica
Keyword(s):  
Molecular Dynamics ◽  
Monte Carlo ◽  
Electrochemical Impedance ◽  
Copper Surface ◽  
Ethanol Solution ◽  
Organic Layer ◽  
Copper Corrosion ◽  
Dynamics Simulations ◽  
The Impact ◽  
Alkylphosphonic Acids

Alkylphosphonic acids are well known for their ability to form self-assembled monolayers on hydroxide surfaces. A crucial step to understanding fundamentally how these surfaces are created is the elucidation of the interaction process that leads to such interface creation. In this study, we employed electrochemical impedance spectroscopy (EIS), Monte Carlo and molecular dynamics to understand this process. The interaction with the Cu(111) surface of three different alkylphosphonic acids (hexyl-, octyl- and decylphosphonic acids) is evaluated in an aqueous acidic and in an ethanol solution by Monte Carlo and molecular dynamics simulations, while EIS measurements are used to put in evidence the impact of the layer made in ethanol on copper protection. Nyquist diagrams of copper samples modified with an alkylphosphonic monolayer showed a higher polarization resistance that mitigates the copper corrosion in an aqueous acid medium. The phase–frequency Bode plots had higher and broader phase maxima for a modified copper surface with phosphonic moieties, which confirmed the ability of this organic layer to prevent copper corrosion.

scholarly journals Poly (Vinyl Butyral-Co-Vinyl Alcohol-Co-Vinyl Acetate) Coating Performance on Copper Corrosion in Saline Environment

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 439
Author(s):  
Adriana Samide ◽  
Claudia Merisanu ◽  
Bogdan Tutunaru ◽  
Gabriela Eugenia Iacobescu
Keyword(s):  
Vinyl Acetate ◽  
Vinyl Alcohol ◽  
Electrochemical Impedance ◽  
Copper Surface ◽  
Copper Sample ◽  
Electrochemical Measurements ◽  
Copper Corrosion ◽  
Nacl Solution ◽  
Force Microscopy ◽  
Vinyl Butyral

Poly (vinyl butyral-co-vinyl alcohol-co-vinyl acetate) named further PVBA was investigated as a protective coating for copper corrosion in 0.9% NaCl solution using electrochemical measurements such as, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization associated with atomic force microscopy (AFM). The PVBA coating on the copper surface (Cu-PVBA) was modeled in methanol containing PVBA. Its inhibitory properties against corrosion was comparatively discussed with those of the copper sample treated in methanol without polymer (Cu-Me) and of untreated sample (standard copper). A protective performance of PVBA coating of 80% was computed from electrochemical measurements, for copper corrosion in NaCl solution. Moreover, AFM images designed a specific surface morphology of coated surface with PVBA, clearly highlighting a polymer film adsorbed on the copper surface, which presents certain deterioration after corrosion, but the metal surface was not significantly affected compared to those of untreated samples or treated in methanol, in the absence of PVBA.

Nickel Corrosion Inhibition in Sulfuric Acid—Electrochemical Studies, Morphologies, and Theoretical Approach

CORROSION ◽  
10.5006/0508 ◽  
2012 ◽  
Vol 68 (8) ◽  
pp. 699-712 ◽  
Author(s):  
M.A. Amin ◽  
H. Shokry ◽  
E.M. Mabrouk
Keyword(s):  
Sulfuric Acid ◽  
Electrochemical Impedance ◽  
Theoretical Studies ◽  
Electrochemical Studies ◽  
X Ray ◽  
Linear Polarization Resistance ◽  
Tafel Polarization ◽  
Inhibition Performance ◽  
Experimental Findings ◽  
Good Agreement

The inhibition performance of three selected dihydrazide derivatives, namely, malonic acid (MAD), succinic acid (SAD), and adipic acid (AAD) dihydrazide, was tested in relation to nickel corrosion in 1.0 M sulfuric acid (H2SO4) solution. Electrochemical methods (Tafel polarization, linear polarization resistance [LPR], and electrochemical impedance spectroscopy [EIS]) were used, complemented with scanning electron microscopy/energy-dispersive x-ray (SEM/EDX) examinations. Computational studies were also used to confirm experimental findings and to optimize the adsorption structures of dihydrazide derivatives. Results showed that the three tested dihydrazides inhibited Ni corrosion (mixed-type inhibitors) to an extent, depending on the type and concentration of the introduced inhibitor. SEM studies revealed that the corroded areas on the surface were decreased in the presence of additives to an extent, depending on the type and concentration of the tested inhibitor. Results obtained from electrochemical measurements are in good agreement with theoretical studies.

scholarly journals Poly(Vinyl Butyral-co-Vinyl Alcohol-co-Vinyl Acetate) Coating Performance on Copper Corrosion in Saline Environment

2019 ◽  
Author(s):  
Adriana Samide ◽  
Claudia Merisanu ◽  
Bogdan Tutunaru ◽  
Gabriela Eugenia Iacobescu
Keyword(s):  
Vinyl Acetate ◽  
Vinyl Alcohol ◽  
Electrochemical Impedance ◽  
Copper Surface ◽  
Copper Sample ◽  
Electrochemical Measurements ◽  
Copper Corrosion ◽  
Nacl Solution ◽  
Force Microscopy ◽  
Vinyl Butyral

