| The micro mixing reactor can effectively strengthen the mixing,mass transfer and reaction process of the reaction process at the micro scale,and provide uniform reaction conditions and environment for chemical reactions.However,the internal channels of the micro reactor may cause scaling or blockage due to particle precipitation in the process of preparing solid particles by using the micro mixing reactor,which causes obstacles to the research and scale-up application of the micro mixing technology.In this paper,on the basis of previous studies,the Y-type micro-jet reactor was used to prepare solid silver particles.Firstly,the mixing efficiency of the reactor was evaluated.Then,the selected Y-type microjet reactor was used to uniformly and controllable prepare silver neodecanoate particles and ultra-fine spherical silver powder.Its characteristics are that the collision and mixing process of reaction solution can be carried out outside the reactor,which can effectively avoid the problem of scaling or blocking of the channel inside the reactor,while strengthening the mixing process.The main contents of this paper are as follows:1.Study on the mixing efficiency of Y-type micro jet reactor.The Villermaux-Dushman(iodide-iodate)parallel competitive reaction was used to investigate the influence of jet angle,channel diameter,volume flow rate and other factors on the mixing efficiency of Y-type microjet reactor,which was characterized by the separation index Xs(the separation index is between 0-1,and the smaller its value,the higher the mixing efficiency).The results show that the lowest separation index of the Y-type microjet reactor is between 0.003-0.004,which is significantly lower than that of the conventional mixing(0.009-0.017).It verifies that the Y-type micro jet reactor has higher mixing efficiency.2.The organic silver compound(silver neodecanoate)was rapidly synthesized by Y-type microjet mixing reactor.The appearance morphology and thermal decomposition characteristics of silver neodecanoate particles were compared between micro-jet reaction method and conventional tirring method.Then,the corresponding samples according to the same process to form a particle free conductive silver paste.And the macroscopic and microscopic differences in the sintering process of the two kinds of silver paste were systematically analyzed.The results show that the Y-type micro jet reactor can prepare silver decanoate particles with specific surface area of 1.744 m~2/g and initial decomposition temperature of 175℃,and compared with the conventional stirring reaction preparation,the sintered layer of the prepared particle free conductive silver paste was more uniform and dense.3.The ultrafine spherical silver particles with an average diameter of 1-3μm and uniform particle size distribution were prepared by Y-type micro jet reactor.The results show that a Y-type micro jet reactor can strengthen the mixing process of reaction.And compareing with the conventional mixing method,it can quickly form primary particles with finer particle size,and these primary particles are orderly aggregated into spherical micron silver particles with an average diameter of 1-3μm in the process of jet mixing.This process was affected by the use of surfactants,the jet mixing time,temperature of reaction solution,the factors of jet angle and jet flow.The spherical superfine silver powder prepared by jet mixing pilot device has stable and controllable product parameters,which can meet the application requirements of crystal silicon solar cell positive silver paste.It has certain application value for micro jet mixing strengthening technology in the controllable preparation of ultrafine silver powder. |
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