类球状Co_3O_4粉料的制备研究

Study in the Preparation of Near-spherical Co_3O_4 Powder

采用碳酸钴热分解法制备Co3O4`粉料,以Na2CO3作沉淀剂,通过添加反应助剂氨水,防止了Co2+生成胶状沉淀,使沉淀容易过滤和洗涤,工艺效率高,适合工业化生产。控制Na2CO3与氨水量比、pH值、温度、加料速度和反应时间等条件,可制得类球状Co3O4粉料,其平均粒径为2.5μm,粒度分布窄,分散性好,Na含量为0.005%。类球状Co3O4粉料制备ZnO压敏电阻的电性能优于草酸钴热分解法Co3O4粉料。

The Co3O4 powder was prepared in thermal decompounding of cobalt carbonate. Using Na2CO3 solution as reaction regent, cobalt ions （Co^2＋ ） precipitate to form cobalt carbonate as precursor. Colloidal precipitation particles are avoided formation because of adding a mount of NH3 to Na2CO3 solution. It is easy to wash and filtrate the precipitation. Therefore the precipitation particles process is high-efficiency and suitable for industrialization. The micrograph of Co3O4 powders can be controlled through the molar ratio of Na2 CO3 to NH3, pH, the reaction temperature, the addition rate of reagent and the reaction time. Accordingly, near- spherical Co3O4 powder with an average diameter of 2.5 μm and the amount of Na less than 0. 005% is produced. The near-spherical Co3O4 powder has narrow size distribution and excellent dispersing property. ZnO varistors made from the resulting spherical--like Co3O4 powder exhibit better electrical properties as compared with those made from the Co3O4 powder conventionally prepared by the thermal decomposition of cobalt oxalate.