Science topic

Corrosion - Science topic

The gradual destruction of a metal or alloy due to oxidation or action of a chemical agent. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
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Greetings,
I want to re-create some published work that use formaldehyde as the wall material for microcapsules. The purpose of this microcapsules are to encapsulate some oil for anticorrosion purpose. However, as we know that formaldehyde is not good for human and animal. And since this microcapsules is planned to be used in coatings and applied to metal-based infrastructure, I am worried about its toxicity effect to the environment.
So, can someone suggest some materials to replace formaldehyde but with similar characteristic and efficiency?
Initially, I planned to make Urea-Formaldehyde (UF) microcapsules.
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Hello,
I have calculated the equilibrium products of high-temperature gaseous reactions from thermodynamic calculations. Meanwhile, I am curious about determining the kinetics of those reactions. I checked various resources, however cannot find any information on the kinetics of the reactions given below:
CO2 <--> CO + O2
2CO <--> C + CO2
CO2 + CH4 <--> 2CO + 2H2
CH4 <--> C + 2H2
Can you please provide me the procedure or references where I can estimate the kinetics of those reactions? Many thanks!
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While the chemical equilibrium is strictly dictated by thermodynamics, the kinetics expressions depend on the type of catalyst (these reactions are usually catalysed) and may vary from one another. Some typical expressions can be found in Chemical Engineering Journal (2007), 134(1–3), 138–144. https://doi.org/10.1016/j.cej.2007.03.051
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Some magnesium alloys do not corrode on the surface when immersed in a corrosive solution, but the surface is darkened, why?
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Hi,
I want to reduce the corrosion rate of Grey Cast Iron (Lamelar) by 50 %. The environement is atmospheric + salt + pollution.
I have seen the possibility to use austenitic iron (that is very good but also expensive), but I am wondering if it could be possible to obtain a slight mitigation of corrosion by adding only few percent of Cr, Mo and/or Ni.
Does anyone have ideas on that ?
Clément
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Dear Clement,
Unfortunately, small additions of the elements you listed will not only not reduce, but, on the contrary, will increase the corrosion of cast iron. The fact is that these elements in small quantities will create additional microgalvanic pairs with iron, which will accelerate corrosion. Alloying of iron and cast iron with chromium leads to an abrupt increase in corrosion resistance, but only with certain amounts of chromium additive. For mild steel, the minimum addition of chromium leading to an increase in corrosion resistance is 13%, and for chromium cast irons, even more is needed (corrosion-resistant high-chromium cast irons contain 20-30% chromium). As for small additions to cast iron, it is not chromium, nickel or molybdenum that gives some effect in terms of increasing corrosion resistance, but silicon, aluminum, magnesium, and also phosphorus, although it greatly worsens the mechanical properties of cast irons.
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I'm running a corrosion testing equipment to find breakdown potential of SUS 304 samples. However, all the samples exhibit crevice corrosion rather than the preferred center corrosion. I'm using a AmeTek flat cell with the gasket provided along with it for seal. I already tried replacing the gasket to a new one, but still seeing the same results. How can I prevent/minimize this?
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Dear Dr. Richard Selvaraj ,
perhaps another way to reduce crevice corrosion in the vicinity of the gasket / sample area could be to generate a microflow of corrosive solution (closed circuit), in a laminar and non-swirling way as possible so that the oxygen concentration remains almost constant and the electrochemical measurement is not significantly disturbed.
Easy to say, a little more complicated to do ...
My best regards, Pierluigi Traverso
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Hello All
I have measured the corrosion current and corrosion rate through the Tafel polarisation three-electrode system.
Working electrode - mild steel, the counter electrode - graphite., reference electrode - SCE, Electrolyte - seawater.
The corrosion rate and corrosion currents are increased with the linear increase of operational current (instrument current range) from 10 nA to 1 A.
Please can anyone share the reason for this? and how do I fix the current range (e.g., 1 mA, 100 mA) for corrosion measurement?
Thanks
Vinooth.
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I apologize but I can't understand your question easttamente; generally using the Tafel method, once the stability of the open circuit potential Eoc has been reached, the potential is changed (both in the cathodic and anodic sense, preferably with single measurements for the two polarizations, naturally on identical samples prepared for the same mode), recording the generated current density on a logarithmic scale. Then the data analysis is carried out ....
Occasionally problems may arise if we are dealing with particular materials or more banally "random" discrepancies from the normal operating protocol but, generally, this methodology is rather easy and reliable, especially if you work by comparison between different types of materials.
Allow me to suggest some documents that may be of help to you:
- Getting Started with Electrochemical Corrosion Measurement by Gamry
- Metrohm White Paper - Fundamentals of Electrochemical Corrosion Research by Metrohm
- Tafel Plot and Evans Diagram by Palmsens
but you can also find many others…
Good luck and my best regards, Pierluigi Traverso.
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Hello,
I would like to compare the corrosion resistance of coatings on gym material components (black oxide, zinc, chrome, cerakote and bare steel).
I did extended literature search however cannot find any reliable scientific literature comparing the corrosion resistance and other physical properties. Kindly let me know any references or papers that have experimentally analysed the mentioned coatings.
Thanks in advance!
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I suggest you to have a look at the following documents:
-PERFORMANCE CERAMIC COATINGS FOR THE FITNESS INDUSTRY by Cerakote
-Stainless Steels in Sports and Leisure Equipment by ISSF - International Stainless Steel Forum
Pag. 24 – Indoor Fitness
-Powder Coating for Gym and Fitness Equipment by AR Powder Coating
... but these are only general indications that you will have seen too, they are not scientific studies which, as such, require a precise and specific determination of the parameters of the products and the corrosive environment in relation to which the considerations on the phenomena studied are made.
Personally, if possible, I would consider stainless steels (even if more expensive than carbon steels), perhaps using specific surface finishes and not coatings, for aesthetic reasons, ease of disinfection, durability (they are also used in the marine environment) and eco-friendly production.
Good luck and my best regards, Pierluigi Traverso.
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I am performing a static immersion test using artificial saliva for Co-Cr base alloy. For weight loss measurement, I need to remove the corrosion product from the sample surface. Please suggest which chemical to use to remove corrosion products.
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I suggest you to have a look at the following regulation: ASTM G1-Standard Practices for Preparing,Cleaning, and Evaluation of Corrosion Test Specimens.
My best regards, Pierluigi Traverso.
