scholarly journals Corrosion Behavior of Mg-Al/TiC Composites in NaCl Solution

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
L. A. Falcon ◽  
E. Bedolla B. ◽  
J. Lemus ◽  
C. Leon ◽  
I. Rosales ◽  
...  
Keyword(s):  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Base Alloy ◽  
Electrochemical Techniques ◽  
Al Alloy ◽  
Nacl Solution ◽  
The Matrix ◽  
Diffusion Phenomena ◽  
Lower Corrosion Rate

The corrosion behavior of TiC particles reinforced Mg-Al alloy in 3.5% NaCl solution has been evaluated using electrochemical techniques. Tested alloys included an Mg-9Al (Mg AZ91E) alloy with and without 56 wt. % TiC particles. Electrochemical techniques included potentiodynamic polarization curves, linear polarization resistance, electrochemical noise, and electrochemical impedance spectroscopy measurements. All techniques showed that the composite exhibited a lower corrosion rate than the base alloy. Evidence of galvanic effects that increased the composite corrosion rate was found between the matrix and the TiC particles. Additionally, the tendency to suffer from pitting corrosion was higher for the base alloy than that for the composite. Electrochemical impedance results showed the importance of adsorption/diffusion phenomena in both materials.

Corrosion Behavior of Al-Sn-Bi Alloys in Ethylene Glycol-Water Mixtures

CORROSION ◽  
2012 ◽  
Vol 68 (5) ◽  
pp. 421-431
Author(s):  
J.L. Gama-Ferrer ◽  
J.G. Gonzalez-Rodriguez ◽  
I. Rosales ◽  
J. Uruchurtu
Keyword(s):  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Corrosion Rate ◽  
Ethylene Glycol ◽  
Corrosion Behavior ◽  
Potentiodynamic Polarization ◽  
Electrochemical Noise ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Potentiodynamic Polarization Curves

A study of the effect of Sn (1, 2, 3.5, 4.5, and 5 wt%) and Bi (0.5, 1.5, 3, and 4%) on the corrosion behavior of Al in ethylene glycol (C2H6O2)-40% water mixtures at 20, 40, and 60°C has been carried out using electrochemical techniques. Techniques include potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS), and electrochemical noise (EN) measurements. The three techniques have shown that additions of either Sn or Bi contents increased the corrosion rate of pure Al in all cases, and that generally speaking, the corrosion rate increased by increasing the temperature except for the alloy containing 1% Sn + 4% Bi, which showed the lowest corrosion rate at 60°C. This was because of a galvanic effect from the presence of Sn and/or Bi particles on the surface alloy, which acted as local cathodes, leading to an acceleration of corrosion. Nyquist diagrams showed two semicircles at 20°C and only one at 40°C or 60°C for all the alloys, showing two different corrosion-controlling mechanisms. EN measurements showed evidence of a mixture of both localized and uniform types of corrosion for all Al-based alloys.

Influence of Titanium Additions on the Corrosion Behavior of Cu-Al-Ni Shape Memory Alloys

2021 ◽  
Vol 1021 ◽  
pp. 55-67
Author(s):  
Nawal Mohammed Dawood ◽  
Abdul Raheem Kadhim Abidali
Keyword(s):  
Corrosion Rate ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Corrosion Behavior ◽  
Sea Water ◽  
Base Alloy ◽  
Energy Dispersive Spectrometer ◽  
Rapid Quenching ◽  
Industrial Applications ◽  
Nacl Solution

