煅烧工艺对钽粉微观结构和电性能的影响

Microstructure and Electrical Properties of Tantalum Powder with Different Calcining Technology

采用K2TaF7金属钠还原-高温高真空煅烧-镁还原脱氧工艺制备了电容器用高比容钽粉，系统研究了高真空和一定的升温速率下，煅烧温度、煅烧时间对钽粉微观结构和高压电性能的影响。用场发射式扫描电镜（FESEM）、BET分析仪和激光粒度分布仪（LDSA）对电容器用高比容钽粉的微观结构进行表征，对该钽粉制成的烧结阳极的湿式电性进行检测。结果表明：随着煅烧温度的升高或煅烧时间的延长，粉末团聚体的尺寸增大，烧结颈变粗，团聚体的大小趋于均匀一致，团聚体之间微细孔隙明显减少；钽粉烧结阳极的电性能在高压（大于55V）形成时得到优化，表现为漏电流（Lc）小，容量（CV）高，损耗（tgδ）小，但低压（小于40V）形成时钽粉烧结阳极的容量（CV）低。研究认为，比表面积介于1．30～1．50m0·g-1的还原粉在1300℃煅烧40min，钽粉综合性能最优。

Tantalum powder with high capacitance employing capacitor was prepared by K2TaF7 sodium metal reduction, high tem- perature and high vacuum calcining and magnesium reductive deoxygenating technology. The effects of calcining temperature and resi- dence time on the microstructure of tantalum powder and high voltage electrical property under high vacuum and certain heating rate were studied systematically. Microstructure of tantalum powder with high capacitance was characterized by field emission scanning elec- tron microscopy （FESEM）, BET and laser particle size analyzer （LDSA） and the wet electrical property of sintering anode reading of tantalum powder was tested. The results showed that with the increase of calcining temperature and residence time the size of aggregate increased, the sintering neck coarsened, the size of aggregate tended to be uniform and the fine pores between aggregate decreased sig- nificantly. The performance of tantalum powder sintering anode was optimized at high formation voltage （greater than 55 V） character- ized by small leakage current （LC）, high capacity （CV） and small loss （tgS）, but the tantalum powder sintering anode formed at low voltage （less than 40 V） had low capacity （CV）. Research suggested that reductive tantalum powder with specific area of 1.40 m2 .g-L and calcined under 1300 ℃ for 40 min had the best comprehensive performance.