scholarly journals Corrosion Behavior of Alloyed Cast Iron in Ethylene Glycol-Based Engine Coolants at Elevated Temperature

Coatings ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 357
Author(s):  
Gaurav Argade ◽  
Anusha Chilukuri ◽  
Justin Perry ◽  
Monica Viers ◽  
Jacob Steenhoek ◽  
...  
Keyword(s):  
Cast Iron ◽  
Elevated Temperature ◽  
Electrochemical Impedance ◽  
Engine Performance ◽  
Sharp Decrease ◽  
Charge Transfer Resistance ◽  
Organic Additives ◽  
Transfer Resistance ◽  
Electrochemical Tests ◽  
Engine Coolant

For enhanced engine performance, corrosivity of the engine coolants would play a significant role. In this work, corrosion investigation was performed on cast iron material in pre-mixed engine coolant environment to understand the threshold limits of contaminants. The pre-mixed coolant contained combination of organic additives viz. sebacate (SA), 2-ethylhexonate (2-EH), and tolyltriazole (TTA) with varying concentrations of chloride contaminant. Constant immersion of cast iron samples in engine coolant with different chloride levels at 90 °C was followed by room temperature electrochemical tests. The potentiodynamic polarization tests showed no instability until 100 ppm chloride additions exposed up to 28 days. At lower frequencies in electrochemical impedance spectroscopy (EIS) spectra, inhibition layer characteristics changed from highly capacitive to highly resistive and concurrently a sharp decrease in charge transfer resistance was observed with time for samples exposed to >100 ppm chloride levels. In the longer duration corrosion tests, higher pit depths with increased number density of attacks were observed for cast iron samples exposed to engine coolants containing >100 ppm chloride. For elevated temperature exposures a threshold limit of <200 ppm chloride was established for cast iron samples.

scholarly journals Synthesis of MoIn2S4@CNTs Composite Counter Electrode for Dye-Sensitized Solar Cells

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Gentian Yue ◽  
Renzhi Cheng ◽  
Xueman Gao ◽  
Leqing Fan ◽  
Yangfan Mao ◽  
...  
Keyword(s):  
Counter Electrode ◽  
Electrochemical Impedance ◽  
Dye Sensitized Solar Cells ◽  
Charge Transfer Resistance ◽  
Transfer Resistance ◽  
Electrochemical Tests ◽  
One Step ◽  
Low Charge ◽  
Adsorption Desorption ◽  
Sensitized Solar Cells

Abstract A ternary and composite MoIn2S4@CNTs counter electrode (CE) with a hedgehog ball structure was synthesized by using a facile one-step hydrothermal method. The composite MoIn2S4@CNTs film possesses large specific surface area through N2 adsorption-desorption isotherms test, which is advantageous to adsorb more electrolyte and provide larger active contact area for the electrode. In addition, the composite MoIn2S4@CNTs CE exhibits low charge transfer resistance and fine electrocatalytic ability made from a series of electrochemical tests including cyclic voltammetry, electrochemical impedance, and Tafel curves. Under optimal conditions, the DSSC based on the MoIn2S4@CNTs-2 composite CE achieves an impressive power conversion efficiency as high as 8.38%, which remarkably exceeds that of the DSSCs with the MoIn2S4 CE (7.44%) and the Pt electrode (8.01%). The current work provides a simplified preparation process for the DSSCs.

Electrochemical Study of the Additive-Effect on Sn Electrodeposition in a Methansulfonate Acid Electrolyte

2012 ◽  
Vol 460 ◽  
pp. 7-10 ◽  
Author(s):  
Jin Ming Long ◽  
Zhu Zhang ◽  
Zhong Cheng Guo ◽  
Xiao Yun Zhu ◽  
Hui Huang
Keyword(s):  
Cathodic Polarization ◽  
Electrochemical Impedance ◽  
Charge Transfer Resistance ◽  
Organic Additives ◽  
Tin Coating ◽  
Coating Quality ◽  
Transfer Resistance ◽  
Faradaic Impedance ◽  
Fine Grained ◽  
Cathodic Overpotential

The effect of three organic additives in stannous methanesulfonate baths on cathodic overpotential and Faradaic impedance of tin-electrodeposition were studied by measuring cathodic polarization curves, galvanostatic responses and electrochemical impedance spectroscopy. The results show that the composite additive consisting of three organic compounds can significantly increase the cathodic polarization, crystallization overpotential and charge transfer resistance, which is very beneficial to improve coating quality and result in a fine-grained and smooth matt tin coating.

