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UN1001: REACTOR CHEMISTRY AND CORROSION Section 1: Introduction to Corrosion

2. Did you know?. Internationally, 1 tonne of steel turns into rust every 90 seconds.The energy required to make 1 tonne of steel is approximately equal to the energy an average family consumes over three months.Of every tonne of steel from the world's production, approximately 50% is required t

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UN1001: REACTOR CHEMISTRY AND CORROSION Section 1: Introduction to Corrosion

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    1. 1 UN1001: REACTOR CHEMISTRY AND CORROSION Section 1: Introduction to Corrosion By D.H. Lister & W.G. Cook Department of Chemical Engineering University of New Brunswick

    2. 2 Did you know? Internationally, 1 tonne of steel turns into rust every 90 seconds. The energy required to make 1 tonne of steel is approximately equal to the energy an average family consumes over three months. Of every tonne of steel from the world’s production, approximately 50% is required to replace rusted steel. Source: Zinc Today, newsletter of the American Zinc Association (Spring 1997)

    3. 3 What is corrosion? Usually, it is the reaction of a metal with its environment: e.g. rusting of iron: 4 Fe + 3 O2 + 2 H2O ? 4 FeOOH (lepidocrocite) BUT: at high temperature the corrosion of iron can produce: 3 Fe + 4 H2O ? Fe3O4 (magnetite) + 4 H2 Sometimes, non-metals are said to corrode: e.g. degradation of graphite moderator in a CO2 cooled nuclear reactor C + CO2 ? 2 CO (may be inhibited by addition of CH4)

    4. 4 Discussion points: Other examples of metal corrosion? Do buildings corrode (brick, stone, concrete)? What about erosion? - is it a corrosion phenomenon? Can corrosion be desirable? Other types of corrosion (e.g., plastic, wood, etc.)?

    5. 5 Why does metal corrode? Energy is released as material proceeds towards “natural” state i.e. the thermodynamically stable state. Thus, rusting of iron is a reversion towards the (hydrated - usually) ore; e.g., if lepidocrocite is dehydrated, we get: 2Fe OOH ? Fe2O3 (haematite) + H2O Corrosion, especially of metals, is usually an oxidative process i.e. the metal loses electrons: e.g., 4 Cu + O2 ? 2 Cu2O Zn + 2HCl ? ZnCl2 + H2

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