scholarly journals Surface Modification on Ti-6Al-4V Alloy During Corrosion in a High Temperature Ionic Liquid

2020 ◽  
Vol 71 (4) ◽  
pp. 207-219
Author(s):  
Elena Ionela Neacsu ◽  
Virgil Constantin ◽  
Kazimir Yanushkevich ◽  
Cristina Donath ◽  
Mihai Anastasescu ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Ionic Liquid ◽  
Molten Salts ◽  
Anodic Polarization ◽  
Degradation Mechanism ◽  
Xps Analysis ◽  
Protective Oxide ◽  
Protective Properties ◽  
Protective Oxide Layer ◽  
Molten Electrolyte

Corrosion behavior of Ti-6Al-4V alloy was investigated by anodic polarization curves in LiF-NaF-KF molten salts mixture at 823K. The surface alloy (native composition and its modification and corrosion resistance after 4 hours immersion) was studied by XRD, SEM and XPS. XPS analysis shows TiO2 with small amount of V2O5, Al2O3 and TiF4, while in the electrolyte it was showed the presence of V in a very low concentration. AFM demonstrates that formation of a rough and non-protective oxide layer should be responsible for the weak protective properties of the alloy. The degradation mechanism of the alloy during corrosion is based on the formation of TiF4 and of the passing of vanadium in the molten electrolyte.

scholarly journals Exploring the Effect of Silicon on the High Temperature Corrosion of Lean FeCrAl Alloys in Humid Air

2021 ◽  
Author(s):  
T. Sand ◽  
A. Edgren ◽  
C. Geers ◽  
V. Asokan ◽  
J. Eklund ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
High Temperature ◽  
Oxidation Behavior ◽  
High Temperature Corrosion ◽  
The Other ◽  
Oxide Scales ◽  
Protective Oxide ◽  
New Approach ◽  
Fecral Alloys ◽  
Cr Evaporation

AbstractA new approach to reduce the chromium and aluminium concentrations in FeCrAl alloys without significantly impairing corrosion resistance is to alloy with 1–2 wt.% silicon. This paper investigates the “silicon effect” on oxidation by comparing the oxidation behavior and scale microstructure of two FeCrAl alloys, one alloyed with silicon and the other not, in dry and wet air at 600 °C and 800 °C. Both alloys formed thin protective oxide scales and the Cr-evaporation rates were small. In wet air at 800 °C the Si-alloyed FeCrAl formed an oxide scale containing mullite and tridymite together with α- and γ-alumina. It is suggested that the reported improvement of the corrosion resistance of Al- and Cr-lean FeCrAl’s by silicon alloying is caused by the appearance of Si-rich phases in the scale.

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 Electrochemical Anodizing Treatment to Enhance Localized Corrosion Resistance of Pure Titanium

2017 ◽  
Vol 15 (1) ◽  
pp. 19-24 ◽  
Author(s):  
Davide Prando ◽  
Andrea Brenna ◽  
Fabio M. Bolzoni ◽  
Maria V. Diamanti ◽  
Mariapia Pedeferri ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Titanium Alloys ◽  
Oxide Layer ◽  
Corrosion Behavior ◽  
Pure Titanium ◽  
Localized Corrosion ◽  
Anodic Current Density ◽  
Anodic Current ◽  
Protective Oxide ◽  
Pitting Potential

Background Titanium has outstanding corrosion resistance due to the thin protective oxide layer that is formed on its surface. Nevertheless, in harsh and severe environments, pure titanium may suffer localized corrosion. In those conditions, costly titanium alloys containing palladium, nickel and molybdenum are used. This purpose investigated how it is possible to control corrosion, at lower cost, by electrochemical surface treatment on pure titanium, increasing the thickness of the natural oxide layer. Methods Anodic oxidation was performed on titanium by immersion in H2SO4 solution and applying voltages ranging from 10 to 80 V. Different anodic current densities were considered. Potentiodynamic tests in chloride- and fluoride-containing solutions were carried out on anodized titanium to determine the pitting potential. Results All tested anodizing treatments increased corrosion resistance of pure titanium, but never reached the performance of titanium alloys. The best corrosion behavior was obtained on titanium anodized at voltages lower than 40 V at 20 mA/cm2. Conclusions Titanium samples anodized at low cell voltage were seen to give high corrosion resistance in chloride- and fluoride-containing solutions. Electrolyte bath and anodic current density have little effect on the corrosion behavior.