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How to clean the corrosion products from Co-Cr base alloy?
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We are running an accelerated corrosion experiment on large-scale RC specimens. The accelerated corrosion technique we are implementing is the impressed constant current. In the corrosion setup, we have the anode (the steel reinforcement in the specimens), and the cathode which is an external steel mesh. The specimens are immersed in NaCl solution. The cathode steel mesh, while being connected to the DC power supply unit, produces smoke that comes out from the rebar ends, as in the attached video. Does any one have an explanation for this? I would appreciate if anyone can share expertise on this.
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your cathode is probably very over-polarized to drive the current to the anode, so it comes to gas evolution or something like that. cause is maybe a too high resistance in your circuit (via the concrete) and/or the cathode area is way too small compared to the anode area.
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If possible, provide a bibliography that demonstrates how to get to the equation given in the question.
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Dear Sir
Please specify the data on the paper, Year, Vol, Journal ...
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Hello
In the corrosion reaction, hydrogen ions are released through hydrolysis.
Will hydrogen ions decrease the pH of the solution or change the pH of the solution?
Please anyone help me with this.
Note: Hydrogen ion releases from corrosion reaction.
Regards
Vinooth.
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I am interested in understanding the impact on corrosivity of crude oils containing these two components. Specifically in Distillation Units equipment and piping (atmospheric and vacuum).
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The corrosion current and resistance estimated from linear polarization in the case of GO-PPy coatings is not related with the electrode dissolution only but with the state of the PPy coating (oxidized, reduced or overoxidized). I doubt that the estimated current is the corrosion current.
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Dr. Chaitanya Kumar Kanukula thank you so much sir…
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I'm doing a Thesis about corrosion in AISI 310. I have a data from lab but cannot find
carbon diffusion coefficient to do a flick law 2 for discuss with my professor.
please help me find a paper or a key word for searching.
T 600-900 C
the file below is a diffusion coefficient that I want
I usally found 304 316 except 310
with respect,
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Diffusion coefficient is the proportionality factor D in Fick's law (see Diffusion) by which the mass of a substance dM diffusing in time dt through the surface dF normal to the diffusion direction is proportional to the concentration gradient grad c of this substance: dM = −D grad c dF dt.
Diffusion hardening is a process used in manufacturing that increases the hardness of steels. In diffusion hardening, diffusion occurs between a steel with a low carbon content and a carbon-rich environment to increase the carbon content of the steel and ultimately harden the workpiece.
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this was a galvanic corrosion on the pure ferrite. I would like to know what type of corrosion with which mechanism has here happened? why grain boundaries and small holes inside of has at the same time happened?
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Dear Mandana
I agree with Professor Hussein.
The observations of localized galvanic corrosion of a pure ferrite phase could occurred due to the present of differential regions of dislocation density, i.e.,
inhomogeneous distribution of strained and unstrained regions, in the phase.
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Is there a computational or analytical method to calculate the corrosion resistance of a superalloy based on the composition of the alloy and thermodynamic parameters obtained by ThermoCalc?
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Dear Dr. Shubhansu Singh ,
I suggest you to have a look at the following, interesting paper:
- Determination of Al-2.18Mg-1.92Li Alloy’s Microstructure Degradation in Corrosive Environment
Franjo Kozina, Zdenka Zovko Brodarac, Sandra Brajčinović and Mitja Petrič
Crystals 2021, 11(4), 338; https://doi.org/10.3390/cryst11040338
My best regards, Pierluigi Traverso.
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Please, I have a question to ask regarding the solubility of a ternary alloy.
I have a U-bend of alloy 600 and I want to carry out a high temperature electrochemical analysis using 0.5L autoclave, but I need to calculate the solubility of this alloy in this environment (chloride 0.01M) as I intend to use multiple alloy for a comparative analysis.
Please, how can I calculate the solubility of this alloy
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Dear Dr. Nkem Chidi ,
if I understand your question correctly, you would like to verify the quantity of soluble corrosion products in the aggressive solution, leaving out those adhering to the sample (insoluble corrosion products).
Their quantity will depend on the exposure time and will depend on the resistance of the material to corrosive attack. For the determination of soluble metals present you could use an analytical determination by flame absorption spectrophotometry (generally the determination is at the ppm level) or if the quantities are lower you could use the absorption spectrophotometry with graphite furnace (and here you can reach levels of ppb).
For many metals, you can have as an alternative (at ppm level) the determination by colorimetric methods and determination with UV-Visible spectrophotometer.
My best regards, Pierluigi Traverso.
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What is the reason for the low corrosion rate of low carbon steel immersed in different water media
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Steel corrosion requires two components: water and oxygen. If water does not contain dissolved oxygen, the corrosion rate of steel under water drops to practically zero. The maximum rate of corrosion is found at the three-phase boundary (water, air, steel) where both corrosive media come together.
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Hi,
I have a question about tribocorrosion tests.
I have evaluated corrosion and tribocorrosion behaviors of carbon steels exposed to solution including corrosion inhibitors.
The results showed that the current density is higher when we don’t have any sliding on the metal surface. However, when sliding applied on the surface, the current density will be declined.
Does anyone know How sliding action can reduce corrosion of carbon steel exposed to solution including corrosion inhibitors?
Thank you very much.
Best Regards,
Mohammad
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I am using carbon steel and a silicon nitride ball which is placed on the metal surface. Steel and ball are immersed in emulsion-based solution including oil, surfactant and corrosion inhibitors.
I applied the potential 1mV versus OCP and measured current density over time.
current density is lower when there is sliding on the metal surface compare to without sliding.
so, sliding reduced current density and current is higher when there is no touching between metal surface and ball.
I need to know How sliding action can reduce corrosion of carbon steel exposed to solution including corrosion inhibitors?
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The UV light, which is chiefly used in a photocatalytic reactor, is corrosive in nature." For a non-corrosive design, the cost of the UV light is replaced with solar energy for photocatalytic activity. what is the reason for the corrosiveness of UV light?
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Dear Dr. Rahul Binjhade ,
I suggest you to have a look at the following, interesting paper:
-Photodegradation and photostabilization of polymers, especially polystyrene: review
Emad Yousif and Raghad Haddad
Springerplus, 2: 398 (2013)
My best regards, Pierluigi Traverso.
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Dissolved salts and other factors involved in inplant corrosion and modeling of Inplant corrosion.
