Ferrocerium

 ( Ferroalloys ) 

Ferrocerium (also known in Europe as Auermetall) is a synthetic Pyrophoricity alloy of mischmetal (cerium, lanthanum, neodymium, other trace lanthanides and some iron – about 95% lanthanides and 5% iron) hardened by blending in oxides of iron oxide and/or magnesium oxide. When struck with a harder material, friction produces hot fragments that oxidize rapidly when exposed to the oxygen in the air, producing sparks that can reach temperatures of . The effect is due to the low ignition temperature of cerium, between .

Ferrocerium has many commercial applications, such as the ignition source for lighters, strikers for gas welding and cutting torches, deoxidization in metallurgy, and ferrocerium rods. Because of ferrocerium's ability to ignite in adverse conditions, rods of ferrocerium (also called ferro rods, spark rods, and flint-spark-lighters) are commonly used as an emergency firelighting device in . The ferrocerium is referred to as a "flint" in this case, as both are used in fire lighting. However, ferrocerium and natural flint have opposite mechanical operation.

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Discovery Ferrocerium alloy was invented in 1903 by the Austrian chemist Carl Auer von Welsbach. It takes its name from its two primary components: iron (from ), and the rare-earth element cerium, which is the most prevalent of the lanthanides in the mixture. Except for the extra iron and added to harden it, the mixture is approximately the combination found naturally in mine tailings from thorium mining, which Auer von Welsbach was investigating.

(1995). 9781558598546, Abbeville Press. ISBN 9781558598546

The pyrophoric effect is dependent on the brittleness of the alloy and its low autoignition temperature.

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Composition In Auer von Welsbach's first alloy, 30% iron (ferrum) was added to purified cerium, hence the name "ferro-cerium". Two subsequent Auermetalls were developed: the second also included lanthanum to produce brighter sparks, and the third added other heavy metals.

A modern ferrocerium firesteel product is composed of an alloy of 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.

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Uses Ferrocerium is used in firelighting in conjunction with a striker, similarly to natural flint-and-steel, though ferrocerium takes on the opposite role to the traditional system; instead of a natural flint rock striking tiny iron particles from a firesteel, a striker (which may be in the form of a hardened steel wheel) strikes particles of ferrocerium off of the "flint". This manual rubbing action creates a spark due to cerium's low ignition temperature between . Any material that is harder than the rod itself may be used to produce sparks. Though the striker must have a sharp corner, sharp edge, or a knurled surface in order to produce sparks, carbon steel is not required. The idea that carbon steel is needed to produce sparks from a ferrocerium rod is an oft repeated myth, though carbon steel does make the spark more prevalent when striking.

Ferrocerium is most commonly used to start and oxyacetylene welding torches.

About 700 tons were produced in 2000.

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