The Cu- Al-Ni shape memory alloys have numerous industrial applications such as actuators, Cryofit hydraulic couplings, fire safety valves ,etc. while the parts that soaked in the sea water suffer severe corrosion that lead to worsening in the properties of the alloys. In the current research, the effect of adding titanium on corrosion behavior of the shape memory alloys (Cu-13wt. %Al-4wt. %Ni) were studied. Titanium was added in different weight ratios (0.4, 0.8, and 1.2 wt.%) to the base alloy. The alloys were prepared using powder metallurgy, whereby the alloys were sintered with two stages of heating under Argon atmosphere, at 550°C for (120 min.) and 950°C for (180 min.)respectively. All the sintered samples are solution treated by heating the samples at 900 °C for (60 min.) followed by rapid quenching in ice water at ( 3 ~ 6) °C. After that aging heat treatment has been done for quenched samples at 200 °C for (30 hrs.) followed by rapid quenching in iced water. Several tests such as microstructures observation and phase analysis using scanning electron microscope, energy dispersive spectrometer, and X-ray diffraction analysis have been done. Further , Corrosion behavior for all samples in aged conditions in 3.5%NaCl solution have been performed. Corrosion test results have showed that the highest corrosion resistance was found in the addition of (1.2 wt.% Ti) which give the lowest corrosion rate (0.003 mpy) in 3.5% NaCl solution . Noted that the corrosion rate of base alloy was (9.021)mpy. EDS analysis showed chemical composition of the aged surface and also mapping images for the distribution of Cu, Al, Ni, and Ti elements on the surface. Phases formed on aged samples conditions are α-Cu and AlCu3.

scholarly journals Corrosion Behavior of Fe40Al Alloy with Additions of Ti, Ag, and Cr in Molten KCl +ZnCl2

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
R. Ademar ◽  
J. G. Gonzalez-Rodriguez ◽  
J. Uruchurtu ◽  
J. Porcayo-Calderon ◽  
V. M. Salinas-Bravo ◽  
...  
Keyword(s):  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Intermetallic Alloy ◽  
Corrosion Performance ◽  
Linear Polarization Resistance ◽  
Potentiodynamic Polarization Curves ◽  
Eis Measurements ◽  
The Stability

The effect of 2.5 at.% Cr, Ti, and Ag on the corrosion behavior of Fe40Al intermetallic alloy in KCl-ZnCl2(1 : 1 M) at 670°C has been evaluated by using electrochemical techniques. Techniques included potentiodynamic polarization curves, linear polarization resistance (LPR), and electrochemical impedance spectroscopy (EIS) measurements. Results have shown that additions of both Cr and Ti were beneficial to the alloy, since they decreased its corrosion rate, whereas additions of Ag was detrimental, since its additions increased the corrosion rate, although the alloy was passivated by adding Ag or Cr. The best corrosion performance was obtained with the addition of Cr, whereas the highest corrosion rate was obtained by adding Ag. This is explained in terms of the stability of the corrosion products formed film.

EVALUATION OF PITTING CORROSION OF THE SiCP/5A06 ALUMINUM METAL COMPOSITE IN 3.5% NaCl SOLUTION BY MEANS OF ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY (EIS)

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1497-1502 ◽  
Author(s):  
IRFAN AZIZ ◽  
QI ZHANG
Keyword(s):  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Matrix Alloy ◽  
Metal Composite ◽  
Nacl Solution ◽  
Composite Surface ◽  
Pitting Potential ◽  
The Matrix

The corrosion behavior of the silicon carbide particulates (17.5 vol.%) reinforced 5A06 aluminum alloy metal matrix composite (MMC) and the 5A06 aluminum matrix alloy has been studied in 3.5% NaCl solution at 35°C by using electrochemical impedance spectroscopy (EIS). Analysis of the results, which were obtained from optical (OM) and scanning electron microscopy (SEM) attached with energy dispersion spectroscopy (EDS), indicate that the corrosion behavior of the materials studied was mainly localized corrosion due to the presence of intermetallics ( Al ( Mn , Fe ), Al ( Si , Mg )) on the surface and crevices at the interface of SiCp/matrix . More numerous, wider spread, smaller and shallower pits were noted on the composite surface relative to the unreinforced matrix alloy during immersion. However, the pitting morphology on both materials was completely different from crystallographic type of pitting. Crystallographic pitting occurred by anodically polarizing the materials above the pitting potential. Further, the occurrence of an inductive time constant at lower frequencies region and the lower impedance as compared to that of the matrix alloy indicate that the corrosion extent of the composite was more severe than that of the matrix alloy, both materials were immersed for varied periods. Two different equivalent circuits were proposed and applied to analyze the EIS measurements, which can simulate the impedance of the composite and the matrix alloy under corrosive environment.

scholarly journals Corrosion of Steel Rebars in Anoxic Environments. Part I: Electrochemical Measurements