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Corrosion impants
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A question about measuring and checking corrosion with a potentios device that shows the voltage positive for blank of acid and salt, where is the problem?
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I suggest you to have a look at the following, interesting document:
-Troubleshooting on potentiostat experiments by Palmsens
Where there is a list to enable the users to find the sources of trouble to keep the frustration level as low as possible.
Good luck and my best regards, Pierluigi Traverso.
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Hi,
I have a question about current achieved through corrosive wear tests.
I am working on corrosive wear of solutions with and without corrosion inhibitors. the pin is applied on the metal surface at various sliding speeds while it is immersed in my various solution. When sliding starts, current versus time is measured. The applied initial and final E is 0.001 V versus OCP.
The current for metal surface immersed in solution without corrosion inhibitors at various sliding speeds are positive and current increases with time.
But current for metal surface immersed in solution with corrosion inhibitors becomes negative with increasing sliding speed so that the current becomes +200 Nano ampere when sliding speed is 2 mm/s and when speed increases (3.5, 5 and 10 mm/s), the current become negative around -40 micro ampere to -60 micro ampere.
Does anyone know why the current becomes negative for solutions including corrosion inhibitors at high sliding speeds?
Thanks a lot
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Dear Dr. Mohammad Palimi ,
I suggest you to have a look at the following, interesting papers:
- Tribocorrosion of Passive Materials: A Review on Test Procedures and Standards
A. López-Ortega , J. L. Arana, and R. Bayón
International Journal of Corrosion, Vol. 2018, Article ID 7345346, 24 pages
- Effect of Applied Cathodic Potential on Friction and Wear Behavior of CoCrMo Alloy in NaCl Solution
Yong Sun and Richard Bailey
Lubricants, 8, 101 (2020); doi:10.3390/lubricants8110101
Available at: file:///C:/Users/User/AppData/Local/Temp/lubricants-08-00101-1.pdf
- Effect of sliding wear and electrochemical potential on tribocorrosion behaviour of AISI 316 stainless steel in seawater
Sabri Alkan, Mustafa Sabri Gök
Engineering Science and Technology, an International Journal, Vol. 24, Issue 2, Pages 524-532 (2021)
My best regards, Pierluigi Traverso.
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Hello,
Yesterday I measured some samples on Orbitrap IDX with LC Vanquish- measurement ended with nasty leak on top of IDX source, in the connection between PEEK and needle. After various solutions I tried to look at the capillary under magnifying glass and found completly corroded inner end of the needle (viz picture).
Mobile phases used were Water with 20 mM Ammonium formate, pH 7 (adjusted with MS grade ammonia) and acetonitrile with 20 mM ammonium formate.
Is it possible, that some of the additives is responsible for corrosion? All of them are used quite worldwide for LC/MS systems, so I'm really not sure.
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how to plot an adsorption isotherm using surface coverage (theta) for corrosion inhibitors?
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Thank you for your response. I shall look into more details through literature
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Is it the oxidation power of a material (like Trichloroisocyanuric Acid (TCCA)) that leads to corrosion of equipment or the presence of individual elements and reactions, especially chlorine?
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individual elements certainly. TCCA just replaces the Cl and gets hydroxylated which drops the pH. Although that low pH has an effect on corrosion to some extent, but Cl would compete with that!
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Can chlorine-related corrosion issues exist in organic acids such as (Trichloroisocyanuric Acid (C3Cl3N3O3)) like NaCl in equipment like pumps…?
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Dear Ali Behrad Vakylabad, the oxidation is a process that involves the exchange of electron(s), so any couples (or more) that are ready to give/receive the free electrons are in fact performing oxidation/reduction. My Regards
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Why it is important to understand the chemical composition of the corrosion product form during seawater corrosion of steels? How this information help us to combat corrosion? Any thoughts?
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You may find a valuable thoughts recently presented by Philippe Refait et al. in [1]. I hope it helpful, as its contents related the corrosion product layers forming on carbon steel in natural seawater and the link between the mineralogical composition of these layers and the corrosion mechanisms.
Best regards
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When chromates are used as a corrosion inhibitor, is there an optimum concentration for all alloy systems?
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Dear Dr. Vinod Upadhyay ,
I suggest you also to have a look at the following, interesting paper:
-Chromate replacement: what does the future hold?
Oumaïma Gharbi, Sebastian Thomas, Craig Smith and Nick Birbilis
npj Materials Degradation, 2:12 (2018) - doi:10.1038/s41529-018-0034-5
This paper highlights the negative impact of chromium compounds on the environment and human health.
This has led to the need to revisit most of the current industrial corrosion protection measures.
The work traces the origins of the reasons for replacing chromium, introducing the various regulations
actions to reduce the use of chromium compounds and critically review preventive alternatives to corrosion technologies developed in the last decades.
My best regards, Pierluigi Traverso.
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Greetings dear researchers,
Can anyone suggest a simple and correct way for me to clean the formed corrosion product on my mild steel sample after it has been immersed in a corrosive solution for few days? I have some approaches from ASTM G1-90, but it use several chemicals and I am worried that it might induced corrosion instead of cleaning it. Thank you.
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It is possible to remove corrosion products without resorting to chemistry at all. There are two groups of methods for this: mechanical and thermal. Mechanical removal of corrosion products consists, for example, in sandblasting a dry surface with a product that does not damage the metal. It can be frozen carbon dioxide, glass microspheres or ground nut shells. Also mechanical methods include high-pressure water jet cleaning. Thermal methods include various heating methods that destroy corrosion products, but do not damage the metal. The most interesting of these methods is laser cleaning.
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So my question here is there limit to SRB after we exceed it will happened or just with present it at any value, and if there are value for SRB which standard mentioned it.
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I suggest you to have a look at the following, interesting papers:
-Influence of Sulfate-Reducing Bacteria on the Corrosion Behavior of High Strength Steel EQ70 under Cathodic Polarization
Fang Guan, Xiaofan Zhai, Jizhou Duan, Meixia Zhang, and Baorong Hou
PLoS One, 11(9): e0162315 (2016)
- Microbially Influenced Corrosion of Stainless Steel by Acidithiobacillus ferrooxidans Supplemented with Pyrite: Importance of Thiosulfate
Yuta Inaba, Shirley Xu, Jonathan T. Vardner, Alan C. West, and Scott Banta
Appl Environ Microbiol., 85(21): e01381-19 (2019)
My best regards, Pierluigi Traverso.
