scholarly journals Microstructural Evolutions and its Impact on the Corrosion Behaviour of Explosively Welded Al/Cu Bimetal

Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 634
Author(s):  
Mohammad Reza Jandaghi ◽  
Abdollah Saboori ◽  
Gholamreza Khalaj ◽  
Mohammadreza Khanzadeh Ghareh Shiran
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Potential ◽  
Electrochemical Impedance ◽  
Corrosion Behaviour ◽  
Welding Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Aluminium Copper ◽  
Melting Pool ◽  
Intermetallic Layers

In this study, the microstructural evolutions and corrosion resistance of aluminium/copper joint fabricated through explosive welding process have been thoroughly investigated, while stand-off distance was variable. Microstructural analyses demonstrate that, regardless of grain refinement in the welding boundary, increasing the stand-off space is followed by a higher thickness of the localized melting pool. X-Ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS) analyses recognized the binary intermetallic layers as a combination of Al2Cu and AlCu. Polarization and electrochemical impedance spectroscopy (EIS) corrosion tests revealed that a higher stand-off distance resulted in the increment of corrosion potential, current rate, and concentration gradient at the interface owing to the remarkable kinetic energy of the collision, which impaired corrosion resistance.

scholarly journals Effect of Molybdenum Content on the Corrosion and Microstructure of Low-Ni, Co-Free Maraging Steels

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 852
Author(s):  
Asiful H. Seikh ◽  
Hossam Halfa ◽  
Mahmoud S. Soliman
Keyword(s):  
Corrosion Resistance ◽  
Electrochemical Impedance ◽  
Microstructural Analysis ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Alloying Element ◽  
X Ray ◽  
Maraging Steels ◽  
Eds Analysis ◽  
Electroslag Refining

Molybdenum (Mo) is an important alloying element in maraging steels. In this study, we altered the Mo concentration during the production of four cobalt-free maraging steels using an electroslag refining process. The microstructure of the four forged maraging steels was evaluated to examine phase contents by optical microscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analysis. Additionally, we assessed the corrosion resistance of the newly developed alloys in 3.5% NaCl solution and 1 M H2SO4 solution through potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. Furthermore, we performed SEM and energy-dispersive spectroscopy (EDS) analysis after corrosion to assess changes in microstructure and Raman spectroscopy to identify the presence of phases on the electrode surface. The microstructural analysis shows that the formation of retained austenite increases with increasing Mo concentrations. It is found from corrosion study that increasing Mo concentration up to 4.6% increased the corrosion resistance of the steel. However, further increase in Mo concentration reduces the corrosion resistance.

Role of chromium in anomalous behaviour of the passive layer in Ni-Cr-Mo alloys in 1M HCl solution

CORROSION ◽  
10.5006/3767 ◽  
2022 ◽  
Author(s):  
Malvika Karri ◽  
Amit Verma ◽  
J.B. Singh ◽  
Sunil Kumar Bonagani ◽  
U.K. Goutam
Keyword(s):  
Corrosion Resistance ◽  
Electrochemical Impedance ◽  
Corrosion Behaviour ◽  
Underlying Mechanism ◽  
Passive Layer ◽  
X Ray ◽  
Superior Corrosion Resistance ◽  
Hcl Solution ◽  
Cr2o3 Layer

This work seeks to understand the underlying mechanism involved in passivity of Ni-Cr-Mo alloys in a less concentrated HCl solution (1M) by systematically varying contents of Cr and Mo solutes in model Ni-Cr-Mo alloys. Corrosion behaviour was evaluated based on potentiodynamic polarisation tests carried out in conjunction with electrochemical impedance and x-ray photoelectron spectroscopies of passive films that formed on alloys during their exposure to the HCl solution. Results have shown that an increase in Mo alone is not sufficient to improve the corrosion resistance of the alloys at lower concentrations of HCl. Optimum concentrations of Cr and Mo solutes have been found to be in the vicinity of ~17 wt.% Cr and ~19 wt.% Mo for superior corrosion resistance of the alloys. This was attributed to the protection of the Cr2O3 layer as a consequence of the enrichment of Mo6+ ions in the passive film in 1M HCl solution.