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2491
Author(s):  
Elena Garcia ◽  
Julio Torres ◽  
Nuria Rebolledo ◽  
Raul Arrabal ◽  
Javier Sanchez
Keyword(s):  
Corrosion Rate ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Chloride Content ◽  
Offshore Platforms ◽  
Anoxic Conditions ◽  
Current Limit ◽  
Anoxic Environments ◽  
Corrosion Of Steel ◽  
Steel Rebars

The number of reinforced concrete structures subject to anoxic conditions such as offshore platforms and geological storage facilities is growing steadily. This study explored the behaviour of embedded steel reinforcement corrosion under anoxic conditions in the presence of different chloride concentrations. Corrosion rate values were obtained by three electrochemical techniques: Linear polarization resistance, electrochemical impedance spectroscopy, and chronopotenciometry. The corrosion rate ceiling observed was 0.98 µA/cm2, irrespective of the chloride content in the concrete. By means of an Evans diagram, it was possible to estimate the value of the cathodic Tafel constant (bc) to be 180 mV dec−1, and the current limit yielded an ilim value of 0.98 µA/cm2. On the other hand, the corrosion potential would lie most likely in the −900 mVAg/AgCl to −1000 mVAg/AgCl range, whilst the bounds for the most probable corrosion rate were 0.61 µA/cm2 to 0.22 µA/cm2. The experiments conducted revealed clear evidence of corrosion-induced pitting that will be assessed in subsequent research.

scholarly journals Assessment of nickel titanium and beta titanium corrosion resistance behavior in fluoride and chloride environments

2013 ◽  
Vol 83 (5) ◽  
pp. 864-869 ◽  
Author(s):  
Elisa J. Kassab ◽  
José Ponciano Gomes
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Fluoride Concentration ◽  
Nickel Titanium ◽  
Localized Corrosion ◽  
General Corrosion ◽  
Nacl Solution ◽  
Galvanic Coupling ◽  
Beta Titanium

ABSTRACT Objective: To assess the influence of fluoride concentration on the corrosion behavior of nickel titanium (NiTi) superelastic wire and to compare the corrosion resistance of NiTi with that of beta titanium alloy in physiological solution with and without addition of fluoride. Materials and Methods: NiTi corrosion resistance was investigated through electrochemical impedance spectroscopy and anodic polarization in sodium chloride (NaCl 0.15 M) with and without addition of 0.02 M sodium fluoride (NaF), and the results were compared with those associated with beta titanium. The influence of fluoride concentration on NiTi corrosion behavior was assessed in NaCl (0.15 M) with and without 0.02, 0.04, 0.05, 0.07, and 0.12 M NaF solution. Galvanic corrosion between NiTi and beta titanium were investigated. All samples were characterized by scanning electron microscopy. Results: Polarization resistance decreased when NaF concentration was increased, and, depending on NaF concentration, NiTi can suffer localized or generalized corrosion. In NaCl solution with 0.02 M NaF, NiTi suffer localized corrosion, while beta titanium alloys remained passive. Current values near zero were observed by galvanic coupling of NiTi and beta titanium. Conclusions: There is a decrease in NiTi corrosion resistance in the presence of fluoride. The corrosion behavior of NiTi alloy depends on fluoride concentration. When 0.02 and 0.04 M of NaF were added to the NaCl solution, NiTi presented localized corrosion. When NaF concentration increased to 0.05, 0.07, and 0.12 M, the alloy presented general corrosion. NiTi corrosion resistance behavior is lower than that of beta titanium. Galvanic coupling of these alloys does not increase corrosion rates.