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A research on corrosion prediction in a gas pipeline using artificial neural network is the core interest. This time, an experimental data to model and train the ANN is required. Thanks in anticipation.
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Dear Dr. Nurudeen Sabi ,
I suggest you to have a look at the following, interesting web site regarding a pipeline safety project, available at:
My best regards, Pierluigi Traverso.
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Greeting,
As you can see in the figure attached, I want to ask, if I have a sample that has been immersed for few days already. What is the suitable duration and stab. (mV/s) I should use for the EIS and Potentiodynamic polarization measurements?
The sample is a coated mild steel. Thank you.
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in addition to what Dr. Khaled J. Habib correctly said, I suggest you to have a look at the following, interstig book:
- RECENT RESEARCHES INCORROSION EVALUATION AND PROTECTION
Edited by Reza Shoja Razavi
Published by InTech (2011) - ISBN 978-953-307-920-2
Enjoy readings and my best regards, Pierluigi Traverso.
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Everyone in the materials science and engineering field may have heard about the Ashby diagram --- a scatter plot which displays two or more properties of many materials or classes of materials. I am wondering whether it is possible/rational to plot the corrosion properties versus other properties (strength). It is well known that corrosion measurements are very sensitive and are impacted by many internal and external factors. So I am not sure if plotting corrosion vs strength would be a good idea. That is a diagram I had never seen. I would appreciate your comments on this topic as well as if you have seen a diagram of this type in the literature.
See an example for Ashby diagram in the attachment. In my case, I intend to plot Strength (Y axes) vs Corrosion properties (X axes).
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in the example, intrinsic properties of the specific material are considered, which are not dependent on the environment. However, the corrosion process involves the material and the environment. The approach is then totally different. Moreover, only the surface properties of the material are relevant for the corrosion process so I cannot imagine what type of plot can be considered other than Pourbaix type.
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Hello everybody
reinforced concrete structures that are exposed to aggressive water environments are damaged or even deteriorated. many water quality parameters like pH, alkalinity, sulfate and chloride concentrations, etc. affect on deterioration rate, so to determine whether the water is aggressive or not, indices like the Ryznar index, etc. have been proposed. the question is which one is more reliable.
sincerely
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When I design concrete exposed to chemical action (groundwater, exposure class AX1, AX2, AX3), I take into account the type, minimum amount of cement, minimum class of concrete and maximum w/c. Never heard of Ryznar index.
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I used a platinum crucible a couple of times to melt some samples wrapped in Al-foil. Now, there are some residual materials in the crucible (solidified), not easy to remove out.
I would like some efficient chemical treatment to clean and remove the residual without losing (etching) platinum.
Thanks in advance!
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Dear Mohammad Tauseef in addition to the expert answers which have already been provided by RG members, it might also be worth having a look at the answers given to the following closely related question which has been asked earlier on RG:
How to clean up the platinum crucible used in thermal analysis?
(10 answers)
For more general information, please also check the following potentially useful guides:
The Correct Use of Platinum in the XRF Laboratory
and
A Guide to Cleaning Platinum Crucibles
Both articles are freely available as full texts. I hope this helps solving your problem. Good luck with you work and best wishes, Frank Edelmann
P.S. I fully agree with Rémi Losno in that you should avoid working with HF if at all possible because of its very high toxicity.
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Corrosion rate (mpy) = 3.27x icorr x Ew /d --------------------------------------------(i)
Where, Ew-Equivalent weight of mild steel, d is the density of mild steel.
Is it the same formula for calculating corrosion rate?
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Congratulation
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Dear all,
I am investigating the corrosion properties of SS having Ceramic thin layer over it, however it shows different ocp value and tafel curve, when tested the same samples at different location keeping all the parameters constant.
how it can be overcome, so that repeatability can be maintained to the best.
Thank you
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Several factors can play roles in such a case. Even if your thin film is homogenous (in terms of thickness, structure, and composition), you may consider two more factors: 1. if the SS substrate has a uniform roughness (if not, it can cause roughness variation on the thin film top surface that ends up to different electrochemical responses) and 2. how large is the area that you measure on your sample? if it is too small, then it is possible to get scattered OCP and Tafel behaviour.
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Greetings,
My question is very simple. We all know that essential oil does not mix with water and will just float on the water surface. So, let say I want to test its corrosion inhibitive property for a steel that is immersed in 3.5% NaCl, if I just simply added the essential oil, I do not think it will be in contact with the steel.. Not to mention its dispersibility in the water will be not so good. But, I have seen quite a number articles published to highlight the corrosion inhibitive nature of essential oils. So, can someone enlighten me on how to make this possible? (Do I need an emulsifier or not?)
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in addition to what Dr. Yuri Mirgorod has already said, you could create an essential oil layer on your metal sample in different ways, as if it were a normal coatings ... dipping, spraying, spreading a film ... the doubt that arises , having never worked directly with essential oils - even if I have worked on the protection of materials using particular lubricating oils that can be used as "temporary corrosion inhibitors" in the marine environment - characterize the surface layer, after preparation and after immersion in solution of NaCl (for different periods of time ...). To determine its presence, especially after exposure, I used IR spectrophotometry (with a suitable FT-IR instrument equipped with an accessory for specular reflectance). The quantity of inhibitor in contact with the sample could be determined before the immersion tests in a gravimetric way but if the compound is poorly adherent and the situation becomes more complicated ...
If you need, let me know any details ...
My best regards, Pierluigi Traverso.
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When preparing tin bronze gold phase, I ground it from 600 to 2000, and then used 2.5 diamond polishing agent on silk polishing cloth. And 0How to avoid scratches after corrosion.5 diamond polishing agent, and finally polish the neoprene with 0.05 silica. After polishing, no scratches can be seen under the microscope, but there will be more scratches after corrosion. The corrosive solution is 5g FeCl3 + 10ml HCl + 100ml H20,How to avoid scratches after corrosion?
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As Alec Ladonis noted, the preparation phase might be time-consuming. However, I recommend that you first determine the stage at which the scratches after etching might have developed by examining the size and direction of the scratches.
Then, if you are certain that the problem is caused by the polishing procedure, please try the following techniques: It should continue at least twice as long as it takes to remove scratches from the previous step of polishing for each level of polishing. It is preferable to use a longer-nap cloth for final polishing rather than a nap-less or short-nap cloth for rough polishing. Finally, lightly etch! and successively until it is needed.
