Corrosion process and control (TKK-2289)

Slides:



Advertisements
Similar presentations
Electricity from Chemical Reactions
Advertisements

Y12 HSC Chemistry Shipwrecks and Corrosion R. Slider
Metals Nat
Created by C. Ippolito March 2007 Updated March 2007 Chapter 22 Electrochemistry Objectives: 1.describe how an electrolytic cell works 2.describe how galvanic.
FORMS OF CORROSION Corrosion may be classified in different ways
Thermodynamics in Corrosion Engineering
Chapter 23 Electrochemistry
Fuel cells differ from batteries in that the former do not store chemical energy. Reactants must be constantly resupplied and products must be constantly.
CHAPTER 16: CORROSION AND DEGRADATION
CHAPTER 16: CORROSION AND DEGRADATION
Surface Technology Part 4 Corrosion
ISSUES TO ADDRESS... Why does corrosion occur ? 1 What metals are most likely to corrode? How do temperature and environment affect corrosion rate? How.
Chapter 19 Electrochemistry
Crack grows incrementally typ. 1 to 6 increase in crack length per loading cycle Failed rotating shaft --crack grew even though K max < K c --crack grows.
Corrosion of metals and their protection
Lesson 2. Galvanic Cells In the reaction between Zn and CuSO 4, the zinc is oxidized by copper (II) ions. Zn 0 (s) + Cu 2+ (aq) + SO 4 2-  Cu 0 (s) +
Corrosion & Associated Degradation
MSE-536 ISSUES TO ADDRESS... Why does corrosion occur ? 1 What metals are most likely to corrode? How do temperature and environment affect corrosion rate?
Electrochemistry 18.1 Balancing Oxidation–Reduction Reactions
Batteries and Fuel Cells
Corrosion & degradation
Corrosion is when metals react with substances in the Air to produce compounds. The metal is changing from an atom to an ion. The metal atom looses electrons.
Corrosion of Metals.
1 Electrochemistry Chapter 17 Seneca Valley SHS Voltaic (Galvanic) Cells: Oxidation-Reduction Reactions Oxidation-Reduction Reactions Zn added.
Chapter ISSUES TO ADDRESS... Why does corrosion occur ? What metals are most likely to corrode? How do temperature and environment affect corrosion.
Properties of Materials & Corrosion Eng. Shadi Sawalha.
Types of corrosion Dr. Syed Hassan Javed.
CHAPTER 17: CORROSION AND DEGRADATION
CORROSION By: MANAN JAIN ( ) T32
Electrochemistry is the chemistry of reactions which involve electron transfer. In spontaneous reactions electrons are released with energy which can.
Chapter 22 REDOX.
Electrochemistry. Electrochemical Cells  Electrons are transferred between the particles being oxidized and reduced  Two types –Spontaneous = Voltaic.
Chapter 23 Corrosion.
Chapter 20 Electrochemistry.
Corrosion is the unwanted oxidation of a metal.. Oxidation of all Metals in general is called corrosion Oxidation of All Metals is called Corrosion.
 Deals with the relation of the flow of electric current to chemical changes and the conversion of chemical to electrical energy (Electrochemical Cell)
Electrochemistry: Oxidation-Reduction Reactions Zn(s) + Cu +2 (aq)  Zn 2+ (aq) + Cu(s) loss of 2e - gaining to 2e - Zinc is oxidized - it goes up in.
Cell potential is related to concentrations Electrodes can be used that are sensitive to specific ions They measure concentrations of specific ions which.
6/2/20161 CHAPTER 2 CORROSION PRINCIPLES Chapter Outlines 2.1 Oxidation and Reduction Reactions 2.2 Standard Electrode Half- Cell Potentials 2.3 Standard.
Chapter 17 Corrosion and Degradation of Materials.
Shipwrecks, Corrosion and Conservation Summary Slides PART 3 – Jack Dengate.
ENVIRONMENT ASSISTED CRACKING  When a metal is subjected to a tensile stress and a corrosive medium, it may experience Environment Assisted Cracking.
Acid Deposition – the result of air pollutants combining with each other to produce acid precipitation or rainwater that has become acidic. Acid – pH lower.
Corrosion (Rusting) The annual cost of corrosion to the U.S. economy is $350 billion!
Unit 16 Electrochemistry Oxidation & Reduction. Oxidation verses Reduction Gain oxygen atoms 2 Mg + O 2  2 MgO Lose electrons (e - ) Mg (s)  Mg + 2.
Section 14.2 Voltaic Cells p Voltaic cells Voltaic cells convert chemical energy to electrical energy. In redox reactions, oxidizing agents.
Forms of Corrosion: Uniform Pitting Crevice Corrosion or Concentration Cell Galvanic or Two-Metal Stress Corrosion Cracking Intergranular Dealloying Selective.
Corrosion of Iron Since E  red (Fe 2+ ) < E  red (O 2 ) iron can be oxidized by oxygen. Cathode: O 2 (g) + 4H + (aq) + 4e -  2H 2 O(l). Anode: Fe(s)
Chapter 19: Electrochemistry: Voltaic Cells Generate Electricity which can do electrical work. Voltaic or galvanic cells are devices in which electron.
B ATTERIES, FUEL CELLS & CORROSION [ ]. S TANDARD REDUCTION POTENTIALS Place in order of increasing strength as oxidizing agents: Cl 2, Mg +2,
ELECTRO-CHEMICAL CORROSION CHAPTER 3 LECTURER SAHEB M. MAHDI.
In the name of GOD.
Corrosion process and control (TKK-2289)
Definition of Corrosion
Engineering Chemistry CHM 406
CORROSION AND DEGRADATION
Engineering Chemistry (revised edition)
Definition of Corrosion
Corrosion Objectives Corrosion process Environmental factors
Corrosion Intermediate 2.
Corrosion Intermediate 2 Unit 3(c).
Electrochemistry.
Corrosion & Associated Degradation
CHAPTER 13 Corrosion 13-1.
Corrosion Degradation 0f a metal due to reaction with its environment Impairs function and appearance of component.
ISSUES TO ADDRESS... Why does corrosion occur ? 1 What metals are most likely to corrode? How do temperature and environment affect corrosion rate? How.
Ship Related Corrosion Topics
Engineering Materials
Corrosion Fundamentals
Y12 HSC Chemistry Shipwrecks and Corrosion R. Slider
Presentation transcript:

