scholarly journals Evaluation of the Corrosion Resistance of Some Coating Obtained by Thermal Spray in Plasma Jet, on the Surface of Some Crankshafts Made of C45 Steel

2020 ◽  
Vol 71 (10) ◽  
pp. 218-230
Author(s):  
George Mahu ◽  
Corneliu Munteanu ◽  
Bogdan Istrate ◽  
Igor Blanari ◽  
Cornelia Paleu ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Open Circuit Potential ◽  
Open Circuit ◽  
Corrosion Process ◽  
Atmospheric Plasma ◽  
Basic Material ◽  
Main Bearing ◽  
Spray Method ◽  
Polarization Technique

For modern engines the oil change interval can reach up to 30,000 km. If the oils lose their properties and are contaminated, they can adversely affect the corrosion resistance, the surface of the main bearing journals and the main journals of the crankshafts. In this study, the results obtained from the corrosion process were analyzed, in a solution of 3.5% NaCl of the layers obtained after spraying the surface of a C45 steel, used in the construction of crankshafts, with three powders: Cr3C2-(Ni20Cr), Al2O3-13TiO2, Cr2O3-SiO2-TiO2. The corrosion process was determined by the potentiodynamic polarization technique. The variations in time of the open-circuit potential and the Tafel curves were analyzed, for the samples with deposited layers and the basic material. Morphology and characterization of the structure of the layers after corrosion were performed by means of SEM microscopy and EDAX analysis. The results confirm that the powders sprayed by the atmospheric plasma spray method protect the surface of C45 steel from corrosion.

Corrosion Behaviour of Ni-Cr Based Biomaterials in Rondelli Saliva

2008 ◽  
Vol 59 (4) ◽  
Author(s):  
Daniel Sutiman ◽  
Adrian Cailean ◽  
Igor Cretescu ◽  
Mircea Nechita ◽  
Daniel Mareci
Keyword(s):  
Corrosion Resistance ◽  
Open Circuit Potential ◽  
Electrochemical Impedance ◽  
Corrosion Behaviour ◽  
Open Circuit ◽  
Corrosion Process ◽  
Passive Region ◽  
Passive Transition ◽  
Film Electrolyte ◽  
Stable Passive

The corrosion behaviour of nickel-based alloys (Heraenium, Verabond and V alloy) in simulated saliva was studied by gravimetric, pH-metric and conductometric methods, as well as by potentiodynamic polarization and by electrochemical impedance spectroscopy (EIS). The main parameters of the corrosion process were established. Additionally, the results obtained with SEM and AAS analyses were reported. All alloys pass directly into a stable passive region, without exhibiting the usual active-passive transition. The EIS results show that a Ni-based alloy exhibits passivity at open circuit potential. The proposed equivalent circuit contains two R-CPE elements in parallel. The physical meaning given to the circuit is the association of the film/electrolyte interface with the passive film itself. The corrosion resistance of the studied non-precious alloys is in the following order: Heraenium alloy ] V alloy ] Verabond alloy.

scholarly journals Effects of tungsten, chromium and zirconium on the corrosion behavior of ternary amorphous W–Cr–Zr alloys in 1 M NaOh solution

1970 ◽  
Vol 9 (9) ◽  
pp. 39-43
Author(s):  
Basu Ram Aryal ◽  
Jagadeesh Bhattarai
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Rate ◽  
Open Circuit Potential ◽  
Open Circuit ◽  
Corrosion Rates ◽  
Corrosion Resistance Property ◽  
Naoh Solution ◽  
Order Of Magnitude ◽  
Sputter Deposited ◽  
Zr Alloys

Simultaneous additions of tungsten, chromium and zirconium in the chromium- and zirconium-enriched sputter-deposited binary W-xCr and W-yZr are effective to improve the corrosion resistance property of the ternary amorphous W- xCr-yZr alloys after immersion for 240 h in 1 M NaOH solution open to air at 25°C. The corrosion rates of all the examined sputter-deposited (10-57)W-(18-42)Cr-(25-73)Zr alloys is higher than those of alloy-constituting elements (that is, tungsten, chromium and zirconium) in aggressive 1 M NaOH solution open to air at 25°C. The corrosion rates of all the examined sputter−deposited W–xCr–yZr alloys containing 10-57 at% tungsten, 18-42 at% chromium and 25-73 at% zirconium were in the range of 1.5-2.5 × 10−3 mm/y or lower which are more than two orders of magnitude lower than that of sputter-deposited tungsten and even about one order of magnitude lower than those of the sputter-deposited zirconium in 1 M NaOH solution. Keywords: Ternary W–Cr–Zr alloys; Amorphous; Corrosion rate; Open circuit potential; 1 M NaOH. DOI: http://dx.doi.org/10.3126/sw.v9i9.5516 SW 2011; 9(9): 39-43

scholarly journals Corrosion Behavior of Pure Cr, Ni, and Fe Exposed to Molten Salts at High Temperature

