The effect of a substrate on the sintering of constrained films

The discrete element method (DEM) is used to simulate the sintering of a powder compact constrained by a substrate. The constrained sintering of micropillars made of 4000–40,000 spherical particles is simulated using appropriate normal contact laws both for particle–particle and particle–substrate contacts. Tangential viscous forces account for the drag of the substrate on the particles. We show that, in accordance with experimental observations, the presence of a substrate has a significant effect on the microstructure of the constrained sintered films. Simulations confirm that anisotropy develops along the thickness of the film. The microstructure is more porous close to the substrate and the pores have their long axis preferentially oriented perpendicular to the substrate. The effects of film thickness and viscous drag at the film–substrate interface have also been investigated.