(I don't believe there's anything wrong with your etchant solution.)
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Intergranular corrosion/sensitization is a well known phenomenon that occurs in 18-8 austenitic stainless steel. Does it also occur in case of ferritic stainless steel? Why/Why not?
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On the material side, it is always a question of how homogeneously chromium or other important elements are distributed in the material. Grain boundaries are often affected, as this is often where the chromium-rich precipitates are located, with the adjacent Cr-depleted areas. And therefore, of course, it can also affect ferritic stainless steels. On the media side, it is often those conditions that are critical where element-depleted areas cannot passivate or repassivate well. It is mostly related to the passivation and reactivation current density. This can be investigated very well by means of EPR experiments. Therefore, this publication by me and my colleague may be of interest to you:
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Dear all,
I am investigating the corrosion resistance of ceramic coating (deposited by PVD process) on Stainless steel samples using Gamry Instrument with parameters OCP (77.78 mV conducting before tafel curve), then scan rate = 1 mV/s, Potential = -0.5 to 0.5 Vs OCP in 0.5M NaCl environment. During starting of tafel curve, there is overloading error within 3-5 minutes and also coating was seen peeled off at the point of contact/interface between solution and Coating having area .022 cm2.
Kindly suggest the best possible solutions to overcome this problem.
Thank you
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Dear Dr. Shashi Kant ,
I suggest you to have a look at the interesting Application Note CORR-1 by Princeton Applied Research, available at:
My best regards, Pierluigi Traverso.
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I am running the experiment where I am monitoring the OCP of steel in two different media (A & B) for a week and ran the Tafel experiment at the end of OCP.
Compared to medium B, medium A is showing more negative values of OCP and Ecorr of steel at the end of experiment. Is it right to conclude that the corrosion susceptibility of steel in medium A is relatively higher compared to medium B?
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Dear Dr. Sana Mirza ,
long-term change of corrosion potential (open-circuit potential) reflects a change in a corrosion system because the change in corrosion potential depends on the change in one or both of the anodic and cathodic reactions. For example, an increase in corrosion potential can be attributed to a decrease in the anodic reaction with the growth of a passive film or the increase in the cathodic reaction with an increase in dissolved oxygen. A decrease in corrosion potential can be attributed to an increase in the anodic reaction or a decrease in the cathodic reaction. The monitoring of corrosion potential is therefore often carried out (ISO 16429, 2004; JIS T 6002). For the test solution, saline, phosphate buffer saline, Ringer solution, culture medium, serum and artificial saliva are typically used. The corrosion potential of the specimen can be monitored against a reference electrode using an electrometer with high input impedance (1011 Ω ~ 1014 Ω) or a potentiostat.
For more details, please see the source: Monitoring of corrosion potential by S. Hiromoto, in Metals for Biomedical devices, 2010.
The most widely used electrochemical method of determining the corrosion rate is the Stern-Geary method which allows to evaluate the corrosion current (i corr), an essential parameter from which to derive the corrosion rate of the material in that particular environment.
My best regards, Pierluigi Traverso.
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Hello all,
I am preparing finely polished metallography specimens in low alloy steels for SEM analysis and finally do ethanol cleaning. However, the surface is too sensitive that develops oxides on exposure to air. Kindly suggest me some techniques to avoid the development of surface oxide layer.
Thank you.
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As per my experience, keeping the sample in a vacuum desiccator with silica gel is an easiest method to avoid the oxidation of polished surface.
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Is it critical to analyse the surface of the coupons after potentiodynamic testing or surface analysis after simple immersion testing is enough?
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Dear Dr. Sana Mirza ,
in general, you have 4 main different methods to study the corrosion behaviour of a specific material (protected or not by a coating or other surface treatments) in the environment of possible use:
1 - Field tests (according to standard regulations and followed by appropriate characterizations / evaluations) in a corrosive environment very similar to the one of use that require an exposure time of at least one year (or more);
2 - Salt spray chamber tests (these, too, according to standard regulations), conducted in a series of corrosive environments simulating those of real application, with often rapid assessments of a photographic type. These tests require an exposure time of about 1-2 months and are considered "accelerated tests";
3 - Lab tests in free corrosion conditions, in a controlled environment, followed by analysis of weight loss (gravimetric test)and / or morphological and chemical analyzes of the surface of the samples by scientific instrumements, for example Optical Microscopy, SEM, et. (time required about 1 month);
4 - Electrochemical measurements (eg. Potentiodynamic Polarization Curves, EIS, etc.) carried out in an suitable aggressive solution which, once the experimental parameters are optimized, are able to provide a comparative or absolute evaluation, in a time of order of one hour every single measure.
Now all that remains is to choose. Personally I prefer to use at least two of the tests mentioned above ... it is always better to have two results in agreement with each other, if time allows us to do this...
Best regards, Pierluigi Traverso
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Is there any relationship between corrosion potential (Ecorr) and surface area of the sample?
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The electrode potential does not depend on the surface area of the electrodes. Please recall the Nernst equation to see how it is a chemical thermodynamical relationship out of the electrodes surface area.
Best regards
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Hello everyone,
Iˇd like to test corrosion behaviour of Cu-%4 Si alloy. We do not have an accretidated test lab. So we can not apply salt spray testing.
We do not need detailed result. Therefore, what is the simplest method to measure corrosion resistance in a lab environment for this Alloy?
Thank you
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in general, you have 4 main different methods to study the corrosion behaviour of a specific material (protected or not by a coating or other surface treatments) in the environment of possible use:
1 - Field tests (according to standard regulations and followed by appropriate characterizations / evaluations) in a corrosive environment very similar to the one of use that require an exposure time of at least one year (or more);
2 - Salt spray chamber tests (these, too, according to standard regulations), conducted in a series of corrosive environments simulating those of real application, with often rapid assessments of a photographic type. These tests require an exposure time of about 1-2 months and are considered "accelerated tests";
3 - Lab tests in free corrosion conditions, in a controlled environment, followed by analysis of weight loss (gravimetric test)and / or morphological and chemical analyzes of the surface of the samples by scientific instrumements, for example Optical Microscopy, SEM, et. (time required about 1 month);
4 - Electrochemical measurements (eg. Potentiodynamic Polarization Curves, EIS, etc.) carried out in an suitable aggressive solution which, once the experimental parameters are optimized, are able to provide a comparative or absolute evaluation, in a time of order of one hour every single measure.