Corrosion process and control (TKK-2289) 15/16 Semester genap Corrosion process and control (TKK-2289) Instructor: Rama Oktavian; Vivi Nurhadianty. Email: rama.oktavian86@gmail.com Office Hr.: T. 13-15, W. 11-12, Th. 13-15

Tujuan Mengetahui proses korosi dan pencegahan serta pengendaliannya

Pokok bahasan Kuliah ke- Pokok bahasan Metode kuliah 1-4. Pendahuluan dan Pengenalan tentang korosi dan proses korosi: Proses elektrokimia korosi Kinetika korosi Tipe – tipe korosi Ceramah Tugas mandiri 5-8 Proses Korosi di industri kimia Presentasi Studi kasus 9-12 Pengendalian korosi: Cathodic protection Corrosion control by inhibition Coating Pemilihan material 13-16 Pengendalian korosi pada Proses Industri Kimia

Introduction Textbooks 1. Zaki Ahmad,” Principles of Corrosion Engineering and Corrosion Control, Butterworth-Heinemann (2006). Pierre R. Roberge, “Corrosion Engineering: Principles and Practice, Mc Graw-Hill (2008).

Introduction Grading system Grading criteria Percentage (%) Tugas 20 Quiz I / midterm 40 Final exam

Environmental Degradation of Materials Corrosion Environmental Degradation of Materials Materials are “attacked” by their operating environment

So, What exactly is corrosion? Corrosion is an irreversible interfacial reaction of a material (metal, ceramic, polymer) with its environment which results in consumption of the material or in dissolution into the material of a component of the environment. Chemistry is at work. We are talking about a certain class of chemical reactions between a metal and the environment.

Corrosion Example: metal corrosion caused by water results from chemical reaction where metal surface is oxidized to form iron oxide (rust).

Corrosion is an oxidation process occurred at low temperature Corrosion is an electrochemical process Anode, electrode which gives electron. Cathode, electrode which accepts electron

Corrosion

Corrosion • Two reactions are necessary: • Other reduction reactions: -- oxidation reaction: -- reduction reaction: • Other reduction reactions: Zn + 2HCl → ZnCl2 + H2 -- in an acid solution -- in a neutral or base solution

Corrosion • Two outcomes: --Metal sample mass --Metal sample mass --Metal is the anode (-) --Metal is the cathode (+) (relative to Pt) (relative to Pt) Standard Electrode Potential

Corrosion • EMF series • Metal with smaller EMF: Electromotive Force V (i.e., more active) corrodes.Ex: Cd-Ni cell V o o metal metal metal Au Cu Pb Sn Ni Co Cd Fe Cr Zn Al Mg Na K +1.420 V +0.340 - 0.126 - 0.136 - 0.250 - 0.277 - 0.403 - 0.440 - 0.744 - 0.763 - 1.662 - 2.262 - 2.714 - 2.924 o DV = 0.153V EMF: Electromotive Force

Corrosion The EMF of a standard Ni-Cd galvanic cell is -0.153 V. If the standard half-cell EMF for the oxidation of Ni is -0.250 V, what is the standard half-cell EMF of cadmium if cadmium is the anode? Solution: The standard half-cell EMF of the cadmium can be calculated by considering the half-cell reactions:

Corrosion Rusting of iron The oxidation reaction that will occur at the local anodes is Fe → Fe2+ + 2e- (anodic reaction) The reduction reaction that will occur at the local cathodes is O2 + 2H2O + 4e- → 4OH- (cathodic reaction) A piece of iron immersed in oxygenated water, ferric hyroxide [Fe(OH)3] will form on its surface

