Zirconium powder

Zirconium is a highly active metal which, like aluminum, seems quite passive because of its stable, cohesive, protective oxide film which is always present in air or water. Massive zirconium does not bum in air, but oxidizes rapidly above 600°C in air. Clean zirconium plate ignites spontaneously in oxygen of ca 2 MPa (300 psi) the autoignition pressure drops as the metal thickness decreases. Zirconium powder ignites quite easily. Powder (<44 fim or—325 mesh) prepared in an inert atmosphere by the hydride—dehydride process ignites spontaneously upon contact with air unless its surface has been conditioned, ie, preoxidized by slow addition of air to the inert atmosphere. Heated zirconium is readily oxidized by carbon dioxide, sulfur dioxide, or water vapor. 

Finely divided zirconium powder is made by bomb reduction of zirconium oxide with magnesium or calcium. The powder is separated by leaching... 

Zirconium powder reacts exothermically with many other elements, including hydrogen, boron, carbon, nitrogen, and the halogens, although the ignition temperature is usually above 200°C. The reaction between zirconium powder and platinum is especially violent. 

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],... 

Zirconium powder mixed with an approximately equal quantity of 17% potassium bisulfate in concentrated sulfuric acid exploded violently. 

Zirconium powder, with not less than 25 per cent water (a visible axcess of water must be present) (a) mechanically produced, particle size less than 53 microns (b) chemically produced, particle size less than 840 microns 1358... 

MACH I, Inc. USA, has developed a process to make zirconium powder as safe as aluminum powder (passivated Zr powder) and is in the process to develop propellants with high density-impulse for potential use in the ballistic missile defense system. These propellants would produce a high degree of impulse or thrust per unit of volume. 

Hartmann and associates (24G-28G) have conducted a great deal of experimental work on the combustion of dust dispersions. Explosions can be caused by particles as large as 700 microns. Many different dusts, including rosins, metal powders, and coal, have been investigated. Zirconium powder is the most explosive. Coal dust explosibility is closely associated with its volatile combustible content. Representative pressure rises as high as 75 pounds per square inch in an enclosed volume are reported. In all cases this maximum pressure is attained at mixture strengths well beyond stoichiometric. 

ZIRCONIUM POWDER, wetted with not <25% water (UN 1358) (DOT) see ZOAOOO ZIRCONIUM SCRAP (UN 1932) (DOT) see ZOAOOO ZIRCONIUM(IV) SIUCATE (1 1) see ZSSOOO ZIRCONIUM(I 0 SULFATE (1 2) see ZTJOOO ZIRCONIUM TETRACHLORIDE (DOT) see ZPAOOO ZIRCONIUM TETRACHLORIDE, soUd (DOT) see ZPAOOO... 

BARIUM DIHYDROXIDE (17194-00-2) A strong base. Reacts with phosphorus, releasing phosphine gas. Violent exothermic reaction with maleic anhydride. Reacts violently with acids, chlorinated rubber (when heated), 1-nitropropane, zirconium powder or dust. Incompatible with organic anhydrides, acrylates, alcohols, aldehydes, alkylene oxides, substituted allyls, cresols, caprolactam solution, epichlorohydrin, ethylene dichloride, glycols, isocyanates, ketones, nitrates, nitromethane, phenols, vinyl acetate. Attacks chemically active metals (e.g. aluminum, magnesium, zinc). 

---