Technical Study on Preparation of Tantalum Powder for Capacitors by Magnesium Thermal Reduction of Ta2O5
Tantalum powder for capacitors was prepared by the magnesium thermal reductionof Ta2O5.The effects of magnesium addition,holding temperature,and holding time on the composition and electrical properties of the tantalum powder were investigated.The results show that insufficient magnesium addi-tion,low holding temperature,and short holding time result in incomplete reduction of Ta2O5.However,excessive magnesium addition leads to an increase in the leakage current of tantalum powder and the waste of magnesium chips and acid.And high holding temperature and long holding time lead to a decrease in the electric capacity of tantalum powder and an increase in energy consumption,thereby raising the cost.To re-duce costs and improve efficiency,the optimal process conditions include the magnesium addition of twice the theoretical amount,holding temperature of around 960 ℃,and holding time of 6 hours.Under such con-ditions,the prepared tantalum powder exhibits an oxygen content of 0.362 0％,magnesium content of 0.001 1％,leakage current coefficient(K value)of 4.4×10-4 μA/(μF·V),and weight-specific capacity of 15 630 μF·V/g.
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