What are three ways to protect metal from corrosion and how do they work to stop it?

Answer 1

Here are four ways (adapted from the related link):

Corrosion control

Protective coatings: Most widely used corrosion control technique. Protective coatings protect metal from corrosion by separating the surfaces that are susceptible to corrosion from the factors in the environment which cause corrosion to occur.

Cathodic protection: interferes with the natural action of the electrochemical cells that are responsible for corrosion. Cathodic protection can be effectively applied to control corrosion of surfaces that are immersed in water or exposed to soil.

Corrosion inhibitor: Uses one or more of these mechanisms: Adsorption as a thin film on the surface of a corroding material; inducing formation of a thick corrosion product; forming a passive film on the metal surface; changing characteristics of the environment either by producing protective precipitates or by removing or inactivating an aggressive constituent.

Answer 2

Three ways to protect metal from corrosion are:

1. Applying a protective coating such as paint or plating to create a barrier between the metal and the surrounding environment.
2. Using sacrificial anodes that are more reactive than the metal being protected, so they corrode instead of the metal.
3. Employing corrosion inhibitors that can be applied as a film on the metal surface to prevent or slow down corrosion by adsorbing onto the metal surface and forming a protective layer.