Now all that remains is to choose. Personally I prefer to use at least two of the tests mentioned above ... it is always better to have two results in agreement with each other, if time allows us to do this...
Best regards, Pierluigi Traverso
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I am currently working on quaternary titanium alloys like Ti-Nb-Ta-Zr with single and duplex phases. May anyone suggest a better method for study the corrosion behavior of biocompatible titanium alloys like Ti-Nb-Ta-Zr alloys?
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Dear Dr. Swetha P M ,
I suggest you to have a look at the following, interesting papers:
- Biocompatibility and Biological Corrosion Resistance of Ti–39Nb–6Zr+0.45Al Implant Alloy
Yu-Jin Hwang, Young-Sin Choi, Yun-Ho Hwang, Hyun-Wook Cho and Dong-Geun Lee
J. Funct. Biomater., 12, 2 (2021)
Available, as open access, at: https://www.mdpi.com/2079-4983/12/1/2
- Investigation on the corrosion behavior and biocompatibility of Ti-6Al-4V implant coated with HA/TiN dual layer for medical applications
Maryam Kazemi, Shahrokh Ahangarani, Mohammad Esmailian, Ali Shanaghi
Surface and Coatings Technology, Volume 397, 126044 (2020)
My best regards, Pierluigi Traverso.
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I will be very glad if you help me. I dont know how can I find Ecorr and icorr. My samples are AlSi7Mg0.6+SiC+Fe and AlSi7Mg0.6+SiC+Ni.
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I suggest you to have a look at the following, interesting documents:
-Application Note CORR-1 – Basics of Corrosion Measurements by Princeton Applied Research
-Application Note - Getting Started with Electrochemical Corrosion Measurement by Gamry Instruments
-Tafel Plot and Evans Diagram by Palmsens
-Electrochemical Corrosion Studies of Various Metals by Metrohm Autolab
Enjoy reading and my best regards, Pierluigi Traverso.
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UV Curable Adhesives in High Reliability Electronics
1) Do you use UV Curable Adhesives in your application?
2) If not, why? And What adhesive do you use?
3) What are your reasons for using/not using UV curable adhesives?
4) What is your application?
5) Have you had success with UV curable adhesives?
6) Any issues?
7) Have you encountered any electromigration related issues with UV adhesives (current leakage failures, corrosion, etc.)?
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Greg Caswell 1) Do you use UV Curable Adhesives in your application? I have worked on UV curable adhesive.
2) If not, why? And What adhesive do you use?
3) What are your reasons for using/not using UV curable adhesives? External control over curing, seal quickly, spatial and temporal control formation of adhesive, tight sealing.
4) What is your application? Surgical glue.
5) Have you had success with UV curable adhesives? Yes
6) Any issues? Exposure time - compatibility.
7) Have you encountered any electromigration related issues with UV adhesives (current leakage failures, corrosion, etc.)? No
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What i know normally in corrosion inhibition using organic base inhibitors, the organic molecules uses there hetero atom to transfer electrons to the vacant d orbital of the metal, but in case of zinc the d orbital is completely filled, and i believe somehow, the organic inhibitor also transfer these electrons to zinc, please can someone help me understand the chemistry behind it better
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Mohammed Hussein introduced good answer
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For finding the behavior and effect of corrosion in the simulated specimens at a particular location. If the real stress generation due to corrosion with passing times are known at a particular location.
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Hello everyone
i hope to help, i was sent my article to a journal and I got some revision
one of the reviewer comments was :
((According to Table 1, the value of corrosion rate (icorr) corresponds to the change of two parameters: temperature and Ecor. Thus, corrosion at different temperatures occurs under conditions of different potentials. To exclude the influence of two factors simultaneously - temperature and potential - the determination of the corrosion rate at different temperatures should be carried out under conditions of maintaining a constant potential. Therefore, it is incorrect to use the Arrhenius equation and the transition state equation at a changing value of Ecor. But since the author did not maintain the value of Ecor constant with a change in temperature, the values of Ea, ΔH and ΔS given in the article are not true, but are apparent or effective. The author must indicate this in the article”.))
why not I can use Arrhenius eq.?
i attach the data
I hope to help me with how I can reply to the reviewer??
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I agree with Mr. Akula,s suggestion of trying to find the correlation between the two variables. Alternatively, I think the easy option would be to agree with reviewer's suggestion that the values you calculated are not true but effective in getting to the conclusion.
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In chemical adsorption (chemisorption) of inhibitor on metal surface, the amount of surface coverage and inhibitor efficiency (%IE) increased with temperature . In the same time, temperature increased the rate of reaction (corrosion rate). What is the correlation between these two effects? Is the effect of temperature on corrosion rate higher than effect on adsorption process or vise versa?
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  • You have to compare the Activation Energy of each process. A good discussion could be found in "Don't act like a novice about reaction engineering by Jonathan Worstell. CEP (https://www.aiche.org/publications/cep) March 2001, p. 68-72.
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Going by the recent complain in UK about E10 fuel. Please do share your thoughts.
Thank you
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Dear Dr. Toyese Oyegoke ,
I suggest you to have a look at the following paper:
-Corrosion assessment of metals in bioethanol-gasoline blends using electrochemical impedance spectroscopy
Libia M.Baena, Ferley A.Vásquez, Jorge A.Calderón
Helion, Vol. 6, e07585 (2021)
Good reasearch and my best regards, Pierluigi Traverso.
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Could someone suggest using a type of hotplates for digestion of solid samples with HF in the aggressive acid vapors environment (of other acids)? Obviously, ceramic plates are not appropriate, as well as some metal hotplates because of corrosion.
Thank you!
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Hi everybody,
I could find only very few articles on the transpassive corrosion behavior of iron. (Sato 1976, Kozlowski 1984)WITHOUT halide ions. Is it confirmed that the transpassive dissolution of iron does not lead to film breakdown but a constant, potential independent, film thickness? Is this also true for other passivated metals, or are there metals which loose theor oxide film during transpassive dissolution? As far as I know passive films of chromium oxide dissolve completely at potentials exceeding the transpassive potential.
What is the proposed mechanism for transpassive dissolution/corrosion of iron oxide? And why doesnt it lead to complete film dissolution?
Thanks for your answers and discussion.
Best
Ingmar
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You have asked many great questions regarding the transpassivity (and anodic dissolution, in general) of iron.