Poly(vinyl butyral-co-vinyl alcohol-co-vinyl acetate) named further PVBA was investigated as protective coating for copper corrosion in 0.9 % NaCl solution using electrochemical measurements such as, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization associated with Atomic Force Microscopy (AFM). The PVBA coating on the copper surface (Cu-PVBA) was modeled in methanol containing PVBA. Its inhibitory properties against corrosion was comparatively discussed with those of the copper sample treated in methanol without polymer (Cu-Me) and of untreated sample (standard copper). A protective performance of PVBA coating of 80 % was computed from electrochemical measurements, for copper corrosion in NaCl solution. Also, AFM images designed a specific surface morphology of coated surface with PVBA, clearly highlighting a polymer film adsorbed on the copper surface, which presents certain deterioration after corrosion, but metal surface was not significantly affected compared to those of untreated samples or treated in methanol, in the absence of PVBA.

scholarly journals Anticorrosive behaviour of lumefantrine hydrophobic layer on mild steel surface

2016 ◽  
Author(s):  
Pavithra M. Krishnegowda ◽  
Venkateha T. Venkatarangaiah ◽  
Punith Kumar M. Krishnegowda ◽  
Anantha N. Subba Rao ◽  
Shubha H. Nataraj
Keyword(s):  
Mild Steel ◽  
Steel Surface ◽  
Electrochemical Impedance ◽  
Mild Steel Surface ◽  
Theoretical Support ◽  
Acidic Chloride ◽  
Modified Surface ◽  
Inhibition Performance ◽  
Experimental Findings ◽  
3D Profilometer

<span lang="EN-US">The surface modification of mild steel was achieved by chemical treatment in lumefantrine (LF) solution. The surface morphology and wettability of modified surface was analysed by 3D profilometer and contact angle goniometer. The corrosion inhibition performance of modified mild steel surface in 1.0 M HCl solution was investigated by potentiodynamic polarization and electrochemical impedance techniques.Electroche­mical measurements illustrate that the corrosion of mild steel in acidic chloride medium get substantially reduced by introducing LF film on its surface (94 % efficiency). Quantum chemical parameters were evaluated by ab initio method and they confer appropriate theoretical support to the experimental findings.</span>

scholarly journals Numerical Study and Experimental Validation of Deformation of FCC CuAl Single Crystal Obtained by Additive Manufacturing

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 582
Author(s):  
Anton Y. Nikonov ◽  
Andrey I. Dmitriev ◽  
Dmitry V. Lychagin ◽  
Lilia L. Lychagina ◽  
Artem A. Bibko ◽  
...  
Keyword(s):  
Single Crystal ◽  
Numerical Study ◽  
Strain Curve ◽  
Aluminum Bronze ◽  
Partial Dislocations ◽  
Slip Planes ◽  
Loaded Material ◽  
Dislocation Movement ◽  
Dynamics Simulations ◽  
Experimental Findings

The importance of taking into account directional solidification of grains formed during 3D printing is determined by a substantial influence of their crystallographic orientation on the mechanical properties of a loaded material. This issue is studied in the present study using molecular dynamics simulations. The compression of an FCC single crystal of aluminum bronze was performed along the <111> axis. A Ni single crystal, which is characterized by higher stacking fault energy (SFE) than aluminum bronze, was also considered. It was found that the first dislocations started to move earlier in the material with lower SFE, in which the slip of two Shockley partials was observed. In the case of the material with higher SFE, the slip of a full dislocation occurred via successive splitting of its segments into partial dislocations. Regardless of the SFE value, the deformation was primarily occurred by means of the formation of dislocation complexes involved stair-rod dislocations and partial dislocations on adjacent slip planes. Hardening and softening segments of the calculated stress–strain curve were shown to correspond to the periods of hindering of dislocations at dislocation pileups and dislocation movement between them. The simulation results well agree with the experimental findings.

scholarly journals Influence of Large Relative Tip Clearances for a Micro Radial Fan and Design Guidelines for Increased Efficiency

2020 ◽  
Author(s):  
Patrick H. Wagner ◽  
Jan Van herle ◽  
Lili Gu ◽  
Jürg Schiffmann
Keyword(s):  
Pressure Rise ◽  
Leading Edge ◽  
High Sensitivity ◽  
Design Guidelines ◽  
Tip Clearance ◽  
Small Scale ◽  
Blade Tip ◽  
Dynamics Simulations ◽  
Experimental Findings ◽  
Blade Tip Clearance

Abstract The blade tip clearance loss was studied experimentally and numerically for a micro radial fan with a tip diameter of 19.2mm. Its relative blade tip clearance, i.e., the clearance divided by the blade height of 1.82 mm, was adjusted with different shims. The fan characteristics were experimentally determined for an operation at the nominal rotational speed of 168 krpm with hot air (200 °C). The total-to-total pressure rise and efficiency increased from 49 mbar to 68 mbar and from 53% to 64%, respectively, by reducing the relative tip clearance from 7.7% to the design value of 2.2%. Single and full passage computational fluid dynamics simulations correlate well with these experimental findings. The widely-used Pfleiderer loss correlation with an empirical coefficient of 2.8 fits the numerical simulation and the experiments within +2 efficiency points. The high sensitivity to the tip clearance loss is a result of the design specific speed of 0.80, the highly-backward curved blades (17°), and possibly the low Reynolds number (1 × 105). The authors suggest three main measures to mitigate the blade tip clearance losses for small-scale fans: (1) utilization of high-precision surfaced-grooved gas-bearings to lower the blade tip clearance, (2) a mid-loaded blade design, and (3) an unloaded fan leading edge to reduce the blade tip clearance vortex in the fan passage.

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