scholarly journals Corrosion investigations of Al-Si casting alloys in 0.6 M NaCl solution

2021 ◽  
Vol 41 (3) ◽  
Author(s):  
Sunčana Smokvina Hanza ◽  
Ladislav Vrsalović ◽  
Lovro Štic ◽  
Lovro Liverić
Keyword(s):  
Potentiodynamic Polarization ◽  
Electrochemical Behavior ◽  
Die Casting ◽  
Electrochemical Corrosion ◽  
Microstructural Characterization ◽  
Casting Process ◽  
Corrosion Current ◽  
Optical Microscope ◽  
Open Circuit ◽  
Polarization Measurements

This paper presents results of the corrosion investigations of specimens made from finished parts for the automotive industry, produced by high-pressure die casting and gravity die casting process of six Al-Si alloys (40000 series). Open circuit potential and potentiodynamic polarization measurements have been performed using a potentiostat with three-electrode set-up in 0.6 M NaCl naturally aerated solution. Microstructural characterization before and after electrochemical investigations has been carried out with optical microscope to establish the connection between microstructure and corrosion parameters of investigated alloys and to analyze and record surface changes of each sample due to electrochemical corrosion. All alloys show good corrosion resistance, which manifests with low values of corrosion rates, calculated from the corrosion current densities obtained from potentiodynamic polarization measurements. Differences in electrochemical behavior appear due to the distinctions in their chemical composition and microstructure. The type of casting process does not affect electrochemical behavior of Al-Si alloys.

Electrochemical Corrosion Behaviour of ZrN Film in Various Corrosive Fluid

2015 ◽  
Vol 3 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Vishnu R. ◽  
Jiten Das ◽  
S. B. Arya ◽  
Manish Roy
Keyword(s):  
Sea Water ◽  
Corrosion Behaviour ◽  
Water Solution ◽  
Electrochemical Corrosion ◽  
High Hardness ◽  
Corrosion Current ◽  
Plain Carbon Steel ◽  
Open Circuit ◽  
Protective Film ◽  
Hank’S Solution

Recently, ZrN has been attracting interest for its excellent corrosion resistance, biocompatibility, high hardness, good lubricity and ductility. Although tribological study of ZrN coating has been carried out extensively, investigation related to corrosion of ZrN film is limited. In view of this and in view of possible applications of ZrN film in several engineering components, the present investigation has been undertaken to evaluate the corrosion response of ZrN film in seawater solution, Hank's solution, 0.5M H2SO4solution and 0.5M HCl solutions. Towards that purpose, potentiostatic, open circuit potential and potentiodynamic study of ZrN film deposited on plain carbon steel has been carried out in all these solutions. Results indicate that stable protective film is formed on the surface of ZrN coating in all these solution except 0.5M H2SO4 solution. The formation of protective film on ZrN coating is fastest in sea water solution and it is slowest in the Cl¯ ions containing media, 0.5 M HCl. The corrosion current is highest for 0.5M H2SO4 acid solution and least for Hank's solution.

scholarly journals Polyaniline/Palm Oil Blend for Anticorrosion of Mild Steel in Saline Environment

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Mohd Rashid ◽  
Suhail Sabir ◽  
Afidah A. Rahim ◽  
Umesh Waware
Keyword(s):  
Mild Steel ◽  
Palm Oil ◽  
Potentiodynamic Polarization ◽  
Protective Layer ◽  
Corrosion Current ◽  
Charge Transfer Resistance ◽  
Open Circuit ◽  
Oxidation Potential ◽  
Physical Interaction ◽  
Transfer Resistance

The corrosion protective performance of polyaniline/palm oil (PAni-PO) blend coated on mild steel in 3% NaCl aqueous solutions has been evaluated by electrochemical methods, namely, open circuit potential (ocp), potentiodynamic polarization, and EIS spectroscopy. The surface of mild steel was covered by a dark green protective layer due to the physical interaction between the coating and steel. The permanent shifts of ocp and potentiodynamic polarization towards higher positive value of oxidation potential by about 800 mV and by a decrease in corrosion current density by sixfold in magnitude and an increase of 10 orders of magnitude in charge transfer resistance are due to protective coating.

