Title: Zirconium
CAS Registry Number: 7440-67-7
Literature References: Zr; at. wt 91.224; at. no. 40; valence 4; also 3. Group IVB (4). Five naturally occurring isotopes: 90 (51.46%); 91 (11.23%); 92 (17.11%); 94 (17.40%); 96 (2.80%); artificial radioactive isotopes: 81-89, 93, 95, 97-99. Occurrence in earth's crust: 0.023%. Occurs in the minerals zircon, malacon, baddeleyite, zirkelite, eudialyte; frequently found in the rare-earth minerals; in monazite sand. Discovered by Klaproth in 1789; prepd by Berzelius in 1824. Prepn: Fast, Z. Anorg. Chem. 239, 145 (1938); purification of zirconium by ion exchange columns: Ayres, J. Am. Chem. Soc. 69, 1879 (1947). Sepn of zirconium and hafnium: Fischer et al., Angew. Chem. Int. Ed. 5, 15 (1966). Reviews of zirconium and its compds: W. B. Blumenthal, The Chemical Behavior of Zirconium (Van Nostrand, Princeton, 1958); Gmelins, Zirconium (8th ed.) 42, (1958) 448 pp; Larsen, "Zirconium and Hafnium Chemistry" in Adv. Inorg. Chem. Radiochem. 13, 1-333 (1970); Bradley, Thornton, "Zirconium and Hafnium" in Comprehensive Inorganic Chemistry vol. 3, J. C. Bailar, Jr. et al., Eds. (Pergamon Press, Oxford, 1973) pp 419-490.
Properties: Bluish-black, amorphous powder or grayish-white lustrous metal (platelets or flakes) of hexagonal lattice below 865°, body-centered cubic above 865°, mp 1857°; bp 3577°. d 6.5. Brinnell hardness: 85. Can absorb up to 10 atoms per cent of oxygen or nitrogen. Reacts with hydrofluoric acid, aqua regia, hot phosphoric acid. Not attacked by cold, very slightly attacked by hot, concd sulfuric or hydrochloric acid; not attacked by nitric acid. Attacked by fused potassium hydroxide or nitrate. On prolonged heating the compact form combines with oxygen, nitrogen, carbon, and the halogens. The powder form has a very low ignition temp and is very explosive when mixed with oxidizing agents.
Melting point: mp 1857°
Boiling point: bp 3577°
Density: d 6.5
CAUTION: Zirconium and its salts generally have low systemic toxicity. A granulomatous disease of the skin, particularly in the axilla, has been reported in users of a deodorant contg sodium zirconium lactate: see E. Browning, Toxicity of Industrial Metals (Appleton-Century-Crofts, New York, 2nd ed., 1969) pp 356-360. Consult latest Government regulations on use in aerosol antiperspirants.
Use: Pure zirconium (hafnium-free) is a valuable structural material for atomic reactors because of its low nuclear cross-section and high corrosion and heat resistance. Because of hafnium's high neutron absorption characteristics, it must be removed from zirconium which is to be used in nuclear reactors; removal unnecessary for other commercial purposes. As an ingredient of priming or explosive mixtures; flashlight powders; as deoxidizer in metallurgy; as "getter" in vacuum tubes; in constructing rayon spinnerets in lamp filaments, flash bulbs. |