Discuss the corrosion of metals (steel and iron) in chemical process atmospheres
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Due to iron’s tendency to naturally form iron oxides, it is highly reactive in many environments; for this reason, it also possesses a certain degree of corrosion resistance. Sometimes it undergoes an oxidation reaction with the air, forming a protective oxide film on the surface; this film prevents rusting in air with 99% relative humidity. However, the presence of even 0.01% SO2 will disrupt the effect of the membrane, allowing corrosion to continue. Under typical chemical atmospheric conditions, the corrosion rate of ferrous metals increases over time. This is because the accumulation of corrosive pollutants makes the corrosive environment more severe.
The corrosion of iron and steel in chemical atmospheres is mainly due to the natural tendency of iron to form oxides. In a normal environment, these oxides can form a protective film on the surface, effectively preventing rusting. However, once pollutants such as SO2 are present in the air, this protective film is damaged, leading to an accelerated corrosion process. Over time, the accumulation of pollutants in the chemical industry atmosphere exacerbates the corrosive environment, thereby accelerating the corrosion rate of steel and iron. Therefore, additional protective measures are required when using steel in chemical environments to extend its service life. .