1) Corrosion is the destruction and loss of metals through chemical or electrochemical attack by the environment. It occurs through both dry corrosion (in absence of moisture) and wet corrosion (in presence of electrolyte and oxygen).
2) Wet corrosion involves the formation of galvanic cells on metal surfaces where anodic and cathodic reactions occur. At the anode, metal oxidizes and releases electrons. At the cathode, reduction occurs through hydrogen evolution, oxygen absorption, or hydroxyl ion formation depending on conditions.
3) Common types of corrosion include differential metal corrosion, differential aeration corrosion, stress corrosion, and grain boundary corrosion. Corrosion can be controlled through methods like anodizing,
Corrosion Chemistry : Its Causes and RemedyArijitDhali
This Conceptual Power Point project consists of a grieve description about the science of Corrosion, perfect for covering whole topic for short period of time. The project consists of basic knowledge regarding corrosion, its type of causes that is dry and wet corrosion. It also summarizes about different types of differential corrosion and its remedies. Its allover a good conceptual ppt for students of chemistry in their prelims. It's good for the ones achieving for engineering degrees.
Corrosion Chemistry : Its Causes and RemedyArijitDhali
This Conceptual Power Point project consists of a grieve description about the science of Corrosion, perfect for covering whole topic for short period of time. The project consists of basic knowledge regarding corrosion, its type of causes that is dry and wet corrosion. It also summarizes about different types of differential corrosion and its remedies. Its allover a good conceptual ppt for students of chemistry in their prelims. It's good for the ones achieving for engineering degrees.
Corrosion, types of corrosion, examples and mechanism of Dry or Chemical Corrosion, Oxidation Corrosion, Nature of Oxide layer formed, Pilling - Bedworth rule, Passivity or Passivation
Types of Wet or Electrochemical Corrosion, Differential aeration corrosion, Galvanic corrosion, Pitting corrosion, Waterline corrosion, Crevice corrosion, Stress corrosion and their mechanisms and suitable examples.
June 3, 2024 Anti-Semitism Letter Sent to MIT President Kornbluth and MIT Cor...Levi Shapiro
Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
• The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
Model Attribute Check Company Auto PropertyCeline George
In Odoo, the multi-company feature allows you to manage multiple companies within a single Odoo database instance. Each company can have its own configurations while still sharing common resources such as products, customers, and suppliers.
Corrosion, types of corrosion, examples and mechanism of Dry or Chemical Corrosion, Oxidation Corrosion, Nature of Oxide layer formed, Pilling - Bedworth rule, Passivity or Passivation
Types of Wet or Electrochemical Corrosion, Differential aeration corrosion, Galvanic corrosion, Pitting corrosion, Waterline corrosion, Crevice corrosion, Stress corrosion and their mechanisms and suitable examples.
June 3, 2024 Anti-Semitism Letter Sent to MIT President Kornbluth and MIT Cor...Levi Shapiro
Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
• The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
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In Odoo, the multi-company feature allows you to manage multiple companies within a single Odoo database instance. Each company can have its own configurations while still sharing common resources such as products, customers, and suppliers.
How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
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Francesca Gottschalk from the OECD’s Centre for Educational Research and Innovation presents at the Ask an Expert Webinar: How can education support child empowerment?
Macroeconomics- Movie Location
This will be used as part of your Personal Professional Portfolio once graded.
Objective:
Prepare a presentation or a paper using research, basic comparative analysis, data organization and application of economic information. You will make an informed assessment of an economic climate outside of the United States to accomplish an entertainment industry objective.
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This slides describes the basic concepts of ICT, basics of Email, Emerging Technology and Digital Initiatives in Education. This presentations aligns with the UGC Paper I syllabus.
Exploiting Artificial Intelligence for Empowering Researchers and Faculty, In...Dr. Vinod Kumar Kanvaria
Exploiting Artificial Intelligence for Empowering Researchers and Faculty,
International FDP on Fundamentals of Research in Social Sciences
at Integral University, Lucknow, 06.06.2024
By Dr. Vinod Kumar Kanvaria
2. Corrosion is defined as the destruction and consequent loss of metals
through chemical or electrochemical attack by the environment
Metal Oxides, Metal Sulfides,
or Metal Hydroxides
5. Electrochemical theory of corrosion / WET Corrosion
1) Formation of Galvanic cells - Anodic and cathodic areas are formed resulting in a large
number of minute galvanic cells.
2) Anodic Reaction: At the anodic area metal undergoes oxidation with the release of
electrons
Fe → Fe2+ + 2 e-
6. 3) Cathodic Reaction - The electrons flow from the anodic to cathodic area and cause reduction. There are 3 possible
ways in which reduction can take place.
•In acidic medium and absence of oxygen: hydrogen ions are reduced to hydrogen gas.
•In neutral and in the absence of oxygen: If the solution is neutral and in the absence of oxygen, water is
reduced to H2 and OH-
•In neutral and aerated medium: when the solution is neutral and aerated, hydroxyl ions are formed as follows.
• Formation of corrosion product:
The hydroxyl ions migrate towards anode and react with metal ions (Mn+ ions) and forms corrosion
product. In the case of iron OH- reacts with Fe2+ ions and forms an insoluble hydrated ferric oxide known
as brown rust.
8. 1) Differential metal corrosion :
Differential metal corrosion arise when
two dissimilar metals are in contact
with each other
Higher the difference in potential,
higher will be the rate of
corrosion.
– 0.44 V 0.34 V
At anode : Fe → Fe2+ + 2e-
At cathode (either hydrogen evolution or
oxygen absorption)
2 H+ + 2e- → H2↑
O2+ 2 H2O + 4 e- → 4 OH-
9. 2) Differential aeration corrosion :
It occurs when a metal surface is
exposed to differential air (or)
oxygen concentration.