scholarly journals MORPHOLOGICAL, STRUCTURAL, MICROHARDNESS AND ELECTROCHEMICAL CHARACTERIZATIONS OF ELECTRODEPOSITED Cr AND Ni–W COATINGS

2018 ◽  
Vol 24 (3) ◽  
pp. 234 ◽  
Author(s):  
Elkhanssa Aidaoui ◽  
Hachemi Ben Temam ◽  
Okba Belahssen ◽  
El Hachmi Guettaf Temam
Keyword(s):  
Current Density ◽  
Electrochemical Impedance ◽  
Electrochemical Characterizations ◽  
Copper Substrate ◽  
Charge Transfer Resistance ◽  
Applied Current ◽  
Transfer Resistance ◽  
Electrochemical Tests ◽  
Cu Substrates ◽  
Xrd Patterns

<p class="AMSmaintext">Currently, Ni-Cr coatings are widely used in a number of important applications due to their excellent properties. In this study, Ni-Cr alloys were electrodeposited from citrate bath onto Cu substrates by using different values of applied current densities. The effects of plating deposition current density on morphological and structural characterization of Ni-Cr electrodeposited coatings were investigated by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD). Microhardness of the coatings is also evaluated using Vickers’s microhardness. Potentio-dynamic polarization and electrochemical impedance spectroscopy (EIS) tests in 3.5wt % NaCl solution were used to evaluate corrosion résistance of Ni-Cr coatings. The results showed that the surface morphology of the all coatings contained micro cracks and pores. XRD patterns indicate the formation of Ni-Cr and Cr<sub>3</sub>Ni<sub>2</sub> phases. Microhardness measurements show that all Ni-Cr samples are hardener than copper substrate. Electrochemical tests show that 3 A/dm² is an optimal value of applied current density in the sense of the least value of E<sub>corr</sub> and the best charge transfer resistance R<sub>p</sub>.</p>

IMMERSION AND ELECTROCHEMICAL TESTS STUDY ON CORROSION RESISTANCE OF CHROME-FREE CHEMICAL CONVERSION FILM ON AZ91D Mg ALLOY IN 5 wt% NaCl SOLUTION

2005 ◽  
Vol 12 (03) ◽  
pp. 417-424
Author(s):  
X. P. ZHANG ◽  
G. CHEN
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Protection ◽  
Electrochemical Impedance ◽  
Chemical Conversion ◽  
Alloy Coating ◽  
Charge Transfer Resistance ◽  
Mg Alloy ◽  
Nacl Solution ◽  
Transfer Resistance ◽  
Electrochemical Tests

Immersion and electrochemical tests have been applied to study corrosion protection of AZ91D Mg alloy coating with chrome-free chemical conversion (CCC) coat in 5wt% NaCl solution. The immersions tests include weight-loss measurements after full or partial immersion with whole coating and full immersion with damaged coating. The electrochemical tests include electrochemical impedance spectroscopy (EIS) and polarization curves measurement. The results of immersion and electrochemical tests show that chrome-free chemical conversion (CCC) surface treatment can significantly improve the corrosion resistance of AZ91D Mg alloy in 5% NaCl solution, and that the corrosion protection effect of CCC coating is not sensitive to pores or cracks. The equivalent circuit models are fitted from Nyquist plots for the uncoated specimens and the CCC-coated specimens. The charge transfer resistance, R ct , increases from about 1.669 Ω cm2 for the uncoated alloy to about 210 Ω cm2 after the alloy is coated with CCC coating.

CORROSION PROTECTION OF AZ91D Mg ALLOY COATING WITH MICRO-ARC OXIDATION FILM EVALUATED BY IMMERSION AND ELECTROCHEMICAL TESTS

2005 ◽  
Vol 12 (02) ◽  
pp. 279-287 ◽  
Author(s):  
X. P. ZHANG ◽  
G. CHEN
Keyword(s):  
Corrosion Protection ◽  
Electrochemical Impedance ◽  
Alloy Coating ◽  
Charge Transfer Resistance ◽  
Mg Alloy ◽  
Nacl Solution ◽  
Transfer Resistance ◽  
Electrochemical Tests ◽  
Micro Arc Oxidation ◽  
Eis Measurements