Corrosion Behaviour of the Anodised A356 Aluminium Alloy Produced by the Rheo-High Pressure Die Casting Process

2014 ◽  
Vol 1019 ◽  
pp. 67-73 ◽  
Author(s):  
Levy Chauke ◽  
Kalenda Mutombo ◽  
Gonasagren Govender
Keyword(s):  
High Pressure ◽  
Aluminium Alloy ◽  
Corrosion Behaviour ◽  
Die Casting ◽  
Casting Process ◽  
Optical Microscope ◽  
High Pressure Die Casting ◽  
Semi Solid ◽  
Pressure Die Casting ◽  
A356 Aluminium Alloy

<span><p>Semi-solid metal forming of aluminium alloys has demonstrated the capability to produce near net shaped high integrity components. Anodising of these components for aesthetic and/or improved corrosion resistance is specified by some designers or users of this technology. The corrosion behaviour of fully anodised and partially anodised A356 aluminium alloy plates produced using the CSIR Rheo-High Pressure Die Casting (CSIR-RHPDC) process was investigated using immersion testing in a 3.5% NaCl solution with pH = 7. Optical microscope equipped with image analysis software and scanning electron microscope (SEM) equipped with Energy Dispersive X-ray Spectroscopy (EDS) were used to evaluate the behaviour of the corroded samples. The fully anodised sample showed that the anodised surface displayed some surface degradation. This degradation was more severe on the anodised surface with surface liquid segregation (SLS), but provided sufficient protection to prevent corrosion of the base metal. The partially anodised sample showed severe corrosion of the based metal with the corrosion concentrated in the silicon rich eutectic and SLS regions.</p> <span style="font-family: Times New Roman; font-size: medium;" face="Times New Roman" size="3"> </span>

Effect of High-Intensity Pulsed Ion Beam Irradiation on the Electrochemical Corrosion Behavior of AZ31 Magnesium Alloy

2011 ◽  
Vol 189-193 ◽  
pp. 571-574
Author(s):  
Peng Li
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Corrosion Behavior ◽  
Current Density ◽  
Ion Beam ◽  
Electrochemical Corrosion ◽  
Corrosion Current ◽  
Open Circuit ◽  
Electrochemical Corrosion Behavior ◽  
Shot Number

HIPIB irradiation experiment is carried out at a specific ion current density of 1.1 J/cm2 with shot number from one to ten in order to explore the effect of shot number on electrochemical corrosion behavior of magnesium alloy. Surface morphologies, microstructure and corrosion resistance of the irradiated samples are examined by scanning electron microscopy (SEM), transmission electron microscope (TEM) and potentiodynamic polarization technique, respectively. It is found that HIPIB irradiation leads to the increase in open circuit potential, corrosion potential and breakdown potential, and the decrease in the corrosion current density and the corrosion rate as compared to the original sample. The improved corrosion resistance is mainly attributed to the grain refinement and surface purification induced by HIPIB irradiation.

The Effects of Two-Step Solution Heat Treatment of Al-6Si-2Cu Alloy for Lightweight Automotive on Mechanical Properties

2015 ◽  
Vol 1110 ◽  
pp. 158-162
Author(s):  
Seung Pyo Hong ◽  
Chung Seok Kim
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Inductively Coupled Plasma ◽  
Solution Heat Treatment ◽  
Microstructural Characterization ◽  
Casting Process ◽  
Optical Microscope ◽  
Intermetallic Phases ◽  
Single Step ◽  
Gravity Casting

The effects of two-step solution heat treatment of aluminum alloy for lightweight automotive have been investigated. The test specimens, Al-6Si-2Cu alloys are prepared by gravity casting process. Solution heat treatments in this study are applied to improve of mechanical properties through a single-step or two-step solution heat treatment. For the microstructural characterization, inductively coupled plasma mass spectromerty (ICP-MS), optical microscope (OM) and scanning electron microscope (SEM) analyses are conducted in specimen. The X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) analyses are also applied to identify the intermetallic phases with quantitative and qualitative analyses. Micro Vickers hardness and static tensile test are achieved. The microstructure of gravity casting specimen represents a typical dendrite structure having a secondary dendrite arm spacing (SDAS) of 37um. In addition to the Al matrix, a large amount of coarsen eutectic Si, Al2Cu intermetallic phases and Fe-rich phases are identified. After solution heat treatment, the mechanical properties of two-step solution heat treatment alloy show higher values than as-cast and single-step solution specimens. Consequentially, the two-step solution heat treatment could be used in automotive parts to improve mechanical properties.

