A corrosion inhibitor is a substance which, when added to an environment in a small concentration, effectively reduces the corrosion rate of a metal exposed to that environment.

There are three types of corrosion inhibitors:

1. Anodic inhibitors
2. Cathodic inhibitors
3. Mixed inhibitors

Corrosion inhibition usually results from one or more of three general mechanisms:

The inhibitor causes a metal to form its own protective film of metal oxides, thereby increasing its resistance.

The inhibitor reacts with a potentially corrosive substance in the water.

When choosing the corrosion inhibitor for your application, several things need to be considered, as follows:

1. Materials to be protected
2. Method of application (dip, spray, brush, etc.)
3. Type of protection required (in process, storage or shipping)
4. Type and thickness of coating residue desired
5. Storage, packaging and/or shipping conditions (temperature, humidity seasonal conditions)
6. Interaction with subsequent processes, if not removed
7. Environmental, health and safety requirements
8. Type of product (oil/solvent or water-based)

Electrochemical methods are routinely used for the evaluation of corrosion inhibitor efficiency. The advantages of electrochemical methods are their short measurement time and mechanistic information, which help in the design of corrosion protection strategies, as well as the design of new inhibitors.