Corrosion • Ranks the reactivity of metals/alloys in seawater Platinum Gold Graphite Titanium Silver 316 Stainless Steel Nickel (passive) Copper Nickel (active) Tin Lead Iron/Steel Aluminum Alloys Cadmium Zinc Magnesium

Corrosion Consider a magnesium-iron galvanic cell consisting of a magnesium electrode in a solution of 1 M MgSO4 and an iron electrode in a solution of 1 M FeSO4. Each electrode and its electrolyte are separated by a porous wall, and the whole cell is at 25°C. Both electrodes are connected with a copper wire. Which electrode is the anode? Which electrode corrodes? In which direction will the electrons flow? In which direction will the anions in the solution move? In which direction will the cations in the solution move? Write an equation for the half-cell reaction at the anode. Write an equation for the half-cell reaction at the cathode. Mg 25°C Fe 1.0 M 1.0 M Mg + 2 solution Fe 2+ solution

Corrosion The magnesium electrode is the anode. The magnesium electrode corrodes since the anode in a galvanic cell corrodes (oxidizes). The electrons will flow from the anode, Mg, to the cathode, Fe. The SO42− anions will flow toward the magnesium anode. The cations will flow toward the iron cathode. The oxidation reaction that occurs at the magnesium anode is: Mg → Mg2++2e− The reduction reaction that occurs at the iron anode is: Fe2++2e−→ Fe .

Corrosion Types of corrosion: Uniform or general attack corrosion Galvanic or two-metal corrosion Pitting corrosion Crevice corrosion Intergranular corrosion Stress corrosion Erosion corrosion Selective leaching or dealloying

Corrosion 1. Uniform/general attack (korosi umum) This one is common in steel that is unprotected by any surface coating. Most noticeable. Surface effect, leaving rust on the surface. The good thing about this, if there is one, is that the corrosion is widely spread around.

Corrosion 1. Uniform/general attack (korosi umum)

2. Galvanic corrosion (korosi galvanis) Steel screw in Mg Steel screws and brass Dissimilar metals, the damage occurs at the anode.

3. Crevice corrosion (korosi celah)

4. Pitting corrosion (korosi sumur) This is similar to crevice corrosion. It is based on low oxygen concentration at the bottom of the pit. This is very common in materials that protect themselves with a passive layer, i.e. stainless. Also, aluminum.

5. Erosion corrosion (korosi erosi) This is caused by the impingement of a high velocity turbulent flow on a surface. The flow is often multi-phase. This means there can be entrained solid particles, or even gas bubbles, as in cavitation of a propeller. The flow will carry away any protective layer that was intended to protect the material, and even abrade the flow surface.

6. Stress corrosion (korosi tegangan) Sometimes called stress corrosion cracking. Ingredients: (1) tensile stress in the metal (2) corrosive (electrolyte) environment. Accelerators: presence of Chloride ion and high temp. Victims: Stainless steel is unsafe in water above 50C and over a few ppm of chloride, if any tension exists. Others: mild steel in alkaline environment, copper alloys in ammonia env. The anode is the stresses region.

6. Stress corrosion (korosi tegangan)

Kontrol terhadap korosi Corrosion PENCEGAHAN KOROSI Korosi dapat dikontrol dengan berbagai cara. Pertimbangan utama adalah masalah ekonomi, terutama akibat yang ditimbulkannya . Kontrol terhadap korosi Pemilihan material: Logam Non logam Coating (pelapisan): Organik Non organik Disain: menghindari konsentrasi tegangan menghindari kontak dengan logam tidak sejenis menghindari adanya jebakan air Proteksi katodik dan anodik Kontrol lingkungan. (temperatur, konsentrasi oksigen dll).

Corrosion Metallic Selection General rules for metallic selection For reducing or, nonoxidizing conditions such as air-free acids & aqueous solutions, Ni & Cu alloy are often used. For oxidizing conditons, Cr containing alloy are used. For extremely powerful oxidizing conditions, Ti & its alloy are commonly used.

Corrosion Coatings Metallic, inorganic, & organic coatings are applied to metals to prevent or reduce corrosion Metallic coating eg.; Zinc coating on steel (sacrificial anode) Inorganic coating (ceramics & glass) eg.; Glass-lined steel vessels Organic coating eg.; paints, varnishes & lacquers

Alteration of Environment 4 general methods of altering an environment to prevent or reduce corrosion are: Lower the system temperature to lower the reaction rates and thus reduce corrosion. Certain exceptions exist, such as seawater, for which the temperature should be raised rather than reduced. Decrease the velocity of corrosive fluids such that erosion corrosion is reduced while fluid stagnation is avoided. Remove oxygen from water solutions. Reduce the concentration of corrosive ions in a solution which is corroding a metal.

Cathodic protection The protection of a metal by connecting it to a sacrificial anode or by impressing a DC voltage to make it cathode Eg; sacrificial anode Impressed current Cathodic protection of an underground pipeline by using sacrificial Mg anode Cathodic protection of an underground tank by using impressed currents

Thank You !