银粉对压敏电阻浆料性能的影响-中国材料进展

文章信息/Info

Author(s):: DONG Ningli; HA Min; WANG Dan; （Ningxia Special Material Key Laboratory, CNMC Ningxia New Material Co., Ltd., Shizuishan 753000,China）

Keywords:: varistor paste; silver powder; thixotropy; crystallinity; grain size

摘要:: 采用不同还原条件制备了两种微晶银粉，测试了银粉的烧损、颗粒尺寸、比表面积、松装密度和振实密度，结果表明两种银粉的物理性能相近，用其分别制备了压敏电阻浆料,并测试分析了浆料触变指数、浆料层印刷质量及烧结后形貌、电阻、附着力以及银粉的晶粒尺寸。结果表明：银粉的振实密度对浆料粘度影响较大，振实密度高则浆料粘度低，反之则高；银粉的粒度分布影响浆料触变指数，粉末颗粒小且不均匀时，则浆料触变指数高，反之则低；银粉的结晶度和晶粒尺寸对浆料的烧结性能有较大的影响，在相近的粒度分布范围内，高结晶度、大晶粒尺寸的银粉制备的浆料烧结后形成的晶界比较好，浆料层更致密，电阻更低，附着力好。

Abstract:: Two kinds of microcrystalline silver powders were prepared under different reduction conditions, and the burning loss, particle size, specific surface area, bulk density and tap density of silver powders were tested. The results showed that the physical properties of the two kinds of silver powders are similar. The two kinds of sliver powder were applied to concoct varistor paste. The thixotropy index, printing quality, morphology, resistance, adhesion of paste layers, and grain size of silver powders were tested and analyzed. The experimental results showed that the tap density of silver powders has a great influence on the slurry viscosity, high tap density results in low slurry viscosity and vice versa. The particle size distribution of silver powder has a great influence on the slurry thixotropy, if the particle size is small and nonuniform, the thixotropy index is high and vice versa. The crystallinity and grain size of silver powder have great influence on the sintering performance of the slurry. In the similar size distribution range, the grain boundary formed by powders with high crystallinity and larger grain size is better, the sintering is more compact, the paste layer’s resistance is lower, the adhesion is better. Powder with high crystallinity and larger grain size is more suitable for preparing varistor paste.