Living Reference Work Entry

Encyclopedia of Polymers and Composites

pp 1-11

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  • Chris DeArmittAffiliated withLKAB Minerals Inc., Phantom Plastics LLC Email author 


Iron oxide Magnetite High density Microwaveable Specialty filler Radiation shielding


Magnetite is a hard, black, ferrimagnetic, lustrous iron oxide, Fe3O4, which occurs naturally but may also be synthesized, especially when nanoparticles are desired. It is used as specialty filler because of its unique combination of electrical, thermal, and magnetic properties as well as for its exceptionally high density.


Magnetite is a remarkable material with unusual properties and diverse applications. Probably the best-known example is magnetite iron ore used for steel production, which consumes millions of tons per year. Another lesser known use is in water purification, where very high purity magnetite is used as a feedstock to produce iron-based chemicals. It is also used as a catalyst in the production of ammonia. There are many other less well-known places where we encounter magnetite. For example, true gun bluing is a thin layer of magnetite which passivates the surface of iron to help prevent corrosion and to lend a decorative effect. Magnetite and oth ...

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