Zn-TiO2 and ZnNi-TiO2 Nanocomposite Coatings: Corrosion Behaviour

2010 ◽  
Vol 636-637 ◽  
pp. 1079-1083 ◽  
Author(s):  
Augusto Gomes ◽  
I. Almeida ◽  
Tania Frade ◽  
Ana C. Tavares
Keyword(s):  
Room Temperature ◽  
Corrosion Potential ◽  
Corrosion Behaviour ◽  
Pulse Method ◽  
Nanocomposite Coating ◽  
Nanocomposite Coatings ◽  
Tio2 Films ◽  
X Ray Diffraction ◽  
X Ray ◽  
Steel Electrodes

This work presents the corrosion behaviour of the as-prepared of Zn-TiO2 and ZnNi-TiO2 films in neutral Na2SO4 solution and a first attempt to correlate with their composition, morphology and structure. The films were prepared by galvanostatic pulse method onto steel electrodes, at room temperature. The X-ray diffraction study revealed that the ZnNi alloy consists of a homogenous Ni5Zn21 phase and that the preferred crystallographic orientation of Zn deposits changes in the presence of TiO2. The SEM results show that the morphology of the metallic coating is function of the metal phase composition and become more porous in the presence of 1.5 wt% TiO2.The corrosion parameters for the nanocomposite coatings were compared with those of pure Zn and ZnNi electrodeposits, and the ZnNi-TiO2 nanocomposite coating shows the less cathodic corrosion potential.

scholarly journals Studies on electrodeposited Zn-Fe alloy coating on mild steel and its characterization

2018 ◽  
Vol 9 (1) ◽  
pp. 9-16 ◽  
Author(s):  
Ramesh Bhat ◽  
Ampar Chitharanjan Hegde
Keyword(s):  
Corrosion Resistance ◽  
Mild Steel ◽  
Electrochemical Impedance ◽  
Corrosion Behaviour ◽  
Alloy Coating ◽  
X Ray Diffraction ◽  
Xrd Study ◽  
Cathode Current ◽  
Sulphamic Acid ◽  
Electrochemical Impedance Spectroscopic

Chloride bath containing ZnCl2 ∙7H2O, FeCl2 ∙H2O and a combination of sulphamic acid and citric acid (SA+CA) were optimized for electrodeposition of bright Zn-Fe alloy coating on the mild steel. Bath constituents and operating parameters were optimized by the Hull cell method for highest performance of the coating against corrosion. The effect of current density and temperature on deposit characteristics such as corrosion resistance, hardness, thickness, cathode current efficiency and glossiness, were studied. Potentiodynamic polarization and electrochemical impedance spectroscopic (EIS) methods were used to assess corrosion behaviour. Surface morphology of coatings was examined using scanning electron microscopy (SEM). The Zn-Fe alloy with intense peaks corresponding to Zn (100) and Zn (101) phases, evidenced by X-ray diffraction (XRD) study, showed the highest corrosion resistance. A new and economical chloride bath for electrodeposition of bright Zn-Fe alloy coating on mild steel was proposed and discussed.

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.

Corrosion Behaviour of AZ91DSm1.0 with Different Preparation Methods

2014 ◽  
Vol 1004-1005 ◽  
pp. 113-118
Author(s):  
Hong Xia Liu ◽  
Jin Liang ◽  
Jue Zhang ◽  
Xiao Lian Zhang
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Corrosion Resistance ◽  
Corrosion Behaviour ◽  
X Ray Diffraction ◽  
Vacuum Melting ◽  
Potentiodynamic Polarization Curve ◽  
Preparation Methods ◽  
X Ray ◽  
Scanning Electron

Corrosion behaviour of AZ91DSm1.0 with different preparation methods(vacuum melting and common melting) is investigated. X-ray diffraction(XRD), optical microscopy(OM), scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS), corrosion weightless experiment and the potentiodynamic polarization curve are applied to characterize the corrosion behaviour. Results show that vacuum melting alloy possess higher corrosion resistance than common melting alloy. This is attributed to the rod-shaped Al3Sm which was formed in common melting alloy will have certain fragmentation effect on matrix that can lead to defects.

scholarly journals Corrosion Behaviour of Zn-10Al-1.5Cu Alloy

2011 ◽  
Vol 2011 ◽  
pp. 1-6
Author(s):  
C. N. Panagopoulos ◽  
A. G. Tsopani
Keyword(s):  
Electron Microscopy ◽  
Corrosion Resistance ◽  
Corrosion Behaviour ◽  
Solution Concentration ◽  
Solution Temperature ◽  
Nacl Solution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nacl Concentration ◽  
Scanning Electron

The corrosion behaviour of Zn-10Al-1.5Cu alloy in NaCl solution was examined. The used NaCl solution concentrations were 1M, 0.3M, and 0.003M for a constant temperature values of 7°C or 25°C or 45°C. The corrosion behaviour of this alloy was investigated under potentiodynamic corrosion conditions. The surface of the corroded alloy specimens was studied with the aid of scanning electron microscopy and X-ray diffraction techniques. It was observed that the increase of NaCl concentration in the corrosion solution for a constant value of temperature led to lower corrosion resistance of the alloy. For a constant value of solution concentration, the increase of solution temperature also led to the decrease of corrosion resistance of the same alloy.

