A ONE-PHASE MODEL OF THE MIXING OF AL-SIC COMPOSITE MELT

Good mixing of silicon carbide (SiC) particles with liquid aluminum is an important component of the fabrication process of Al-SiC composite s and the casting of mechanical parts from composite melts. A one-phas e flow model has been built in which the mixture is considered as one fluid, and the SiC flow is differentiated from the main mixture flow b y a slip velocity, calculated from the balance of forces exerted on th e particles. The impeller blades' action on the fluid is seen as a qua dratic source of momentum. Sedimentation is simulated by imposing an i ncreased viscosity on the fluid and setting gravity to zero once the S iC volume fraction reaches a critical value. The model is first applie d to a water-SiC system for which some experimental data exist permitt ing a validation of the model. It is then applied to a Al-SiC system f or which some parameter studies are carried out. Compared to the two-p hase flow model published earlier, this one-phase model offers two adv antages: it takes much less computing time and can accommodate a distr ibution of particle sizes instead of being limited to one size.