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.

Improving the Corrosion Resistance of API X56 and API X70 Pipeline Steels by Hot Dip Aluminization

2021 ◽  
Vol 875 ◽  
pp. 315-321
Author(s):  
Muhammad Ramzan Abdul Karim ◽  
Sanam Daniel ◽  
Ehsan Ul Haq ◽  
Akhlaq Ahmad ◽  
Khurram Imran Khan ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Internal Surface ◽  
Passive Layer ◽  
Material Loss ◽  
Pipeline Steels ◽  
Marine Corrosion ◽  
Weight Loss Method ◽  
Loss Method ◽  
Steel Substrates ◽  
Sweet Corrosion

The external surface of the pipeline steels can be protected from corrosion by cathodic protection and a suitable coating system. But to protect the internal surface of steel pipelines from corrosion is always a challenge. In the current study, a protective aluminum coating was applied on the internal surface of steel pipeline grades API X56 and API X70 by hot dip aluminization process to minimize the cost of inhibitors. The steel substrates were dipped in the hot aluminum bath, whose temperature was maintained at 720 °C, for three different dipping times (5, 7.5 and 10 minutes) and then permitted to cool to room temperature. The coated specimens were characterized in terms of their structure and composition by using scanning electron microscopy (SEM) and X-ray diffraction (XRD). SEM micrographs analysis reveal that the hot dip aluminized specimens gave an unwavering and well adherent interface which is essential for corrosion resistance of the substrates. The corrosion behavior was evaluated by weight loss method in case of sweet corrosion (in 1.0 % NaCl + CO2 environment) and, by electrochemical potentiodynamic polarization tests for marine corrosion (in 3.5% NaCl environment). The sweet corrosion rates showed severe material loss (14.17 mpy for API X56 and 6.6 mpy in case of API X70) of uncoated samples as compared to the aluminized samples which showed no corrosion at all even after one week due to the passive layer of Al2O3. Whereas the marine corrosion of aluminized specimens was also reduced to 0.11 mpy (coated specimens) from 0.57 mpy (uncoated specimens).

scholarly journals Corrosion Inhibition Effect of Acidic Extract of Bark of Eucalyptus Globulus on Mild Steel

2020 ◽  
Vol 35 (1) ◽  
pp. 1-10
Author(s):  
Dipak Kumar Gupta ◽  
Laxmi Awasthi ◽  
Anju Kumari Das ◽  
Brahamdeo Yadav ◽  
Anita Ghimire ◽  
...  
Keyword(s):  
Mild Steel ◽  
Corrosion Inhibition ◽  
Eucalyptus Globulus ◽  
Open Circuit Potential ◽  
Inhibition Efficiency ◽  
Acidic Solution ◽  
Open Circuit ◽  
Weight Loss Method ◽  
Loss Method ◽  
Mixed Type Inhibitor

The corrosion inhibition properties of the acidic extract of Eucalyptus globulus (EG) was investigated for mild steel (MS) using the weight loss method and open circuit potential (OCP) measurement. Corrosion inhibition of MS in 0.1M HCl was studied in the absence and presence of various concentrations of the acidic extract of EG barks. The results showed an increase in corrosion inhibition with increasing concentration of the extract. The inhibition efficiency of 100% EG extract was approximately 98.0% after 24 hours immersion in the acidic solution. FTIR spectrum showed the presence of compounds containing oxygen and nitrogen functional groups responsible for forming barrier layers onto MS surface. Open circuit potential (OCP) measurements showed that the EG extract acts as a mixed type inhibitor.

Structure and Resistance to Electrochemical Corrosion of NiTi Alloy

2013 ◽  
Vol 203-204 ◽  
pp. 335-338 ◽  
Author(s):  
Bożena Łosiewicz ◽  
Magdalena Popczyk ◽  
Tomasz Goryczka ◽  
Józef Lelątko ◽  
Agnieszka Smołka ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Niti Alloy ◽  
Electrochemical Corrosion ◽  
High Resolution Electron Microscopy ◽  
Potential Method ◽  
Passive Layer ◽  
Open Circuit ◽  
Experimental Conditions ◽  
Electrochemical Tests ◽  
Reflectivity Method

