Ferrocerium is a synthetic pyrophoric alloy that produces hot sparks that can reach temperatures of 3,000 °C (5,430 °F) when rapidly oxidized by the process of striking.[clarification needed] This property allows it to have many commercial applications, such as the ignition source for lighters (where it is often known by the misleading name "flint"), strikers for gas welding and cutting torches, deoxidization in metallurgy, and ferrocerium rods (also called ferro rods, flint-spark-lighters and wrongly "flint-and-steel" as this is the name of a different type of lighter using a section of high carbon steel and a natural flint). Due to ferrocerium's ability to ignite in adverse conditions, rods of ferrocerium are commonly used as an emergency combustion device in survival kits.
Ferrocerium was invented in 1903 by the Austrian chemist Carl Auer von Welsbach. It takes its name from its two primary components: iron (from Latin: ferrum), and the rare-earth element cerium. The pyrophoric effect is dependent on the brittleness of the alloy and its low autoignition temperature.
While ferrocerium-and-steels function in a similar way to natural flint-and-steel in fire starting, ferrocerium takes on the role that steel played in traditional methods: when small shavings of it are removed quickly enough the heat generated by friction is enough to ignite those shavings, converting the metal to the oxide, i.e., the sparks are tiny pieces of burning metal. The sparking is due to cerium's low ignition temperature of between 150 and 180 °C (302 and 356 °F). About 700 tons were produced in 2000.
It is also known in Europe as Auermetall after its inventor Baron Carl Auer von Welsbach. Three different Auermetalls were developed: the first was iron and cerium, the second also included lanthanum to produce brighter sparks, and the third added other heavy metals. In the Baron von Welsbach's first alloy, 30% iron (ferrum) was added to purified cerium, hence the name "ferro-cerium".
A modern ferrocerium firesteel product is composed of an alloy of rare-earth metals called mischmetal (containing approximately 20.8% iron, 41.8% cerium, about 4.4% each of praseodymium, neodymium, and magnesium, plus 24.2% lanthanum. A variety of other components are added to modify the spark and processing characteristics. Most contemporary flints are hardened with iron oxide and magnesium oxide.
- Reinhardt, Klaus and Herwig Winkler (2000). "Cerium Mischmetal, Cerium Alloys, and Cerium Compounds". In Wiley-VCH, Ullmann's Encyclopedia of Industrial Chemistry. John Wiley and Sons. doi:10.1002/14356007.a06_139.
- van Weert, Ad, Joop Bromet, Alice van Weert (1995). The Legend of the Lighter. New York: Abbeville Press, p. 45.
- Hirch, Alcan (1920). "Ferrocerium, its Manufacture and Uses", Iron Age 106 (Sep. 2): 575–576.
- Cerium flint rod product description Archived 2008-10-24 at the Wayback Machine