This paper describes the preliminary results of corrosion protection of AZ91D Mg alloy coated with a micro-arc oxidation (MAO) coating. The corrosion behavior of coated substrates was evaluated by means of immersion and electrochemical tests in 5 wt.% NaCl solution. The immersions tests include weight loss measurement after full or partial immersion with the whole coat and full immersion with the damaged coat. The electrochemical tests include polarization curves and electrochemical impedance spectroscopy (EIS) measurements. The results of immersion and electrochemical tests show that micro-arc oxidation (MAO) surface treatment can significantly improve the corrosion resistance of the AZ91D Mg alloy in 5% NaCl solution, and the corrosion protection effect of the MAO coating is not sensitive to pores or cracks in the coating. The charge transfer resistance R ct , increases from about 1.669Ωcm2 for the uncoated alloy to about 1113Ωcm2 after being coated with MAO coat.

Improvement of Ti/RuO2–IrO2 Anode Lifetime and Electrocatalytical Properties by Using an Eco-Friendly Thermal Decomposition Method Using Polyvinyl Alcohol as Solvent

2019 ◽  
Author(s):  
Charlys Bezerra ◽  
Géssica Santos ◽  
Marilia Pupo ◽  
Maria Gomes ◽  
Ronaldo Silva ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Polyvinyl Alcohol ◽  
High Efficiency ◽  
Electrochemical Impedance ◽  
Pechini Method ◽  
Low Cost ◽  
Charge Transfer Resistance ◽  
Transfer Resistance ◽  
Calcination Temperatures ◽  
Service Lifetime

<p>Electrochemical oxidation processes are promising solutions for wastewater treatment due to their high efficiency, easy control and versatility. Mixed metal oxides (MMO) anodes are particularly attractive due to their low cost and specific catalytic properties. Here, we propose an innovative thermal decomposition methodology using <a>polyvinyl alcohol (PVA)</a> as a solvent to prepare Ti/RuO<sub>2</sub>–IrO<sub>2</sub> anodes. Comparative anodes were prepared by conventional method employing a polymeric precursor solvent (Pechini method). The calcination temperatures studied were 300, 400 and 500 °C. The physical characterisation of all materials was performed by X-ray diffraction and scanning electron microscopy coupled with energy dispersive spectroscopy, while electrochemical characterisation was done by cyclic voltammetry, accelerated service lifetime and electrochemical impedance spectroscopy. Both RuO<sub>2</sub> and IrO<sub>2</sub> have rutile-type structures for all anodes. Rougher and more compact surfaces are formed for the anodes prepared using PVA. Amongst temperatures studied, 300 °C using PVA as solvent is the most suitable one to produce anodes with expressive increase in voltammetric charge (250%) and accelerated service lifetime (4.3 times longer) besides reducing charge-transfer resistance (8 times lower). Moreover, the electrocatalytic activity of the anodes synthesised with PVA toward the Reactive Blue 21 dye removal in chloride medium (100 % in 30 min) is higher than that prepared by Pechini method (60 min). Additionally, the removal total organic carbon point out improved mineralisation potential of PVA anodes. Finally, this study reports a novel methodology using PVA as solvent to synthesise Ti/RuO<sub>2</sub>–IrO<sub>2</sub> anodes with improved properties that can be further extended to synthesise other MMO compositions.</p>

scholarly journals Electrochemical Immunosensor for the Quantification of S100B at Clinically Relevant Levels Using a Cysteamine Modified Surface

Sensors ◽  
2021 ◽  
Vol 21 (6) ◽  
pp. 1929
Author(s):  
Alexander Rodríguez ◽  
Francisco Burgos-Flórez ◽  
José D. Posada ◽  
Eliana Cervera ◽  
Valtencir Zucolotto ◽  
...  
Keyword(s):  
Frequency Analysis ◽  
Surface Characterization ◽  
Electrochemical Impedance ◽  
Limit Of Detection ◽  
Neuronal Damage ◽  
Charge Transfer Resistance ◽  
Single Frequency ◽  
Response Analysis ◽  
Transfer Resistance ◽  
Therapeutic Decisions

