COMPUTER-SIMULATIONS OF INTERACTIONS BETWEEN ULTRAFINE ALUMINA PARTICLES PRODUCED BY AN ARC-DISCHARGE

We wrote two computer programs, 3D and BUMP, to interpret transmission electron microscope (TEM) micrographs made during a study of the init ial stage sintering of ultrafine alumina particles (UFP's, 20-50 nm in diameter). The first simulated the 3D geometric relationships of part icles, from which we concluded that surface diffusion was the predomin ant sintering mechanism because no shrinkage occurred. BUMP simulated random contact of two particles and showed that the particle chains th at formed before sintering were not formed purely by chance. Instead t he particles experienced a rearrangement process (rotation and sliding ) which reduced the total surface energy.