Transpassivity is often referred to as the increase in current density as more anodic potential are applied (with respect to the passive region), and describes the breakdown of primary passivity. Transpassivity is a bit challenging to define (as an exact point) without much analysis and testing; however, I have found the work of Macdonald and co-workers helpful in this, as they describe it as part of their Point Defect Model (PDM) [Macdonald, D. D. "Some personal adventures in passivity—A review of the point defect model for film growth" Russ. J. Electrochem. 48 (2012) 235–258. doi:10.1134/S1023193512030068.
Additional information regarding the anodic dissolution of iron, in general, can be found in the research of Keddam and co-workers (as well as Bockris and co-workers) where they performed many EIS studies. This book Chapter provides a good starting point: [It is Chapter 3 Anodic Dissolution in Corrosion Mechanisms in Theory and in Practice (3rd ed.), edited by P. Marcus. doi:10.1201/b11020.]
You may also find this work helpful: Avillera, A, Cid, M, and Petit, M.C. Anodic reaction of iron in transpassive range. Journal of Electroanalytical Chemistry and Interfacial Electrochemistry, Vol 105, p 149-160. doi:10.1016/S0022-0728(79)80346-0
With regards to your question on the passive film thickness: The dependence of the passive film thickness on potential has been studied by a number of researchers, typically using surface analysis techniques (e.g. XPS). In general, as more anodic potentials are applied, the oxidation of metals to higher valence species occurs. This is true for iron as it transitions from 2+ to 3+ species during anodic polarization. The work of Strehblow and co-workers provides insight as to the potential dependency of the passive film thickness of Fe, Ni and NiFe alloys (e.g. [Haupt, S., Strehblow, H.H. "Combined electrochemical and surface analytical investigations of the formation of passive layers". Corrosion Science. 29 (1989) 163–182. doi:10.1016/0010-938X(89)90027-9.]
For iron, the passive film thickness is relatively potential independent; however, for Ni, the thickness of the passive film is much more dependent on potential. In my paper, I provide a number of references for the passive film of Ni, Fe, and, in particular, NiFe alloys, as well as provide some insight as to the potential dependency of the passive film thickness for nanocrystalline NiFe alloys: Monaco, L., Sodhi, R.N.S., Palumbo, G. and Erb, U. "XPS study on the passivity of coarse-grained polycrystalline and electrodeposited nanocrystalline nickel-iron (NiFe) alloys," Corrosion Science. 176 (2020) 108902. doi:10.1016/j.corsci.2020.108902.
Lastly, it is important to point out that anodic films can exist on iron (and other metals) other than the passive film. For example, a sulfate-based film has often been reported on Ni and Fe (see references above). During anodic dissolution of Ni in sulfuric acid, for example, this film plays an important role in the dissolution mechanism.
Hopefully these references will provide additional insight for you! Best of luck!
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It has been observed that steel structures subjected to slurry exposure in zinc mines get corroded quite early as zinc slurry contains different type of chemicals. Even coatings get damaged over some time due to the process being adopted in converting minerals to slurry.
Do we have some alternative solution to prevent corrosion of structure in zinc mines?
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Dear sir Om Prakash Chhangani;
Feel atoms are known to be corrosive. They are easily replaced by others in aggressive environments with acids. Methods such as hot-dip galvanizing of somans are used to reduce corrosion activity in order to create a protective coating of 20 to 30 μm. Our latest research shows that the use of nano-galvanized powder can protect the corrosion of steel from 25 to 30 years. Barrier layers are created which do not allow the oxidation of the steel.
You can also browse the literature for other articles on the topic.
I wish you success in your research
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can any researcher help me to find advanced lectrures related to electrochmical corrosion of stainless steel alloys ??
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The following link contains the most recent and advanced review related to electrochmical corrosion metric for not only stainless steel alloys dataset but for wide range of highly corrosion resistant alloys including Al- and Fe-based alloys, high entropy alloys (HEAs), and a Ni-Cr-Mo ternary system. This dataset could be used in the design of highly corrosion resistant of stainless steel alloys.
Best regards
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Hi there,
from LSV measurements it is possible to predict the corrosion rate of general corrosion by the tafel method and calculating the corrosion rate from the corrosion current. It is also possible to measure the pitting potential from LSVs but - as far as I know - the measured pitting potential can only used to qualitative compare the pittng potentials from different metals with each other, to predict which one will show a better protection against pitting corrosion.
Is there a possibility to predict the rate of pitting corrosion (or probability, or something similar) from these LSV measurements (or any other measurement method) in the given environment but without an external potential?
Thanks for your help!
Ingmar
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Dear Dr. Ingmar Bösing ,
localised corrosion can visually investigated by using specimens photographs and macro photographs taken with a high resolution digital camera after different exposure times, in a suitable and specific environment.
Evaluation of the number and area of the points of corrosion can also executed with ImageJ software. We selected and cut a surface of 5 cm×5 cm (25 cm2) from the specimens photographs. After using the programme to process images for brightness and contrast, these areas can be examined through the “Analyze particles” software command.
Pits size can be deeply investigated using an optical metallographic microscope, equipped with a motorized specimenholder table with a display that can showed the movement along the Z-axis. In order to evaluate the maximum pit size we can considered an equivalent pits diameter and the pits depth.
The equivalent pits diameter can be calculated considering the pits boundary as perfect circumferences and using an eyepiece with a graduated reticle. The pits depth was evaluated considering the difference between the focal planes relative to the top and the bottom of each analysed pit.
The measure of the pit depth on the microscope display is visualised in whole increments of micrometre. Therefore, it is possible to make measurements along the Z-axis with a very high precision.
For studying corrosion morphology and chemical composition of corrosion products, the surfaces of the specimens have to first cleaned by blowing air and then analysed under a Scanning Electron Microscope with Electron Probe Micro.
After removing corrosion products by Keller's solution, the surfaces of the specimens can be also studied using a No Contact 3D Optical Profiler, collecting images that are processed with analysis software in order to evaluate pit dimension and depth.
My best regards, Pierluigi Traverso.
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for corrosion study
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The experimental process parameters for chroamperometry test are mainly the value of the constant potential and the exposure time that should apply to the working electrode . The output function of the current variation with time will let you analyzing the stability of the passive layer of the stainless steel 304 and 304L in your specific alkaline medium. In this respect, the constant potential value should previously obtained and defined by the anodic polarization test and taken as the intermediary potential in the passive region (see Fig 1 and Fig 2 in [1]).
