Once you have removed rust from a metal component, one of the most effective ways to protect it and prevent future rusting is to treat the surface. The right surface treatment can help reduce maintenance costs and extend the usable lifespan of the part.
Different part materials and uses will require different anti-rust surface treatments.
Temporary storage oil and grease coatings are used to protect parts for a short period of time, usually for transport, and some wax and ceramic coatings can be used as a combination of lubrication and waterproofing. Temporary surface treatment can also involve things like anti-corrosion paint or varnish.
Permanent coatings tend to be more expensive, but can extend the life of metal parts much further. Some common examples include covering the part with a layer of another metal to isolate it from contact with air and water. These fall into two categories:
Non-reactive coatings that use with a so-called passivating oxidation layer. This could be a metal like tin (especially in the food industry), chromium and cadmium, or a ceramic or carbide (for example tungsten carbide)
Reactive coatings, for example galvanising steel with zinc. The zinc oxidizes and forms a barrier layer that protects the steel beneath.