scholarly journals Corrosion Resistance of Electrochemically Synthesized Modified Zaccagnaite LDH-Type Films on Steel Substrates

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7389
Author(s):  
Michael Kahl ◽  
Teresa D. Golden
Keyword(s):  
Corrosion Resistance ◽  
Layered Double Hydroxide ◽  
Corrosion Potential ◽  
Corrosion Current ◽  
X Ray Diffraction ◽  
X Ray ◽  
Double Hydroxide ◽  
Double Hydroxides ◽  
Steel Substrates ◽  
Deposited Films

Modified zaccagnaite layered double hydroxide (LDH) type films were synthesized on steel substrates by pulsed electrochemical deposition from aqueous solutions. The resulting films were characterized by X-ray diffraction, scanning electron microscopy/X-ray dispersive spectroscopy, and Fourier transform infrared spectroscopy. Structural characterization indicated a pure layered double hydroxide phase; however, elemental analysis revealed that the surface of the films contained Zn:Al ratios outside the typical ranges of layered double hydroxides. Layer thickness for the deposited films ranged from approximately 0.4 to 3.0 μm. The corrosion resistance of the film was determined using potentiodynamic polarization experiments in 3.5 wt.% NaCl solution. The corrosion current density for the coatings was reduced by 82% and the corrosion potential was shifted 126 mV more positive when 5 layers of modified LDH coatings were deposited onto the steel substrates. A mechanism was proposed for the corroding reactions at the coating.

Investigation of corrosion behavior on plastically deformed aa 7075 t651 by shot peening process

2021 ◽  
Author(s):  
Abeens M ◽  
R Murugananthan
Keyword(s):  
Electron Microscopy ◽  
Corrosion Resistance ◽  
Dislocation Density ◽  
Aluminium Alloy ◽  
Electrochemical Impedance ◽  
Corrosion Behaviour ◽  
X Ray ◽  
Transmission Electron ◽  
Aa 7075 ◽  
Micro Structures

Abstract As AA 7075 T651 comprehensively is used in the marine naval vessels, the factor of corrosion performance always plays a significant role. In this work, an investigation is carried out to study the effect of corrosion behaviour of shot peened AA 7075 T651 in 3.5% solution. From the potentiodynamic polarization study, a 27.72% decrease is ascertained in the Icorr in shot peened specimen in correlation to unpeened aluminium alloy. A drop in Icorr from 1.883 to 1.480 mA/cm2 in shot peened specimen, indicates enhanced pitting corrosion resistance. An electrochemical impedance spectroscopy reveals a surge in the oxide layer formation on the peened surface aiding the drop in corrosion rate. Resistance to pit formations and improvement in oxygen deposition in the peened specimen is observed availing a Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray analysis (EDX). The micro structures of the peened and unpeened specimen are captured using optical microscopy and Transmission electron microscopy (TEM). Micro-strain, dislocation density is also calculated from the X- ray diffraction analysis (XRD), in which grain size reduces by 28.07%, dislocation density surges by 38.65% and micro strain increases by 21.95% in peened specimen in correlation to unpeened AA 7075 T651, resulting in a surge in corrosion resistance by 27.92% in the peened specimen in correlation to unpeened aluminium alloy.

Structure and Corrosion Resistance of Zn-Ni and Zn-Ni-W Coatings

2010 ◽  
Vol 636-637 ◽  
pp. 1042-1046
Author(s):  
Magdalena Popczyk ◽  
Antoni Budniok
Keyword(s):  
Corrosion Resistance ◽  
Electrochemical Impedance ◽  
Electrochemical Corrosion ◽  
Diffraction Method ◽  
X Ray Diffraction ◽  
Zinc Bath ◽  
Corrosion Resistant ◽  
X Ray ◽  
Electrochemical Corrosion Resistance ◽  
Galvanostatic Conditions

Zn-Ni and Zn-Ni-W coatings were prepared by the electrodeposition under the galvanostatic conditions (jdep. = -0.020 A cm-2) from the zinc bath containing additionally ions of nickel (Zn-Ni) and ions of nickel and tungsten (Zn-Ni-W). The Zn-Ni coating after electrodeposition was subjected to outside passivation and in the Zn-Ni-W coating the passive function performs tungsten (inside passivation). The surface morphology of the coatings was studied using a scanning electron microscope (JEOL JSM - 6480). Chemical composition of obtained coatings was determined by the X-ray fluorescence spectroscopy (XRF). Phase composition investigations were conducted by X-ray diffraction method using a Philips diffractometer. Electrochemical corrosion resistance investigations were carried out in the 3% NaCl, using potentiodynamic and electrochemical impedance spectroscopy (EIS) methods. On the basis of these investigations it was found that Zn-Ni coating is more corrosion resistant than the Zn-Ni-W coating.

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