Sintering force behind the viscous sintering of two particles

The mechanical principles of viscous sintering were analyzed by finite element simulation of a simple model: the coalescence of two identical spheres. The sintering force in the non-equilibrium process of viscous sintering was defined as the difference between the average pressure on the contact area and the surface tension along its circumference. The average strain rate on the contact plane was proportional to the sintering force, so that the sintering force was the thermodynamic driving force for both neck growth and shrinkage. Conversely, a theoretical method was proposed to elicit the sintering force from neck growth curves. The simulation also shows that the tensor-virial equation, which is an alternative method to describe the overall anisotropic deformation of aggregates of particles, is valid for viscous sintering.