Zirconium pyrophoricity

The product of sorbing hydrogen on to hot zirconium powder bums with incandescence when heated in air [1,2], Ignition and combustion properties of pyrophoric zirconium and zirconium hydride powder (< 10 p), and safety measures are discussed [3], Ignition energies for zirconium hydrides, ZrUx x = 0 — 2, in air have been studied in Japan [4],... 

Metals — Several metals react with water and air with the extent of reactivity being dependent upon the physical state of the metal. The highly reactive metals such as lithium, sodium, and potassium are pyrophoric (i.e., they ignite spontaneously in air without an ignition source). In contrast, the less reactive metals such as magnesium, zirconium, titanium, aluminum, and zinc are highly pyrophoric only as dusts. 

It should be noted that swarf from a zirconium-titanium alloy containing approximately 50% by weight of each element is prone to pyrophoricity in air. It has also been reported that when zirconium is welded to titanium, the welded zone is much more sensitive to corrosion than either of the parent metals. If, therefore, it is proposed to use my construction in which zirconium is welded to titanium, caution should be observed in the machining of welds, and the corrosion behaviour of the weld should be checked by prior testing in the environment with which the construction will be employed. 

The pyrophoric tendency of zirconium in contact with red fuming nitric acid has already been mentioned. 

Zirconium. While almost any metal in the finely divided state exhibits pyrophoric properties, a few metals when abraded emit a shower of sparks of sufficient temp to ignite hydrocarbon vapors. Cerium is the best known metal of this kind for commercial purposes, such as gas lighter flints. For military purposes Zr is the most used. It has found applications in HE and armor-piercing incendiary ammo, the lining of shaped-charge rounds, and in incendiary cluster bombs (Ref 7, pp 100-01)... 

The zirconium sponge thus obtained is highly pyrophoric. The industrial practice is to condition this sponge by the controlled admittance of air-argon mixtures at around 50 °C. Such a treatment results in the formation of a thin, protective oxide film on the sponge this eliminates any major fire hazard in subsequent handling and crushing operations. 

See Other METALS, PYROPHORIC metals, reducants 4928. Zirconium... 

Zinc hydride, 4492 Zirconium hydride , 4493 See COMPLEX HYDRIDES, pyrophoric materials See entry LANTHANIDE-TRANSITION METAL ALLOY HYDRIDES... 

Alloys of reactive metals are often more pyrophoric than the parent metals. Examples are alloys of titanium with zirconium thorium with copper, silver or gold uranium with tin, lead or gold magnesium with aluminium hafnium with iron [1], Cerium amalgams and thorium-silver alloys are spontaneously flammable when dry [2], Individually indexed alloys are ... 

Substances that catch Are spontaneously in air without an ignition source are called pyrophoric. These include phosphoms, the alkali metals and powdered forms of magnesium, calcium, cobalt, manganese, iron, zirconium, and aluminum—all of which may occur at one time or another at a refinery site. Moisture in air is often a factor in spontaneous ignition. 

Zirconium Borohydride (Zirconium Tetrahydro-borate). Zr(BH4)4 mw 150.5 volatile pyrophoric cryst mp 28.7° bp 123° (extrapolated) d l.l3g/cc. Prepn is by reacting Zr tetrachloride with Li borohydride — the yield is 77%. Accdg to Gaylord (Ref 4) the compd is spontaneously flammable in air... 

Zirconium Dibromide. ZrBr2 mw 251.05 pyrophoric blk pdr mp > 350° (decompn) Decompd by w. Prepn is by heating the tribromide in vacuo at 390°. The compd is spontaneously flammable in air, and reacts vigorously with oxidizing materials Refs 1) J. Kleinberg et al, Inorganic Chemistry , Heath, Boston (1960), 498 2) J.R. 

Uranium hydride, UH3, is a reactive black powder. It is a powerful reducing agent and is pyrophoric. A mixture of uranium and zirconium hydrides is used as the fuel... 

Magnesium—nickel hydride, 4458 Plutonium(III) hydride, 4504 Poly(germanium dihydride), 4409 Poly(germanium monohydride), 4407 Potassium hydride, 4421 Rubidium hydride, 4444 Sodium hydride, 4438 f Stibine, 4505 Thorium dihydride, 4483 Thorium hydride, 4535 Titanium dihydride, 4484 Titanium—zirconium hydride, 4485 Trigermane, 4415 Uranium(III) hydride, 4506 Uranium(IV) hydride, 4536 Zinc hydride, 4486 Zirconium hydride , 4487 See COMPLEX HYDRIDES, PYROPHORIC MATERIALS See entry LANTHANIDE—TRANSITION METAL ALLOY HYDRIDES... 

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