Introduction

Abstract

Metal corrosion is, in fact, spontaneous. In nature, only a few kinds of metals such as gold, silver, and platinum exist in elemental state, while most metals form compounds, i.e., they exist as ores, the most stable state, which is called a thermodynamically stable state. When metal is smelted to its elemental state, it becomes thermodynamically unstable. Transition from a thermodynamically unstable state to a stable state is a spontaneous process. Therefore, it can be said that metal corrosion is inevitable and thus we may only take some efforts to slow down this process, but cannot completely prevent it.