Corrosion Resistance Evaluation of a Stainless-Steel Brazed Joint in HCl Solution

2021 ◽  
Vol 1016 ◽  
pp. 997-1002
Author(s):  
Hikaru Nagata ◽  
Masa Ono ◽  
Yasuyuki Miyazawa ◽  
Yuji Hayashi ◽  
Yoshio Bizen
Keyword(s):  
Aqueous Solution ◽  
Stainless Steel ◽  
Corrosion Resistance ◽  
Base Metal ◽  
Corrosion Behavior ◽  
Anodic Polarization ◽  
Filler Metal ◽  
Brazed Joint ◽  
In Situ Observations

To clarify the effect of the acid solution type on corrosion resistance, the corrosion behavior of stainless steel brazed joints in HCl aqueous solution was evaluated through electrochemical measurements. Anodic polarization curves of a ferritic stainless-steel base metal, Ni-based brazing filler metals, and a brazed joint were recorded. In addition, in situ observations were conducted to observe the corrosion behavior of each structure of the brazed joint. Corrosion potentials of the brazing filler metal were lower than that of the base metal. In situ observations of the brazed joint revealed the order of corrosion in aqueous hydrochloric acid. According to the electrochemical measurements, under an actual corrosive environment, the brazing filler metal can function as an anode and selectively corrode. In addition, the anodic polarization curve of the brazed joint showed values between those of the polarization curves of the brazing filler metal and the base metal, indicating that the corrosion resistance could be electrochemically evaluated in HCl aqueous solution.

Ionic Liquids in Surface Protection of Aluminum and Its Alloys

2019 ◽  
Author(s):  
Joaquin Arias-Pardilla ◽  
Tulia Espinosa ◽  
José Sanes ◽  
Ana Eva Jiménez ◽  
Ginés Martínez-Nicolás ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Corrosion Resistance ◽  
Ionic Liquid ◽  
Ionic Liquids ◽  
Industrial Applications ◽  
Energy Storage Devices ◽  
New Techniques ◽  
Surface Protection ◽  
Storage Devices ◽  
Potential Applications

Aluminum and its alloys are used in an increasing number of applications but the development of surface coatings and new techniques for corrosion resistance enhancement and for increasing wear resistance will be determinant for applications under aggressive environments. Ionic liquids have already found many industrial applications, including their use in surface protection. The present article will focus on the use of ionic liquids in aluminum and its alloys surface protection applications, including corrosion protection and inhibition, anodization and passivation processes, wear resistance, and potential applications of ionic liquid electrolytes in energy storage devices.

scholarly journals Review of the Application of Graphene-Based Coatings as Anticorrosion Layers

Coatings ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 883 ◽  
Author(s):  
Karolina Ollik ◽  
Marek Lieder
Keyword(s):  
Corrosion Resistance ◽  
State Of The Art ◽  
Protective Coatings ◽  
Substrate Surface ◽  
Organic Coatings ◽  
Surface Chemical ◽  
Protective Properties ◽  
Current State ◽  
Chemical Inertness ◽  
Graphene Functionalization

Due to the excellent properties of graphene, including flexibility that allows it to adjust to the curvature of the substrate surface, chemical inertness, and impermeability, graphene is used as an anticorrosion layer. In this review, we present the current state-of-the-art in the application of graphene in the field of protective coatings. This review provides detailed discussions about the protective properties of graphene coatings deposited by different methods, graphene-based organic coatings, the modification of graphene-based coatings, and the effects of graphene functionalization on the corrosion resistance of protective coatings.

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