Tantalum metal powder

Preparation of the solutions was similar to that of niobium-containing solutions, i.e. by dissolving tantalum metal powder in hydrofluoric acid, HF, at a concentration of about 40% weight. 

The checkers found this step to be very slow, possibly due to excess tantalum metal powder. 

Tantalum metal powder is produced by the sodium reduction of potassium heptafluotantalate (K2Tap7) in a similar manner to the niobium reaction.23 The particular open reaction technique for niobium was in fact based upon that for tantalum in some details. 

A. Michaelis, C. Schnitter, K. H. Reichert, R. Wolf, and U. Merker. 2002. New tantalum metal powder quality for solid electrolyte capacitors. In Proceedings of the 16th Passive Components Symposium CARTS Europe, 209-212. Port St. Laurent, Electronic Components Institute Internationale Ltd. 

Electrolytic Capacitors. Tantalum, because of its high melting point of 2850°C, is produced as a metal powder. As such, it is molded, sintered, and worked to wire and fod, and used to budd certain types of tantalum capacitors (51). Other capacitors are made by compacting and sintering the tantalum powder. 

Rare earth metals, as well as alkali earth metals, can be used as oxygen getters in the purification of tantalum powder. Osaku and Komukai [608] developed a method for the production of tantalum and niobium metal powder by a two-step reduction of their oxides. The second step was aimed at reducing the oxygen content and was performed by thermal treatment with the addition of rare metals. The powder obtained by the described method is uniform, had a low oxygen level and was suitable for application in the manufacturing of tantalum capacitors. 

Praseodymium tri-iodide, Prl3, as the starting material for reduction reactions, might be easily produced by the oxidation of praseodymium metal with elemental iodine [17]. With catalytic amounts of hydrogen dissolved in praseodymium metal powder, the reaction temperature can be as low as 230 °C [18]. Sublimation in high vacuum in tantalum tubes yields pure Prl3. 

Plasma processes have been successfully demonstrated for production of metals from their oxides and chlorides intermediates. Reducing agents are, of course, to be used. Thus, a plasma-based process involving reduction of tantalum chloride in hydrogenous atmosphere has been claimed to yield highly pure metal powder suitable for making of porous capacitor of high capacitance. 

Commercially available starting materials are employed for the preparations. Tantalum metal may be used in granular form (with 1 mm diameter) or as a powder. Tantalum pentachloride is extremely moismre-sensitive. It should be handled under strictly anhydrous conditions in a drybox or drybag. 

Tantalum metal was obtained from the National Research Corp. as a granular powder of low oxygen content and a stated purity of 99.9+ %. 

Preparation of metal powders by electrolysis of fused salts. III. Tantalum." Ind. Eng. Chem., 23 634-637. 

It has been involved in many industrial explosions. Explodes on contact with aluminum + barium nitrate + potassium nitrate + water. Forms explosive mixtures with aluminum powder + titanium dioxide, ethylene glycol (240°C), cotton lint (245°C), furfural (270°C), lactose, metal powders (e.g., aluminum, iron, magnesium, molybdenum, nickel, tantalum, titanium), sulfur, titanium hydride. Reaction with ethanol + heat forms the explosive ethyl perchlorate. Violent reaction or ignition under the proper conditions with aluminum + aluminum fluoride, barium chromate + mngsten or titanium, boron + magnesium + silicone rubber, ferrocenium diammine-tetrakis(thiocyanato-N) chromate(l —), potassium hexacyanocobaltate(3—), A1 +... 

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