ニオブ・タンタル鉱の塩化について

抄録

Reactivity of Nb-Ta-containing materials when they were heated with charcoal in Cl₂-atmosphere was studied using the thermobalance.
The data of the ignition temperature, (at which the spontaneous reaction began) and the reaction velocity (slope of weight-temp. curve) slowed following results.(1) Highly reactive (Ignition temp. 150-250°C) Ferroniobium, Nb₂O₅+Ta₂O₅ mixture sintered with charcoal at 900-1, 200°C in vacuum. Niobium lower oxide+charcoal.(2) Reactive (Ignition temp. 250-350°C) Nb₂O₅+charcoal, tantalum carbide, Crude Nb₂O₅-Ta₂O₅ mix, ignited at 500-1, 000°C+charcoal.(3) Weakly reactive (Ignitive temp. 350-450°C) Ta₂O₅+charcoal, Tantalum lower oxide+charcoal.
Niobium is usualy more easily chlorinated than tantalum, and is reduced to its lower oxide by hydrogen treduction easier than tantalum. High reactivity of vacuum sintered Nb₂O₅-Ta₂O₅ mix, suggests that Nb₂O₅ iin it is partly reduced to lower oxide at the sintering temp. above 800°C.