Neuronal damage secondary to traumatic brain injury (TBI) is a rapidly evolving condition, which requires therapeutic decisions based on the timely identification of clinical deterioration. Changes in S100B biomarker levels are associated with TBI severity and patient outcome. The S100B quantification is often difficult since standard immunoassays are time-consuming, costly, and require extensive expertise. A zero-length cross-linking approach on a cysteamine self-assembled monolayer (SAM) was performed to immobilize anti-S100B monoclonal antibodies onto both planar (AuEs) and interdigitated (AuIDEs) gold electrodes via carbonyl-bond. Surface characterization was performed by atomic force microscopy (AFM) and specular-reflectance FTIR for each functionalization step. Biosensor response was studied using the change in charge-transfer resistance (Rct) from electrochemical impedance spectroscopy (EIS) in potassium ferrocyanide, with [S100B] ranging 10–1000 pg/mL. A single-frequency analysis for capacitances was also performed in AuIDEs. Full factorial designs were applied to assess biosensor sensitivity, specificity, and limit-of-detection (LOD). Higher Rct values were found with increased S100B concentration in both platforms. LODs were 18 pg/mL(AuES) and 6 pg/mL(AuIDEs). AuIDEs provide a simpler manufacturing protocol, with reduced fabrication time and possibly costs, simpler electrochemical response analysis, and could be used for single-frequency analysis for monitoring capacitance changes related to S100B levels.

scholarly journals Influence of HAP on the Morpho-Structural Properties and Corrosion Resistance of ZrO2-Based Composites for Biomedical Applications

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 202
Author(s):  
Réka Barabás ◽  
Carmen Ioana Fort ◽  
Graziella Liana Turdean ◽  
Liliana Bizo
Keyword(s):  
Electrochemical Impedance ◽  
Artificial Saliva ◽  
Synergetic Effect ◽  
Composite Layer ◽  
Charge Transfer Resistance ◽  
Processing Route ◽  
Dental Alloys ◽  
Metallic Electrode ◽  
Transfer Resistance ◽  
X Ray

In the present work, ZrO2-based composites were prepared by adding different amounts of antibacterial magnesium oxide and bioactive and biocompatible hydroxyapatite (HAP) to the inert zirconia. The composites were synthesized by the conventional ceramic processing route and morpho-structurally analyzed by X-ray powder diffraction (XRPD) and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS). Two metallic dental alloys (i.e., Ni–Cr and Co–Cr) coated with a chitosan (Chit) membrane containing the prepared composites were exposed to aerated artificial saliva solutions of different pHs (i.e., 4.3, 5, 6) and the corrosion resistances were investigated by electrochemical impedance spectroscopy technique. The obtained results using the two investigated metallic dental alloys shown quasi-similar anticorrosive properties, having quasi-similar charge transfer resistance, when coated with different ZrO2-based composites. This behavior could be explained by the synergetic effect between the diffusion process through the Chit-composite layer and the roughness of the metallic electrode surface.

scholarly journals Corrosion behaviors of 316 stainless steel and Inconel 625 alloy in chloride molten salts for solar energy storage

2020 ◽  
Vol 39 (1) ◽  
pp. 340-350
Author(s):  
Mingjing Wang ◽  
Song Zeng ◽  
Huihui Zhang ◽  
Ming Zhu ◽  
Chengxin Lei ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Molten Salt ◽  
Electrochemical Impedance ◽  
Charge Transfer Resistance ◽  
Inconel 625 ◽  
Transfer Resistance ◽  
316 Stainless Steel ◽  
Corrosion Rates ◽  
Inconel 625 Alloy ◽  
Corrosion Behaviors

AbstractCorrosion behaviors of 316 stainless steel (316 ss) and Inconel 625 alloy in molten NaCl–KCl–ZnCl2 at 700°C and 900°C were investigated by immersion tests and electrochemical methods, including potentiodynamic polarization and electrochemical impedance spectroscopy. X-ray diffraction and scanning electron microscopy/energy dispersive spectroscopy were used to analyze the phases and microstructures of the corrosion products. Inconel 625 alloy and 316 ss exhibited high corrosion rates in molten chlorides, and the corrosion rates of these two alloys accelerated when the temperature increased from 700°C to 900°C. The results of the electrochemical tests showed that both alloys exhibited active corrosion in chloride molten salt, and the current density of 316 ss in chloride molten salt at 700°C was 2.756 mA/cm−2, which is about three times the value for Inconel 625 alloy; and the values of the charge transfer resistance (Rt) for Inconel 625 were larger than those for 316 ss. The corrosion of these two alloys is owing to the preferred oxidation of Cr in chloride molten salt, and the corrosion layer was mainly ZnCr2O4 which was loose and porous and showed poor adherence to metal.

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