Material Science and Metallurgy

15

Corrosion and Oxidation

15.1 INTRODUCTION

The unintentional deterioration of a material by an electrochemical process is known as corrosion. Moreover, corrosion process is the reverse process of producing/extracting metal from ores, because pure metals tend to revert to their original state of oxides, sulphides and so on. Except noble metals, gold and platinum, all other metals exist in nature in the form of oxides, sulphides, carbonates and silicates. Lot of energy is consumed in extracting pure metal from its ores as iron is extracted from haematite (Fe₂O₃). So pure metals are of high-energy state, which is unstable, therefore when they come in contact with environment, gases and liquids, they tend to revert to their original form or in ...