Titanium, metal powder, active

The new method produces TiN powders with surface areas exceeding 200 m g that are otherwise only accessible using a forced flow reactor and a microwave plasma activator in which titanium metal is reacted with N2 in the gas phase [14]. TiN powders with considerably lower specific surface area (Sg<60m g ) were also synthesized using the nitridation of 10-15 nm-sized... 

In 1973, the direct potassium metal reduction of zinc salts was reported.3 This active zinc powder reacted with alkyl and aryl bromides to form the alkyl- and arylzinc bromides under mild conditions.4 The reduction of anhydrous zinc salts by alkali metals can be facilitated through the use of electron carriers. Lithium and sodium naphthalenide reduce zinc salts to give highly reactive metal powders under milder and safer conditions. Graphite5 and liquid ammonia6 have also been employed as electron carriers in producing zinc powders. A highly dispersed reactive zinc powder was formed from the sodium metal reduction of zinc salts on titanium dioxide.7... 

The proposal of Scheme 2 appears to be a reasonable approach to the problem. The chlorosilane obviously does not only destroy the oxidic layer of titanium powder (activation effect) but also seems to facilitate the electron transfer from the metal to the substrate [21]. 

Chlorine has caused numerous accidents with metals. Beryllium becomes incandescent if it is heated in the presence of chlorine. Sodium, aluminium, aluminium/titanium alloy, magnesium (especially if water traces are present) combust in contact with chlorine, if they are in the form of powder. There was an explosion reported with molten aluminium and liquid chlorine. The same is true for boron (when it is heated to 400°C), active carbon and silicon. With white phosphorus there is a detonation even at -34°C (liquid chlorine). 

The activation of aluminum with ultrasound or dispersion of liquid aluminum. The suspension of powder aluminum in petrol or n-geptane without oxygen is subjected to ultrasound the tough oxide film on the surface of aluminum is removed and aluminum becomes reactive. The second activation technique is the dispersion of liquid aluminum with argon or purified nitrogen flow into a finely dispersed state. It should be noted, however, that the most reactive aluminum powder for direct synthesis is the powder alloyed with transition metals (titanium, zirconium, niobium, tantalum) with the size of particles from 10 to 125 pm. 

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