Simulation of the Viscous Sintering of Coated Particles

Problems associated with the sintering of mixtures of hard and soft particles can be obviated by coating the hard particles (e.g., alumina) with a soft phase (e.g., glass). An analysis of the sintering kinetics of such materials based on finite-element simulations of the sintering of a pair of rigid spheres coated with a viscous material is presented. Until the contact radius is greater than the thickness of the coating, the sintering kinetics are very similar to those obtained if the rigid core is not present. The sintering rate decreases as the rigid cores approach each other and is limited by flow in the gap between the core particles. If the coating thickness is in excess of 20%, the simulations predict that a packing of such particles sinters to full density at a rate comparable to that of particles without a rigid core.