Research On The Simulation In The Process Of Mixing Of Preparing SiCp/2014Al Composites By Mechanical Stirring

In recent times, the use of particle reinforced metal matrix composite is becoming increasingly wider, so that the study of its preparation is deeper and deeper. Semi-solid mechanical stirring method, which is simple, flexible and inexpensive, is widely used in production. However, it has always been a difficult problem to explore the best mixing process. With the rapid development of CFD simulation software, more and more fluid simulation research appear. We can observe the movement and stress distribution of fluid by CFD simulation. In this thesis, the preparation process of composite materials by mechanical agitation are simulated by using the software FLOW-3D to explore the best technology.In this thesis, the model of SiCp particles are drawn as irregular polygon. The stirrer type, inclination angle, immersion depth and the stirring process(revolving speed and the stirring time) are optimized by CFD simulation. Movement and dispersion of particles are compared and analyzed under different stirring process parameters to get the optimal technology. Meanwhile, simulated results are verified by experiment.The results prove that:inclined blade impeller is better than straight blade impeller. And when the impeller angle is 30°, the mixing performance is best. When the impeller is 25% height off the bottom, the particles are in a better dispersed distribution. Preparation of composite material is more suitable in semi-solid stirring. When the semi-solid stirring temperature is 630 ℃, the better particle dispersion and less casting defects will be obtained. Too slow stirring speed will cause particle aggregation as well as too fast stirring speed will cause casting defects such as air entrapment. When the stirring speed is 500 rpm, the mixing performance is best. When the stirring time is 15 min, distribution of particles is uinform basically. Excessive stirring time will cause more casting defects.In the experiment, customized stirring paddle and crucible are used to stir. Molten metal is chilled rapidly after the mixing. Then, the casting is split along the largest cross section to observe metallographic structure in different positions. The results of experiment is roughly consistent with the simulation results.