Development of New Production Process of Fine Tantalum Powder by Arc-Plasma CVD Method

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Tantalum powder is produced by Na reduction process. However, tantalum powder is cohered each other and its physical property can not be improved by the current production process. From this reason, a new production process of tantalum powder have to be developed by using new raw materials.In the current investigation, fine tantalum powder has been synthesized by Mg reduction process, in which high purity Ta_2O_5 powder was used as raw materials. In an initial experiment, temperature and time dependences were examined for the production of tantalum powder by the following reduction reaction: Ta_2O_5 (s) + 5Mg(l,g) = 2Ta(s) + 5MgO(s). Mg reduction easily proceeded with an increase in temperature above 900℃. However, specific surface area of tantalum powder prepared was low because tantalum particles were cohered one another. Therefore, iMg reduction of tantalum oxide was carried out at the temperatures of 650℃ and 750℃, and physical properties of tantalum powder synthesized were evaluated by SEM observation, specific surface area measurement and paticle size measurement. As a result, specific surface area of tantalum powder prepared by Mg reduction was more larger than that prepared by Na reduction. Its physical property was improved.