Rust is a product of the reaction of iron and oxygen in the presence of water. Usually red in appearance, it is the result of corrosion of iron or its alloys, such as steel. At the atomic level, the oxygen in water combines with the metal forming a new substance called an oxide, leaving the metal bonds weakened. Here are some types of rust prevention which is a goal of good design.
A deaerator is any device or equipment that removes dissolved gases, such as oxygen from liquids. Water that is used in a boiler system must be deaerated. The dissolved oxygen in this water would attach to the walls inside the metal piping and form oxides that would cause corrosion. Deaerator systems reduce the oxygen to extremely low levels, offering protection to a boiler system.
The process of galvanization involves the application of a layer of zinc coating to iron or steel to prevent rusting. Hot-dip galvanizing involves submerging parts into molten zinc. Cold-galvanizing spray involves coating metallic parts with several layers of a spray paint.
Rustproofing refers to the use of coatings such as lacquer, varnish or paint to protect an iron or steel component. In automotive design and manufacturing, these coating is commonly applied to body parts. Usually this type of protection has to be reapplied periodically especially if mechanical wear is present.
In cathodic protection, the rusting process is suppressed by applying an electrical charge. A new cell is formed when an anode material such as zinc, aluminum or magnesium serves as the “sacrificial” metal, while the iron or steel becomes the cathode. Eventually, the anode material wears away unless reapplied.
Rusting is a simple reaction that can have devastating results. For example, reinforcing steel that oxidizes in a structural concrete member will lead to failure which could result in serious injury or death. Rust prevention is crucial to safe, long lasting performance of major mechanical systems.