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
O. Sotelo-Mazón ◽  
C. Cuevas-Arteaga ◽  
J. Porcayo-Calderón ◽  
V.M. Salinas Bravo ◽  
G. Izquierdo-Montalvo
Keyword(s):  
Corrosion Resistance ◽  
Molten Salt ◽  
Molten Salts ◽  
Refractory Compound ◽  
Open Circuit Potential ◽  
Passive Layer ◽  
Open Circuit ◽  
Metallic Surface ◽  
Weight Loss Method ◽  
Loss Method

Corrosion resistance of pure Fe, Cr, and Ni materials exposed in NaVO3molten salt at 700°C was evaluated in static air during 100 hours. The corrosion resistance was determined using potentiodynamic polarization, open circuit potential, and lineal polarization resistance. The conventional weight loss method (WLM) was also used during 100 hours. The electrochemical results showed that Fe and Cr have a poor corrosion resistance, whereas pure Ni showed the best corrosion performance, which was supported by the passive layer of NiO formed on the metallic surface and the formation of Ni3V2O8during the corrosion processes, which is a refractory compound with a higher melting point than that of NaVO3, which reduces the corrosivity of the molten salt. Also, the behavior of these materials was associated with the way in which their corresponding oxides were dissolved together with their type of corrosion attack. Through this study, it was confirmed that when materials suffer corrosion by a localized processes such as pitting, the WLM is not reliable, since a certain amount of corrosion products can be kept inside the pits. The corroded samples were analyzed through scanning electron microscopy.

scholarly journals Preparation and Electrochemical Characterization of Concrete Containing Microencapsulated Calcium Nitrate Corrosion Inhibitor

2019 ◽  
Vol 271 ◽  
pp. 07009
Author(s):  
Changkyu Kim ◽  
Reece Goldsberry ◽  
Ahmad Ivan Karayan ◽  
Jose Milla ◽  
Marwa Hassan ◽  
...  
Keyword(s):  
Corrosion Inhibitor ◽  
Open Circuit Potential ◽  
Concrete Beams ◽  
Electrochemical Impedance ◽  
Calcium Nitrate ◽  
Passive Layer ◽  
Open Circuit ◽  
Optimum Concentration ◽  
Cracked Concrete

We present the preparation and inhibition behavior of rebar in the presence of calcium nitrate (CN)-containing microcapsules with concentrations of 0.50, 2.00, and 5.00 wt.% in concrete. From both open circuit potential (OCP) and electrochemical impedance spectroscopy spectra, it was found that an addition of microcapsules containing CN corrosion inhibitor into concrete beams successfully repassivated or maintained the passivity of the rebar when the concrete was cracked. This corrosion inhibitor repassivated the rebar by forming a passive layer on the rebar surface under the crack. This repassivation process was evident by an increase of OCP values to more positive values or by stable OCP values at around -100 mV vs SCE. An increase in phase angle after corrosion activation for the sample with 2.00 wt.% microcapsule clearly showed this repassivation process. The optimum concentration for maintaining the passivity on rebar in the cracked concrete was found to be 5.00 wt.%.

scholarly journals Synthesis and characterization of sintered hydroxyapatite/lignin coatings on titanium

2012 ◽  
Vol 66 (2) ◽  
pp. 187-192
Author(s):  
Rade Surudzic ◽  
Sanja Erakovic ◽  
Vesna Miskovic-Stankovic
Keyword(s):  
Simulated Body Fluid ◽  
Body Fluid ◽  
Open Circuit Potential ◽  
Electrochemical Impedance ◽  
Open Circuit ◽  
Constant Voltage ◽  
Corrosion Stability ◽  
Similar Chemical ◽  
Titanium Surfaces

In order to improve corrosion stability and biocompatibility of titanium surfaces, hydroxyapatite (Ca10(PO4)6(OH)2, HAP) has been used as coating material due to the fact that it possess similar chemical composition as bone tissue. Lignin?s (Lig) usage in medical applications could be interesting because it could lead to thermal stability, hydrophilicity, biocompatibility and biodegradability of different materials. Bioceramic hydroxyapatite/lignin (HAP/Lig) coatings on titanium were obtained from ethanol suspension by electrophoretic deposition method. The uniform and compact HAP/Lig coatings were deposited at constant voltage of 60 V for 45 s and sintered at 900?C in argon atmosphere. The corrosion stability of sintered HAP/Lig coatings in simulated body fluid (SBF) at 37?C was investigated by open circuit potential-time measurements and electrochemical impedance spectroscopy (EIS). The greater values of open circuit potential, as well as EIS results, indicated improved corrosion resistance and good corrosion stability of HAP/Lig coatings in simulated body fluid at 37?C .

