化学沉淀法制备超细粉体过程行为

Aggregation of Ultra-fines in Chemical Precipitation

应用硫酸铜还原化学沉淀法制备铜的超细粉体,研究了反应温度、浆液密度和表面活性剂对超细铜粉制备过程行为的影响。试验发现,当反应温度较高时,由于还原反应速度较高,晶核的生成速度急剧增加,晶核数量密度过大,在反应器壁上生成铜箔及大的团聚体;当体系中浆液密度较高时,颗粒由于相互间的碰撞在表面能的作用下团聚成纺锤形的大颗粒。这是两种不同的团聚行为,前者由于生长中的晶核的团聚故称为“核级团聚”,后者是由于生长中的颗粒间的团聚称为“粒级团聚”。在适当的反应条件下,控制适度过饱和度,及适度的成核速率,可以得到均匀的球形铜粉。表面活性剂的加入可有效的防止粒子的团聚。

This paper studies influence in the preparation of ultra-fines from chemical reduction precipitation, such as the reaction temperature, the density of recipitated slurry, the surfactant on aggregation of cupper ultrafines. It is found that when the reaction temperature is higher, reaction rate of growing crystal nuclei is very fast and the quickly increasing of the crystal nuclei generation results in that quantity density of the crystal nuclei is too large, the great aggregates and cupper foil are made of crystal nuclei in the reactor. When density of precipitated slurry is too high, because of the collision among particles, big spindly aggregates which are made of ultra-fines are born in reactor at the action of surface energy. They are different aggregation behavior, the former is named “aggregation of nuclei degree”, as the aggregation is caused by growing nuclei, and because the latter happen among growing granules, it is named “aggregation of particle degree”. Spherical ultra-fines are produced in the suitable reaction condition. Surfactant is effective on preventing from aggregation of ultra-fines.