Mechanism of steel corrosion
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This post was last edited by Wang Wei2 on July 21, 2024, at 09:37. The phenomenon in which objects such as metals, concrete, wood, and rubber are damaged due to chemical and electrochemical actions exerted by the surrounding environmental media is called corrosion; among these, the corrosion of metals is the main subject of study. With a few precious metals aside, all metals are obtained from their natural state through energy-consuming processes such as smelting and electrolysis. For example, the iron found in nature isn’t pure iron at all; it is extracted from iron ore in blast furnaces or heating furnaces. Coal mines or coke are also added during the refining process, and the mixture is heated to very high temperatures. In this process, iron ore absorbs a great deal of energy; part of this energy is stored in the steel. Therefore, any piece of steel can be regarded as a charged battery. This steel will later release the stored energy in the form of electricity. During the energy release process, certain components of steel are consumed, which leads to corrosion of the steel. In this way, steel returns to its natural state in which it can exist stably. Therefore, metals have a tendency to return to their natural combined state (ore) at any time and place, releasing energy in the process – this is the tendency of metals to corrode naturally.
The corrosion of steel occurs primarily through electrochemical reactions. When steel comes into contact with moisture and oxygen, iron atoms lose electrons to form iron ions, while the electrons are transferred to oxygen molecules, causing them to be reduced to hydroxide ions. This process causes iron to continue oxidizing, forming rust. This natural tendency causes steel to transition from a high-energy state to a low-energy state, that is, to return from its refined metallic form to a more stable ore form. .
Although the specific principle is not explained, the angle is reasonable