katodipinnoitteen

Katodipinnoite, or cathodic coating, is a surface treatment applied to metal to function as the cathodic component of a galvanic corrosion system. The coating is designed to be more noble than the substrate in an electrolyte, helping to suppress anodic dissolution of the underlying metal and to improve overall resistance to corrosion. In Finnish usage, the term katodipinnoite is common; the genitive katodipinnoitteen appears in technical texts.

In practice, cathodic coatings protect by two mechanisms: the barrier effect of a dense coating that limits electrolyte ingress, and, when the coating is conductive, by acting as a current-carrying layer that maintains a favorable electrochemical potential on the surface. If the coating is damaged, exposed areas can become preferential sites for corrosion unless protected by the surrounding coating.

Applications and methods: Cathodic coatings are usually produced by electrodeposition of inorganic or organic layers, chemical conversion coatings that chemically modify the surface, or by thin ceramic or oxide coatings that provide barrier properties. Materials range from conductive polymers to specialty oxides. Selection depends on substrate, environment, and performance requirements.

Advantages and limitations: Benefits include enhanced corrosion resistance, compatibility with other coatings, and potential reductions in maintenance. Limitations include sensitivity to coating integrity, environmental and cost considerations, and the need for proper surface preparation, controlled deposition, and inspection to ensure uninterrupted protection.

See also: corrosion protection; electrodeposition; conversion coating; cathodic protection.