Simulation of composite particle growth in the dispersion and compounding processes of alloy particles and ceramic powder

The authors investigated a compounding process in which fine WC powder is uniformly dispersed into particulate Ag-Ni alloy with a high-speed elliptical-rotor-type powder mixer. The growth of composite particles is observed as processing time elapses. A model for the growth phenomenon is constructed on the basis of the theory of powder grinding with a ball mill, and of the dynamics of the plastic deformation of metal particles. In the model, a function of the probability that composite particles grow is expressed in terms of three factors that include the compounding conditions as parameters: (1) the probability that particles are caught between a pair of medium balls (zirconia beads), (2) that they have undergone plastic deformation, and (3) the frequency with which the mixture of composite particles and beads is compressed by the elliptical rotor at the minimum clearance per unit time. Temporal change in the size distribution of composite particles has been calculated by using model equations. Comparison of calculated values with the experimental data for particle median diameter shows that they agree closely. It was demonstrated that the model is valid and that it is possible to accurately estimate and control particle size.