14 - CIVE 2700 Civil Engineering Materials, Winter 2007...

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
CIVE 2700 – Civil Engineering Materials, Winter 2007 1 Corrosion Professor George Hadjisophocleous, Ph.D., P.Eng. Carleton University Department of Civil and Environmental Engineering Ottawa, Ontario CIVE 2700 – Civil Engineering materials, Winter 2007, 14.2 Outline • Why study corrosionB • Corrosion of metals • Electrode potential • Corrosion rates • Corrosion prevention
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
CIVE 2700 – Civil Engineering Materials, Winter 2007 2 CIVE 2700 – Civil Engineering materials, Winter 2007, 14.3 Introduction Why study corrosionB Knowing the mechanisms and causes of corrosion and degradation we can take measures to prevent them from occurring. Change material Change environmental conditions Protect material Most materials interact with their environments. This interaction may cause deterioration of the materials mechanical and other properties (strength, ductility, colour). If ignored it may lead to adverse consequences . CIVE 2700 – Civil Engineering materials, Winter 2007, 14.4 Introduction • Deterioration mechanisms are different for metals, ceramics and polymers. – Metals: corrosion, dissolution, oxidation – Ceramics: resistant to deterioration (they may corrode at high temperatures and extreme environments) – Polymers: may dissolve when exposed to a liquid solvent or absorb the solvent and swell. Exposure to electromagnetic radiation may cause alteration of their molecular structure.
Background image of page 2
CIVE 2700 – Civil Engineering Materials, Winter 2007 3 CIVE 2700 – Civil Engineering materials, Winter 2007, 14.5 Corrosion of Metals • Corrosion is defined as the destructive and unintentional attack of a metal; it usually begins at the surface. • Corrosion costs to industrialized societies is approximately 5% of a nation’s income. • Costs include: cost of prevention, maintenance, replacement of products lost or contaminated as a result of corrosion reactions. • Examples: rusting of automotive body panels and radiator and exhaust components. CIVE 2700 – Civil Engineering materials, Winter 2007, 14.6 Corrosion of Metals • Electrochemical corrosion is the most common form of corrosion in metals. • Chemical reaction in which electrons transfer from one chemical species to another. • Metal atoms lose or give up electrons, (oxidation reaction). It occurs mainly in an aqueous medium in which ions are present in water, soil, or moist air. • An electric circuit is created, called an electrochemical cell. • This process is also used to electroplate protective or decorative coatings onto materials.
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
CIVE 2700 – Civil Engineering Materials, Winter 2007 4 CIVE 2700 – Civil Engineering materials, Winter 2007, 14.7 Corrosion of Metals Electrochemical cell – The electrochemical cell has four components 1. The anode 2. The cathode 3. Connection between anode and cathode 4. A liquid electrolyte in contact with both the anode and cathode. CIVE 2700 – Civil Engineering materials, Winter 2007, 14.8
Background image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 20

14 - CIVE 2700 Civil Engineering Materials, Winter 2007...

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online