Titanium pyrophoricity

It readily ignites in air, particularly if moist [1,2], The dichloride on heating under inert atmospheres disproportionates into the tetrachloride and pyrophoric titanium [3],... 

Titanium is resistant to nitric acid from 65 to 90 wt % and ddute acid below 10 wt %. It is subject to stress—corrosion cracking for concentrations above 90 wt % and, because of the potential for a pyrophoric reaction, is not used in red filming acid service. Tantalum exhibits good corrosion resistance to nitric acid over a wide range of concentrations and temperatures. It is expensive and typically not used in conditions where other materials provide acceptable service. Tantalum is most commonly used in appHcations where the nitric acid is close to or above its normal boiling point. 

Titanium trichloride [7705-07-9] M 154.3, m >500 , pKj 2.55 (for hydrolysis of Ti to TiOH ). Brown purple powder that is very reactive with H2O and pyrophoric when dry. It should be manipulated in a dry box. It is soluble in CH2CI2 and tetrahydrofuran and is used as a M solution in these solvents in the ratio of 2 1, and stored under N2. It is a powerful reducing agent. [Inorg Synth 6 52 I960, Synthesis 833 7989.]... 

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. 

Investigation into the effect has been mainly devoted to reactions with red fuming nitric acid . It seems that in red fuming nitric acid a preliminary reaction results in the formation of a surface deposit of finely divided metallic titanium ignition or pyrophoricity can then be initiated by any slight impact or friction. The tendency to pyrophoricity increases as the nitrogen dioxide content of the nitric acid rises from zero to maximum solubility at about 20%, but decreases as the water content rises, the effect being nearly completely stifled at about 2% water. 

Other media in which titanium is subject to pyrophoricity are anhydrous liquid or gaseous chlorine , liquid bromine, hot gaseous fluorine, or oxygen-enriched atmospheres at moderately low pressures. 

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. 

Pyrophoricity and detonation behaviour of titanium hydride powders of various particle sizes were studied in comparison with those of titanium metal powders [1]. Maximum dust explosion pressures of 8.2 bar, with a maximum rate of rise of 816 bar/s have been recorded [2]. 

Fire hazards and pyrophoricity of mixed charges for preparing titanium carbide are discussed. 

When all the iodine has sublimed out of tube C (10 to 12 hours), nitrogen is admitted into the system, and the apparatus is allowed to cool to room temperature. Tube C is removed, and the glass-wool plugs and unreacted titanium (0.23 g.) are removed with a hooked copper wire while purging with nitrogen. Caution. Care should be exercised in removing the unreacted titanium from the tube the titanium may be pyrophoric. Then tube C is cleaned, dried, and reattached to tube B. Tube B is removed from attachment to A and, while holding tube B... 

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 ... 

Heat of combustion, thermal conductivity, surface area and other factors influencing pyrophoricity of aluminium, cobalt, iron, magnesium and nickel powders are discussed [4], The relationship between heat of formation of the metal oxide and particle size of metals in pyrophoric powders is discussed for several metals and alloys including copper [5], Further work on the relationship of surface area and ignition temperature for copper, manganese and silicon [6], and for iron and titanium [7] was reported. The latter also includes a simple calorimetric test to determine ignition temperature. 

Titanium trichloride, pyrophoric or Titanium trichloride mixtures, pyrophoric 2441... 

PYROPHORIC MATERIAL. Any liquid or solid that will ignite spontaneously in air at about 130F (54.4C). Titanium dichloride and phosphorus are examples of pyrophoric solids tnbutylaluminum and related compounds are pyrophoric liquids. Sodium, butyLithium, and lithium hydride are spontaneously flammable in moist air because they react exothermically with water, Such materials must be stored in an atmosphere of inert gas or under kerosene. Some alloys (barium, misch metal) are called pyrophoric because they spark when slight friclion is applied. 

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