Chapter 22 - Corrosion and Wear - PPT, The Science and Engineering of Materials, PDF Download

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1
1
The Science and Engineering 
of Materials, 4
th
ed
Donald R. Askeland – Pradeep P. Phulé
Chapter 22 – Corrosion and Wear
Page 2


1
1
The Science and Engineering 
of Materials, 4
th
ed
Donald R. Askeland – Pradeep P. Phulé
Chapter 22 – Corrosion and Wear
2
2
Objectives of Chapter 22
? To introduce the principles and mechanisms 
by which corrosion and wear occur under 
different conditions. This includes the 
aqueous corrosion of metals, the oxidation 
of metals, the corrosion of ceramics, and 
the degradation of polymers. 
? To give summary of different technologies 
that are used to prevent or minimize 
corrosion and associated problems.
Page 3


1
1
The Science and Engineering 
of Materials, 4
th
ed
Donald R. Askeland – Pradeep P. Phulé
Chapter 22 – Corrosion and Wear
2
2
Objectives of Chapter 22
? To introduce the principles and mechanisms 
by which corrosion and wear occur under 
different conditions. This includes the 
aqueous corrosion of metals, the oxidation 
of metals, the corrosion of ceramics, and 
the degradation of polymers. 
? To give summary of different technologies 
that are used to prevent or minimize 
corrosion and associated problems.
3
3
Chapter Outline 
? 22.1 Chemical Corrosion
? 22.2 Electrochemical Corrosion
? 22.3 The Electrode Potential in 
Electrochemical Cells
? 22.4 The Corrosion Current and Polarization
? 22.5 Types of Electrochemical Corrosion
? 22.6 Protection Against Electrochemical 
Corrosion
? 22.7 Microbial Degradation and 
Biodegradable Polymers
? 22.8 Oxidation and Other Gas Reactions
? 22.9 Wear and Erosion
Page 4


1
1
The Science and Engineering 
of Materials, 4
th
ed
Donald R. Askeland – Pradeep P. Phulé
Chapter 22 – Corrosion and Wear
2
2
Objectives of Chapter 22
? To introduce the principles and mechanisms 
by which corrosion and wear occur under 
different conditions. This includes the 
aqueous corrosion of metals, the oxidation 
of metals, the corrosion of ceramics, and 
the degradation of polymers. 
? To give summary of different technologies 
that are used to prevent or minimize 
corrosion and associated problems.
3
3
Chapter Outline 
? 22.1 Chemical Corrosion
? 22.2 Electrochemical Corrosion
? 22.3 The Electrode Potential in 
Electrochemical Cells
? 22.4 The Corrosion Current and Polarization
? 22.5 Types of Electrochemical Corrosion
? 22.6 Protection Against Electrochemical 
Corrosion
? 22.7 Microbial Degradation and 
Biodegradable Polymers
? 22.8 Oxidation and Other Gas Reactions
? 22.9 Wear and Erosion
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4
? Chemical corrosion - Removal of atoms from a material 
by virtue of the solubility or chemical reaction between 
the material and the surrounding liquid.
? Dezincification - A special chemical corrosion process by 
which both zinc and copper atoms are removed from 
brass, but the copper is replated back onto the metal.
? Graphitic corrosion - A special chemical corrosion 
process by which iron is leached from cast iron, leaving 
behind a weak, spongy mass of graphite.
Section 22.1                              
Chemical Corrosion
Page 5


1
1
The Science and Engineering 
of Materials, 4
th
ed
Donald R. Askeland – Pradeep P. Phulé
Chapter 22 – Corrosion and Wear
2
2
Objectives of Chapter 22
? To introduce the principles and mechanisms 
by which corrosion and wear occur under 
different conditions. This includes the 
aqueous corrosion of metals, the oxidation 
of metals, the corrosion of ceramics, and 
the degradation of polymers. 
? To give summary of different technologies 
that are used to prevent or minimize 
corrosion and associated problems.
3
3
Chapter Outline 
? 22.1 Chemical Corrosion
? 22.2 Electrochemical Corrosion
? 22.3 The Electrode Potential in 
Electrochemical Cells
? 22.4 The Corrosion Current and Polarization
? 22.5 Types of Electrochemical Corrosion
? 22.6 Protection Against Electrochemical 
Corrosion
? 22.7 Microbial Degradation and 
Biodegradable Polymers
? 22.8 Oxidation and Other Gas Reactions
? 22.9 Wear and Erosion
4
4
? Chemical corrosion - Removal of atoms from a material 
by virtue of the solubility or chemical reaction between 
the material and the surrounding liquid.
? Dezincification - A special chemical corrosion process by 
which both zinc and copper atoms are removed from 
brass, but the copper is replated back onto the metal.
? Graphitic corrosion - A special chemical corrosion 
process by which iron is leached from cast iron, leaving 
behind a weak, spongy mass of graphite.
Section 22.1                              
Chemical Corrosion
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©2003 Brooks/Cole, a division of Thomson Learning, Inc.  Thomson Learning
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is a trademark used herein under license.
Figure 22.1  Molten lead is held 
in thick steel pots during 
refining.  In this case, the 
molten lead has attacked a weld 
in a steel plate and cracks have 
developed. Eventually, the 
cracks propagate through the 
steel, and molten lead leaks 
from the pot.