MICROSTRUCTURE EVOLUTION AND CORROSION PROPERTY OF MEDIUM-CARBON ALLOY STEEL AFTER HIGH-TEMPERATURE CARBURIZATION PROCESS

2016 ◽  
Vol 23 (05) ◽  
pp. 1650038
Author(s):  
DENG DEWEI ◽  
NIU TINGTING ◽  
LIU HAIYING ◽  
ZHANG LIN ◽  
SUN QI
Keyword(s):  
Electron Microscope ◽  
Electrochemical Corrosion ◽  
Corrosion Current ◽  
Optical Microscope ◽  
Corrosion Property ◽  
Carbon Steels ◽  
Smooth Transition ◽  
Hardness Profile ◽  
Medium Carbon ◽  
Transmission Electron

In the present study, the effects of carburization treatment on the microstructure and corrosion property of medium-carbon steels (40Cr) were investigated by means of X-ray diffraction (XRD), electron microprobe analyzer (EMPA), optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM) and electrochemical corrosion, respectively. It was found that the microstructures beneath the surface were refined and a smooth transition microstructure from the surface to the core was observed in carburized samples. The fine plate-like but not granular carbide precipitation (Cr7C3) was observed in carburized sample by heat-treatment. The carburized specimens exhibited some effectiveness in the improvement of hardness and a smooth transition hardness profile. Corrosion resistance of 40Cr was improved by carburization treatment, resulting in the higher self-corrosion potential and the lower self-corrosion current density.

scholarly journals The Video Microscopy-Linked Electrochemical Cell: An Innovative Method to Improve Electrochemical Investigations of Biodegradable Metals

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1601
Author(s):  
Tycho Zimmermann ◽  
Norbert Hort ◽  
Yuqiuhan Zhang ◽  
Wolf-Dieter Müller ◽  
Andreas Schwitalla
Keyword(s):  
Electrochemical Cell ◽  
Electrochemical Corrosion ◽  
Corrosion Current ◽  
Cell System ◽  
Open Circuit ◽  
Dynamic Conditions ◽  
Electrochemical Tests ◽  
Oxide Deposition ◽  
Set Up ◽  
Voltammetry Methods

An innovative, miniature video-optical-electrochemical cell was developed and tested that allows for the conducting of electrochemical corrosion measurements and simultaneous microscopic observations over a small, well-defined surface area of corroding or degrading samples. The setup consisted of a miniature electrochemical cell that was clamped onto the metal sample and fixed under a video microscope before being filled with electrolyte. The miniature cell was comprised of afferent/efferent electrolyte ducts as well as a connection to the Mini Cell System (MCS) for electrochemical measurements. Consequently, all measured and induced currents and voltages referred to the same small area corroding completely within the field of view of the microscope, thus allowing for real-time observation and linking of surface phenomena such as hydrogen evolution and oxide deposition to electrochemical data. The experimental setup was tested on commercial purity (cp) and extra-high purity (XHP) magnesium (Mg) samples using open circuit potential and cyclic voltammetry methods under static and flowing conditions. The corrosion potential was shifted more anodically for cp Mg in comparison to XHP Mg under dynamic conditions. The corrosion current assessed from the cyclic voltametric curves were higher for the cp Mg in comparison to XHP Mg. However, there were no differences between static and flow conditions in the case of XHP Mg in contrast to cp Mg, where the current density was two times higher at dynamic conditions. The measurements and observations with this new method pave the way for a more detailed understanding of magnesium corrosion mechanisms, thus improving predictive power of electrochemical corrosion measurements on newly developed magnesium or other biodegradable alloys applied for medical devices. Different electrochemical tests can be run under various conditions, while being easy to set up and reproduce as well as being minimally destructive to the sample.

scholarly journals Electrochemical Corrosion Resistance and Electrical Conductivity of Three-Dimensionally Interconnected Graphene-Reinforced Cu Composites

2021 ◽  
Vol 59 (11) ◽  
pp. 821-828
Author(s):  
Xue Li ◽  
Ateeq Ahmed ◽  
Byung-Sang Choi
Keyword(s):  
Electrical Conductivity ◽  
Corrosion Resistance ◽  
Carbon Content ◽  
Chemical Species ◽  
Electrochemical Corrosion ◽  
Chemical Vapor ◽  
Corrosion Current ◽  
Optical Microscope ◽  
Electrochemical Corrosion Resistance ◽  
Pure Cu

