Why are ceramics resistant to corrosion?

• A. Because they are metals with strong bonding
• B. Because they are composed of cations and anions that are effectively already oxidized and reduced
• C. Because they have high ductility
• D. Because they are always inert to all chemical reactions

Answer: (B)

Corrosion is essentially a redox process driven by the environment reacting with a material. Ceramics resist corrosion because their structure is made of ions held together by very strong ionic or covalent bonds, forming chemically stable compounds. The ions that make up these ceramics are already in stable oxidation states within the compound, so there’s little thermodynamic drive for them to undergo further oxidation or reduction when exposed to typical environments. In short, the constituent cations and anions are effectively already in the states that are not easily changed, and the solid’s high lattice energy and low solubility make chemical attack slow. This combination explains their strong resistance to corrosion.