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| Introduction: These pages explain the process of corrosion and the results of our experiments. They will provide a good overall understanding of rusting and corrosion, how it occurs and how it can be prevented. |
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The fundamental reason for corrosion lies in the metals themselves. Basically, metals do not want to exist as pure metal. Very few are found naturally as metal, most are mined as a rock like substance called ore (such as iron ore). Metal ores are oxides. Iron ore is iron oxide, aluminium ore (bauxite) is aluminium oxide. |
| By adding a huge amount of energy and heat to these ores, we can pull the oxygen out of the oxide and turn the metal ore into pure metal . Unfortunately, as soon as the pure metal is given the chance to recombine with oxygen and become a metal oxide again, it will do so. If we turn the iron oxide of iron ore into pure iron through the smelting process (a chemical reaction called reduction), the iron metal we create will try to recombine with oxygen and change back into iron oxide again as soon as possible (a reaction called oxidation). |
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| This is corrosion. When iron metal oxidises, it turns into iron oxide: the brown "rust" familiar to all of us. So in a simple sense, corrosion is simply a metal trying to return to it natural state. |
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As we know from everyday life some metals, such as gold, do not corrode. Gold is actually one of the few metals that does not corrode, which is why it is also one of the few metals that we do find naturally as pure metal. Gold mines do not produce gold ore, they produce gold! Gold does not corrode because its natural form is pure metal. |
This provides an explanation for our observation that oxygen is required for rusting to occur that we made in experiment 1. However, water is also required. Why is that ? |
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