Best regards
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Heating, due to welding causes microstructural changes in duplex stainless steel. Besides changing the 50:50 balance ratio of austenite: ferrite, hard phases such as sigma are formed at specific temperatures.
Why sigma phase reduces the corrosion and/or pitting resistance of the DSS in seawater?
How to avoid the formation of the sigma phase during welding?
Is there any procedure or heat treatment that could be done to get rid of the sigma phase from the HAZ!!
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sigma phase is a chromium rich intermetallic phase found in duplex stainless steels, that forms when steel is cooled slowly through the range from around 1000degC to 550degC. Upon controlled heat input results very less inter pass temperature followed by PWHT ( Solution annealing at 1050 °C ) might be avoid sigma or intermetallic phases at high rich chromium in two phase materials
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Which better In the experimental work for corrosion inhibition of metallic alloys, the calculation for determining the inhibition efficiency (E%) by the equation from corrosion rate (CR) by the electrochemical test or calculate the E% from weight loss technique?
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Dear Dr. Ali Sabea Hammood,
the following equation determined the inhibition efficiency (I.E.) and surface coverage (θ) by weight loss measurements, where W1 and W0 are the weight loss values in the presence and absence of inhibitor.
📷
The inhibition efficiency (IE) and corrosion rate (CR) were calculated by Electrochemical measurements by using the formulae:
📷
where i’corr and icorr are the corrosion current density of the substrate in the presence and absence of inhibitor. M = Atomic mass of metal, ρ = density of corroding metal, Z = Number of electrons transferred per metal atom.
For more details, please see the source:
- Synthesis, characterization and corrosion inhibition efficiency of N-(4-(Morpholinomethyl Carbamoyl Phenyl) Furan-2-Carboxamide for brass in HCl medium
N. Zulfareen, K. Kannan, T. Venugopal, S.Gnanavel
Arabian Journal of Chemistry, Vol. 9, Issue 1, Pages 121-135 (2016)
In addition to the presence of the inhibitor, its surface morphology and its distribution are of extreme importance. These characteristics are strongly linked to its protective power towards the substrate and a detailed surface analysis can often provide interesting information.
My best regards, Pierluigi Traverso.
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I am running a coupon of 304L in HCl (pH of 3) and getting a corrosion current of 181 nA. How likely is this accurate?
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If the resolution of your potentiostat is good enough, you can certainly have this little amount of corrosion current. However, you need to put this in perspective. Turn this value into a corrosion rate (mpy or similar). Does it make any sense? Is this value consistent with other measurements, say weight-loss experiments?
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method
techniques
sample preparation
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just to understand the topic more
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My current research is dealing with creating rough copper surfaces with certain attributes. Because the performance of the copper substrate is reliant on this specific surface topography, I am looking to determine how these features may change over time in different environments. Of particular interest is the effect of a biological environment, as well as the effect of air at room temperature. I have already done some research about the effect of a biological environment on copper surfaces and have concluded that in general corrosion occurs, but am unsure how a roughened surface would impact this effect. Any ideas or references is greatly appreciated.
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The rougher the metal surface, the larger the contact surface of corrosive media and the stronger and more quickly the corrosion. This is a general rule for most cases. In addition, corrosion of the rough surfaces is intensified by prolonged retention of water in depressions. In individual cases, this effect can lead to pitting corrosion. Another characteristic of the corrosion of rough surfaces is the condition of corrosion products: the rough the surface, the thicker the layer of corrosion products can be and the better this layer adheres to the metal.
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I am doing research on theoretical computational chemistry.
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I do not know some free software. But I know that some software of quantum mechanics such as Gaussian, Hyperchem, Material Studio, Gamess, and so on could support you to solve well it.
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If we increase or decrease the ductility of 1060 grade aluminum tube then then what is the effect on the corrosion property.
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Dear Sir Abdulaziz Albannai ,
Thank you for replying me.
This is Refrigerant aluminum tube. Pitting corrosion occur in the bend position.
we know that bend property depends on ductility of a materials. But maximum pitting corrosion occur in the bend position.
So have any relation pitting corrosion and ductility?
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no supportive machines, I just put the Az31 in Hanks' solution, and see the corrosion process
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Thank you for interesting question. The surface morphology of AZ31 magnesium alloy may vary with immersion time, since the formation of protective Mg(OH)2-film on rapidly after 2 h immersion in HBSS.
This film layer become more compact with increasing of immersion time and after a certain time (say 24h) the film began to degrade as the Mg(OH)2 layer on the surface is dissolved by Cl- into soluble MgCl2.
This dissolution reaction, in case of stagnant corrosion systems, increases the local hydroxide ions concentration near the surface and so the degradation leads to a local alkalization of the HBSS near alloy surface. After 48h immersion, the degradation promoting a greater tendency for film formation as the local pH increase above 10. At this time and after, the a layer of magnesium phosphate Mg3(PO4)2 and hydroxiapatite Ca10(PO4)6(OH)2 may observed on the surface and that covered by MgO and Mg(OH)2 corrosion products .
Now, it is a clear that the microscopy observations of the surface morphology are related by the immersion time and become clearly visible after 2h of immersion and higher up to a week for obtaining full observations.
best regards
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Is it an acceptable method to use a bounded Warburg element to fit EI spectra associated with metal corrosion and O2 diffusion across a porous layer? I suppose that Orazem & Tribollet have proposed more elaborated and correct solutions to this case. Anyway, can the Warburg element be used as an approximation independent of more exact solutions? Under which considerations?
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I suggest you to have a look at the following, interesting document:
- How to Model Warburg Impedance in Circuit Simulators by Cadence PCB Solutions
My best regards, Pierluigi Traverso.
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I came across this paragraph "Sulphuric acid is an example in which corrosion does not necessarily increase with increasing concentration. This acid is reducing at low and intermediate concentrations, but oxidising when concentrated"
I was wondering why? Thanks a lot!
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Dear Dr. Nazrin Babashova ,
in my early work on corrosion, many years ago, I addressed this topic.
I suggest you to have a look at the following paper:
-“Effect of sulphides on corrosion of Cu–Ni–Fe–Mn alloy in sea water”
Pierluigi Traverso, A. M. Beccaria, G. Poggi
British Corrosion Journal 29(2):110-114 (1994)