Corrosion Behavior of Surfaced AM50 Magnesium Alloys under Stress Conditions

2010 ◽  
Vol 95 ◽  
pp. 79-83
Author(s):  
Amir Eliezer
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloys ◽  
Open Circuit Potential ◽  
Electrochemical Impedance ◽  
Spinel Phase ◽  
Ceramic Coatings ◽  
Open Circuit ◽  
Stress Conditions ◽  
X Ray Diffraction ◽  
X Ray

Micro-arc oxidization of AM50 magnesium alloys was studied. The influence of micro-arc oxidization process was investigated; phase structure were analyzed using X-ray diffraction (XRD). Open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) were used to evaluate the corrosion resistance of ceramic coatings formed on magnesium alloys under stress conditions. XRD analyses indicate that the ceramic coatings fabricated on the surface of magnesium alloys by micro-arc oxidization are composed of spinel phase MgAl2O4 The corrosion resistance of ceramic coatings is improved compared with magnesium alloy substrate.

A study of the electrochemical behaviour of cobalt in aqueous H2CO3/HCO3–/CO32– solutions at pH 7–9

2004 ◽  
Vol 82 (5) ◽  
pp. 583-594 ◽  
Author(s):  
Stéphan Simard ◽  
Danick Gallant
Keyword(s):  
Open Circuit Potential ◽  
Competitive Adsorption ◽  
Carbonic Acid ◽  
Acid Corrosion ◽  
Electrochemical Behaviour ◽  
Open Circuit ◽  
Corrosion Process ◽  
Rotating Disc ◽  
Solution Interface ◽  
Potential Decay

The electrochemical behaviour of a cobalt rotating electrode in H2CO3/HCO3–/CO32– aqueous solutions was investigated in the pH region from 7 to 9. The effects of H2CO3/HCO3–/CO32– concentration, pH, and the presence of phosphates as inhibitors was explored using a rotating disc electrode at 1000 rpm. Some potentiodynamic experiments indicate that for pH 8.5 and higher, carbonate and bicarbonate species play a key role on the rate of electrooxidation of cobalt. For pH lower than 8.5, the electrochemical behaviour of cobalt changes drastically and very aggressive corrosion is observed. The involvement of carbonic acid must be considered in the corrosion process of cobalt in this pH region. The study of passive film potential decay under open circuit potential and galvanostatic reduction was performed on preanodized cobalt electrodes in solutions of various compositions. These experiments indicated the phenomena occurring at the electrode–solution interface during the corrosion process. A mechanism involving competitive adsorption of different species is suggested on the basis of the experimental evidence.Key words: cobalt, bicarbonate, phosphate, carbonic acid, corrosion.

Influence of pH on the Electrochemical Bahavior of 00Cr15Ni7Mo2Cu2 Supermartensitic Stainless Steel in 3.5% NaCl Solutions

2012 ◽  
Vol 581-582 ◽  
pp. 1058-1061
Author(s):  
Jia Qun Rui ◽  
Jun Li ◽  
Hu Dai Sun ◽  
Kun Yu Zhao ◽  
Zhi Dong Li ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Open Circuit Potential ◽  
Electrochemical Impedance ◽  
Open Circuit ◽  
Pitting Potential ◽  
Supermartensitic Stainless Steel ◽  
Pitting Corrosion Resistance ◽  
Polarization Technique ◽  
Current Densities ◽  
Influence Of Ph

This objective is to study the influence of pH on the electrochemical behavior of 00Cr15Ni7Mo2Cu2 supermartensitic stainless steel in 3.5% NaCl solutions using potentiondynamic polarization technique, open circuit potential tests and electrochemical impedance spectroscopy (EIS).The study reveals that the pitting potential (Eb) is higher, the passivation current densities (ip) is lower and the electrochemical impedance increases with the pH. The results indicate that this stainless steel offer good pitting corrosion resistance with the pH increasing in 3.5% NaCl solutions.

scholarly journals Experimental evaluation of corrosion resistance of the alloys used in the fixed dental prosthesis

2015 ◽  
Vol 61 (2) ◽  
pp. 117-120
Author(s):  
Costin Coman ◽  
◽  
Raluca Monica Comăneanu ◽  
Violeta Hâncu ◽  
Horia Mihail Barbu ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Current Density ◽  
Applied Research ◽  
Open Circuit Potential ◽  
Corrosion Potential ◽  
Artificial Saliva ◽  
Corrosion Current ◽  
Open Circuit ◽  
Metal Alloys ◽  
Fixed Dental Prosthesis

Objectives. In this study we evaluated corrosion resistance of three types of metal alloys (two NiCr and one CoCr). Methods. Samples (coded A, B, C) of circular shape, with dimensions 13 x 1.5 mm, sanded and polished, were introduced in Fusayama Meyer artificial saliva at pH 5.2 and 37 ± 0.5°C and tested in terms of corrosion resistance with a potentiostat/galvanostat (model 4000 PARSTAT, Princeton Applied Research). Results. Open circuit potential EOC [mV] ranged between 21.316 and 5.75. Corrosion potential Ecor [mV] was between -73.536 and -395.662, and the corrosion current density icor [A/cm2] was between 1.237 x 10-6 and 905.13 x 10-9. Conclusion. The best corrosion behavior in Fusayama Meyer artificial saliva at pH 5.2 and at a temperature of 37 ± 0.5°C is the alloy A, followed by the alloy C.

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