The difference in oxygen concentration
produces a potential difference and causes
corrosion current to flow from cathode to
anode
Part of the metal below the water level acts as anode
undergoes corrosion and the part above the water
level acts as cathode and remain unaffected.
10. Waterline corrosion is a case of differential aeration corrosion.
Water line corrosion
A distinct brown line is formed just below
the water line due to the deposition of rust.
12. 1)Anodizing
Process of anodizing of Aluminum
Anodizing is generally produced on non-ferrous metals like Al, Zn, Mg and their alloys.
Aluminium when made cathode allows the passage of electrons but cease to
conduct when it is made anode in aqueous solution of chromic acid (or)
H2SO4.This is because of the formation of a thin layer of Al2O3 over the metal.
Anode: Aluminum
Cathode: Cu / Steel/Lead
Electrolyte: 5-10 % chromic acid (or) 10 %
H2SO4
Temperature: 35oC
Voltage: 40 V
Current density: 100 A /m2
13. At anode
(Oxidation): 2Al + 3 H2O → Al2O3 + 6 H++6 e-
At cathode
(Reduction): 6 H+ + 6 e- → 3 H2
Overall reaction: 2 Al + 3H2O → Al2O3 + 3H2
A current density of 100 A/m2 is applied which
oxidizes the outer layer of Al to Al2O3
14. Advantages
• Increases the corrosion resistance
• Increases in surface hardness and abrasion resistance
• Provides better adhesion for paint primers
• Electrical and thermal insulation
• Porous layer allows for the coloring and sealing of the coating
Application
Anodized articles are used as soap boxes, tiffin carriers, window frames,
nameplates decorative object.
15. 2) Cathodic protection
In cathodic protection electrons are provided from an external source so that the
metal or alloy remains as cathode.
It is broadly divided into two:
Sacrificial anodic protection: SAP method
Impressed current cathodic protection: ICCP method
16. Sacrificial anodic protection: SAP method
Metals like Mg, Al and Zn are more active
and hence are used as anodes.
These metals being more active acts as anode
undergo corrosion and supply electrons to
the specimen.
Since anodic metals are scarified to protect
the metal structure this technique is called
sacrificial anode method.
17.
18. Benefits
• No power source is required
• Simple to install, operate and maintain
• Additions easily installed
Example: Mg block connected to buried oil storage tanks,
Zn wire fixed to the sides of ocean-going ships
19. 3) Metal coating
Galvanization
The process of depositing a protective layer of zinc on steel or iron
is called galvanization.
Zinc coatings are generally obtained by
hot dipping of the base metal in a
molten zinc bath and the process is
called galvanization
Why Zn ?
• Low cost of zinc
• easy application of the coating
• efficient anodic protection afforded.
20. Hot dip galvanization
Base metal surface is
washed with organic
solvents
remove organic impurities
such as oil and grease
water wash
remove excess organic
solvents
Washed with dilute
sulphuric acid
(pickling)
remove rust and other
inorganic deposits.
water wash
remove excess acids
Steam zone process
(Drying process)
Treating with Flux
mixture of aqueous solution ZnCl2
and NH4Cl which acts as flux
flux treatment enhances the adsorption
process of base metal
Dry
Dipped in
molten zinc
4500 C.
Passing the metal
through rollers
Excess zinc is released
Annealing
(calcination)
enhances the adsorption and
coating efficacy
21.
22. Advantages
Since the coating is anodic in nature the exposure of base metal will not cause
corrosion.
Disadvantages
Since Zn salts are poisonous , food materials cannot be stored in container.
Uses/Applications
• To make galvanized articles
• Galvanized Iron objects are used as roofing sheets, wires, pipes
• To manufacture automobile parts, bolts & nuts, nails etc
23. Corrosion Penetration Rate (CPR)
thickness loss per unit of time.
Several pieces of data must be collected to calculate the corrosion penetration rate
for any given metal:
The weight lost (the decrease in weight of the metal during the period of
reference).
The density of the metal.
The total surface area initially present.
The time taken for the metal to corrode.
24. CPR = (k x W) / (D x A x T)
where k = a constant
W = total weight lost
T = time taken for the loss of metal
A = the surface area of the exposed metal
D = the metal density in g/cm³
25. CPR in mpy (mil per year)
k = 534
W = mg
D = g/cm3
A = inch2
T = hours
CPR in mmpy (millimetre
per year)
k = 87.6
W = mg
D = g/cm3
A = cm2
T = hours
SI units for CPR
For most application a corrosion penetration rate
less than 20 mpy (0.5 mm/yr) is acceptable.
26. Numerical problem:
Q1) A piece of corroded metal alloy plate was found in a submersed
ocean vessel ,it was estimated that the original area of plate was 800
cm2 and that approximately 7.6 Kg had corroded a way during the
submersion , assuming a corrosion penetration rate of 4 mm/yr for this
alloy in seawater , estimate the time of submersion in years , the
density of alloy is 4.5 g/cm3.
27. Q2: A steel of area 100 inch2 is exposed to air near the seashore. After 1 year it was
found that the steel sheet has lost 485 g due to corrosion. What is the value of CPR in
mils/year and in mm/year ? Can such steel sheet be applicable for the construction
purpose where the steel sheet is exposed?
Editor's Notes
Water line corrosion is observed usually in steel water tanks and ships floating in sea water for a long time
The rate of material removal as a consequence of the chemical action is an important corrosion parameter, this may be expressed as the corrosion penetration rate CPR, or the thickness loss per unit of time.