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微米及亚微米级球形银粉具有良好的导电性,在太阳能电池正面银浆料中应用广泛。利用化学还原法制备球形银粉是目前主要的制备方法之一,但制备的银粉存在分散性差,粒径分布宽的缺点。因此为制备粉体粒径分布范围窄、球形度良好且分散性好的银粉,本实验在化学还原法基础上,选用聚乙二醇(PEG-6000)和乳液分散两种不同的分散体系制备球形银粉。以聚乙二醇为分散剂制备银粉,主要改变分散剂含量、反应温度、反应液pH值等制备因素,而以乳液作为分散剂制备银粉时,主要改变表面活性剂含量、O/W比(油/水比)和乳液的HLB值(亲水亲油平衡值)。通过调整制备条件比较银粉的粒径分布、球形度。发现利用聚乙二醇制备银粉在分散剂含量为7%、温度为50℃、pH为9时分散度较好,但是球形度较差,平均粒径在1.59μm;利用乳液法制备银粉时在分散剂含量为3%、乳化转速为11000 r·min-1、W/O比为1∶1、HLB=4.5时粉体分散度较好,且粉体球形度好,平均粒径为0.91μm。分析实验结果发现,利用乳液法制备的银粉粒径分布均一、球形度良好,且分散性明显提高。
Micron and submicron spherical silver powder has good conductivity, and is widely used in the silver paste of solar cells. Preparation of spherical silver by chemical reduction method is one of the main preparation methods, but the preparation of silver powder has poor dispersion, particle size distribution of the shortcomings. Therefore, in order to prepare silver powder with narrow particle size distribution, good sphericity and good dispersibility, this experiment was conducted on the basis of chemical reduction method using two different dispersion systems of PEG-6000 and emulsion dispersion Spherical silver. Preparation of silver powder with polyethylene glycol as dispersant mainly changes the preparation factors such as dispersant content, reaction temperature and pH of the reaction solution. When the emulsion is used as the dispersant, silver powder is mainly used to change the content of the surfactant, the ratio of O / W Oil / water ratio) and the HLB value (hydrophilic-lipophilic balance) of the emulsion. By adjusting the preparation conditions silver particle size distribution, sphericity. It was found that the dispersity of silver powder prepared by polyethylene glycol was 7%, the temperature was 50 ℃ and the pH was 9, but the sphericity was poor and the average particle size was 1.59μm. When the silver powder was prepared by emulsion method, The dispersant content is 3%, emulsifying speed is 11000 r · min-1, W / O ratio is 1: 1, HLB is 4.5, and the powder has good sphericity and average particle size of 0.91μm . Analysis of the experimental results found that silver powder prepared by the emulsion method uniform particle size, good sphericity, and dispersion significantly improved.