Dry corrosion of metals — Industrial cases: halogens

Many industrial environments contain halogens (Cl, F, I, Br) which accelerate the corrosion of metallic materials. Among halogens, chlorine is the most widespread, and will be the focus of this article. It is present in petrochemical processes, with the chlorination of hydrocarbons, the cracking of ethylene dichloride for the production of vinyl chloride; in hydrogen production with the thermal decomposition of seawater; in energy production with waste incineration or during the combustion or conversion of coal. Due to the high vapor pressures of metal chlorides, chlorination is also an important step in extractive metallurgy in the production of titanium, zirconium, tantalum, niobium, tungsten but also nickel or TiO ₂ or SiO ₂ . These processes generally involve oxidizing conditions with a significant content of Cl ₂ , HCl or other chlorine-containing compounds. The presence in the gas of other species such as CO, CO ₂ , H ₂ S, SO ₂ often complicates the corrosion mechanisms involved. Halogen attack also occurs in industrial processes using fuel oils or fossil fuels containing impurities such as sodium and potassium. Halogens react rapidly to form salts, including NaCl and KCl, which will generate corrosion problems that we address in the article .