The NiTi alloy (50.6 at.% Ni) passivated for 30 min at 130°C by autoclaving has been studied towards corrosion resistance in aqueous solutions of 3% NaCl, 0.1 M H2SO4, 1 M H2SO4 and HBSS. Structure and thickness of the passive layer (TiO2, rutile) were examined by X-ray reflectivity method and high resolution electron microscopy. Corrosion behavior of this oxide layer was investigated by open circuit potential method and polarization curves. It was found that the corrosion resistance of the passivated NiTi alloy is strongly dependent on the type of corrosive environment. The higher corrosion resistance of the tested samples was revealed in sulfate solutions as compared to chloride ones. The highest resistance to electrochemical corrosion of the NiTi alloy was observed in 0.1 M H2SO4 solution. Susceptibility to pitting corrosion of the tested samples was observed which increased with the concentration rise of chlorine anions in solution. Electrochemical tests for 316L stainless steel carried out under the same experimental conditions revealed a weaker corrosion resistance in all solutions as compared to the highly corrosion resistant NiTi alloy.

scholarly journals Electrochemical Behavior of Al(III) and Formation of Different Phases Al-Ni Alloys Deposits from LiCl-KCl-AlCl3 Molten Salt

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2113
Author(s):  
Yaru Peng ◽  
Zeng Chen ◽  
Ying Bai ◽  
Qingqing Pei ◽  
Wei Li ◽  
...  
Keyword(s):  
Molten Salt ◽  
Molten Salts ◽  
Deposition Potential ◽  
Open Circuit ◽  
Electrochemical Behaviors ◽  
X Ray ◽  
Ni Alloys ◽  
Wave Voltammetry ◽  
Deposition Processes ◽  
Key Parameter

The electrochemical behaviors of Al(III) deposits on Ni substrates were investigated in LiCl-KCl-AlCl3 (2 wt.%) molten salts. Various electrochemical methods, including cyclic voltammetry (CV), square wave voltammetry (SWV), and open circuit chronopotentiometry (OCP) were used to explore the deposition processes of Al(III) on Ni substrates. Five kinds of Al-Ni alloys phase were firstly electrodeposited by the regulation of deposition potential form LiCl-KCl-AlCl3 (2 wt.%) molten salts at 753 K. The formation of Al-Ni alloys, such as AlNi3, Ni5Al3, AlNi, Al3Ni2, and Al3Ni were confirmed by X-ray diffractometer (XRD) and the cross-section morphologies were investigated by scanning electron microscope (SEM). Meanwhile, it was found that the temperature of molten salt was another key parameter for the controlling of alloys phase. No Al-Ni alloys phase other than AlNi3 and Ni5Al3 could be deposited at 703 K.

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 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.%.

Study on Corrosion Resistance of Brass in Circulating Cooling Water with Different Concentration Ratio

2012 ◽  
Vol 511 ◽  
pp. 70-73
Author(s):  
Yu Chun Li ◽  
Xiao Wei Liu ◽  
Rui Feng Zhang ◽  
Kang Juan ◽  
Fan Gao
Keyword(s):  
Weight Loss ◽  
Corrosion Resistance ◽  
Concentration Ratio ◽  
Water System ◽  
Cooling Water ◽  
Cooling Water System ◽  
Circulating Cooling Water ◽  
Weight Loss Method ◽  
Ratio Condition ◽  
Loss Method

Abstract: The corrosion resistance of brass H70-1A cooling water was studied through weight-loss method and electrochemistry measurement in different concentration ratio condition. The results obtained from this study showed that brass inhibitor was necessary to add to circulating cooling water system when concentration ratio was in the range of 3~7.

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.

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.

Evaluation of Polymeric Coatings in CO2 Containing Environment

2019 ◽  
Vol 965 ◽  
pp. 133-141
Author(s):  
Rayane Z.C. Demoner ◽  
Alexandre R.P. Castro ◽  
Adriana L. Barros ◽  
J.P. Quintela ◽  
Jefferson R. de Oliveira ◽  
...  
Keyword(s):  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Polymeric Coating ◽  
Metallic Surface ◽  
Polymeric Coatings ◽  
X Ray Diffraction ◽  
X Ray ◽  
Linear Polarization Resistance ◽  
Weight Loss Method ◽  
Loss Method

Two types of polymeric coating were applied on an AISI 1020 steel, where one of them was reinforced by carbon nanotubes, with the objective of protection against corrosion in a medium containing saline solution, NaCl 3% wt satured with CO2, at 75 bar and tested at 50oC and 75oC for 360 hours. Electrochemical techniques, such as Linear Polarization Resistance, (LPR), Electrochemical Impedance Spectroscopy (EIS), Tafel curves and weight loss method, were used for coating evaluation performance. Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) were used to determine both the morphology and chemical composition of the layer formed on the analyzed surfaces. The coating adhesion to metallic surface was evaluated using pull-off test according to ASTM D4541-09. For the studied conditions, the results obtained showed that there was no adequate coating protection, occurring failures and indicating that both coatings may not be used in the tested conditions.

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