A three-dimensionally interconnected graphene-reinforced Cu (3Di Gr-Cu) composite was synthesized using a simple two-step process technique which involves the mechanical compaction of micronsized Cu particles followed by chemical vapor deposition (CVD) at 995 ℃. The microstructural properties of pure Cu and the 3Di Gr-Cu composite were investigated by optical microscope, scanning electron microscope, and X-ray diffractometer. The electrical and corrosion behaviors of the 3Di Gr-Cu composite and Cu only, prepared by powder metallurgy (PM Cu), were studied and compared. The electrical conductivity (EC) of the 3Di Gr-Cu composites was found to be 38.8 MSm−1 at a carbon content of 73 ppm, and exhibited a 12% higher EC than the PM Cu. Due to the interconnected graphene around the Cu grains, the corrosion current density and corrosion rate of the 3Di Gr-Cu composite decreased by 29% and 40%, respectively, compared to the PM Cu. The EC of the 3Di Gr-Cu composite depended on the carbon content. The improvement in the EC of the 3Di Gr-Cu composite is attributed to the electron-carrying ability of the three-dimensionally interconnected graphene network (3DIGN) formed at the grain boundaries in the composite. The enhancement in corrosion resistance is due to the impermeability of graphene to various chemical species.

Electrochemical Behavior of Potassium Zinc Phosphates Extract and Coating

2012 ◽  
Vol 152-154 ◽  
pp. 64-67 ◽  
Author(s):  
Dong Ping Wei ◽  
Shao Mei Ma ◽  
Ze Guang Zhou ◽  
Zeng Wei Huang ◽  
Ai Qun Yuan ◽  
...  
Keyword(s):  
Electrochemical Behavior ◽  
Corrosive Medium ◽  
Open Circuit Potential ◽  
Zinc Phosphate ◽  
Electrochemical Impedance ◽  
Electrochemical Corrosion ◽  
Immersion Test ◽  
Open Circuit ◽  
Zinc Phosphates ◽  
Pigment Extract

The electrochemical corrosion inhibitions of potassium zinc phosphate were studied by polarization, open circuit potential measurements, electrochemical impedance of the pigment extract and coating immersion test. Dynamic analysis shows that in pH=7 3.5% NaCl extract, KZn2(PO4)(HPO4) functions as a cathodic inhibitor on steel and its efficiency is even superior to other phosphates. The inhibiting efficiency of the pigments on steel decrease in the order: KZn2(PO4)(HPO4) > aluminum zinc phosphate > zinc phosphate ≧ aluminum triphosphate The coating tests show that potassium zinc phosphate can efficiently enhance the inhibition properties of coating and prevent the erosion of the corrosive medium by improving the barrier and hydrophobicity of the coating. The anticorrosive property of the pigments decrease in the order: KZn2(PO4)(HPO4)> aluminum zinc phosphate > zinc phosphate ≈APW-1.

Effect of mechanical stress on electrochemical corrosion of X65 carbon steel in CO2 saturated brine

2020 ◽  
Vol 62 (8) ◽  
pp. 803-808
Author(s):  
Wei Yan
Keyword(s):  
Mechanical Stress ◽  
Applied Stress ◽  
Electrochemical Impedance ◽  
Electrochemical Corrosion ◽  
Experimental Tests ◽  
Corrosion Current ◽  
Weak Acid ◽  
Open Circuit ◽  
Electrochemical Process ◽  
Metal Corrosion

Abstract Applied mechanical stress could accelerate the chemical or electrochemical process of metal corrosion in weak acid solution. Series of experimental tests were conducted in this research. The results show that there is no obvious correlation between OCP (open circuit potential) values and applied stresses. However, The LPR (linear polarization resistance)corrosion rate increased intensively under the applied stress of 400 MPa. Correspondingly, the EIS (electrochemical impedance spectroscopy) Nyquist diagrams show that all of the plots contain a semicircle over the whole frequency range and the semicircle size decreased with increasing applied stress. The real-time corrosion current square waves triggered by the mechanical stress were successfully monitored by using the potentiostatic method in CO2 saturated brine under 200 mv (above OCP), flow and lower pH condition. This result is significant for many research fields, such as petrochemistry, aerospace and nuclear industries, which suffer weak acid corrosive environment.

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