Corrosion Behavior of Duplex Stainless Steel in Industrial White Liquor

CORROSION ◽  
10.5006/2558 ◽  
2017 ◽  
Vol 74 (5) ◽  
pp. 543-550 ◽  
Author(s):  
Luiza Esteves ◽  
Mônica M.A.M. Schvartzman ◽  
Wagner Reis da Costa Campos ◽  
Vanessa F.C. Lins
Keyword(s):  
Weight Loss ◽  
Stainless Steel ◽  
Corrosion Rate ◽  
Duplex Stainless Steel ◽  
Corrosion Behavior ◽  
Extrapolation Method ◽  
White Liquor ◽  
Duplex Steel ◽  
Kraft Mill ◽  
Lower Corrosion Rate

Specimens of lean duplex and duplex stainless steel were exposed at 200°C in industrial white liquor from a Brazilian kraft mill using an autoclave to simulate the same conditions of digester processing. Tafel extrapolation method and weight loss were used to evaluate corrosion behavior of duplex steel in white liquor. The higher alloy steel, although presenting a lower corrosion rate than the lean duplex, presents a more severe selective attack on ferrite, at 200°C and 1.8 MPa, after Tafel extrapolation method in industrial white liquor.

scholarly journals Effect of Structural Modification on Corrosion Behavior of Hypo Eutectic Al-Si Alloy

2018 ◽  
Vol 778 ◽  
pp. 16-21
Author(s):  
Muhammad Mansoor ◽  
Muhammad Kamran Yaseen ◽  
Shaheed Khan
Keyword(s):  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Earth Metal ◽  
Alloy System ◽  
Eutectic Phase ◽  
Al Alloy ◽  
General Corrosion ◽  
Corrosion Properties ◽  
Unmodified Alloy ◽  
Cast Alloys

Al-Si eutectic cast alloys are widely used in aeronautical and automobile industries where significantly high strength, toughness and wear resistance are required. This class of cast alloys exhibit relatively low corrosion resistance in brine environments. The mechanical properties of the alloy system mainly depend upon the shape of Si rich eutectic phase, which mainly has acicular geometry. In present research, the effect of modified microstructure of 12 wt. % Si-Al alloy on corrosion behavior was studied. The needle like Si rich eutectic phase was modified to disperse spherical structure using rare earth metal halides. The corrosion rate and pitting behavior of modified and unmodified alloy were evaluated in 3.5% NaCl solution by general corrosion for calculated time. It was observed that the corrosion rate and pitting tendency of modified alloy had been appreciably reduced as compare to unmodified alloy. The improvement of corrosion properties were the attributes of changed morphology and distribution of Si rich eutectic phase.

scholarly journals Corrosion of Mechanically Alloyed Nanostructured FeAl Intermetallic Powders

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
A. Torres-Islas ◽  
C. Carachure ◽  
S. Serna ◽  
B. Campillo ◽  
G. Rosas
Keyword(s):  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Corrosion Current ◽  
Test Time ◽  
Uniform Corrosion ◽  
Mechanically Alloyed ◽  
Solution Ph ◽  
Surface Corrosion ◽  
Electrochemical Testing

The corrosion behavior of the Fe40Al60nanostructured intermetallic composition was studied using electrochemical impedance spectroscopy (EIS) and linear polarization resistance (LPR) techniques with an innovative electrochemical cell arrangement. The Fe40Al60(% at) intermetallic composition was obtained by mechanical alloying using elemental powders of Fe (99.99%) and Al (99.99%). All electrochemical testing was carried out in Fe40Al60particles that were in water with different pH values. Temperature and test time were also varied. The experimental data was analyzed as an indicator of the monitoring of the particle corrosion current densityicorr. Different oxide types that were formed at surface particle were found. These oxides promote two types of surface corrosion mechanisms: (i) diffusion and (ii) charge transfer mechanisms, which are a function oficorrbehavior of the solution, pH, temperature, and test time. The intermetallic was characterized before and after each test by transmission electron microscopy. Furthermore, the results show that at the surface particles uniform corrosion takes place. These results confirm that it is possible to sense the nanoparticle corrosion behavior by EIS and LPR conventional electrochemical techniques.

scholarly journals Exfoliation Corrosion Behavior of Cold-Rolled Mg-14 mass% Li-1 mass% Al Alloy in NaCl Solution

2013 ◽  
Vol 54 (9) ◽  
pp. 1863-1866 ◽  
Author(s):  
Taiki Morishige ◽  
Hirokazu Doi ◽  
Takayuki Goto ◽  
Eiji Nakamura ◽  
Toshihide Takenaka
Keyword(s):  
Corrosion Behavior ◽  
Al Alloy ◽  
Nacl Solution ◽  
Exfoliation Corrosion ◽  
Cold Rolled
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