研究了PTC(正温度系数陶瓷热敏电阻)电极浆料用超细银粉制备过程中温度和分散剂对泡沫高度的影响,探讨了几种消泡方法的优劣.结果表明,高温时,反应热聚集会造成液体局部沸腾,使泡沫高度增加；添加分散剂可增加泡沫液膜厚度和泡沫高度,高温高分散剂浓度使得银粉制备过程中必须进行消泡.消泡剂对生成银粉的粒径、灼烧失重等的影响较大,冷水降温消泡法用水量较大,负压消泡法效果显著.酒精、冷水消泡法可用于小批量生产,负压消泡法是提高生产量的好方法.%The influences of temperature and dispersant on the foam height were investigated in the synthesis of ultraflne silver powders used in PTC electronic paste. The differences among several defoaming methods were investigated detailedly. The results show that the aggregation of reaction heat will lead part of liquid to boiling at high temperature, which makes the foam height higher. The film thickness and foam height are increased by the addition of dispersant. So defoaming will be needed because of the existence of high temperature and high concentration of dispersant in the course of silver preparing. Antifoams exert a large influence on the average particle size of prepared ultrafine silver powders, the weight loss of ignition and so on. Much water is used in the process of defoaming by cold water. The effect of negative-pressure defoaming is remarkable. Defoaming method by using alcohol or cold water is often used for small systems, but the negative-pressure defoaming can be used to increase the production.
展开▼
