Preparation of the micro-size flake silver powders by using a micro-jet reactor

The micro-size flake silver powders were prepared through wet-chemical reduction method by using a micro-jet reactor. Herein ascorbic acid was used as a reducing agent, and sulfuric acid was used as a stabilizer. And the lauric acid was used as a dispersing agent to prevent particles' agglomeration. The micro-jet reactor collides the two solutions together and uniformly mixes outside the reactor, to avoid the problem of clogging in the microchannel. The effects of dispersant addition and micro-jet flow rate on the morphology, particle size, and other parameters of silver powder is investigated in the present work. Interestingly, the addition of dispersant agent and stabilizer have a significant impact on the morphology and parameter of the silver particles. Under the conditions of micro-jet flow rate of 50 mL center dot min(-1), sulfuric acid addition amount of 2%, and lauric acid addition amount of 0.8% by the weight of silver nitrate, a kind of flake silver powders with 4.40-4.70 mu m can be prepared. The volume resistivity of the silver paste prepared from the obtained flake silver powders is in the range of 1.4-1.6 x 10(-4) omega center dot cm(-1), which meets the application test requirements of conductive silver paste.